Periodontal Microsurgery - EndoExperience

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ADMINISTRATIVE BOARD

EDITOR-IN-CHIEF

Harald O. Heymann, DDS, MEd

ASSOCIATE EDITOR

Edward J. Swift Jr, DMD, MS

ASSISTANT EDITOR

André V. Ritter, DDS, MS

EDITORIAL ASS ISTANT

Betty T. Cates

SECTION EDITORS

Edward P. Allen, DDS, PhDStephen C. Bayne, MS, PhDRobert Berger, CDTTerence Donovan, DDS, MSVincent G. Kokich, DDS, MSDJorge Perdigão, DMD, MS, PhDLouis F. Rose, DDS, MDEdwin S. Rosenberg, BDS,

H.Dip.Dent, DMDRichard E. Walton, DDS, MS

EDITORIAL ADVISORY BOARD

Leonard Abrams (USA)Steve Aquilino (USA)Pinhas Adar (USA)Donald Arens (USA)Luiz Narciso Baratieri (Brazil)Urs Belser (Switzerland)Markus Blatz (USA)Joe Camp (USA)Gerard J. Chiche (USA)Noah Chivian (USA)Gordon J. Christensen (USA)Don Cornell (USA)Jim Dunn (USA)Jack Ferracane (USA)Mauro Fradeani (Italy)Mark J. Friedman (USA)David A. Garber (USA)Jaime A. Gil (Spain)Ronald E. Goldstein (USA)Van B. Haywood (USA)Tom Hilton (USA)Abraham Ingber (USA)John Kanca (USA)Masahiro Kuwata (Japan)Paul Lambrechts (Belgium)Karl F. Leinfelder (USA)William Liebenberg (Canada)Pascal Magne (Switzerland)

Ronald I. Maitland (USA)Lloyd Miller (USA)Preston D. Miller (USA)Ivar A. Mjör (Norway/USA)Dan Nathanson (USA)Linda C. Niessen (USA)David H. Pashley (USA)William R. Proffit (USA)Ariel Raigrodski (USA)François Roulet (Germany)Cliff Ruddle (USA)Frederick A. Rueggeberg (USA)Fortunato Santos (Brazil)Cherilyn G. Sheets (USA)Richard Simonsen (USA)Dan Sneed (USA)Frank Spear (USA)Howard F. Strassler (USA)Jörg Strub (Germany)Daniel Sullivan (USA)Dennis P. Tarnow (USA)Jeff Thomas (USA)Martin Trope (USA)Arnold S. Weisgold (USA)John West (USA)Ray Williams (USA)David C. Winkler (Denmark)Robert Winter (USA)

OFFICIAL PUBLICATION OF THE AMERICAN ACADEMY OF ESTHETIC DENTISTRY

JAPAN ACADEMY OF ESTHETIC DENTISTRYINTERNATIONAL FEDERATION OF ESTHETIC DENTISTRY

AMERICAN ACADEMY OF COSMETIC AND ADHESIVE DENTISTRYBELGIAN ACADEMY OF ESTHETIC DENTISTRYDUTCH ACADEMY OF ESTHETIC DENTISTRY

Journal of Esthetic and Restorative Dentistry

Journal ofEsthetic andRestorativeDentistryB

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PERSPECTIVES

S16 Microscopy in DentistryCherilyn G. Sheets, DDS, Jacinthe M. Paquette, DDS

ARTICLES

S17 Definitive Diagnosis of Early Enamel and Dentinal Cracks Based on Microscopic EvaluationDavid J. Clark, DDS, Cherilyn G. Sheets, DDS, Jacinthe M. Paquette, DDS

S117 CommentaryJoel H. Berg, DDS, MS

S118 Periodontal MicrosurgeryDennis A. Shanelec, DDS

S124 CommentaryE. Patrick Allen, DDS, PhD

S125 Use of Magnification in Dental TechnologyRobert R. Winter, DDS, Donald F. Cornell, CDT, Greg J. Vingoren, DDS,

R. Bradford Patrick

S132 CommentaryRobert Berger, CDT, FNBC

S133 Microscopic Photography for the Restorative DentistGary B. Carr, AB, DDS

S142 Introduction to MagnificationDonald E. Arens, DDS, MSD

J O U R N A L O F E S T H E T I C A N D R E S T O R A T I V E D E N T I S T R YSI6

MICROSCOPY IN DENTISTRY

Perspectives

Today we are witnessing the introduction into our profession of a technology thatmay change the practice patterns of current and future generations of dentists. The

use of the clinical microscope in dentistry has already revolutionized the specialty ofendodontics, and it is now being used extensively or experimentally in all the specialtiesand disciplines of clinical dentistry and dental technology. Being able to see the dentalfield magnified and illuminated is addictive. Clinicians become accustomed to theimproved visibility, which allows them to more consistently achieve precision in theirwork—in diagnosis, treatment, and final assessment of the procedures performed.Additionally, the ergonomic advantages to working in a relaxed supported posture thatdoes not strain the body or contribute to stress breakdown include allowing one topractice the profession longer and improving the overall quality of life.

As you read this issue of the Journal, you will meet many of the early pioneers of or“early adaptors” to using the clinical microscope, and learn of the microscope’s impacton their various specialties. Don Arens highlights the history and introduction of themicroscope into endodontics. The uses of the microscope in microsurgical periodonticsare explored by Dennis Shanelec. Gary Carr discusses the importance of image andinformation management of microscopic information, and Don Cornell and Bob Winterand colleagues illustrate the laboratory uses of magnification. David Clark, JacinthePaquette, and Cherilyn Sheets share new diagnostic capabilities with this technology.

We hope that this special issue of the Journal will encourage you in your personal journey into the world of high-level magnification and illumination. If you have not yet experienced dentistry with this technologic aid, we hope that you will soon. It is asimple technology with a powerful impact.

Cherilyn G. Sheets, DDSJacinthe M. Paquette, DDS

Co-editors, Special Issue on Magnification

©2003 BC Decker Inc

V O L U M E 1 5 , S P E C I A L I S S U E , 2 0 0 3 SI7

Macroscopic and symptom-driven diagnoses have been

the accepted modalities for crackedteeth. The inherent limitations ofthe lack of visual confirmationresult in therapies that often cometoo late in the treatment process.One lasting first impression ofvision through a clinical microscopeis the staggering array of cracksthat exist within tooth structures.Traditional visualization (unaided

or ocular assisted) limits the clini-cian’s ability to assess the presenceor severity of the majority of thesecracks (Figure 1).

At extreme magnification levels(×14 and greater), the translucentnature of enamel yields a wealth ofinformation. Subtle color changeswithin the enamel may indicate earlydecay, microleakage, and a lack ofstructural integrity of dentin and

enamel. Being able to see previouslyinvisible clues can lead restorativedentists to more appropriate earlytreatment of compromised teethbefore devastating fractures, pulpalinvolvement, and periodontalbreakdown occur. The value of earlydiagnosis of the structural break-down of teeth will become evenmore significant with our agingpopulation coupled with increasedtooth retention in this population.

*President, Academy of Microscope Enhanced Dentistry†Co-executive director, Newport Coast Oral Facial Institute, Newport Beach, CA; clinical professor,Restorative Dentistry, USC School of Dentistry, Los Angeles, CA, USA ‡Co-executive director, Newport Coast Oral Facial Institute Newport Beach, CA; associate professor,Restorative Dentistry, USC School of Dentistry, Los Angeles, CA, USA

Definitive Diagnosis of Early Enamel and DentinalCracks Based on Microscopic Evaluation

DAVID J . CLARK, DDS*

CHERILYN G. SHEETS, DDS†

JACINTHE M. PAQUETTE, DDS‡

ABSTRACT

The diagnoses of cracked teeth and incomplete coronal fracture have historically been symptombased. The dental operating microscope at ×16 magnification can fundamentally change a clini-cian’s ability to diagnose such conditions.

Clinicians have been observing cracks under extreme magnification for nearly a decade. Patternshave become clear that can lead to appropriate treatment prior to symptoms or devastation totooth structure occur. Conversely, many cracks are not structural and can lead to misdiagnosisand overtreatment. Methodic microscopic examination, an understanding of crack progression,and an appreciation of the types of cracks will guide a doctor to making appropriate decisions.

Teeth can have structural cracks in various stages. To date, diagnosis and treatment are veryoften at end stage of crack development.

CLINICAL SIGNIFICANCE

This article gives new guidelines for recognition, visualization, classification, and treatment ofcracked teeth based on the routine use of ×16 magnification. The significance of enamel cracks asthey relate to dentinal cracks is detailed.

(J Esthet Restor Dent 15:XXX–XXX, 2003)


D E F I N I T I V E D I A G N O S I S O F E A R L Y E N A M E L A N D D E N T I N A L C R A C K S

The purpose of this article is to pre-sent an intuitive system for detect-ing and describing enamel anddentinal cracks based on visualexamination at ×16 magnification.Experienced clinicians using theclinical microscope have reached ageneral consensus that ×16 providesan ideal magnification level for theevaluation of enamel cracks, with arange of ×14 to 18.1 A ×16 magnifi-cation level provides optimal infor-mation about enamel cracks andfalls within the range of magnifica-tion the majority of current micro-scopes feature today.

To highlight the contents of thisarticle, numerous clinical photo-graphs are shared depicting enameland dentinal cracks. Unless other-wise noted, at the time the photo-graphs were taken, all teeth shownwere asymptomatic and had beenpreviously restored with Class Iamalgams.

ditions of the cracked tooth, pro-ducing numerous classification andnomenclature systems in an attemptto assist the clinician in the diagno-sis (Table 1). The primary emphasisin existing literature has been cen-tered on symptom-driven diagnosis.The current nomenclature and clas-sification has been formulated fordramatic end stages in which pul-pal involvement, bone loss, andoften devastating weakening of thedentinal structure have occurred.To date there is little description or classification of enamel cracksbased on a visual diagnosis donewith a clinical microscope.

Current American and Canadianliterature on this topic group cracks

REVIEW OF THE LITERATURE

A significant effort has been madeinternationally to describe the con-

Figure 1. Lower first molar. Unimpressive at lower (×2–6)magnification, this crack gives a wealth of information whenobserved with the microscope. A significant vertical crackwas observed in the dentin after amalgam removal.

TABLE 1. COMMONLY USED NOMENCLATURE IN LITERATURE FOR

INCOMPLETE DENTAL FRACTURES.

Nomenclature Study (yr)

Cuspal fracture odontalgia Gibbs2 (1954)

Fissured fracture Thoma3 (1954)

Incomplete tooth fracture Ritchey et al4 (1957)

Fissural fracture Down5 (1957)

Crack lines Sutton6 (1961)

Greenstick fractures Sutton7 (1962)

Cracked tooth syndrome Cameron8 (1964)

Hairline fracture Wiebusch9 (1972)

Incomplete crown-root fracture Hiatt10 (1973)

Incomplete coronal fracture Talim and Gohil11 (1974)

Split-root syndrome Silvestri12 (1976)

Enamel infraction Andreasen13 (1981)

Hairline tooth fracture Caufield14 (1981)

Crown craze/crack Johnson15 (1981)

Craze lines/tooth structure cracks Abou-Rass16 (1983)

Cracked cusp syndrome Kruger17 (1984)

Tooth infraction Lost et al18 (1989)

C L A R K E T A L


and fractures as incomplete coronalfractures, cracked tooth syndrome,horizontal root fractures, and retro-grade root fractures. Fractures areeither incomplete or complete.2–18

The British approach differs. Theterm incomplete tooth fracture (ITF)is used to describe all cracks. Addi-tionally, vertical cracks in virginanterior teeth are included in thisITF classification system.19 In NorthAmerican journals the authors typi-cally classify vertical cracks in vir-gin anterior teeth as craze lines.

HISTORIC VISUAL EVALUATION

TECHNIQUES

Historically, methylene blue dye,caries indicator, transillumination,and alternative hydration and dehy-dration of tooth structure have aidedin the visualization of cracks. Transil-lumination is probably the mostcommon modality for traditionalcrack diagnosis. There are two draw-backs to using transilluminationwithout magnification. First, transil-lumination dramatizes all cracks tothe point that craze lines appear asstructural cracks. Second, subtlecolor changes are rendered invisible.

Methylene blue dye has been usedextensively by endodontists to high-light radicular cracks and fractures.It is beginning to be promoted as anaid for visualizing coronal cracks.Methylene blue dye is helpfulbecause of its pooling tendency. Itsflocculent nature makes it differentfrom other dies such as caries indi-cator. However, the limitations ofmethylene blue dye should be rec-ognized and are as follows:

• Plaque stains profusely, andrepeated deplaquing may berequired.

• Lightly decalcified enamel anddentin absorb the dye, actuallyobscuring any cracks (Figure 2).

• Prolonged exposure to sodiumhypochlorite can cause massiveabsorption of dye by dentin.Therefore, it is recommendedthat when searching for radicularcracks, one applies the stain assoon as pulp chambers and rootcanal systems are accessed.

• Methylene blue obscures subtlecolor changes deeper in theenamel.

• Methylene blue may lead clini-cians inexperienced with the useof the clinical microscope to mis-takenly believe that benigncracks or simple anatomicgrooves are structural cracks.

• Over-reliance on dyes may hand-icap a clinician’s ability to rou-tinely discover early cracks.

PROTOCOL FOR MICROSCOPIC

EXAMINATION

This article focuses on the assess-ment of cracks in the posterior dentition because anterior and pos-terior teeth have significant differ-ences in crack propagation. Thesedifferences relate to the differentanatomic design of the teeth andthe direction and intensity ofocclusal forces. Anterior cracks will be evaluated in future articles.

A cleaning and desiccation protocolis important prior to crack inspec-tion because plaque and moisturemake microscopic cracks virtuallyimpossible to visualize at any mag-nification. All posterior teeth to beevaluated are polished with a rub-ber cup and coarse pumice slurry.The teeth are then completely desic-cated. If desired, methylene blue isapplied with a disposable applica-tor tip. The tooth is viewed throughthe clinical microscope in the mag-

Figure 2. Upper first molar. Occlusal reduction for the crown is inprogress. An oblique dentinal crack was better visualized before dyeapplication. When this occurs a 10-second etch with phosphoric acidremoves most of the unwanted dye and the dye in the crack remains.Another important clue is demonstrated; the crack itself is often lessobvious than is the color difference of dentin on either side of the crack.



nification ranges of ×14 to 18, withthe maximum lighting intensity set-ting. This view provides an oppor-tunity for photograph taking fordocumentation, patient education,patient records, or research.

