Dio Gnosis

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The Maya civilization has been shown to have used

the earliest known examples of endosseous implants

(implants embedded into bone). While excavatingMaya burial sites in Honduras in 1931,archaeologists found a fragment of mandible ofMaya origin, dating from about 600 AD. This

mandible, which is considered to be that of a womanin her twenties, had three tooth-shaped pieces ofshell placed into the sockets of three missing lowerincisor teeth.
http://en.wikipedia.org/wiki/Dental_implantshttp://en.wikipedia.org/wiki/Dental_implants


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1809- Maggiolo Introduced use of Gold in the shape

of a tooth root.

1887- Harris Introduced use of teeth made ofPorcelain in to which lead-coated platinum postswere fitted .

1900s- Lambotte fabricated implants of Al,Ag ,Brass,

Red Copper , Magnesium,Gold & soft steel platedwith gold & nickel.

HISTORY


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1909- The first root form design that differed

significantly from the shape of tooth root was GreenfieldLatticed

cage design made of iridoplatinum.

1938- Strock surgical Co-Cr-Mo alloy was introduced toOral Implantology. He replaced a single maxillary leftincisor teeth with a root form one piece implant( lastedfor more than 15 years)


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1940- Bothe & Coworkers A direct bone Implant

interface to titanium was initially called bone fusing . 1946-Strock designed the first titanium two piece screw

implant that was initially inserted without thePermucosal Post.

1952- Branemark began microscopic circulation ofbonemarrow healing.


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1960s- Ten year Implant Integration was established inDogs with no adverse reactions to hard or soft tissues.


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The Goal of modern Dentistry is to restore the

patient to normal contour, function, comfort,

esthetics, speech & health . Implant Dentistry is unique in its ability to acheive

the goal regardless of atrophy,disease or injury of thestomatognathic system.

Rationale for Dental

Implant


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Increased need and use of implant related treatmentsresult from combined effect of several factors including-

Ageing population living longer .

Tooth loss related to age .

Consequences of fixed prosthesis failure .

Anatomic consequences of edentulism. Poor performance of removable prosthesis.

Consequences of RPD


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Psychological aspects of tooth loss & needs & desires of

ageing baby boomers. Predictable long term results of implant supported

Prosthesis

Advantages of Implant supported restorations

Increased Public awareness.


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The most common choice to replace a posterior

single tooth is a 3 unit FPD. & hence became the t/t

of choice for last 6 Decades. Estimated mean life span of FPD (50%survival)

reported at ten years.

Caries is the most common cause of FPD Failure.

15% of FPD abutments require endodontics.

Single Tooth

Replacement-FPD


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Failure of abutment teeth of FPD 8%-12% at ten

years & 30% at 15years.

80% of teeth adjacent to missing teeth have no orminimal restoration.


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Comparative Evaluation.


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Rather than removing sound tooth structure and

giving crown 2 or more teeth thus increasing the risk

of decay & endodontic therapy a Dental Implantmay replace a single tooth.

Advantages-

High Success rates ( above 97% ) for ten years.

Decreased risk of caries of adjacent teeth.Decreased risk of endodontic Problems on adjacent

teeth.

Single Tooth Implant


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Improved ability to clean the Proximal surfaces of

the adjacent teeth.

Improved Aesthetics of adjacent teeth. Improved maintanance of bone in edentulous site.

Decreased cold or contact sensitivity of adjacentteeth

Psychological advantage.


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Decreased abutment tooth loss.


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Anatomical Consequences

of Edentulism


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Loss of anterior ridge and nasal spine causing

increased denture movement and sore spots during

function. Increased risk of mandibular body fracture from

advanced bone loss.

Effect of bone loss on esthetic appearance of lower

third of face.More active role of tongue in mastication.


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Paresthesia from dehiscent mandibular

neurovascular canal.

Loss of basal bone. Thinning of mucosa with sensitivity to abrasion.

Forward movement of prosthesis from anatomicalinclination.


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Attached,keratinized gingiva is lost as bone is lost.Unattached mucosa for denture support causes

increased soft spot.

Thickness of tissue decreases with age and systemicdisease causes more sore spots for dentures.

Tongue increases in size , which decreases denturestability.

Soft Tissue Consequences

of Edentulism


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Tongue has more active role in mastication , which

decreases denture Stability.

Decreased Neuromuscular control of Jaw in theelderly.


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Decreased Facial Height.

Loss of labiomental angle.

Deepening of vertical lines in lip and face.

