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BRITISH DENTAL JOURNAL, VOLUME 191, NO. 11, DECEMBER 8 2001 597

PRACTICE occlusion

7

Why should trauma from occlusion beconsidered to have a role in the aetiologyof periodontal disease?

Occlusal trauma has been defined as‘injury to the periodontium resulting fromocclusal forces which exceed the reparative

capacity of the attachment apparatus’: ie the tissueinjury occurs because the periodontium isunable to cope with the increased stresses itexperiences. Compare this definition with theone for inflammatory periodontal disease:

‘Periodontitis is the result of an interactionbetween a susceptible host and bacterial factors indental plaque, which exceeds the inherent protec-tive mechanisms of the host’.

Both processes result in injury to the attach-ment apparatus because the periodontium isunable to cope with the pathological insultwhich it experiences. It is quite right, there-fore, that dentists should ask themselves twoquestions:

1. Does occlusal trauma have a role in theaetiology of periodontal disease?

2. Should occlusal treatment be consideredfor the patient with compromised peri-odontal attachment?

Before attempting to answer these twoquestions, the different types of trauma fromocclusion need to be defined.

How is trauma from occlusion classified?Historically trauma from occlusion has been clas-sified as either primary or secondary. Primaryocclusal trauma results from excessive occlusal

force applied to a tooth or to teeth with normaland healthy supporting tissues.

Secondary occlusal trauma refers to changeswhich occur when normal or abnormalocclusal forces are applied to the attachmentapparatus of a tooth or teeth with inadequate orreduced supporting tissues. Recently, the dis-tinction between primary and secondaryocclusal trauma has been challenged as mean-ingless since the changes that occur in the peri-odontium are similar irrespective of the initiallevel of periodontal attachment. More usefully,occlusal trauma can also be described as acuteor chronic.

Acute trauma from occlusion occurs follow-ing an abrupt increase in occlusal load such asoccurs as a result of biting unexpectedly on ahard object. Chronic trauma from occlusion ismore common and has greater clinical signifi-cance. In the context of this paper occlusaltrauma will mean chronic occlusal trauma.

Question 1Does occlusal trauma have a role in theaetiology of periodontal disease?This is a key question because the answer willdetermine:

• Whether occlusal forces influence the onsetof plaque-induced inflammation.

• Whether occlusal forces enhance the rate ofperiodontal destruction.

Considerable energy has been directed at try-ing to determine the answer to these questions,because of the possibility that trauma fromocclusion might contribute to the pathogenesisof periodontal disease. Research studies

Occlusal considerations inperiodonticsS. J. Davies,1 R. J. M. Gray,2 G. J. Linden,3and J. A. James,4

Periodontal disease does not directly affect the occludingsurfaces of teeth, consequently some may find a section onperiodontics a surprising inclusion. Trauma from the occlusion,however, has been linked with periodontal disease for manyyears. Karolyi published his pioneering paper, in 1901‘Beobachtungen uber Pyorrhoea alveolaris’ (occlusal stress and‘alveolar pyorrhoea’).1 However, despite extensive researchover many decades, the role of occlusion in the aetiology andpathogenesis of inflammatory periodontitis is still notcompletely understood.

In this part, we will discuss:• Whether occlusal

trauma is significant in the aetiology ofperiodontal disease

• Whether occlusaltreatment is indicatedfor patients sufferingfrom periodontal disease

• Making a diagnosis oftrauma from occlusion

• Tooth mobility • Occlusal equilibration

and the splinting ofteeth

1*GDP, 73 Buxton Rd, High Lane,Stockport SK6 8DR; P/T Lecturer inDental Practice, University DentalHospital of Manchester, HigherCambridge St., Manchester M15 6FH;2Honorary Fellow, University DentalHospital of Manchester, HigherCambridge St., Manchester M15 6FH 3Reader in Periodontology, Divsion ofRestorative Dentistry, School ofDentistry, Queen’s University, BelfastBT12 6BP 4Lecturer in Oral Pathologyand Periodontics, University DentalHospital of Manchester, HigherCambridge Street, Manchester M15 6FH*Correspondence to : Stephen Daviesemail: [email protected] PAPER