Debris retention can also be animportant diagnostic aid. Particlesize of coarse pumice (Henry Scheinlaboratory pumice coarse 100-2796,Melville, NY, USA) can vary from200 to 700 µ (Figure 3). Significantpumice retention indicates thatcrack width is at least 200 µ. Asdeplaquing of the tooth should bepart of the microscopic protocol,debris or pumice retention in signif-icant cracks is a constant.

Posterior teeth with mesio-occlu-sodistal restorations provide someof our greatest challenges to micro-scopic visualization. They requireexquisite deplaquing and, fordeeper restorations, gentle tissue

at ×16 and existing opinions in thecurrent literature. It is importantthat the clinician recognize thatthese are diagnostic “clues” and nota definitive diagnosis. The clinicianmust also bear in mind whileassessing enamel cracks that othervariables, such as the age of thepatient, the location of wear facets,parafunctional activity patterns,and the actual position of the crackas it relates to occlusal loading andexisting restorations, must be con-sidered in the diagnostic process. Asadditional research is added to thiscurrent clinical data, it will providea more systematic approach fordiagnosis and treatment.

Type I: Little or No Risk of Underlying PathologyIt is proposed that type I cracksinclude the following:

A. Craze lines–these are usually linear and vertical and do notwiden or become more pro-nounced as they extend fromgingival to occlusal (Figure 4)

B. Vertical cracks not associatedwith restorations and withoutenvironmental stain penetration

C. Cracks that follow naturalanatomic grooves (Figure 5)

D. Cracks with superficial envi-ronmental stain penetration(Figure 6)

E. Cracks that result from poly-merization shrinkage of com-posites (Figure 7)

Proposed treatment modalities fortype I defects include preventive

retraction with an explorer or briefplacement of an interproximalwedge. The coaxial shadowlesslight from the microscope furtherassists in the inspection of thisimportant area.

Although additional technologiesare being developed that will enable us to measure the structuralintegrity of teeth, these products are not currently available. Visualexamination, therefore, remains our most critical part of diagnosis.

NOMENCLATURE AND

CLASSIFICATION SYSTEM FOR

ENAMEL CRACKS

With the introduction of high-levelmagnification and illuminationthrough the clinical microscope, arefined nomenclature and classifica-tion system for enamel cracks isindicated. The following is a pro-posed template for a classificationsystem of enamel cracks based on acombination of visual observation

Figure 3. Coarse pumice at ×24.

C L A R K E T A L


measures such as no treatment,continued observation, occlusaladjustments, and protectiveocclusal splints.

Type II: Moderate Risk of Underlying PathologyIt is proposed that type II cracksinclude the following:

A. Wedge-shaped enamel ditchingresulting from a loss of enameltooth structure with no priorrestoration, often associatedwith a wear facet and localizedocclusal loading centered overan otherwise benign crack

B. Wedge-shaped enamel ditchingresulting from a loss of enameltooth structure with an adjoin-ing restoration, often associatedwith a wear facet and localizedocclusal loading centered overan otherwise benign crack (Fig-ure 8)

C. Cracks that detour from or donot follow anatomic grooves(Figure 9)

Proposed treatment modalities fortype II defects include preventivemeasures, a review of patient his-tory of thermal and functional sen-sitivity, restorative investigation, ordefinitive restorative treatment ifthe current restoration is deemedcompromised.

Type III: High Risk of Underlying PathologyIt is proposed that type III cracksinclude the following:

A. Diagonal cracks branching offfrom a vertical crack; theseoften are indicative of a late-stage oblique incomplete frac-ture (Figure 10)

B. Horizontal or diagonal cracksthat normally emanate from the

Figure 4. Lingual view of a lower firstmolar. Craze lines (right and left) arepresent along with a diagonal crack(center). In this example subtle brownand gray halos are centered over thediagonal crack in a bull’s-eye pattern.

Figure 5. Occlusal view of a lower sec-ond bicuspid. Many posterior teeth inadults have these types of cracks. Notreatment is indicated.

Figure 6. Distal marginal ridge of anupper first molar. During subsequentcrown preparation (not pictured), nounderlying dentinal cracks wereobserved that corresponded with thisenamel crack.

Figure 7. An undermined mesiolingual cusp was no matchfor polymerization shrinkage of a bonded composite. Severalhorizontal enamel cracks are present but do not extend intothe dentin.



corner of a restoration; theynarrow as they extend gingivallyand are typically nonlinear (seeFigures 4 and 11)

C. Cracks that house debris, withor without previous restorations(indicative of a crack size ofapproximately 200 µ or greater)(see Figure 1)

D. Pairs of cracks that outline anarea (cusp[s] or marginal ridge)of discolored enamel; theseshow a high potential for anunderlying dentinal crack andfuture complete fracture (seeFigures 1 and 12)

E. Cracks with a corresponding“halo” of brown, gray, or whitecentered on the crack (see Fig-ures 4 and 13)

There are several proposed treat-ment modalities for type III defects.The protocol for high-risk enamelcracks calls for removal of the oldrestoration, if present. If decay ormicroleakage is the underlyingpathology, standard treatment is rec-ommended. If a dentinal (structural)

crack is the underlying pathology,protection of the incomplete fracturefrom occlusal forces is indicated.How early and in what manner teethwith microscopic dentinal cracksshould be treated depends upon theclinician’s assessment.

CUMULATIVE DIAGNOSIS

The sources of enamel cracks can bemultifactorial and can develop overlengthy time frames. The presence ofenamel cracks, even dramatic ones,does not necessarily indicate thepresence of an incomplete coronalfracture or cracked tooth syndromebecause enamel cracks do notalways penetrate into dentin. Also,significant enamel cracks often existin the absence of dentinal cracks.Three types of underlying pathologyare often seen accompanying enamelcracks: dentinal cracks, decay, andseverely undermined enamel thatallows microleakage.

Recognition of most enamel cracktypes becomes routine after signifi-cant experience with the micro-

Figure 8. Occlusal view of a lower sec-ond bicuspid. Although dramatic, thistype II-B crack (wedge-shaped enamelditching centered over an otherwisebenign crack) will be monitored.

Figure 10. Upper first molar. The verti-cal crack readily accepts dye. The diag-onal crack (arrows) does not accept thedye. A diagonal crack is an indicator ofthe final stage of cuspal fracture.

Figures 11. A and B, Three cracks are present on a facial view of the lower rightfirst molar. After the amalgam is removed, we observe that a diagonal crack on theleft has severely undermined the distobuccal cusp. A vertical crack (center) wasinsignificant. The tooth was symptomatic.

Figure 9. Lingual view of a lower sec-ond molar. Note the lingual groove tothe left and crack to the right. The crackis nonlinear, nonvertical, and widens asit extends occlusally. Significant verticaland oblique dentinal cracks were viewedafter amalgam removal.

A B

C L A R K E T A L


scope. The exception is that typesII-A and II-B (wedge-shaped enamelditching centered over a benigngroove) can be mistaken for typeIII-C (cracks that houses debris).Type II-A and II-B cracks are com-mon and dramatic in appearance athigh magnification. At first appear-ance they give the impression thatthe tooth is splitting. However, theyare misleading and, in fact, areoften fairly superficial (Figure 14).There are two keys to differentia-tion. An enamel ditch does notretain pumice and debris. It is not atrue crack. Additionally, a ditch isshallow and does not continue api-cally. This is revealed at clinicalexamination at ×16 to 24 (Table 2).

Dentinal cracks should be consid-ered structural cracks. They typi-cally fall into two types: vertical,generally positioned in the middle ofthe pulpal floor; and oblique, gener-ally positioned at line angles of cav-ity preparations (Figure 15).20 Thesevery early fractures are preliminary

and need protection to minimizecrack propagation (Figure 16).

CRACK PROGRESSION

Vertical cracks can initiate via sev-eral pathways. If the tooth is unre-stored, the crack initiates in theenamel and progresses to the denti-nal layer. If a Class II restoration is

present, depending on the designand surfaces involved, the crack canbegin in enamel or dentin. They aremost commonly observed in thecenter of cavity preparations. Thecracks then progress apically (Fig-ure 17). Most vertical cracks extendin a mesiodistal direction, but theycan occasionally extend from a buc-

Figure 12. Distopalatal cusp with sub-tle darkening. This tooth was sympto-matic. The palatal view is featured inFigure 10. A significant dentinal crackwas observed after amalgam removal.The patient was frustrated because herprevious dentist could not find anythingwrong with the tooth.

Figure 14. Lower right second molar. Enamel ditching is pre-sent centered over a benign crack. It looks dramatic underthe microscope until the old restoration is removed. It is clearthat no dentin is involved. The tooth is structurally sound;however, the distal marginal ridge will continue to deterio-rate. Either the occlusal contact or the finish line will need tobe moved if an intracoronal restoration is to be placed.

Figure 13. Lingual view of the lower left first molar. Asubtle darkening or halo is centered on a crack thatdoes not follow the anatomic groove and houses veryfine debris. The prepared tooth shows a dentinal crack.The occlusal view of this tooth is shown in Figure 15.



cal position lingually. Complete ver-tical fractures have been observedin virgin teeth by many clinicians(Figure 18).20

Oblique cracks typically initiate indentin. A commonly observed start-ing point is at the line angle directlyunder the cusp, and cracks most

often follow the internal line anglesas they progress. Visualization ofcracks in the internal portions oftooth preparations presents uniquechallenges. Crisp line angles canmasquerade as cracks and viceversa. Magnification of ×24 withadditional contrast provided bydyes and alternate hydration/dehy-dration are all indispensable toolsand techniques.

Oblique cracks may have a verticalcomponent if the crack crosses amarginal ridge or a buccal/lingualgroove. In such a situation the termoblique is not completely reflectiveof the crack’s three-dimensionalnature. As the crack nears completefracture, diagonal or horizontalcrack lines begin to appear inenamel. These diagonal and hori-zontal enamel cracks are subtle inthe early stages, and visualizationmay require levels of magnificationhigher than ×16. Additionally, theexternal manifestations of incom-plete fracture are so slight that they

Figure 15. Lower first molar. A tiny crack in the alloy corre-sponds to a significant crack on the distal marginal ridge.Once the alloy is removed, a significant oblique dentinalcrack is visible.

Figure 16. A very early (microscopic) coronal dentinal crackfalls into one of two categories: a vertical (pulpal floor) crack(left) or an oblique (line angle) crack (right).

TABLE 2. QUICK REFERENCE GUIDE FOR MICROSCOPIC CRACKS IN

POSTERIOR TEETH.

General rules • Most teeth in aging adults display enamel cracks.• Enamel cracks, even dramatic ones, do not necessarily indicate that the tooth

is cracked.• Many enamel cracks do not penetrate significantly into dentin.• Many enamel cracks have multiple features; many teeth have multiple cracks.• Three types of underlying pathology produce enamel cracks: dentinal cracks,

decay, and undermined enamel often contributing to microleakage around arestoration.

• Dentinal cracks should be considered structural cracks.• Dentinal cracks fall generally into two types: (1) vertical, generally positioned

in the middle of the pulpal floor—“preradicular,” and (2) oblique, generallypositioned at line angles of cavity preparations—“precuspal.”

• Many teeth exhibit both types of dentinal cracks; hybrid cracks are also com-mon. Rigorous classification is less important than early recognition and treat-ment. All teeth with dentinal cracks should be considered structurally unsound.

Associated microscopic findings• Microscopic cracks in restorative materials can also indicate a lack of coronal

structural integrity (see Figure 16).• Well-defined discoloration of a cusp or cusps can indicate a lack of structural

integrity (see Figure 12). • Unusual or unilateral gapping between an occlusal restoration and tooth

structure can indicate a lack of structural integrity.

C L A R K E T A L


generally do not accept methyleneblue dye (see Figure 9).

A clinician has unimpeded visionwhen a restoration is removed. Thisis the opportunity to absolutely ver-ify the presence or absence of struc-tural dentinal cracks.

PREVENTIVE CAVITY DESIGN AND

PROACTIVE TREATMENT

Traditional cavity designs and ma-terials for incipient lesions are beingquestioned as to whether they predis-pose posterior teeth to fracture.21–23

Minimally invasive preparationscombined with the flexibility ofcomposite bonded restorations pro-vide alternative treatment options to the traditional designs and ma-terials.24 The goal of preventivepreparations is to minimally involvedentin and to avoid connecting indi-vidual occlusal preparations to eachother or to interproximal cavitypreparations (Figures 19–21). A bet-ter understanding of crack propaga-tion could allow more preventivedesign preparation modifications.

Once the diagnosis of structuraldentinal cracks has been made,appropriate preparation designselection is critical. Some authorshave recommended equilibrationand bonded intracoronal restora-tions to stop crack progression.25,26

However, future research may indi-cate that this is insufficient to stopstructural breakdown and that

more protective extracoronal cover-age is indicated.

Vertical cracks often extend into theperiodontium. When this occurs thechoice must be made as to the loca-tion of the gingival margin as itrelates to the biologic width. Thismay leave vertical cracks that extendapical to the gingival margin. Long-term outcomes of this choice willFigure 17. Late-stage progression of coronal cracks. Endodontic, peri-

odontal, and restorative problems are now brought into play. Regularmicroscopic examinations can significantly reduce the number of teeththat reach traditional symptom-driven diagnosis and treatment.

Figure 18. Unrestored upper left firstmolar with a complete vertical toothfracture. The tooth was subsequentlyextracted. Note that the fracture didnot follow the anatomic groove distally.

Figure 19. An extracted lower thirdmolar has a traditional interproximalcavity preparation in the left side of thetooth. On the right side a conservativeinterproximal cavity preparation is fin-ished. A fissurotomy (red arrow) is inprogress. Each enamel defect (blackarrows) should be accessed individually.The traditional cavity preparation temptsus to “connect the dots.” An enlightenedunderstanding of crack progression willdirect more preventive designs.