Chin rotates forward gives a Prognathicappearance.

Decreased horizontal labial angle of lip-makespatient look unhappy.

Loss of tone in muscles of Facial expression.

Esthetic consequences of

bone loss


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Thinning of Vermilion border of the lips from loss of

muscle tone.

Deepening of nasolabial groove. Increase in Columella-Philtrum angle.

Increased length of Maxillary lip , so less teeth showat rest and smiling ages the smile.

Ptosis of Buccinator muscle attachment leads toJowls at side of face.

Ptosis of Mentalis muscle attachment- leads towitchs chin


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WitchS Chin


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Jowls at side of face


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Bite force is decreased from 200Psi-to 50 Psi

15-year denture wearers have reduced bite force to

6Psi.Masticatory effieciency is decreased.

More drugs are necessary to treat GIT disorders.

Life span may be decreased.

Food selection is limited.

Healthy food intake is decreased.

Negative effects of

removable Prosthesis.


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20% of edentulous patients dont wear both

removable prosthesis all the time. (NIH Oral

health of US adults national findings Publ No87 1987)

7% of edentulous patients are not able to wear

their dentures at all (NIH).

88% of denture wearers have difficulty withspeech (Misch LS Misch CE DentureSatisfaction:a patients perspective,Int J Oral Implant1991)


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62.5% of mandibular denture wearers had

awareness of movement (Misch)

50% of denture wearers avoided certain food(Misch)

17% of denture wearers masticated better

without prosthesis (Misch)

16.5% of mandibular denture wearers never

wear denture (Misch)


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Low survival rate- 60% at four years.

35% survival rate at 10 years.

Repair of abutment teeth rate 60% at 5years & 80%at ten years.

Increased mobility , plaque bleeding upon probingand caries of abutment teeth .

44% abutment teeth loss with in ten years.Accelerated bone loss in edentulous region if

wearing RPD.

Problems with Removable

Partial Denture.


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1.Average bite force in first molar area 150-250 PSI

with electronic strain gauge studies and edentulous

person with dentures 50 PSI ( Howell, 1948). 2. 32% less masticatory efficiency with natural teeth

compared to complete dentures(Rissen et alJ ProsthDent1978)


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4.Tissue borne dentures yield: Increased bone loss,increased caries on rest teeth, increased mobility of restteeth, increased bleeding upon probing, greater plaque

retention, non compliance of use, speech inhibition, tasteinhibition.(Vermeulen A et al:Ten year evaluation ofremovable partial dentures:survival rates based onretreatment,not wearing and replacement,J Prosthet Dent1996)


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Range from minimal to Neuroticism.

Romantic situations affected.

Oral Invalids unable to wear dentures. 88% claim some difficulty with speech & 25% claim

significant problems.

More than $200 million each year spent on denture

adhesive to decrease embarrassment.Dissatisfaction with appearance , low self esteem.

Avoidance of social contact.

Psychological Effects of

tooth loss


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REPLACEMENT

ANALOGIES


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Maintain Bone.

Restore and maintain occlusal vertical dimension.

Maintain facial esthetics. Improve esthetics ( teeth positioned for appearance

versus decreasing denture movement.

Improve Phonetics.

Advantages of Implant

supported Prosthesis.


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Improve Occlusion.

Improve/ regain oral proprioception occlusal

awareness. Increase Prosthesis success.

Improve masticatory Performance/ maintainmuscles of mastication and facial expression .

Reduce size of Prosthesis.


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Improve stability and retention of removable

prosthesis.

Increase survival times of Prosthesis.No need to alter adjacent teeth.

More permanent replacement.

Improve Psychological health.


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ALLOPLASTIC- Related to Implantation of an inert foreign body. ANKYLOSIS-A condition of joint or tooth immobility resulting from

oral pathology ,surgery, or direct contact with bone.

ANODIZATION-An oxidation process in which a film is produced on the

surface of a metal by electrolytic treatment at the anode.

KEY TERMS:


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BIOACCEPTANCE-Ability to be tolerated in a biological environment in spite of

adverse effects.

BIOACTIVE-Capable of promoting the formation of hydroxyapatite &

bonding to bone.

BIOCOMPATIBILITY-Ability of a material to elicit an appropiate biological

response in a given application in the body.


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BIOINTEGRATION-

Process in which bone or other living tissue becomesintegrated with an implanted material with no

intervening space . ENDOSTEAL IMPLANT-A device that is placed in to the alveolar and / or basal

bone of the mandible or maxilla , which transects only

one cortical plate.