© British Dental Journal2001; 191: 597–604

Occlusal traumaInjury to the

periodontium resultingfrom occlusal forces which

exceed the reparativecapacity of the

attachment

PeriodontitisThe result of an

interaction between asusceptible host and

bacterial factors in dentalplaque, which exceedsthe protective mecha-

nisms of the host

598 BRITISH DENTAL JOURNAL, VOLUME 191, NO. 11, DECEMBER 8 2001

designed to examine the effects of occlusion fallinto three categories:

• Human cadaver investigations• Animal studies• Human clinical studies.

1. Human cadaver investigationsStudies published in the 1960s and 1970s wereinconclusive.2,3

2. Animal studiesIn these studies the variables were the level ofperiodontal attachment and the characteristicsof an applied force, and the way in which itmight be varied (See Figure 1 for a summary ofthe results).

The periodontal attachment level is one ofthree types:

• A normal healthy periodontal support• A healthy periodontal support but a reduced

bone height. This is the experimental modelequivalent of a post-periodontal therapylevel

• An active plaque-induced periodontitis.

The type of force that can be applied to theanimal tooth is:

• Either a jiggling force, which is produced bymulti-directional displacement of a tooth inalternating buccolingual or mesiodistal

directions. This is usually created in the ani-mal by the provision of a supraoccludingonlay.

• Or is an orthodontic force, created by a springand is a unilateral force that results in thedeflection of the tooth away from the force.

3. Human clinical studiesFew clinical studies have identified a clear rela-tionship between trauma from the occlusionand inflammatory periodontitis in humans. A major problem with clinical studies of thistype is the lack of a reliable index for measuringthe degree of occlusal trauma to which a toothis subjected.

If trauma from occlusion exists there are obvi-ous difficulties in assessing whether the rate ofattachment loss is greater in patients with a con-tinuing plaque induced periodontitis. This isbecause secondary referral units where themajority of clinically based studies are carriedout, do not routinely monitor patients whomaintain good plaque control.

On the system level ideal occlusion is or is notideal for the rest of the articulatory system: thetemporomandibular joints and the masticatorymuscles. It has, however, been stressed that thereis no such thing as an intrinsically bad occlusalcontact, because the effect is a product of notonly the‘quality’ of the contact or contacts but

PRACTICE occlusion

It is the aim of thissection to answertwo questions

Question 1

Does occlusaltrauma have a rolein the aetiology of periodontal disease?

Question 2

Should occlusaltreatment be considered for thepatient with a compromised periodontal attachment?

Fig. 1 Summary of the results from animal studies

Orthodonticforce

Jiggling force

Healthy periodontium Normal bone height

Increased mobility Tooth movement No change in position of junctional epithelium or connective tissue attachment

Increased periodontal ligament space Some loss in crestal bone height and bone volume No loss of attachment Increased tooth mobility which is reversible upon the removal of the force

Healthy periodontium Reduced bone height

Increased mobility Tooth movement No gingival inflammation No further loss of connective tissue attachment

Increased periodontal ligament space Some loss in height of crestal bone height and bone volume No gingival inflammation No further loss of attachment. Increased tooth mobility which is reversible upon the removal of the force

Plaque-induced periodontitis

No progression of periodontal disease

Gradual widening of the periodontal ligament space Progressive mobility Angular bone loss


PRACTICE occlusion

also the frequency at which the contact or con-tacts are made. Also, it is widely accepted thatsome patients, at some times will have an articu-latory system which is compromised by otherfactors which reduce their tolerance to a less thanideal occlusion. Factors may range from a sys-temic disease such as rheumatoid arthritis to thedebilitating effects of chronic long term stress.