Figure 20. An interproximal view of atraditional class II preparation revealsthe inherent weakening that is caused.



need study. Idiopathic periodontalbreakdown is a concern (Figure 22).

CONCLUSIONS

For some clinicians the microscope isto cracks as radiographs are to decay.The nature of very early incompletefractures requires the use of high-level magnification for discovery. Theclinical microscope at magnificationlevels of ×14 and above allows detec-tion of significant cracks long beforeincomplete coronal fractures andcracked teeth become symptomatic.Increasing numbers of clinicians arebeginning to visualize these condi-tions through the clinical micro-scope. The preponderance andmagnitude of enamel and dentinalcracks is just now beginning to berevealed. The microscope providesclinicians, especially restorativedentists and periodontists, theopportunity to circumvent potentialdevastation to posterior teeth.

Prevention of dental disease in thepast has meant brushing, flossing,

fluoride, and sealants. Today pre-vention of oral disease has a muchbroader definition and shouldinclude early methodic detection ofenamel and dentinal cracks. Use ofthe clinical microscope makes pos-sible the treatment of asymptomaticbut structurally unsound posteriorteeth. Although this may require afundamental change in the thoughtprocess for some clinicians, waitingfor symptoms in teeth with high-risk enamel cracks may eventuallybe compared with waiting untilsymptoms occur to treat decay.

DISCLOSURE AND

ACKNOWLEDGEMENTS

The authors would like to thankJihyon Kim and Paul Piontkowskifor their contributions.

REFERENCES

1. Piontowski P, Clark DJ. Enamel and denti-nal cracks observed under the operatingmicroscope. Presented at the Academy ofMicroscope Enhanced Dentistry inauguralmeeting, 2002.

2. Gibbs JW. Cuspal fracture odontalgia.Dent Dig 1954; 60:158–160.

3. Thoma KH. Oral pathology. 4th Ed.St. Louis, MO: Mosby, 1954.

4. Ritchey B, Mendenhall R, Orban B. Pulpi-tis resulting from incomplete tooth frac-ture. Oral Surg 1957; 10:665–670.

5. Down CH. The treatment of permanentincisor teeth of children following trau-matic injury. Aust Dent J 1957; 2:9.

6. Sutton PRN. Transverse crack lines in per-manent incisors of Polynesians. Aust DentJ 1961; 6:144–150.

7. Sutton PRN. Greenstick fracture of thetooth crown. Br Dent J 1962; 112:362–363.

8. Cameron CE. Cracked-tooth syndrome. J Am Dent Assoc 1964; 68:405–411.

9. Wiebusch FB. Hairline fracture of a cusp.Report of case. J Can Dent Assoc 1972;5:192–194.

10. Hiatt WH. Incomplete crown-root fracturein pulpal-periodontal disease. J Periodon-tol 1973; 44:369–379.

11. Talim ST, Gohil KS. Management of coro-nal fractures of permanent posterior teeth.J Prosthet Dent 1974; 31:172–178.

12. Silvestri AR. The undiagnosed split-rootsyndrome. J Am Dent Assoc 1976; 92:930.

13. Andreasen JO. Traumatic injuries of theteeth. 2nd Ed. Copenhagen: Munksgaard,1981.

14. Caufield JB. Hairline tooth fracture: a clin-ical case report. J Am Dent Assoc 1981;102:501–502.

15. Johnson R. Descriptive classification oftraumatic injuries to the teeth and sup-porting structures. J Am Dent Assoc 1981;102:195–197.

16. Abou-Rass M. Crack lines: the precursorsof tooth fractures—their diagnosis andtreatment. Quintessence Int 1983;4:437–447.

17. Kruger BF. Cracked cusp syndrome. AustDent J 1984; 29:55.

18. Lost C, Bengel W, Hehner B. Tooth infrac-tion. Incomplete tooth fracture—a reviewof various aspects of the disease with casereports. Schweiz Monatsschr Zahnmed1989; 99:1033–1040.

19. Ellis SG. Incomplete tooth fracture—pro-posal for a new definition. Br Dent J 2001;28:190(8):424–428.

20. West JD. The cracked tooth syndrome.Dent Today 2002; 21:88–97.

21. Khairy MA. Fracture resistance in conserv-ative Class II cavity preparation: box vstunnel. Egypt Dent J 1994; 40:751–756.

Figure 21. Little dentin is removedwith a conservative preparation. Notethe preservation of a bridge of dentinand enamel. This is the area wheremany oblique (line angle) cracks origi-nate when the occlusal and interproxi-mal cavity preparations are joined.Tunnel preparations are taught as beingconservative, but they may weaken thetooth because they involve the dentin.

Figure 22. This patient had an uppersecond molar crowned 15 years previ-ously. A stoma presented on the distalside at a recall examination. An electricpulp test indicated that the tooth wasvital and that no mobility was present.Surgical exploration of the lesion withan operating microscope revealed ahopeless furcal bone loss. The osseouslesion was not consistent with typicalperiodontal breakdown. An idiopathicperiodontal lesion associated with adeep vertical crack was the diagnosis.

C L A R K E T A L


22. Toparli M, Gokay N, Aksoy T. An investi-gation of the stress values on a toothrestored by amalgam. J Oral Rehabil1999; 26:259–263.

23. Caron GA, Murchison DF, Cohen RB,Broome JC. Resistance to fracture of teethwith various preparations for amalgam. J Dent 1996; 24:407–410.

24. Simonsen RJ. The preventive resin restora-tion: a minimally invasive, nonmetallicrestoration. Compendium 1987;8:428–432.

25. Trushkowsky R. Restoration of a crackedtooth with a bonded amalgam. Quintes-sence Int 1991; 22:397–400.

26. Agar JR, Weller RN. Occlusal adjustmentfor initial treatment and prevention of thecracked tooth syndrome. J Prosthet Dent1988; 60:145–147.

Reprint requests: David J. Clark, DDS, 3402South 38th Street, Tacoma, WA, USA98409; e-mail: [email protected]©2003 BC Decker Inc

COMMENTARY

DEFINITIVE DIAGNOSIS OF EARLY ENAMEL AND DENTINAL CRACKS BASED ON MICROSCOPICEVALUATION

Joel H. Berg, DDS, MS*

The use of magnification as a means for enhanced visual assessment and diagnosis of conditions within the dentitionand supporting tissues has become progressively more prevalent over the past 10 to 15 years. As evidence of the likeli-hood that this trend will be sustained, many dental schools now strongly recommend or even require the use of magni-fying loupes by the entering students. Once the bar is raised to allow a new level of diagnostic sensitivity, it is unlikelythat a regression toward a lesser capability will occur.

This article does an outstanding job of focusing on the use of the surgical optical microscope within the specific exam-ple of identification of enamel cracks. The review presented herein provides exceptionally important information for therestorative dentist from several different perspectives. The authors provide excellent pictorial examples of cracks thatare “native,” and they give the reader the understanding with which to differentiate native cracks from those crackscaused by other factors, including the placement of intracoronal restorations. The article also clearly identifies theimportance of training oneself on the use of microscopic evaluation so that false-positive identification does not resultin overtreatment. Such training to increase the specificity of one’s examination is essential to proper use of the addi-tional information gained, whether it pertains to assessing enamel cracks or evaluating the radicular pulp orifices duringroot canal therapy.

The clarity and quality of the photographic images presented demonstrate to the reader the facility and importance ofusing the microscope for diagnosis and patient education. As a means to structure one’s assessment of enamel surfacesfor cracking, the authors have provide a structured approach for screening cracks found during microscopic examina-tion and have given the clinician the ability to immediately implement a valuable diagnostic tool upon installation of amicroscope into the practice.

Many clinicians who use microscopes in their practice as opposed to or in addition to loupes, use the microscope as anadjunctive device for enhanced sensitivity in viewing certain aspects of their treatment. Examples commonly cited aremarginal preparations within crown and bridge preparations, marginal integrity assessments of cast restorations, andfinishing of resin composite restorations. This article provides clear examples of how the microscope can have greatvalue for patient care, even if used only some of the time or within certain scenarios.

As the authors emphatically point out, it is important to be as precise as possible since the microscope providesincreased sensitivity. Having said this, one can recognize the important role future randomized controlled clinical trialswill have in determining the appropriate treatment for enamel cracks of various sorts, now that they are so much morevisible under microscopic examination. In the meantime, this article gives clinicians a means by which to hone theirmicroscopic skills and to understand more about what they are seeing. Patients can immediately benefit from the use ofthe tools described in this important article.

*Professor and chair, Department of Pediatric Dentistry, University of Washington School of Dentistry, Seattle, Washington, USA


Microsurgery refers to a surgi-cal procedure performed

under a microscope. It is a practicethat embraces three distinct values.First is enhancement of motor skillsto improve surgical ability. This isevident in the smooth hand move-ments accomplished with increasedprecision and reduced tremor. Sec-ond is the decreased tissue traumaat the surgical site, which is appar-ent in the use of small instrumentsand a reduced surgical field. Thirdis the application of microsurgicalprinciples to achieve passive andprimary wound closure. The aim isthe elimination of gaps and deadspaces at the wound edge to cir-cumvent new tissue formationneeded to fill surgical voids. Apainful and inflammatory phase ofwound healing can then be avoided.

The history of microsurgery datesfrom 1922 when Nylen first per-formed eye surgery under a microscope.1,2 By the 1960s micro-surgery was standard in many spe-cialties such as neurology andophthalmology.3,4 A factor in itsacceptance was lessened morbidityassociated with smaller wounds.Microsurgery has been practiced inendodontics since 1986.5 It wasintroduced to the specialty of periodontics in 1992.6

MAGNIFICATION IN DENTISTRY

Loupes have long been used in dentistry, but it is only in the pastdecade that microscopes have beenapplied to clinical dentistry. It isnow recognized that magnificationhas more to offer than correctivevision. Ergonomic benefits and

improved clinical skills are welldocumented.7–9 Why is the microscope not used routinely indentistry? Those who use no mag-nification believe that normalvision is adequate to deal with clinical work. This is born of theingrained certainty that the eye sees the world as it is. It is a per-ceptual bias deeply imprinted sincechildhood. Any challenge to visualreality is a fundamental challengeto the world as it is experiencedand is not readily believable. Clini-cians understand magnification,having been exposed to binocularsand cameras. However, the notionthat improved hand skills derivefrom magnification has not yetbeen appreciated.

*Director, Microsurgery Training Institute, Santa Barbara, CA, USA

Periodontal Microsurgery

DENNIS A. SHANELEC, DDS*

ABSTRACT

The purpose of this article is to introduce the history of microsurgery in the surgical disciplines.It reviews the benefits and potential applications of magnification and microsurgery in the spe-cialty of periodontics. Esthetic procedures encompassing periodontal plastic microsurgery aredescribed with an emphasis on clinical cases to demonstrate their application.


The use of magnification, in particular the use of surgical operating microscopes, has increased inmany areas of dentistry. This article demonstrates the usefulness of microscope-enhanced peri-odontal surgery and addresses many issues involved in its application to the surgical discipline ofperiodontics.


S H A N E L E C


ADVANTAGES OF THE

MICROSCOPE IN PERIODONTICS

The surgical microscope allowshigh-level motor skills and accuracyin clinical care. This has been mea-sured in many surgical disciplinesbut cannot be fully appreciated untila surgeon tries his or her handunder the microscope. At ×40 mag-nification, vascular microsurgeonsroutinely anastomose vessels with adiameter of < 1 mm.10,11 At ×120magnification, biologists performsubcellular operations on mitochon-dria and chromosomes. Periodontalmicrosurgery is commonly per-formed at ×10 to 20 magnification.With normal vision the highest pos-sible visual resolution is 0.2 mm.12

At this level of visual acuity, thegreatest accuracy possible for thehuman hand movement is 1 mm.13

Physiologic tremor can furtherreduce the accuracy of movementto 2 mm.14 Under magnification of×20, the accuracy of hand movementapproaches 10 µ and visual resolu-tion approaches 1 µ (Figure 1).15

Proprioceptive guidance is of littlevalue under the microscope.16

Instead, visual guidance is used toaccomplish mid-course correctionof the hand to accomplish the finestmovement with skill and dexter-ity.17,18 This means incisions areaccurately mapped, flaps are ele-vated with minimal damage, andthe wound is closed precisely andwithout tension. For the patient thismeans that postoperative morbiditycan potentially be substantiallyreduced (Figures 2–8).

Figure 1. Microsurgical implant expo-sure with 557 bur.

Figure 2. Case 1. Miller Class I maxil-lary cuspid recession.

Figure 3. Case 1. Intrasulcular microin-cision using ophthalmic scalpel.

Figure 4. Case 1. Connective tissue graftpositioned with the first stay suture.

Figure 5. Case 1. Connective tissue graftpositioned with the second stay suture.

Figure 6. Case 1. Both stay sutures tied.

Figure 7. Case 1. Auxiliary microsuturesto prevent micromovement of the graft.

Figure 8. Case 1. Postoperative healingat 2 weeks.


P E R I O D O N T A L M I C R O S U R G E R Y

MICROSURGERY IN PERIODONTICS

The reason microsurgery has gainedacceptance among some periodon-tists is not reduced morbidity.Rather, the end-point appearance ofmicrosurgery is simply superior tothat of conventional surgery. Thedifference is shown in cleaner inci-sions, closer wound apposition,reduced hemorrhage, and reducedtrauma at the surgical site. The dif-ference is self-evident and can bestartling when compared with con-ventional surgery (Figures 9–11). Asmuch as judgment and knowledgeplay a role in surgery, in the end it isa craft. Surgeons appreciate crafts-

manship, especially when it rises toartistic levels greater than those pos-sible with conventional surgery.With a little training, an averageperiodontist can consistently pro-duce more finely crafted work thancan the most gifted conventionalsurgeon. The clinician’s personalgratification in performing moreideal work may be an importantfactor in the acceptance of micro-surgery in periodontics (Figure 12).