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EPITHELIAL IMPLANT-A DEVICE PLACED WITH IN THE ORAL MUCOSA.

IMPLANTATION- Process of grafting or inserting a material such as an

inert foreign body( ALLOPLAST) Or tissue with in thebody.

ION IMPLANTATION- Process of altering the surface of a metal with desirable

ionic species.


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OSSEOINTEGRATION- Process in which living bony tissue forms to with in

100A of the implant surface without any intervening

fibrous connective tissue. OSTEOINDUCTIVE-Ability to promote bone formation through a

mechanism that induces the differentiation of

osteoblasts. PASSIVATION- Process of transforming a chemically active surface of a

metal to a less active surface.


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REPLANTATION- Reinsertion of a tooth back in to its jaw socket soon after

intentional extraction or accidental removal.

SUBPERIOSTEAL IMPLANT-A dental device that is placed beneath the periosteum

and overlies cortical bone.

TEXTURING: Process of increasing surface roughness of the area to

which bone can bond.


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Transosteal Implant-A device that penetrates both cortical plates and the

thickness of the alveolar bone.


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IMPLANT MATERIALS


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Historically,titanium has been used extensively in aerospace,

aeronautical and marine applications because of its high

strength and rigidity, its low density and corresponding low

weight, its ability to withstand high temperatures and its

resistance to corrosion.


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Titanium's useful range of applications in biomedical

devices. Today, titanium and titanium alloys are usedfor the fabrication of prosthetic joints, surgical

splints,stents and fasteners, dental implants, dental

crowns and partial denture frameworks.


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Titanium Metal


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Titanium, in the form of the oxide rutile, is abundant in

the earth's crust. Titanium ore can be refined to metallic

titanium through the Kroll process.

In its metallic form at ambient temperature, titanium

has a hexagonal, close-packed crystal lattice (ex phase),

which transforms into a body-centered cubic form (B

phase) at 883C (with a melting point of 1,680 C).


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This reactivity is responsible for many of titanium's

favorable properties. The metal oxidizes almost

instantaneously in air to form a tenacious and stable

oxide layer approximately 10 nanometers thick.

This oxide layer provides a highly biocompatiblesurface and a corrosion resistance similar to that of noble

metals.


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In addition, the oxide layer allows for bonding of

fused porcelains, adhesive polymers or, in the case of

endosseous implants, plasma-sprayed or surface-nucleated apatite coatings.

y


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There are currently more than 90 implant body

designs offering combinations of design features-

Screws, Baskets, Plateaus,balls , Cylinders,diameters, lengths, Prosthetic connections & surfaceconditions.

The most common root form design combines a

separate implant body and Prosthodontic abutment.

Generic Implant body

terminology

D i & i l


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To achieve clinical rigid fixation that corresponds to

a microscopic direct bone to implant interface

without intervening fibrous tissue occuring oversignificant portion of the implant body before theProsthetic phase of the Procedure.

Design & surgical

Philosophy


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Three different surgical approaches have been used

for 2 piece Implant System

A) Two Stage ( Healing Submerged then uncoverysurgery)

B) One stage ( Implant with Permucosal healing nouncovery surgery)

C) Immediate restoration ( Restoration Placed at thetime of the surgical Placement.


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Submerged approach in which implant is placed below or

at the level of the bone, requiring second surgery to placethe abutment (A)

Non-submerged two-piece implants in which both theimplant and abutment are placed during the first-stagesurgery, eliminating the need for second surgery (b).

Non-submerged one-piece implants in which implant and

abutment are there as one piece with no micromovementbetween implant and abutment and no microgap.Moreover, there is no need of second surgery( c).


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There are three primary types of root form body

endosteal implant based on design Cylinder, Screw

Or Combination.Cylinder (Press fit) root form implants depend on a

coating or surface condition to Provide Microscopicretention to the bone.

Surface is either coated with a rough material (Hydroxyapatite ,Titanium Plasma Spray) or a macroretentive design ( Sintered Balls)

IMPLANT BODY REGIONS


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Crest Module( Cervical Geometry).

A body.

An Apex.

IMPLANT BODY REGIONS


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IMPLANT BODY- Designed for surgical ease or

Prosthetic loading to implant bone interface.

Round Implant permits round surgical drill.

Smooth walled Cylinder implant- Implant to be

Pressed or tapped in to position.(c/o ) single tooth

implant application if adjacent to teeth with tall clinical

crown)


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Solid screw Implant Body most commonly reported in

literature. Solid screw body or implant of circular cross

section without penetrating any vents or holes.