On the tooth level an occlusion may or maynot be ideal for the attachment apparatus, andthe same consideration must be given to thefrequency of occlusal contact, ie Does parafunc-tion occur? In addition, the ability of the attach-

ment apparatus to withstand a less than idealocclusion may be compromised by periodontalinflammation.

This leads to the second question:

Question 2Should occlusal treatment be consideredfor the patient with compromisedperiodontal attachment?If it is accepted that increased occlusal forcescould result in a further loss of attachment forteeth with an active inflammatory periodonti-tis, then it follows that a treatment plan aimed

Fig. 2 Trauma from occlusion: monitoring examination sheet

Patient Date

Firstexamined

Periodontal status

RV no: Date of Last RV Interval

CI 1

Tooth drifting

Mobility

Fremitus

CI 1I CI III

Persistent discomfortupon eating

Discontinuity inlamina dura

Radiolucency ofalveolar bone

Condensation ofalveolar bone

Rootresorption

Thickening oflamina dura

Widening orfunneling of

periodontal ligmanent

Radiographic changes


PRACTICE occlusion

at preserving these teeth must address bothproblems. This does not mean that traumafrom occlusion causes periodontitis; rather, itmeans that occlusal forces may exceed the‘resistance threshold’ of a compromised attach-ment apparatus thereby exacerbating a pre-existing periodontal lesion. While we know thattrauma from occlusion can have an effect onthe supporting tissues of the teeth, there is noevidence, at present, that trauma from occlu-sion is an aetiological factor in human peri-odontal disease.

It follows, therefore, that even thoughocclusal trauma is not a proven aetiologicalfactor in periodontal disease dentists as part oftheir responsibility to help patients keep theirteeth for as long as possible in maximumhealth, comfort and function must carry out athorough occlusal examination. Treatmentaimed at reducing occlusal forces so that theyfall within the adaptive capabilities of eachpatient’s dental attachment apparatus willbenefit; particularly those with, or at futurerisk, of periodontitis.

TechniqueExamination:Clinical diagnosis of trauma from occlusionIncreased tooth mobility is not always indica-tive of trauma from occlusion. It is important,however, that hypermobility which doesoccur as a result of trauma from occlusion isdetected in patients with reduced periodontalattachment. The reason for this is that traumafrom occlusion may accelerate further reduc-tion in attachment in a patient with activeperiodontitis.

A clinical diagnosis of occlusal trauma canonly be confirmed where progressive mobilitycan be identified through a series of repeatedmeasurements over an extended period. Thismeans that simple but reliable monitoringneeds to be undertaken. A simple monitoringprotocol is needed (Fig. 2).

The common clinical signs of occlusal traumaare:

• Increasing tooth mobility and migration ordrifting (Fig. 3)

• Fremitus• Persistent discomfort on eating.

The common radiographic signs of occlusaltrauma are (Fig. 4):

• Discontinuity and thickening of lamina dura• Widening of periodontal ligament space

(‘funnelling or saucerisation’)• Radiolucency and condensation of alveolar

bone/or root resorption.

Tooth mobilityConventional methods for measuring toothmobility are based on the application of aforce to the crown of the tooth to assess thedegree of tooth movement in the horizontaland vertical directions. Pathological mobilityis defined as horizontal or vertical displace-ment of the tooth beyond its physiologicalboundaries. Normal physiological movementis thought to vary between 10 µm and 150 µmand would not be detectable on clinical exam-ination. Clinically detectable mobility indi-cates some change in the periodontal tissues(ie it is pathological) and the cause of themobility needs to be diagnosed.

Fig. 3 UR 2 (12) has migrateddistally. Examination of thedynamic occlusal contacts ofthis tooth indicate that themarked wear facet fits closelyagainst those of LR 2 and LR1(42, 41) during a right lateralexcursion of the mandible

Fig. 4 All radiographs showsigns of occlusal trauma todiffering degrees


PRACTICE occlusion

Tooth mobility can be recorded using Miller’sIndex:

I — up to 1 mm of movement in a horizontaldirection

II — greater than 1 mm of movement in ahorizontal direction

III — excessive horizontal movement and vertical movement.