Periodontal surgery viewed underthe microscope reveals the coarse-ness of most surgical manipula-tion.19,20 What appears as gentle

handling of tissues is discovered tobe a gross crushing and tearing (Fig-ure 13). The microscope is a toolthat permits less traumatic and lessinvasive surgery. Using of 7-0 to 9-0microsutures allows more precisewound closure (Figures 14–16).This encourages repair through pri-mary healing, which is rapid andrequires less formation of granula-tion or scar tissue. Wound healingstudies show anastomosis of micro-surgical wounds within 48hours.6,21,22 Secondary wound heal-ing is slower because new tissueformation is required to fill voids atthe edge of the partially closed

Figure 9. Case 2. Miller Class I maxil-lary cuspid recession.

Figure 10. Case 2. Microsuturing.

Figure 12. Example of the geometry ofmicrosuturing.

Figure 13. Example of conventionalsurgery suturing later viewed under amicroscope.

Figure 11. Case 2. Postoperative heal-ing at 2 weeks.

S H A N E L E C


wound. Because surgical trauma isminimized during microsurgery, lesscell damage and necrosis occurs.This means less inflammation andreduced pain (Figures 17–19).

Periodontal microsurgery does notcompete with conventional peri-odontal surgery. It is an evolutionof surgical techniques to permitreduced trauma. Its methodologyimproves existing surgical practiceand introduces the possibility forbetter patient care to periodontics.

Periodontal Plastic SurgeryPlastic surgery is a clinical disci-pline in which surgical techniquesare employed to reconstruct orrepair bodily structures. These maybe missing, defective, or damagedthrough injury or disease. Plasticsurgery relies on mobilization ofsoft tissue flaps for advancement orretraction in combination with theaddition or removal of tissuebeneath the flap. Such techniquesare capable of molding tissues torestore a lost part or improve func-

tion and esthetic appearance. Theapplication of plastic surgical prin-ciples to periodontal tissues com-prises the field of periodontalplastic surgery. Periodontal plasticsurgery, with its emphasis on esthet-ics, is an important aspect of peri-odontal practice.23,24

Types of Periodontal Plastic Micro-surgery. There are two basic perio-dontal procedures in whichperiodontal plastic microsurgerymay be applied: those relative to

Figure 14. Case 3. Preoperative MillerClass I maxillary cuspid recession.

Figure 15. Case 3. Microsurgical closure. Figure 16. Case 3. Postoperative heal-ing at 2 weeks.

Figure 17. Case 4. Miller Class Imandibular cuspid recession.

Figure 18. Case 4. Microsurgery withintrasulcular incisions.

Figure 19. Case 4. Postoperative viewat 1 week with microsutures in place.



the level of the dentogingival junc-tion and those relative to the eden-tulous ridge. With regard to thedentogingival junction, micro-surgery can be employed to addgingival tissue where it is absent orto remove gingival tissue where it is excessive. Periodontal plasticmicrosurgery of the edentulousridge most often involves the addi-tion of bone and or soft tissue.

Correcting Gingival Recession.Periodontal plastic microsurgicalreconstruction of gingival tissueover denuded roots can be routineand predictable using subepithelialconnective tissue grafting. The colormatch and esthetic appearance ofsuch grafts is greatly improved overthe original free gingival graft tech-nique. When carefully closed, palataldonor sites can heal by primaryintention without a painful period ofopen granulation. This greatlyreduces postoperative morbidity.

Establishing an Esthetic Smile Line.An abnormal smile line may resultfrom a number of causes, includinggingival recession, abnormal erup-tive patterns, incisal wear, andexcessive tissue growth of variousetiologies. The creation of an idealesthetic smile with harmonious gin-gival contours involves many fac-tors. Foremost among these aresymmetry, lip position, and relativegingival levels of adjacent teeth.Complex periodontal plastic micro-surgery involving removal of tissueon some teeth and replacement onothers may be required.

Restoring the Edentulous Ridge.Ridge augmentation can involve avariety of techniques, includingguided bone regeneration, block andparticulate grafts, soft tissue grafts,and a combination of these. In addi-tion to establishing adequate verticalheight, sufficient soft tissue thick-ness must be created to provide an

emergence profile for pontics or adental implant prosthesis. Papillareconstruction may be viewed con-ceptually as a microsurgical variationof ridge augmentation periodontalplastic microsurgery between twoadjacent teeth (Figures 20–22).25,26

CONCLUSIONS

Periodontal microsurgery is in itsinfancy but will play a role in thefuture.27,28 It is a skill that requirespractice to achieve proficiency. Thesmall scale of microsurgery presentsspecial challenges in dexterity andperception. Its execution is tech-nique sensitive and more demandingthan are conventional periodontalprocedures. As the benefits of themicroscope are realized, it will beapplied more universally.

There are many indications in whichperiodontal microsurgery can bebeneficial. It appears to be a naturalevolution for the specialty of peri-

Figure 20. Case 5. Papilla loss owingto periodontal surgical misadventure.

Figure 21. Case 5. Papilla reconstruc-tion via a microsurgical procedure.

Figure 22. Case 5. Papilla reconstruc-tion at 4 weeks postoperatively.

S H A N E L E C


odontics. Microsurgery offers newpossibilities to improve periodontalcare in a variety of ways. Its benefitsinclude improved cosmetics, rapidhealing, minimal discomfort, andenhanced patient acceptance.

DISCLOSURE

REFERENCES

1. Daniel RK. Microsurgery: through thelooking glass. N Engl J Med 1979;300:1251–1258.

2. Barraquer JI. The history of the micro-surgery in ocular surgery. J Microsurg1980; 1292.

3. Serafin D. Microsurgery: past, present,and future. Plast Reconstr Surg 1980;66:781–785.

4. Leknius C, Geissberger M. The effect ofmagnification on the performance of fixedprosthodontic procedures. J Calif DentAssoc 1995; 23:66–70.

5. Carr GB. Microscopes in endodontics. J Calif Dent Assoc 1992; 20:55–61.

6. Shanelec DA, Tibbetts LS. Periodontalmicrosurgery, continuing educationcourse, 78th American Academy of Periodontology annual meeting, Nov. 19,1992, Orlando, FL.

7. Rucker LM. Surgical magnification: pos-ture maker or posture breaker? In: Mur-phy DD, ed. Ergonomics and the dentalcare worker. Washington, DC: AmericanPublic Health Association, 1998:192–206.

8. Carr GB. Microscopes in endodontics. J Calif Dent Assoc 1992; 20:55–61.

9. Mounce RE. Surgical operating micro-scope in endodontics; the paradigm shift.Gen Dent 1995; 43:346–349.

10. Jacobsen JA, Suarez EI. Microsurgery inanastomosis of small vessels. Surg Forum1960; 11:243–245.

11. Banowsky LH. A review of optical magni-fication in urological surgery. In: Silber SJ,ed. Microsurgery. Baltimore: Williams andWilkins, 1979:443–462.

12. Carr GB. Magnification and illuminationin endodontics. In: Hardin JF, ed. Clark’sclinical dentistry. Vol. 4. New York:Mosby, 1998:1–14.

13. Glencross DJ. Control of skilled move-ments. Psychol Bull 1977; 84:14–29.

14. Stephans JA, Tylor A. The effects of visualfeedback on physiological muscle tremor.Clin Neurophysiol 1974; 36:456–464.

15. Harwell RC, Ferguson RL. Physiologicaltremor and microsurgery. Microsurgery1983; 4:187–192.

16. Gibbs CB. The continuous regulation ofskilled response by kinaesthetic feedback.Br J Psychol 1954; 45:24–39.

17. Simon RJ, Dare CE.

18. Shanelec D, Tibbetts L. Periodontal micro-surgery. Periodontal Insights 1994; May.

19. Shanelec D, Tibbetts L. An overview ofperiodontal microsurgery. Curr Sci 1994;2:187–193.

20. Shanelec D, Tibbetts L. Recent advances insurgical technology. Clinical periodontol-ogy. 8th ed. Philadelphia: W.B. Saunders,1996.

21. Langer B, Calagna L. The sub-epithelialconnective tissue graft. Int J PeriodonticsRestorative Dent 1982; 2:22–27.

22. Holbrook T, Ochsenbein C. Coverage ofthe denuded root with one-stage gingivalgraft. Int J Periodontics Restorative Dent1983; 3:9–27.

23. Shanelec D, Tibbetts L. Periodontal micro-surgery. Curr Opin Periodontol 1996;3:118–125.

24. Klopper P, et al, eds. Microsurgery andwound healing. Amsterdam: Exerpta Med-ica, 1979.

25. Van Hattum A, et al. Epithelial migrationin wound healing, Virchows Arch Biol1979; 30:221–230.

26. Shanelec D. Current trends in soft tissuegrafting. J Calif Dent Assoc 1991;19:57–60.

27. Shanelec D. Optical principles of dentalloupes. J Calif Dent Assoc 1992;20:25–32.

28. Shanelec D, Tibbetts L. Current status ofperiodontal microsurgery. Periodontol2000 1996; 2:88–92.

Reprint requests: Dennis A. Shanelec, DDS,Director, Microsurgery Training Institute,1515 State Street, Suite 1, Santa Barbara,CA, USA 93101; e-mail [email protected]©2003 BC Decker Inc

COMMENTARY

PERIODONTAL MICROSURGERY

E. Patrick Allen, DDS, PhD*

In this article the author presents his impression of the significance of performing periodontal surgery under a micro-scope. The benefits of microsurgery in general use are described, and the advantages of less trauma, less invasivesurgery, and rapid wound healing are suggested as benefits in periodontal surgery. Finally, applications in periodontalplastic surgery are shown in illustrations.

There is no doubt that a more precise surgical technique can be accomplished under the microscope than with thenaked eye. However, there are no controlled clinical studies that have demonstrated either an immediate surgical benefitor an early or long-term difference when compared with surgery performed without a microscope. This lack of evidencemay account for the fact that the use of the microscope has not found the same acceptance in periodontics that it has inother fields such as endodontics.

The author indicates that use of the microscope in periodontics is rather limited at this time but suggests that it willbecome more universally applied as its benefits are realized. Although this is probably true, the message of the impor-tance of more precise surgical techniques has been well received. Improvements in surgical instruments, surgical design,and sutures have led to more precise surgery even without the use of a microscope (Figures 1–4). Although the immediatesurgical appearance may not be quite as good as in the author’s cases that involved the microscope, it is far better thanthat shown in examples of surgery without the microscope. Ironically, these improvements, derived from the influence ofthose who have embraced the microscope, may impede the widespread use of the microscope in periodontal surgery.



*Full-time practice, Dallas, TX; clinical professor, Department of Periodontics, and founder of Center for Advanced Dental Education, BaylorCollege of Dentistry, Dallas, TX, USA

Figure 1. Recession involving the canineteeth and premolars

Figure 2. Graft placed in pouch prepara-tion, and pouch coronally positioned andsutured.

Figure 3. Postoperative view at 3 weeks. Figure 4. Postoperative view at 10 weeks.


Restorative dentistry requires acritical blending of art and a

science to change, repair, or replacemissing natural tooth structure. It isdirectly dependent on the profes-sion of dental technology to achieveits goals through fabrication of thenecessary restoration (Figure 1).Recently there has been significantattention paid to the artistic aspector esthetic outcome of restorativedentistry. Although what consti-tutes an esthetic outcome may be

subjective or in the eye of thebeholder, there are numerous facetsto the scientific side of dental tech-nology that can be evaluated objec-tively. Technical excellence can bemeasured and quantified to exact-ing tolerances. The use of magnifi-cation from ×12 to 20 in dentaltechnology has been the standardfor decades, although it is not welldocumented in the literature.1 Theuse of magnification during techni-cal procedures defines the techni-

cian’s level of commitment to excel-lence because the procedures beingperformed involve meeting toler-ances beyond the resolution of thehuman eye.2

Visualization of fine detail isenhanced by increasing the imagesize of the object and the task beingperformed. The basic premise, Youcan do well what you see, if you cansee well what you do, dates back tothe fifteenth century when magnifi-

*Adjunct assistant clinical professor, University of Washington School of Dentistry, Seattle, WA, USA†

‡Adjunct assistant clinical professor, University of California—Los Angeles, Center for Dental Esthetics, Los Angeles, CA, USA§

Use of Magnification in Dental Technology

ROBERT R. WINTER, DDS*

DONALD F. CORNELL, CDT†

GREG J . VINGOREN, DDS‡

R. BRADFORD PATRICK§

ABSTRACT

Binocular stereoscopic microscopes have been used in dental technology for decades to improvevisual acuity during the fabrication process. Technicians endeavor to produce a restoration thathas marginal discrepancies of < 50 µ and to polish the surface of the restorative material so thatthere is minimal bacterial accumulation. There are six key areas in which the use of magnifica-tion is critical to fabricating high-quality restorations: inspection of the impression; trimming andmarking of the margin on the die; waxing of the margin; fitting of the initial casting, pressing, ormilled unit; final fitting of the restoration; and polishing of the restoration. This article explainssome of the specific areas in which dental technicians rely on magnification to increase the prob-ability of a long-term biologically acceptable restoration.


Precision in the dental laboratory during fabrication of indirect restorations is crucial to long-term clinical success. An intimate but passive fit to the restoration ensures complete seating at thetime of cementation with excellent marginal integrity and subsequent minimal occlusal adjust-ments. A restorative surface that is smooth and well polished in the gingival third results in onlyminimal bacterial accumulation and a healthy periodontium.