Thread may be V shaped , Buttress, Reverse buttress or

square.


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THREAD PROFILING


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Most Common Specifications-

Outer thread Diameter 3.75mm,

Thread Depth- 0.38mm,

Thread Pitch- 0.6mm


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Thread Terminology


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Body Length7-16mm.(5-56mm available)


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Crest Module of an Implant body is that portion designed

to retain the Prosthetic component in a one Piece or two

piece implant system.

Represents the transition zone from the Implant body

design to the transosteal region of the implant at the crest

of the ridge.

Crest Module


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Crest Module


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Implant Body has design to transfer Stress Strain to the

bone during occlusal loads e.g threads or large spheres

where as-

Crest Module is designed to reduce Bacterial

Invasion.e.g (smoother to impair plaque retention ifcrestal bone loss occurs.)

Its smoother dimension varies greatly from one systemto another (0.5-5mm)


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When the crest module is smooth , polished metal is

often called a cervical collar.

The Prosthetic connection to the crest module is

received by Slip fit or friction fit with a butt or bevel

joint.


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Implant Surgery


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A first stage cover screw is placed in to the top of

Implant to prevent Bone, Soft tissue & Debris from

invading the abutment connection area during healing .

When supporting bone interface is developed a secondstage Procedure is performed to expose the two stage

Implant or to attach a transepithelial portion .

Implant Surgery


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This Transepithelial portion is called Permucosal

Extension because it extends the Implant above the soft

tissue results in development of Permucosal seal.

Transepithelial portion or Permucosal extension been

called a healing abutment since Stage 2nd uncovery

surgery uses this device for initial soft tissue healing .

Prosthetic


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The Abutment is the portion of the Implant that

supports or retains a Prosthesis or Implant

Superstructre .A Superstructureis defined as a metal framework that

attaches to the Implant abutment and Provides eitherretention for a removable Prosthesis ( A cast barretaining an overdenture with attachments ) or theframework for the fixed Prosthesis.

Prosthetic

Attachments

3 categories of


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According to method by which the Prosthesis or

Superstructure is retained to the abutments-

1) An abutment for Screw retention uses a screw to retainthe Prosthesis or superstructure.

2) An abutment for cement retention uses dental cement toretain the Prosthesis or Superstructure

3) An abutment for attachment uses an attachment deviceto retain a removable Prosthesis( O ring attachment)

3 categories of

Implant Abutments

Ab i d b b l ifi d


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Above mentioned abutment types be classified asstraight or angled abutments describing the axialrelationship between the Implant body and theabutments.


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Straight or angled abutment.

Prosthesis


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An impression is necessary to transfer the position and

design of the Implant or abutment to the mastercast forProsthesis fabrication.

A transfer coping is used in traditional Prosthetics toposition a die in an Impression .

A transfer Coping is used to position an analog in anImpression and is defined by the Portion of the Implantit transfers to the master cast.

Prosthesis

Fabrication

Basic Implant


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An Indirect transfer coping is screwed in to the

abutment or implant body and remains in place when atraditional closed tray Impression is set and removedfrom the mouth.

Uses an Impression material requiring elastic Properties.

Restorative Techniques


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Direct Transfer


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Consists of a hollow transfer component often

square& a long central screw and secure it to theabutment or Implant body may be used as a Pick-up

Impression coping.An Open tray impression tray is used to permit

direct access to the long central screw securing theIndirect transfer coping.

After Impression material is set the direct transfercoping screw is unthreaded to allow removal of theimpression from the mouth.

Direct Transfer

coping


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Direct Transfer Copings take advantage of

Impression materials having rigid Properties &

eliminate the errors of permanent deformation sincethey remain with in Impression until the mastermodel is poured.

Laboratory


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An Analog is defined as that is analogous or similar

to something else.

An Implant analog is used in the fabrication of themaster cast to replicate the retentive portion of theImplant body or abutment( Implant Body Analogue,Implant Abutment analogue.)

Laboratory

Fabrication


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After the master Impression is obtained the

corresponding analog is attached to the transfer

coping & the assembly is poured in stone to fabricatethe master cast.


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THANKYOU!

THANK YOU

THANKS

THANK YOU!

THANK YOU!