How can tooth mobility be measured?

Manual evaluation Manual evaluation of mobility is best carriedout clinically using the handles of two instru-ments to move the teeth buccally and lingually.

FremitusFremitus is the movement of a tooth or teethsubjected to functional occlusal forces, thiscan be assessed by palpating the buccal aspectof several teeth as the patient taps up anddown.

PeriodontometersA periodontometer was a research tool used inthe 1950s and 1960s to standardise the mea-surement of even minor tooth displacement.To date, this instrument has been used in a fewclinical studies and has limited practical use.

Periotest ®This device (Fig. 5) was produced in Germanyin the late 1980s to provide a more reliablemethod for determining tooth mobility. It isdesigned to measure the reaction of the peri-odontium to a defined percussion, delivered bya tapping instrument. Again this is of limiteduse in general dental practice.

Tooth drifting or migrationIndependent of the state of the supporting tis-sues of a tooth, if it has moved its position inthe mouth, then some force has been responsi-ble for pushing or pulling it. Clearly that forcemay be extrinsic such as can be seen in pipesmokers or in pencil chewers. Secondarily asoft tissue force may be responsible as withtongue thrusting or lip position (Fig. 6). How-ever, the force may be from an occlusal contactespecially parafunction. A frequently encoun-tered scenario is drifting of an upper lateralincisor. This is a common reason for referral ofan adult patient to an orthodontist; a referralmade usually at the patient’s request, with theaim of restoring their appearance. It is impor-tant to discover the cause of the drifting beforeconsidering any treatment.

Discomfort upon eatingIt is important to evaluate how tooth mobilityaffects the patient. If there is discomfort when

Fig. 5 The Periotest ® device

Phot

o: P

erio

test

-Equ

ip

Fig. 6 Initial examination of theUR 1 (11), in Fig. 6a, maysuggest an occlusal cause of thedrifting; however, as is shown infigure 6b the reason is therelationship with the lower lip

Fig. 7 The lower anteriors havebeen temporarily immobilisedby a labial splint in order to beable to identify the prematurecontacts and subsequentlyequilibrate the teeth in orderto reduce the trauma fromocclusion. (Note: Theadjustment to the loweranteriors was only to the labialaspect of the incisal edges: theexposed dentine was alreadypresent!)


PRACTICE occlusion

eating this will have a direct influence upontreatment. The decision will need to be taken, inconsultation with the patient, whether to acceptthe discomfort, extract or splint.

Treatment(Occlusal considerations in the treatment ofperiodontitis)

EquilibrationOcclusal equilibration is the modification of theocclusal contacts of teeth to produce a moreideal occlusion.

Is there a need for occlusal equilibration in theperiodontally compromised dentition?The literature does not give an answer to thisquestion. Some studies have shown occlusaltherapy to be beneficial in the management ofperiodontal disease, whilst others have failed todo so.7–9 Burgett et al. reported that occlusaladjustment to reduce tooth mobility beforeconventional periodontal treatment, leads toprobing attachment gain after such therapy.7

The current dental literature, however, suggeststhat if occlusal adjustment is required it shouldbe carried out after periodontal treatment.

There is no evidence at the present time tosuggest that occlusal equilibration is an appro-priate method for preventing the progression ofperiodontitis. It would, however, be useful toknow whether equilibration of a periodontallycompromised dentition is beneficial for thelong-term preservation and comfort of teeth, inthose patients who fail to achieve an excellentlevel of plaque control.

Equilibrating mobile teethIn a patient with mobile teeth, it may be necessaryto temporarily stabilise those teeth before equili-bration is possible (Fig. 7a,b). If a tooth is mobile,it is very difficult if not impossible to effectivelymodify its shape with the aim of reducing theocclusal forces acting upon it (equilibration).