U S E O F M A G N I F I C A T I O N I N D E N T A L T E C H N O L O G Y

cation was first used.3 Certain den-tal procedures were performed withthe aid of magnification in the late1800s, and the first microscope usedin clinical procedures was intro-duced by Apotheker in 1981.4,5 Theuse of magnification in clinical andtechnical dentistry has become thestandard since 1990, when its usebecame more widespread.6–9

Visual acuity is improved with opti-cal magnification and an appropri-ate increase in illumination. Correctlighting is important to maintainstereoscopic (three-dimensional)perception. An appreciation formagnification is realized when ele-ments are seen that have not beenseen before. Low-power magnifica-tion (×2) enlarges what is seen withthe unaided eye and provides aslight enhancement of that not seenpreviously. Higher-power magnifi-cation (×12 to 20) brings to viewwhat was not previously visible.10

The field of view is narrowed, andthe focus of attention is increasedon the task being performed. Thiselevates the degree of precision withwhich work can be accomplished.The more one is able to see, themore one can understand the limi-tations of materials and techniques,making problem solving possible.10

The resolving power of the unaidedhuman eye is 0.2 mm (200 µ).11

This means the eye can determine a0.2 mm separation between twopoints or lines. Marginal discrepan-cies > 0.1 mm (100 µ) can bedetected with a sharp explorer tipthrough tactile sense.12 Marginaldiscrepancies < 0.1 mm (100 µ) aretherefore deemed clinically accept-able. From the perspectives ofresearch, material evaluation, andtechnical achievement, the marginaldiscrepancies should be 0.05 mm(50 µ) or less.13 The film thicknessof cements used today is approxi-

mately 0.025 mm (25 µ). Discrep-ancies in fit in this range are easilydiscernible through a stereoscopicmicroscope. The resolving powerimproves with ×20 magnification toapproximately 0.01 mm (10 µ). Acombination of poor marginal sealand rough surface of the restorativematerial may lead to secondarydecay and/or gingival inflamma-tion.14 It is important to achieve anintimate fit and smooth surface sothat subsequent to cementationthere is minimal chance for bacter-ial accumulation at the margin.

There are numerous materials, tech-niques, and instruments used by thedental technician during restorationfabrication. Evaluation of dentalmaterials and instrumentation isdone by “feel,” ease of use, andaccuracy. Accuracy can be betterevaluated under high-power magni-fication. Understanding the role ofmagnification is a significant step inachieving a precision restoration.

There are six key areas of the fabri-cation of restorations in whichmagnification is essential. They areas follows:

• Inspection of the impression• Trimming and marking of the

margin on the die• Waxing of the margin• Fitting of the initial restoration • Final fitting of the restoration,

including the addition of materialand adjustments

• Final polishing of the marginalthird of the restoration.

Figure 1. The primary goal in restorative dentistry isto create restorations that are biologically acceptable,functionally enduring, and esthetically pleasing. Theprecision fit and smooth surface of the restorationincrease the likelihood of a long-term outcome. Themaxillary left central incisor is a metalloceramiccrown with a ceramic margin.

W I N T E R E T A L


INSPECTION OF THE IMPRESSION

The dentist and technician shouldinspect the impression of the pre-pared tooth for accuracy and detail.The impression of tooth structurethat extends apical to the prepara-tion or just beyond the marginshould be clearly visible to theunaided eye (Figure 2). It shouldthen be inspected for clarity under a minimum of ×12 (Figure 3). Themargin should appear well defined,smooth, and void of any irregulari-ties. The following are commondeficiencies that may be identifiedunder magnification:

• Rough irregular margins• Tears in the impression material

at the margin• Voids or bubbles at the margin or

critical angles on the preparation• Excessively smooth or shiny areas

caused by moisture contamination• Pulls caused by the initial setting

of the syringe impression materialand subsequent pulling or drag-ging by the tray material

TRIMMING AND MARKING

OF THE DIE

The die is made from the impres-sion and subsequently trimmed.The selection of die material isbased on its accuracy, expansion,abrasion resistance, and stabilityover time regarding absorption ofmoisture. The die is trimmed under×20 magnification. It is recom-mended that the die not be ditchedto the margin, which undermines it,but, rather, that the excess materialbe trimmed to the apical extent of

the impression (Figure 4). Thisleaves the natural contour of thetooth beyond the preparation mar-gin and can aid in the final contour-ing of the crown.6 Once the die istrimmed, the preparation margin is

marked under ×20 magnificationwith a sharp red pencil (Figure 5).Only the terminal edge of the mar-gin should be marked. The die isthen sealed to increase surfacestrength and smoothness.

Figure 2. The final impression isinspected with unaided vision for anygross bubbles or voids. The impressionof the prepared tooth should clearlyreveal the margin of the preparation aswell as any impression of tooth struc-ture apical to the margin.

Figure 3. The final impression, specifi-cally, the prepared tooth, is inspectedwith under a magnification of ×12 to20. The impression should be free ofbubbles, irregularities at the margin,tearing of the impression material, andmoisture contamination resulting inshiny areas or areas that are ill defined.

Figure 4. The die is trimmed under ×20 magnification with asmooth cutting carbide bur (H77EF 029, Brasseler USA).The die should be trimmed to the level at which the impres-sion begins. This leaves the tooth structure apical to the mar-gin. This technique maintains the strength of the die materialin the area of the margin. It also allows the technician toevaluate the tooth contour apical to the margin. This can aidthe technician in developing the proper physiologic contourof the restoration.



WAXING OF THE MARGIN

Most indirect restoration fabrica-tion requires the use of dental wax.There are numerous waxes, eachwith a unique purpose and han-dling characteristic. Some are bestsuited for carving anatomy, whereasothers are best for margin adapta-tion. The thermal conductivity,degree of “memory,” carvability,brittleness or softness, and “bur-nishability” a wax possesses affectthe technician’s ability to seal amargin properly. The wax adapta-tion to the die is also dependentupon the film thickness of the dielubricant used.

An excessive amount of lubricantor a very viscous film negativelyimpacts the adaptation of the waxto the die and, thus, the accuracy.Every procedure that deals with thefit of the restoration is best per-

formed under ×20 magnification(Figure 6). The definitive fit ofmany restorations is dependentupon the adaptation of the waxand can not be enhanced once it iscast in metal. The waxing andcarving instruments play an inte-gral role. It is important to useinstruments at their most effectiveangles to ensure an accurate mar-ginal seal and physiologic contourof the restoration.

FITTING OF THE INITIAL CASTING

After casting, ×20 magnification isused to inspect the internal aspectsof the casting (Figure 7). Workingunder the stereoscopic microscope,all imperfections are removed fromthe internal surfaces of the castingbefore it is tried onto the die. Thisprocess prevents abrasion of the dieand a subsequent false seating ofthe restoration on the prepared

tooth. Upon inspection, bubblesare identified. Usually they are toosmall to be seen with the unaidedeye. With the help of magnifica-tion, a one-quarter round bur isused to remove the bubbles. Ifthese imperfections are overlookedand not eliminated, the casting willnot seat completely on the die andsubsequently on the tooth. This can result in open margins, occlusaldiscrepancies, or pressure points on the dentin, which can causetooth sensitivity.

FINAL FITTING OF THE

RESTORATION

Once the bubbles or imperfectionsare removed from the casting, it isfitted to the die. The die is firstcoated using a wet-erase fine-pointmarker (Figure 8). When this mate-rial has dried, the casting is lightlyseated on the die. Small marks are

Figure 5. Using ×20 magnification, the terminal edgeof the die margin is marked with a sharp red pencil.This aids the technician in identifying the margin insubsequent steps of the restoration fabrication. Thedie is then coated with a thin layer of die sealer tosmooth and harden the die’s surface and secure themarginal marking.

Figure 6. Upon completion of the wax-up, the marginis resealed and subsequently carved under ×20 magni-fication. This is essential when the definitive margincan not be changed after the wax-up is complete andthe margin has been cast in metal. If an all-ceramicrestoration is being fabricated, the highest precision isdesirable so that minimal or no corrections to themargin are necessary during the glazing procedure.

W I N T E R E T A L


identified internally on the castingand are selectively adjusted under×20 magnification (Figure 9). Thisprocedure is performed as neededto achieve the most accurate mar-ginal seal. The same procedure isused when fitting porcelain mar-gins, after glazing the restoration,

and for porcelain laminate veneerrestorations (Figures 10–15). Therestoration should be viewed per-pendicularly under magnification toevaluate for marginal discrepancies.It should then be viewed on a 25°tilt to evaluate the extent of possi-ble over- or undercontour.

FINAL POLISHING OF THE

RESTORATION

If a cast restoration is being fabri-cated, the polishing of the metalmargin is accomplished after the fit-ting of the casting to the die. Rub-ber wheels are used in addition tobristle brushes and suede wheels

Figure 8. The die is coated with a wet-erase fine-point marker and allowed to dry. The restoration isthen carefully placed onto the die without pressure.Subsequently it is removed and inspected.

Figure 9. Using ×20 magnification small marks thatindicate initial contact to the die are identified and elim-inated with a one-quarter round bur. This is repeated asnecessary to obtain complete seating of the restorationon the die. Theoretically, if procedures are done cor-rectly, there should not be a gap. However, dependingon the angle of evaluation and the intensity of magnifi-cation, a gap may be visible but should be < 50 µ.

Figure 7. A–E, After casting, the internal aspect of the restoration is evaluated for any flaws or irregularities. With unaidedvision only the gross flaws can be identified. With increasing magnification, the small addition reaction bubbles are identifiedand removed with a one-quarter round carbide bur.

A B C D E



with polishing compounds. At thetime of the try-in and cementationof cast restorations, additional pol-ishing and burnishing of the mar-gins is performed. These techniquesare beyond the scope of this article.

The polishing of the ceramic mater-ial to 1.0 mm of the margin is per-formed as the final step in therestoration fabrication. It is doneafter the final margin correctionand glazing of the restoration.Magnification of ×12 to 20 is used(Figures 16–18). Polishing wheelsare used to achieve a smooth sur-

face and high luster. This decreasesbacterial adhesion compared with arough surface.15

It is not recommended to use anytype of rotary instrument that mayscratch or roughen the ceramic sur-face after it is bonded or cementedon the tooth because of the chal-lenge of repolishing the ceramicsurface, especially if it is subgingi-val. With a precision fit margin anda well-polished gingival aspect tothe restoration, there will be a long-term biologically healthy outcome(Figure 19).

Figure 10. When fabricating an all-ceramic restoration—in particular, thepressed ceramic—frequently the margindoes not require a correction firing toachieve a more precise fit. However,when fabricating a metalloceramicrestoration with a ceramic margin, 100%of the margins require a correction firingto achieve a precise fit. This ×20 originalmagnification shows the marginal dis-crepancy before the correction firing.

Figure 11. Using ×20 magnificationsmall amounts of ceramic are added toclose the gap that is present. Theceramic used is 10% margin powderand 90% dentin powder. This additionof ceramic is added during the glaze firing of the ceramic. If necessary, afurther correction of the fit can beaccomplished after the glaze firing.

Figure 16. When fabricating a porce-lain veneer restoration on a refractorydie, the same techniques are followedfor trimming and marking of the mar-gins. This ×20 original magnificationshows the completed veneer before itsremoval from the die. The ceramic ispolished back to the margin with a pol-ishing wheel. In addition, the ceramic isthinned at the margin, and a final pol-ish is achieved with the gray Dialite(Brasseler USA) wheel.

Figure 13. The same steps are followedfor fitting the final ceramic margin thatare used for fitting the metal casting.The final fit of the ceramic margin isequivalent to the that of the metal mar-gin if both care and magnification areused in the process of fabrication.

Figure 12. After the glaze firing, theinternal aspect of the restoration isinspected at ×20. Small amounts ofceramic material are identified and subsequently removed with a fine dia-mond bur before the restoration isseated on the die.

Figure 14. The surface of the ceramic isrough because of the addition of mater-ial to correct the marginal fit. Under×20 magnification this is polished usingfirst pink and then gray Dialite (Bras-seler USA) polishing wheels.

Figure 15. The final glazed and pol-ished surface is inspected for smooth-ness. The marginal gap is well under the50 µ standard for fit.

W I N T E R E T A L


CONCLUSIONS

Magnification has been used in den-tal technology for decades. It is usedto perform procedures that require ahigh visual acuity and for evaluationpurposes. A binocular stereoscopicmicroscope is used with magnifica-tions between ×12 and 20. Steps aretaken during fabrication of therestoration to achieve a precision fitmargin and a well-polished surfaceto achieve a biologically acceptablelong-term outcome.

DISCLOSURE

The authors have no financial inter-est in any of the companies orproducts mentioned in this article.

REFERENCES

1. Friedman MJ, Landesman HM. Microscope-assisted precision dentistryadvancing excellence in restorative dentistry.J Calif Dent Assoc 1998; 26:900–905.

2. Chou TM, Pamaijer CH. The applicationof microdentistry in fixed prosthodontics.J Prosthet Dent 1985; 54:36–42.

3. Cohen B. On Leevwenhoek’s method ofseeing bacteria. J Bacteriol 1937;34:343–346.

4. Michaelides P. Use of the operating micro-scope in dentistry. J Calif Dent Assoc1996; 24:45–50.

5. Apotheker H. A microscope for use indentistry. J Microsurg 1981; 3:7.

6. Maratignoni M, Schonenberger A. Precision fixed prosthodontics. Chicago:Quintessence, 1990.

7. Carr GB. Microscopes in endodontics. J Calif Dent Assoc 1992; 20:25.

8. Ruddle CJ. Endodontic perforation repair:using the surgical operating microscope.Dent Today 1994; May:49–53.

9. Shanelec D, Tibbetts L. An overview ofperiodontal microsurgery. Curr Sci 1994;2:187–193.

10. Mora AF. Restorative microdentistry: anew standard for the twenty-first century.J Prosthet Dent Rev 1998 1(1).

11. Carr GB. Clinical dentistry. Vol. 4.Mosby, 1998.

12. Christensen G. Marginal fit of gold inlaycastings. J Prosthet Dent 1966; 16:297–305.

13. Ostlund LE. Cavity design and mathemat-ics; their effect on gaps at the margins ofcast restorations. Oper Dent 1985;10:122–137.

14. Felton DA, Kanoy BE, Bayne SC, Whirthman GP. Effect of in vivo crownmargin discrepancies on periodontalhealth. J Prosthet Dent 1991; 65:357–364.

15. Muller HP. The effect of artificial crownmargins at the gingival margin on the periodontal conditions in a group of perio-dontally supervised patients treated withfixed bridges. J Clin Periodontal 1986;13:97–102.

Reprint requests: Robert R. Winter, DDS,2429 West Coast Highway, Suite 210, Newport Beach, CA, USA 92663; e-mail:[email protected]

Figure 17. The refractory die materialis removed, and final fitting to the mas-ter die is accomplished as describedelsewhere.

Figure 18. The marginal integrity of thispressed ceramic restoration (Empress®

2, Ivoclar Vivadent, Amherst, NY, USA)is well within the 50 µ standard. Thecore material is stable throughout theceramic firings and rarely requires acorrection fire to improve the fit.

Figure 19. The patient’s left maxillarycentral incisor is restored with anEmpress® 2 restoration (IvoclarVivadent, Amherst, NY, USA) . Byusing the binocular stereoscopic micro-scope during the laboratory fabricationand following the clinical protocol forchecking the restoration fit, a successfuloutcome is achieved.



COMMENTARY

USE OF MAGNIFICATION IN DENTAL TECHNOLOGY

Robert Berger, CDT, FNBC*

Reasonably priced stereoscopic microscopes, designed specifically for dental technicians, are readily available fromdental dealers. Beyond loupes, which only allow the work piece to be brought closer to the eye making it appearlarger, stereoscopic microscopes magnify the work piece, disclosing greater detail at a normal working distance.Stereoscopic microscopes allow the operator to actually work under the scope while viewing the work piece at agreater magnification.

Magnification allows the technician to perform intricate and delicate procedures, such as removing a discrepancyfrom the internal surface of a crown margin without damaging the margin’s finishing edge. Working under themicroscope, the technician can remove discrepancies from internal crown surfaces that would normally be unnoticedby the naked eye. Precise fitting of the crown to the master die by the laboratory technician saves hours of chair timeand limits aggravation created by poor-fitting prostheses. Being able to see clearly, owing to the aid of greater magni-fication, reduces technician errors and thereby translates into greater accuracy and the achievement of consistentlybetter-fitting prostheses.

Given today’s higher demand by dentists and patients for precision in restorative dentistry, the stereoscopic microscopeshould, without question, be an integral part of every dentist and technician’s armamentarium. This article does anexcellent job of reiterating these salient points.

*


The adoption of the operatingmicroscope for use in restora-

tive dental procedures is a welcomeadvancement to the restorative art.As discussed in the accompanyingarticles, the use of a microscope ina restorative practice providesmany tangible and intangible bene-fits for clinicians and patientsalike.1–5 This article reviews thephotographic uses of the micro-scope for a restorative practice.

The ability to acquire rapid serialphotographs of restorative proce-dures at multiple magnificationswithout interrupting the naturalflow and sequence of the procedure

is one of the tangible benefits ofusing a microscope in a restorativepractice. Once the clinician mastersthe visual and ergonomic skillsneeded to perform most tasks underthe microscope, the photographicskills are easy to acquire.

Restorative procedures require low,medium, and high magnification.One of the many advantages ofusing a microscope instead ofloupes or operating telescopes is theability to change magnificationseasily and quickly without inter-rupting the procedure itself. Aproperly configured microscope forrestorative dentistry should have a

magnification range of ×2.5 to 15.Figure 1 demonstrates the six stan-dard magnifications seen through amicroscope configured for restora-tive dentistry.

For restorative dentists, the lowerrange of magnification is the mostimportant as the need to view anentire arch or quadrant is essentialin restorative dentistry. Micro-scopes configured from ×3.5 to 4.5(the lowest power) are poor choicesfor restorative dentists. At thispower it is difficult to line uppreparation angles along an entirequadrant. At ×2.5 magnification,with wide-field optics, the entire

*Founder and director, Pacific Endodontic Research Foundation, San Diego, CA, USA

Microscopic Photography for the Restorative Dentist

GARY B. CARR, AB, DDS*

ABSTRACT

Obtaining quality 35 mm photographs through an operating microscope challenges even the bestof operators, and few clinicians have actually mastered the technique. This article discusses howto easily obtain quality high-resolution digital photographs at various magnifications using anoperating microscope by adopting a technique that is easy to master and can be accomplished byany clinician who learns the skills. This review summarizes the advantages and disadvantages ofmicroscopic photography, with a particular emphasis on digital photography. There is a discus-sion of the required equipment and necessary technique. The value of using digital photographiclibraries at chair-side is explored.


Since the photographic skill with digital photography is easily mastered, clinicians can now morethoroughly document their cases and enhance their case-presentation skills. Teachers and lectur-ers can also draw upon large photographic relational databases to expand their presentationcapabilities.

(J Esthet Restor Dent 15: XXX–XXX, 2003)

dentition can be visualized andmost restorative procedures can becompleted from start to finish

under the microscope. A correctlyconfigured six-step microscope isshown in Figure 2.

Dental operating microscopesemploy Galilean optics. In Galileanoptics the optical paths are parallel


M I C R O S C O P I C P H O T O G R A P H Y F O R T H E R E S T O R A T I V E D E N T I S T

A B

C D

E F

Figure 1.

C A R R


A B

Figure 2.

Figure 3.

and focused at infinity. This reducesthe need to have the eyes convergeto focus and thereby reduces eye-strain. Galilean optics also allowfor the insertion of a beam splitterinto the optical path so that someof the transmitted image can beredirected to imaging devices with-out affecting the view through theoperator’s binoculars. A beam split-ter attachment is seen in Figure 3.

Beam splitters usually have twoviewing ports for connecting acces-sory viewing attachments such asvideo cameras, 35 mm cameras,digital cameras, or assistant’smicroscopes. Devices that actuallyconnect the viewing device to thebeam splitter are referred to by avariety of names, usually related towhether it is a still camera or avideo camera. For example, thedevice that connects a video camerato the beam splitter is called a cineadapter (after cinema). The devicethat connects a 35 mm camera is

(74 mm) because a magnificationhigher than 100 mm requires con-stant centering of the image duringrecording, which can be disruptiveto the procedure. Phototubes gener-ally have higher focal lengths(107 mm–140 mm) because thatlevel of magnification is usuallydesirable in 35 mm photography.Several attachment devices are

referred to as a phototube adapter.These attachment devices are allsimilar except that they have differ-ent end fittings that correspond tothe particular device to which theyare attached. They also have differ-ent focal lengths depending on howmuch magnification the cliniciandesires. For example, cine adaptersusually have lower focal lengths



shown in Figures 4 and 5. It is alsopossible to combine both video andfilm devices by using a dual cineadapter. This device is actually asecond beam splitter, which reducesthe light again by one half. Its use isnot recommended for dental appli-cations because of this additionallight reduction. A dual cine adapteris seen in Figure 6.

DOCUMENTING THROUGH AN

OPERATING MICROSCOPE

One of the advantages of an operat-ing microscope is that one can doc-ument restorative procedurescontinuously with little interruptionto the normal work flow. Unlikeusing an intraoral camera, whichrequires significant interruption inthe restorative sequence, micro-scopic photography is done con-temporaneously. Contrary to anintraoral video camera, the micro-scopic camera is positioned awayfrom the work area and does notphysically intrude or interfere withthe work as it is done. These advan-tages mean that the operator cantake serial high-resolution photo-graphs with little or no interruptionto the operative procedures. Thiscan be accomplished at many dif-ferent magnifications, thereby sav-ing time and acquiring many morephotographs than one would usingconventional methods.

The highest-quality documentationthrough an operating microscope isunquestionably with 35 mm film.However, 35 mm film photographythrough a microscope is time con-

Figure 4.

Figure 5.

Figure 6.

C A R R


suming, expensive, and requires apracticed technique and some degreeof experience. As one who hastaught 35 mm photography througha microscope to dentists for 10years, my experience has been thatonly a few ever master the tech-nique and even fewer practice thetechnique after they master it.

Digital photography through themicroscope, on the other hand, isrelatively inexpensive, easy to learn,and is mastered quickly. Anyoneusing digital photography needs tohave an understanding of the prin-ciple of resolution. Resolutionrefers to the amount of detail orinformation in a picture. The ele-ments of a digital image are calledpixels and are basically square orround dots containing informationabout the color and light at thatparticular point in the image. Thesmaller the dots and the greatertheir number, the higher the resolu-tion and the more detail the picturecontains. Digital cameras measuretheir resolution by counting the ver-tical and horizontal pixels. Typicalresolutions are 640 × 480 (VGA),800 × 600 (SGA), 1,024 × 768(XGA), 2,048 × 1,684 (SXGA).Newer digital cameras will haveeven higher resolutions. A 35 mmfilm corresponds to about 4,000pixels across the film plane. A digi-tal camera that has a resolution of4,096 × 2,736 will therefore havethe same resolution attributes as35 mm film. Within a short time,digital cameras will surpass film-based cameras in resolution.

Currently the best digital camerafor use with the microscope is theNikon® 950 (Nikon). Althoughthere are later models available withhigher resolutions, the Nikon 950(for reasons not fully understood)takes the best pictures. Its statedresolution is 1,600 × 1,200 pixels,and its ISO (speed) is 100. The pic-tures acquired with the Nikon 950are of sufficient quality for mostpresentation and publishing pur-poses. Figures 7 to 10 are examples

from the Nikon 950 shot with aGlobal® 6-step microscope (GlobalSurgical Corporation, St. Louis,MO, USA). Figure 11 shows theNikon 950 mounted on a Globalmicroscope.

One limitation of microscopic digi-tal photography is in the area ofesthetic photography.

The light from an operating micro-scope is confocal with the viewing

Figure 7. Figure 8.

Figure 9. Figure 10.



angle, thereby making estheticphotography difficult. A confocallight source tends to overexposehighlight areas and does a poor jobof showing the subtleties andnuances required for good estheticphotography. Additionally, micro-scopic digital photography gener-ally requires larger f-stops becauseof the need for greater light levels.Therefore, microscopic picturesoften lack the necessary depth offield required in esthetic photogra-phy. Hand-held digital cameras arebetter for this purpose because thelight can be directed from more ofan angle and the f-stop can beincreased to give a higher depth offield. Comparisons between micro-scopic and hand-held digital cam-eras are shown in Figure 12.

ERGONOMICS AND POSITIONING

Correct positioning of patient, doc-tor, and microscope is essential forgood photographic technique.Because the depth of field using adigital camera on a microscope is

much less than with intraoral hand-held cameras, the plane of the pho-tograph is important. For example,when taking pictures of maxillaryinteriors, you want the plane of thecavosurface of the teeth to be as par-allel as possible to the film plane, asis shown in Figure 13. Mouth retrac-tors, black backdrops, and intraoralphotographic mirrors are all used in

microscopic photography as they arein extraoral photography.

The advantage of microscopic photo-graphy is that one can easily docu-ment in a serial manner the steps ina restorative procedure using multi-ple magnifications. For example, inexplaining to a patient the presenceof a distal marginal fracture, thevarious magnifications are useful.

PHOTOGRAPHIC DIGITAL DATABASES

The use of digital microscopic photography results in large num-bers of photographs being taken ina short period of time. Organizingthis material into a digital databaseis imperative. Being able to presentdigital information at chair-side andhaving large digital databases avail-able at your fingertips immediatelyraise the level of communicationbetween the doctor and patient.


Figure 13.

C A R R


Case presentations become muchmore sophisticated and compelling.For example, if there is a need toexplain a complex treatment to apatient, such as crown lengtheningto maintain biologic width, havinga digital database library at yourcommand is invaluable. You not

only can show the procedure itself,you can also show examples inwhich biologic width was violated,which provides for compelling casepresentations. A digital database,correctly organized, can provideyou with this sort of control overyour case-presentation material.

In evaluating commercial productsavailable for digital databases,develop a good understanding ofwhat is important to you as a clini-cian. With any kind of digital imag-ing, it is important that the imagebe acquired contemporaneously asthe work is actually being done. Toreturn to the case after it has beencompleted to organize this materialis time consuming and inefficient.You should be able to acquire mate-rial and save to the database inmultiple categories simultaneously.For example, when a picture isacquired, a clinician should be ableto place that picture in both thepatient’s record and a subject cate-gory. Other desirable attributes of adigital database are the ability toreorganize the sequence of pictures,display a slide show of selected pic-tures, and annotate selected slides ifdesired. Provisions for altering the

Figure 14.




Figure 17.

Figure 18.

Figure 18.

C A R R


color, shape, and contours of teethare also valuable tools to havewithin a database.

CONCLUSION

Developing photographic skillsusing an operating microscope paysmany dividends for a restorativedentist. By following a few basicrules and with a little practice, anyclinician should be able to masterthese skills in a short period of time.

DISCLOSURE

I am the developer of The DigitalOffice for Endodontists, a softwareprogram designed for endodontists.I am also the inventor of the CarrAdapter, a digital photo adapter foroperating microscopes.

REFERENCES

1. Sheets CG, Paquette JM. Is magnificationfor you? Dent Econ 2001; Jan:102–106.

2. Apotheker H. A microscope for use indentistry. J Microsurg 1981; 3:7.

3. Friedman MJ, Landesman HM. Micro-scope-assisted precision dentistry: a chal-lenge for new knowledge. J Calif DentAssoc 1998; 26:900–905.

4. Friedman MJ, Mora AF, Schmidt R.Microscope assisted precision dentistry.Compendium 1999; 20:723–736.

5. Freidman MJ, Landesman HM. Micro-scope-assisted precision dentistry: advanc-ing excellence in restorative dentistry.Contemp Esthet Restorative Dent 1997;Sept:45–50.

Reprint requests: Gary B. Carr, AB, DDS,6440 Lusk Boulevard, Suite D-211, San Diego, CA, USA 92121; e-mail:[email protected]©2003 BC Decker Inc


Three hundred fifty years agoRobert Hooke, a brilliant

physicist and biologist, looked intoa compound microscope he devel-oped and saw an image he called acell.1 Since that time the micro-scope has helped us learn how tis-sues develop, deteriorate, infect,repair, and regenerate. However, itwas not until the latter half of the

twentieth century that physiciansrecognized the practicality andbenefits of physically treating dam-aged and diseased tissues underhigher magnification. Today, spe-cialists in the fields of ophthalmol-ogy, otolaryngology, neurology,and vascular and cardiac surgeryuse microscopes in their everydayoperating routines. Procedures

that once required damaging exposure of large tissues, muscles,and organs to gain access for treat-ment are now accomplishedthrough relatively small arthro-scopic openings. As a result, heal-ing time has been dramaticallyreduced, and the patient and thedoctor have reaped the benefits ofthis paradigm shift.