When to equilibrate (Fig. 8)Whether occlusal equilibration is indicated willdepend upon:

• Whether the inflammatory periodontitishas been treated successfully. If there is aninflammatory periodontal process thisshould be treated initially. Subsequentlywhen the periodontal condition is stable,occlusal therapy may be necessary for somepatients and could involve either occlusalequilibration or splinting.

• The radiographic appearance of the peri-odontal support. Occlusal equilibration isconsidered an effective form of therapy forteeth with increased mobility which hasdeveloped together with an increase in thewidth of the periodontal ligament (PDL).Reducing the occlusal interference on atooth with normal bone support will nor-malise the width and height of the PDL.Eliminating any occlusal interferences for atooth which has a reduced bone height as aresult of periodontal disease will result inbone formation and remodelling of thealveolus only to the pre-trauma level.

In contrast, if the hypermobile tooth hasreduced bone height but normal periodontalligament width, then elimination of occlusaltrauma will not alter the mobility of thetooth. In this situation occlusal equilibra-tion is only indicated if the patient is com-plaining of loss of function or discomfort.

Occlusal therapy in a periodontal treatment planis established practice‘The World Workshop of the American Acad-emy of Periodontology’,13 issued some guide-lines for situations when occlusal equilibrationmay be indicated:

• When there are occlusal contact relationshipsthat cause trauma to the periodontium,joints, muscles or soft tissues

• When there are interferences that aggravateparafunction

• As an aid to splint therapy.

SplintingWhen should teeth be splinted together in thepatient with reduced periodontal support?(Fig. 8)

Also outlined13 were some indications for

EquilibrationAll these stages may be necessary

before equilibration of the patient’s teeth can be completed

Successfulstabilisation splint

therapy

Study modelsmounted to CR ona semi-adjustable

articulator

Mock equilibrationon duplicatedstudy models


PRACTICE occlusion

splinting, not only restricted to patients withreduced periodontal support:

• To stabilise teeth with increased mobility thathave not responded to occlusal adjustmentand periodontal treatment

• To prevent tipping or drifting of teeth and theovereruption of unopposed teeth

• To stabilise teeth after orthodontic treatment• To stabilise teeth following acute trauma.

The first guideline refers to patients withreduced periodontal support. There are two sit-uations in which splinting may be beneficial:

• Where tooth mobility is progressive withincreased periodontal ligament width andreduced bone height then splinting is indi-cated as part of periodontal therapy.

• When patient comfort and function will beimproved by splinting, then it is indicated, asan adjunct to periodontal therapy.

This means that if periodontal treatmentresults in a stable periodontal condition whichis comfortable, splinting is not needed.

Fig. 8 Indications for occlusal treatment and splinting4,8–11

Clinical features

Increased mobility

Increased mobility

Increased mobility

Patient NOTfunctioning comfortably

Increased mobility

Patient functioning comfortably

Radiographic features

Increased width of PDL

Normal bone height

Increased width of PDL

Reduced bone height

Normal width of PDL

Reduced bone height

Normal width of PDL

Reduced bone height

Treatment requiredin addition toperiodontal therapy

Occlusal equilibration

Occlusal equilibration

Occlusal equilibration ± splinting

No occlusal adjustment required

Treatment outcome

Normalises PDL width.

Bone fill of angular defect. Bone level stabilised. Normal width PDL

Patient’s comfort and function may improve. (This is not periodontal therapy, but an adjunct to it)

No further deterioration

Summary: Trauma from occlusion in theaetiology and treatment of periodontal disease

• There is no scientific evidence to show that traumafrom occlusion causes gingivitis or periodontitis oraccelerates the progression of gingivitis to periodon-titis.

• The periodontal ligament physiologically adapts toincreased occlusal loading by resorption of the alveo-lar crestal bone resulting in increased tooth mobility.This is occlusal trauma and is reversible if theocclusal force is reduced.

• Occlusal trauma may be a co-factor which canincrease the rate of progression of an existing peri-odontal disease.