*Professor of Endodontics and director of Continuing Education, Indiana University School of Dentistry,Indianapolis, IN; professor of Endodontics, Nova Southeastern College of Dental Medicine, Fort Lauderdale,FL; visiting professor of Endodontics, Loma Linda University School of Dentistry, Loma Linda, CA, USA

Introduction to Magnification

DONALD E. ARENS, DDS, MSD*

ABSTRACT

Dentistry has recently recognized the practicality and benefits of treating damaged and diseasedoral tissues under magnification. Initially, enhanced vision was more-or-less restricted to the useof prescription bifocals, awkward magnifying loops, and heavy cumbersome telephoto glasses;the microscope drew little interest and was quickly viewed as another useless and expensive den-tal gadget. However, owing to the very nature and demands of the therapy, endodontists werequick to accept and adopt this technology, and the manufacturers were quick to adapt and mar-ket their surgical microscopes to the endodontic office. Since acceptance leads to progression, weare currently witnessing manufacturers adapting the microscopic and other magnifying lenses toother areas of dentistry. However, choosing and purchasing a microscope involves a great num-ber of issues, including the adequacy of one’s present vision, the type of practice conducted, thedemands one places on the quality of his or her dentistry, and the amount of time and expenseone wishes to devote to becoming competent in using magnification. In addition, one mustbecome familiar with what the different levels of magnification offer, what different depths andwidths of field meet their normal practice needs, the amount of space required for the equipment,and whether the investment is cost effective. This article details all of the benefits as well as thedifficulties encountered when embarking on a magnification journey.


The art of dentistry is based on precision. The human naked eye is capable of distinguishing finedetail, but it is no match for what can be accomplished when an image is sharpened andenlarged. The microscope and other forms of magnification fill that need.

(J Esthet Restor Dent 15: XXX–XXX, 2003)

A R E N S


Since the oral cavity provides imme-diate and accommodating access tothe teeth, magnification has untilrecently been looked upon as anasset in dentistry only by the ageddentist. Consequently, enhancedvision has been essentially restrictedto the use of prescription bifocals,awkward magnifying loops, andheavy cumbersome telephotoglasses. Although Noah Chivian, anendodontist, made an attempt tointroduce the Storz one power (×8)microscope to endodontists in theearly 1980s, it drew limited interestand was quickly viewed as anotheruseless, awkward, and expensivedental gadget. Gary Carr, anotherendodontist, built a multipowerscope from discarded microscopeparts, and in the late 1980s began tolecture and offer courses on the ben-efits of high-power magnification inendodontic surgery. It was not longbefore endodontists, who provide adental service that challenges theirvision, recognized the value of themicroscope in all facets of root canaltherapy. Manufacturers quicklyadapted their scopes to the demandsof endodontic therapy and began to market their surgical microscopesto the endodontic office. With theAmerican Dental Association Council on Dental Education’srecent inclusion of microscopic com-petency in the endodontic graduate-level curriculum requirements, it isvery possible that we may see themicroscope become the standard of care in endodontics.

Manufacturers are continuing tomake the dental microscope userfriendly; as a result, we are witness-ing the acceptance of microscopes foruse in almost all areas of dentistry.Carr’s oft-quoted statement, “Youcan’t treat what you can’t see,” hasinspired a great number of dentiststo add the microscope or some otherselective form of magnification totheir normal armamentarium.

BENEFITS

Uses in DiagnosisCracked Tooth Syndrome. We havealways relied on a patient’s signsand symptoms to identify toothfracture. Because enamel rods differfrom dentinal tubules in size, struc-ture, hardness, and to some degreedirection, they respond quite differ-ently to injury. An isolated area ofenamel may craze or crack whensubjected to a blow or when apatient bites into something hard.Although the damage may initiallyincite pain, the cushioning effect ofthe underlying dentin tooth struc-ture may be resilient and suffi-ciently forgiving to keep the crownintact. Most of these superficialfractures are relatively undetectablewith normal vision, but whenviewed under high power, hairlinecracks appear as crevasses.

Marginal Leakage. Restorationsrely on mechanical adaptationand/or chemical adhesion for reten-tion. For a number of physical andchemical reasons including fit and

material breakdown, microleakageat the restorative interface may notbe detected during a routine exami-nation. As a result, caries mayadvance uninterrupted under thatrestoration for a lengthy period oftime. This situation is more apt tooccur when the restoration is a fullcrown and the metal of the restora-tion predisposes and compromisesvisual evaluation and radiographicassessment of the underlying toothstructure. Thus, recognition ofdamage, particularly beneathcrowns associated with bridges, isoften delayed until the restorationtotally dislodges or the patient pre-sents with pain and/or gingivalbleeding/swelling. Directing aminor occlusally angled force at thegingival margin of the restorationoften discloses a micromovementthat is not visible to the eye but isevident and easily detected whenviewed under high power.

Soft Tissue Evaluation. Patientsoften present with pain and otherrelated symptoms that indicate thepresence of inflammation/infection,but visual and radiographic evalua-tions do not always clearly identifythe problem. At times an infectedintraosseous lesion trephinates thelabial plate but defies detection bynormal diagnostic procedures.Under high levels of magnification,an inconspicuous sinus tract may be located, and by inserting a gutta-percha cone into the opening, apath to the primary source of infec-


I N T R O D U C T I O N T O M A G N I F I C A T I O N

tion quickly becomes radiographi-cally identifiable.

Gingival Swelling. Foreign objects,such as popcorn kernels, celeryhusks, fruit pits, tooth chips, meat,fish bones, and even fingernail clip-pings, are often wedged and com-pressed between teeth and/orbeneath pontics. The resultingswelling and persistent bleeding of the associated tissues makes thelocation, identification, and removalof the impediments difficult, chal-lenging, and painful. When manag-ing these situations, the naked eyeand the illumination provided by anormal overhead operating lampare often inadequate, compromisethe treatment, escalate the degree of procedural difficulty, and createunnecessary stress for both thepatient and the doctor. Theseobstructions when viewed underthe microscope are identified,grasped, and removed with ease.

Uses in Restorative DentistryPulp Involvement. According toReeves and Stanley, noted oralpathologists specializing in pulpbiology, bacterial invasion of thepulp takes place when the remainingdepth of the dentin is within 0.2 mmof the pulp tissue.2 When dentin,particularly at this level, is stainedfrom caries and/or prior restora-tions, a minute pulp exposure maygo undetected and place the toothand any future restoration in peril.Under high levels of magnification,

the floor of the cavity may be judi-ciously explored and appropriateinterceptive pulpal treatment (eg,pulp cap, pulpotomy, pulpectomy)may be immediately instituted.

Coronal Preparation. Restorativedentistry, particularly when esthet-ics is crucial to success, demandsmarginal accuracy. Even minute dis-crepancies in chamfer finish canmean the loss of gingival integrityand an uncomplimentary exposureof the crown-root interface. Preci-sion is essential to prevent adversetissue responses and to achievepatient satisfaction.

Impression Quality. Indirect restora-tive procedures rely on capturing animpeccable image of the entirecrown preparation as well as theuntouched coronal root junction.Any deviation in this moulage repre-sentation is transferred to the dye,cause a restorative misfit and, ifseated, marginal leakage. Examiningthe impression surface for imperfec-tions, distortions, and marginalinadequacies under high magnifica-tion at the time the impression istaken eliminates laboratory guess-work and avoids the disappoint-ment and frustration of redoing therestoration at a later appointment.A simple rejection of a flawedimpression is the professional andfinancially sound decision.

Evaluating the Restoration Under-surface. It is not unusual for the

undersurface of a metal casting orceramic baked restoration to havesurface irregularities. These smallimperfections, naked to the eye butvisible under high magnification,can interfere with the seating of therestoration, alter occlusion, and, ifseated, invite marginal leakage.Worse yet, the imperfect crown-tooth interface can be likened to awedge when forced to place, and assuch will fracture the preparedtooth at the point of contact.

Restoration Delivery and Polish.The final seating of a precisioncrown normally requires little adhe-sive and only a light intraoral pol-ish. However, the slightest amountof residual cement left on the root-crown interface margin stimulatesan adverse response from theapproximating tissue. The subse-quent and painful loss of gingivalintegrity leads to severe inflamma-tion and recession. The restorationmargins are ultimately exposed, andall esthetic quality is lost. Examin-ing the surfaces with a high level ofmagnification and illumination isthe only way one can be assured ofcrown-root interface cleanliness.

Bonded Restoration. The bondedrestoration presents unique andmore difficult finishing requirementsand therefore demands greater careand precision to create a marginthat is smooth and nonirritating tothe gingival tissues. As one pro-gresses through the regimen of finer

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and finer burs and finishing disks, itbecomes more difficult to evaluatethe surface texture of the finishedcrestal edge. Only when this junc-tion is fine tuned under magnifica-tion can one be assured that thegingival tissues will not becomeinflamed, bleed, recede, or exposethe critical root-filling interface.

Uses in Endodontic Therapy Coronal Access. Pulp tissue respondsto age, repeated restorative proce-dures, trauma from injury, andocclusal wear by depositing layersof amorphic calcified dentin. In achamber that has obliterated itselfwith secondary and tertiary dentin,the possibility of perforating thefloor during endodontic coronalaccess becomes a real concern.Unless one is using high levels ofmagnification when approachingthe floor of the pulp chamber, it isdifficult to discern the roof of thechamber from the natural floor.Proceeding blindly without the aidof magnification invites perforationand subsequent failure.

Locating Orifices. We are no longerunder the delusion that a root has asingle canal and exit. Studies haveindicated that the potential for mul-tiple canals and intracanal commu-nications exists in virtually everyroot, and success and failure restson locating and negotiating all ofthese canal aberrations.3 The floorof a chamber when magnified andproperly cleared of tissue tags and

calcified debris exposes a series oftroughs that virtually outlines path-ways to the various canal orifices.Once located and identified, theseminute openings become obviousand the orifices are more easilynegotiated with no. 06 or 08 stain-less steel files.

Locating and Retrieving ForeignObjects. One is often faced with re-treating a canal whose entry isblocked by a post/core. Of evengreater concern is the fragmenta-tion or separation of an instrumentthat can occur during the course of cleaning and shaping a canal.Finding and removing these canal-blocking obstacles without perfo-rating the root requires theenhanced vision and illuminatingproperties of a high-poweredmicroscope and the careful and pre-cise circumferential troughing ofthe approximating dentin with anappropriate ultrasonic computedtomographic tip. Troughing with-out magnification invites failure.

Repairing Iatrogenic and IdiopathicPerforations. Locating and repair-ing canal–periodontal ligamentcommunications through a delicateand precise intracanal access canonly be accomplished with the aidof enhanced vision and illuminationfrom a high-powered microscope.

Endodontic Surgery. Probably themost significant contribution of themicroscope in endodontic therapy

occurs when surgical access to anendodontic problem becomes theonly alternative to tooth extraction.The success of endodontic surgeryis often compromised by anatomicrestrictions and root aberrations (ie,the number and location of canalexits). To improve the chances ofclinically detecting multiple exitsand isthmi and to parallel the retro-preparation and root-end filling tothe root axis, one must depend onintense illumination and an unob-structed magnified view.4

Uses in Periodontal TherapyPeriodontal Scaling. The success ofa periodontal scaling is based onthe elimination of even the minutestparticles of plaque and a corre-spondingly positive response of thehost’s gingival tissues to a smoothand polished root surface. Althoughroutine prophylactic periodontalcare may be accomplished underthe naked eye, it is best achievedwith the aid of relatively low levelsof magnification (×2.5–3.5).

Inflammation and Swelling. Inflam-mation and swelling associatedwith the tissues of diseased pocketscompromise visibility and access.The treatment of the root surfacesat the depths of these osseousdefects demands a clear and unob-structed view. To gain such access,these diseased roots must be clini-cally exposed and aggressivelyplaned. Critical comprehensiveperiodontal therapy, such as chemi-



cal etching, tetracycline dressing,osseous shaping, artificial bonegrafting, and resorbable membraneinsertion, is best accomplished athigh levels of magnification.

Uses in Implant PlacementRestoring edentulous areas withimplants demands precision. Therestorative dentist must choreographthe treatment plan and, with theinterdisciplinary involvement of thesurgeon, insert an implant thataccepts a metallic fixture upon whicha ceramic crown is placed. Althoughpreparing the surgical insert site isbest performed with the assistanceof some form of magnification(×2.5–4.5), the surgeon may onlyrequire a microscope when the sinusbecomes exposed or the palatine ormandibular vessels are encounteredduring the surgical procedure.

The restorative dentist has evengreater vision and precision demandsthan has the surgeon. He or shemust choreograph the treatmentplan and choose the fixtures thatbest meet the esthetic requirementsof the patient. This role includesmaking the metal of the fixture vir-tually invisible by fabricating andfinishing a ceramic crown that issufficiently dense and shaded butthat does not appear thicker andmore noticeable then the adjacentteeth. The art of feathering the gin-gival edge of the ceramic to give thenatural appearance that the restora-tion flows into the crestal, for

example, requires precision that canonly be met with high levels ofmagnification and illumination.

FACTORS TO CONSIDER WHEN

SELECTING A MAGNIFICATION

SYSTEM

Tenets of MagnificationThe following are commonly heldtruths about magnification:

• The width and depth of a fielddecreases as the power of magni-fication increases.

• The length and weight of a tele-scope increases with every powerincrease.

• Focal points must be addressedindividually.

• Loupes and telescopes offer noillumination. To complete thehigher magnification system,lighting equipment, which may be heavy and cumbersome, mustbe considered.

Issues of ManufacturingPrior to purchasing any magnifica-tion equipment certain questionsregarding manufacturing should be explored:

• Will the magnifying lens, whenfocused, meet my needs regardingthe buccal/lingual depth of field?

• Is the magnified image as clear on the peripheral edges as it is inthe center?

• Is the lens coated to minimizelight scatter and flaring whenfocused on a mirror or any otherreflective surface?

• What are the advantages and dis-advantages of fixed solid and flip-up telephoto lenses and the lensesof a microscope?

• I wear bifocals; will I have trouble adjusting to binocularmagnification?

• Do I have flexibility, or must Ihave the lenses set for a particularworking depth?

• What are my illumination options?• Will the dimensions of my oper-

ating room accommodate amicroscope?

• What microscope accessories areavailable, (eg, splitters, cameras,video)?

• What accessories are included inthe purchase price? Are there anyinstallation costs?

• Can I add accessories at a latertime?

• What are the company’s warrantyand support policies?

Knowledge of MicroscopyPrior to purchasing any magnifica-tion equipment, it is wise to attenda continuing education microscopycourse or visit the office of arestorative dentist who actively and consistently uses high levels ofmagnification. One should ask thefollowing questions:

• Is working at high levels of mag-nification fatiguing?

• Did you have to change your nor-mal chair-side position?

• Was there a long learning curve?Was the adjustment difficult forthe assistants?

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• Did you need to purchase instru-ments that were more suitable formicroscopic dentistry?

• How did your patients react tothe scope? Did they feel intimi-dated or claustrophobic when itwas placed over their head?

• Did the system you chose meetyour practice needs?

Have you found the use of magnifi-cation, particularly the microscope,to be time and cost effective?

Personal Aspects Once the preliminary exploration iscomplete, one must now considerthe personal aspects of the decision:

• Does using microscopy fit mycurrent practice philosophy?

• Do I believe microscopy willimprove the quality of my work?

• Do I believe microscopy willmake dentistry easier, less stress-ful, and more fun?

• Am I willing to commit to theadjustment and the learningcurve?

• Am I willing to commit to teach-ing my assistants?

• Am I willing to change my nor-mal chair-side position?

• If the operating room dimensionsdo not accommodate a micro-scope, am I willing to invest inthe structural changes necessaryto make it work?

• What accessories would I enjoyhaving (eg, splitters, cameras,video)?

• Am I willing to invest in instru-ments that are more suitable formicroscopic dentistry?

• How can I make the use of mag-nification, particularly the micro-scope, cost effective?

• How will my patients respond tothe fee increase that justifies theuse of the scope?

• How badly do I want to usemicroscopy?

EQUIPMENT SELECTION

The ultimate goal is to select equip-ment that can be easily adjusted tothe patient, the assistant, and thedoctor to make the more difficultdental procedures comfortable andnonfatiguing experiences. The keyto microscopic dentistry is to learnand adapt.

Microscope MountingAlthough most operators wouldprefer a wall or ceiling mount, thedimensions, decor and renovationcost of the existing operatingroom(s) may force one to adjust toa cumbersome rolling floor model.

Flexibility The location of immovable cabi-nets, mounted radiographymachines, and dental chairs mayrestrict flexibility. Sometimes thepatient, doctor, and assistant arerequired to be placed in unusuallocations to use the microscope onboth the right and left sides of theoral cavity.

VersatilitySome room restrictions can beaccommodated with couplers,binoculars, cameras, and monitors.

Patient’s Headrest The headrest for the patient shouldbe large enough to centrally posi-tion and maintain the patient’s headin the proper operating plane. Sincethe microscope focus is normallyfixed on the mirror when address-ing the teeth in the upper arch, it isbest to position the patient belowand in front of the operator formaxillary targets. The patient’smandibular teeth generally lendthemselves to a more directapproach. The patient chair shouldbe set below the operator; the tar-get tooth dictates the doctor’s posi-tion (ie, front, side, or behind).

Operator Chairs A number of chair styles for micro-surgeons and microassistants areavailable from most microscopemanufacturers. They offer right-and left-side supporting armreststhat fold back for access and com-pact storage. Most chairs are madeto tilt forward, and for perfect posi-tioning should be raised to a levelat which the operator’s and assis-tant’s backs are vertical andunstrained and the legs are free andunrestricted. Most chair heights canbe adjusted at levels ranging from40 to 53 cm above the floor. Acomfortable height is normallyfound when the thighs are parallelwith the floor.



Position of the Operator. Unless theoperator is comfortable, even theshortest and simplest proceduresare tiring. It is difficult to set theposition parameters because of thedifferences in people’s hand prefer-ences (right handed vs left-handed)and chair-side approaches (front,side, and back). When possible, theoperating room should allow thedoctor to position the chair on theoperating side of the patient. Theoperating-room conditions mayrestrict such freedom. In suchinstances the patient should beinstructed to turn to positions thataccommodate the doctor and thescope. This position may be tiringfor the patient to maintain. There-fore, when long procedures areplanned, appropriate time shouldbe allotted to offer the patient aperiod(s) of rest.

BinocularsMost companies offer 180° inclin-able binoculars that can be adjustedto any desired viewing angle. Oncethe microscope is positioned andfocused, the only operator-adjustingvariable during the viewing is themirror. Some companies offer anoptional feature that allows one toadjust the angle of the binocularsegment itself without changing theviewing angle of the lens. Thisoffers greater flexibility and allowsfor incredible back comfort.

Position of the Assistant. Depend-ing on the extent of the microscopeequipment purchased and the room

layout, an assistant’s duties mayrange from working directly in theoperating field through the beamsplit assistant-scope binoculars toworking indirectly via a monitor. If the assistant-scope attachment is not purchased, a video on-linecamera must be used to capture and transfer a quality image onto a small liquid crystal display screen positioned at the chair. Amore affordable yet practical alter-native is to purchase and position a quality television monitor thatdisplays the target image for every-one in the operating room to view simultaneously.

To prevent constant refocusing bythe operator and microscope assis-tant, any other assistants must becognoscente of the procedure andconstantly aware (via the monitor)of the operator’s progress. Withappropriate training on the timelypassing of appropriate instrumentsthroughout the procedure not onlydoes the operator enjoy the luxuryof having an uninterrupted focus onthe operating field but also the timeneeded to complete the treatment issubstantially reduced.

Magnifying SystemsAlthough magnification systemsmust meet individual needs andpreferences, the following unitsoffer quality and warranty support.

Binocular Telescopes. There is noaccepted standard for how magni-fying power is defined for surgical

loupes. Loupe systems contain mul-tiple positive and negative lenses(compound loupes). Because correc-tive prescription lenses may also beemployed, the effective diopter(refractive) power of a loupe is notconsistently related to its magnify-ing power. The resolution and fieldsize of the operating site are muchmore relevant quality criteria thanis the size of the image. One mustgive the most attention to thesharpness of the image at the mostappropriate and comfortable work-ing distance (eye to site).

The following are details of qualityunits and manufacturers:

• Designs for Vision (1-800-345-4009, Ronkonkoma, NY, USA).Available magnification: Galileanstandard field optics: ×1.7, ×2.5,×3.5, ×4.5; prismatic expandedfield: ×2.5, ×3.5, ×4.5, ×6, ×8.Imbedded or flip-up lenses,coated lenses, working distanceand angle adjustable, side shieldsavailable.

Orascopic Research (1-800-369-3698, Madison, WI, USA). Availablemagnification: Galilean system:class II ×2.0–2.9 (two power); pris-matic system class III ×3.0–3.9(three power); prismatic system classIV ×4.0–4.9 (four power). Imbeddedor flip-up lenses, coated lenses,working angle adjustable, greatestfield width, side shields available.

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Carl Zeiss, Inc. (1-809-442-4020,Thornwood, NY, USA). Availablemagnification: ×2.5, ×3.0, ×3.5.Prism loupe, flip-up paddle, coatedlenses, working angle adjustable,great field width and depth, sideshields available.

Microscopes: Direct View. The fol-lowing are details of quality unitsand manufacturers:

• Global Surgical Corporation:Entrée 3-Step, Entrée Extra 4-Step,Protégé 5-Step, and Protégé Plus6-Step (1-800-861-3585, St. Louis,MO, USA). Available magnifica-tion: ×2.1, ×3.2, ×5.1, ×8.0,×12.8, ×19.2. Manually con-trolled levels of magnification;ultrawide aperture optics, antire-flective lens coating, outstandingdepth of field, adjustable workingangle, fine focus control, beamsplitter for assistant scope, 35 mmcamera and or video camera,exceptional halogen-producedillumination.

Carl Zeiss Surgical Products: OPMI pico, OPMI PROergo (1-800-442-4020, Thornwood, NY,USA). Manual or foot-controlledmagnification levels, 1:6 zoom sys-tem focusing slowly at high andquickly at low magnifications,apochromatic lens coating, ultraw-ide aperture optics, antireflectivelens coating, outstanding depth offield, adjustable working angle, fine focus control, beam splitter for assistant scope, 35 mm camera

and or video camera, intense fiber-optic produced illumination, acti-vating hand grip.

Jedmed Instrument Company (1-314-845-3370, St. Louis, MO,USA). Manually controlled levels ofmagnification; available magnifica-tion: ×4, ×6, ×10; ultrawide apertureoptics; lens coating; outstandingdepth of field; adjustable workingangle; fine focus control; beamsplitter for assistant scope; 35 mmcamera and/or video camera; halogen-produced illumination.

Seiler Precision Microscopes (1-800-489-2282, St Louis, MO, USA).

Leica Microsystems Inc.: M300 (1-877-702-9671).

Endoscopy: Indirect View. The following are details of a qualityendoscope: Karl Storz Endoscopy-America (1-508-248-1590, Charlton,MA, USA). Fiber-optic probes intwo sizes: 0.7 mm, 1.8 mm; eachprobe angled at 45° (0.7 mm) or30° (1.8 mm); 1.8 mm probe usesimage bundle of 30,000 fibers;depth of field instantaneous from1 mm to infinity; working angleadjustable; offers flexibility; fiberoptics–produced illumination; ver-satile: 0.7 mm fiber fits in a canal;video reproduction capability.

Instrument SelectionAs magnification increases, one’sfield of vision decreases proportion-ately. This makes the normal-sized

hand instrument cumbersome touse. Manufacturers (HuFriedy,Chicago, IL, USA; SybronEndo,Orange, CA, USA; Jedmed Instru-ment Company, St. Louis, MO,USA) have responded to this needand offer miniaturized instruments,burs, and diamonds that do notobscure the view when used underhigh power.

Because of its internal turbine tech-nology, the head of a normal high-speed or contra-angled slow-speedhandpiece cannot be miniaturized.Medidenta’s Air King America,(Medidenta International Inc, LongIsland City, NY, USA) and Sybron’sImpact Air (Sybron Endo, Orange,CA, USA) are safe autoclavable air-turbine handpieces. The 45° offsethead provides maximum visibility.These ergonomically friendly hand-pieces are capable of producingspeeds of 400,000 rpm, are vibra-tion free, and produce a nonau-tomized stream of coolant water.

CONCLUSIONS

The American Dental Associationhas done a marvelous job educatingthe public about the need to carefor their teeth. In addition, denti-frice companies are spending enor-mous amounts of money on theenhancement of smiles. As a result,people have become more aware ofwhat dentists are capable of doingto improve a person’s appearance.For those reasons, patients havebecome more demanding aboutwhat they want and are more criti-



cal about what kind of results theyare willing to accept. Such patientscrutiny demands a self-criticism onthe part of the dentist. Althoughthere are no quality-based studiesto reference, one only has to spenda short time using a microscope toappreciate how precise the interfacefinish line of a ceramic or resinrestoration could be or how mucheasier and faster it would be to findthe fourth canal in a maxillarymolar, remove a broken root tip, orlocate the last piece of plaque in thedepth of a 6- to 7-mm pocket withthe aid of microscopy.

Buying a microscope is an invest-ment that takes a commitment. Thedecision must be based on the kindof practice one wants to conduct. Inmaking that decision, remind your-self of the statement, “You cannottreat what you cannot see,” andperhaps interpret it for what itreally means: What am I missing?

DISCLOSURE

REFERENCES

1. Ham AW. Histology. 7th Ed. 1974.

2. Reeves R, Stanley HR. The relationship ofbacterial penetration of pulpal pathosis incarious teeth. Oral Surg Oral Med OralPathol 1966; 22:59–65.

3. Sigueira JF. Aetiology of root canal treat-ment failure: why well treated teeth canfail. Int Endod J 2001; 34;1–10.

4. Arens DE, Chivian N, Rubinstein R, Torabinejad M. Practical lessons inendodontic surgery. Quintessence Publish-ing Co. Inc., 1998.

Reprint requests: Donald E. Arens, DDS,MSD, Indiana University School of Den-tistry, Center for Advanced ProfessionalStudies, 719 Indiana Avenue, Suite 209,Indianapolis, IN, USA; e-mail:[email protected]©2003 BC Decker Inc

Figure 1. One of the many difficult and uncomfortable posi-tions in which a practicing dentist may be found.

Figure 2. A typical unenhanced 1 to 1view.

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Figure 4. A 2.5 power enhanced view.

Figure 5. Battery / electric powered illumination source. Figure 6. Normal operating position with enhanced magnifi-cation and illumination. Note the tiring neck position.

Figure 7. A typical 35 mm camera attached to an operatingmicroscope.

Figure 8. The advantageous variable inclinable binoculars.

Figure 3. A classic telescopic fixed lens.



Figure 9. The enhanced view at 5×power.

Figure 11. Four enhanced views of acalcified canal orifice.

Figure 10. An ergonomically positive straight back chair sideworking position.

Figure 12. The operating microscope equipped with a videocamera, a 35mm camera and an all important assistant’s scope.

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Figure 13. Note the uncomfortable and fatiguing ergonomi-cally uncomfortable position of the assistant working withoutthe scope.

Figure 14. An 8× powered microscopic view of an ultrasonictip preparing a root-end preparation in a resected root.

Figure 15. An 8× powered view of a root-end filling compaction.

Figure 16. An SEM view of the canal exits at the apex of atypical root.

Figure 17. An SEM view of a resectedmesial-buccal root of a maxillary firstmolar with 2 unprepared canals.(MB-1, MB-2)



Figure 18. A 17× powered view of the 2 mesial-buc-cal roots of a maxillary first molar after ultrasonicpreparation.

Figure 19. Final examination of a completedendodontic surgery at 8 ×.



Figure 22. An SEM view of an untreated intercanal commu-nicating isthmus.

Figure 23. A 17 powered view of a apically resected rootdemonstrating an untreated isthmus.

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Figure 24. The retreatment of the canals and isthmus at 17power.

Figure 25. The quality of the case records can be comprehensive and unchallengeablewhen magnified views of the treatment procedures and operating difficulties are cap-tured. This is particularly important when records are requested by referring doctors,insurance adjusters and attorneys and patients.

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Periodontal Microsurgery - EndoExperience