• There is a place for occlusal therapy in the manage-ment of periodontitis, especially when related to thepatient's comfort and function.

• Occlusal therapy is not a substitute for conventionalmethods of resolving plaque-induced inflammation.


PRACTICE occlusion

Guidelines of good occlusal practice

1 The examination of the patient involves the teeth, periodontal tissues and articulatory system.2 There is no such thing as an intrinsically bad occlusal contact, only an intolerable number of times to parafunction on it. 3 The patient’s occlusion should be recorded, before any treatment is started.4 Compare the patient’s occlusion against

the benchmark of ideal occlusion.5 A simple, two dimensional means of recording the patient's occlusion

before, during and after treatment is an aid to good occlusal practice. 6 The conformative approach is the safest way of ensuring that the

occlusion of a restoration does not have potentially harmful consequences.

7 Ensuring that the occlusion conforms (to the patient’s pre-treatment state) is a product of examination, design, execution and checking (EDEC)

8 The ‘reorganised approach’ involves firstly the establishment of a ‘more ideal’ occlusion in the patient’s pretreatment teeth or provisional restorations; and then adhering to that design using the techniques of the ‘conformative approach’

9. An ‘ideal occlusion’ in removable prosthodontics is one which reduced de-stabilising forces

10. The occlusal objective of orthodontic treatment is not clear, but a large discrepancy between centric occlusion and centric relation should not be an outcome of treatment

11. An ‘orthodontic’ examination of the occlusion should include: the dynamic occlusion; and the jaw relationship in which the patient has centric occlusion

12. The occlusion of periodontally compromised teeth should be designed to reduce the forces to be within the adaptive capabilities of the damaged periodontia

1 Karolyi M. Beobachtungen uberPyorrhoea alveolaris. Ost-Unt VjschrZahnheilk 1901; 17: 279.

2 Glickman I, Smulow J B. Alterationin the pathway of gingivalinflammation into the underlyingtissues induced by excessive occlusalforces. J Periodontol 1962; 33: 8-13.

3 Waerhaug J. The infrabony pocketand its relationship to trauma fromocclusion and subgingival plaque. J Periodontol 1979; 50: 355-365.

4 Green M S, Levine D F. Occlusionand the periodontium: A review andrationale for treatment. J Calif DentAssoc 1996; 24: 19-27.

5 Jin L J, Cao C F. Clinical diagnosis oftrauma from occlusion and itsrelation with severity ofperiodontitis. J Clin Perio 1992; 19:92-97.

6 Philstrom B L, Anderson K A, AeppliD, Shafter E M. Association betweensigns of trauma from occlusion andperiodontitis. J Periodontol 1986; 57:1-6.

7 Burgett F G, Ramford S T, Nissle RR,Morrison E C, Charbeneau T D,Caffesse R G. A randomised trial ofocclusal adjustment in the treatmentof periodontitis patients. J ClinPeriodontol 1992; 19: 381-388.

8 Galler C, Selipsky H, Philips C,Amnons W F Jr. The effects ofsplinting on tooth mobility. II. Afterosseous surgery. J Clin Periodontol1979; 6: 317-333.

9 Linde J, Nyman S. ClinicalPeriodontology and Implant Dentistry.3rd Ed. Ch 23: Occlusal Therapypp711-726 Copenhagen:Munksgaard, 1997.

10 Svanberg G K, King G T, Gibbs C H.Occlusal considerations inperiodontology. Periodontol 20001995; 9: 106-117.

11 Walton G, Heasman P. The role ofocclusion in periodontal disease.Dent Update 1998; 25: 209-216.

12 Polson A M, Zander H A. The effectof periodontal trauma uponinfrabony pockets. J Periodontol1983; 54: 586-592.

13 Proceedings of the World Workshop inClinical Periodontics. Chicago.Consensus report: Occlusal Trauma.The American Academy ofPeriodontology 1989: III-1/III-23.

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