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Diognostic Imaging &Techniques

IMAGING


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The decision of when to image along with which

imaging modality to use depends on the threephases-

IMAGING

OBJECTIVES-

Presurgical Imaging (


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Preprosthetic implant imaging (Phase 1): The objectivesof this phase are to determine the quantity, quality, andangulation of bone; the relationship of critical structuresto the prospective implant sites; and the presence orabsence of disease at the proposed surgery sites.

Presurgical Imaging (

Phase 1)


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Surgical and Interventional implant imaging (Phase 2): The objectives of this phase are to evaluate the surgery

sites during and immediately after surgery, assist in theoptimal position and orientation of dental implants,

evaluate the healing and integration phase of implantsurgery, and ensure abutment position and prosthesisfabrication are correct.


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Post prosthetic implant imaging (Phase 3): It

commences just after the prosthesis placement andcontinues as long as implant remains in the jaw.

The objectives of this phase are to evaluate the long-term maintenance of implant rigid fixation andfunction, including the crestal bone levels aroundeach implant, and to evaluate the implant complex.

Types of Imaging


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Periapical Radiography.

Panoramic Radiography.

Occlusal Radiography.Cephalometric Radiography.

Tomographic Radiography.

Computed Tomography.

Magnetic Resonance Imaging.

Interactive Computed Tomography.

Types of Imaging

Modalities:


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Basic radiographicprinciples


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1. Adequate number and type of images to provide theneeded anatomic information.

2. The type of imaging technique selected should be able toprovide the required information with adequate precisionand dimensional accuracy.

3. There must be a way of relating the images to patient'sanatomy. For edentulous regions of jaw, this generally meansthe use of a stent with radiopaque markers during imaging.

4. All images should be of adequate density and contrast withminimal distortion and should be free from artifacts.

5. Imaging information should be balanced with the radiationdose and cost to the patient. The ALARA (as low asreasonably achievable) principle should govern the selectionof suitable technique .

principles

Ideal imaging modality


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Acco rding to Pharoah MJ 1993

1. Cross-sectional views for the visualization of thespatial relationship of internal structures, such as theinferior alveolar canal, and as a means of obtaining

accurate dimensions in both the vertical and thehorizontal planes.

2. Minimal image distortion to permit accuratemeasurements.

3. Depiction of the density of the cancellous bone andthickness of the cortical plates of bone. This is of value ifinitial stabilization of the implant is required.

Ideal imaging modality

characteristics


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4. Spatial relationship of the cross-sectional views of

the mandible and maxillae to one another. 5. A simple means of identifying the exact location of

each cross-sectional image to the implant site thatcan be provided at the time of surgical placement.

6. Ready availability and reasonable cost.

7. Patient radiation dose should be small as possible .


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Bone classification related to

implant dentistry

grading scale


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According to this system alveolar bone has been divided

into 4 classes:

1. Almost the entire jawbone is composed ofhomogenous compact bone.

2. Thick layer of compact bone surrounds a core ofdense trabecular bone.

3. A thin layer of compact bone surrounds a core ofdense trabecular bone of favourable strength.

4. A thin layer of compact bone surrounds a core of lowdensity trabecular bone.

The quality of the implant site in terms of relativeproportion and density of cortical and medullary bonehad frequently been assessed using a grading scheme.

classification of alveolar


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It is a recent method of classification based on

periapical radiographs that grades the medullarybone as

A) Dense

B) Sparse and

C) Alternating dense and sparse trabeculation.

classification of alveolarbone


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Classification by Lenkholm and Zarb:

(I) the jaw consists almost exclusively of

homogeneous solid bone structure; (II) a wide compacta surrounds a denselyspongiosa;

(III) a small compacta surrounds a denselyspongiosa with a good resistance;

(IV) a small corticalis surrounds porous

.

Classification


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Dl - Dense cortical bone,

D2 - Thick dense to porous cortical bone on crest and

coarse trabecular bone within,D3 - Thin porous cortical bone on crest and finetrabecular bone within,

D4 - Fine trabecular bone and

D5 - Immature, non-mineralized bone.

Classification


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Radiographic


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Bone density may be more precisely determined by

tomographic radiographs, especially computerizedtomograms. Computerized tomography (CT) producesaxial images of the patient's anatomy, perpendicular tothe axis of the body.

The bone density may be different near the crestcompared with the apical region where the implantplacement is planned.

The most critical region of bone density is the crestal 7 to

10 mm of bone. Therefore when the bone density variesfrom the most crestal to apical region around the implant,the crestal 7 to 10 mm determines the treatment planprotocol .

g p

bone density

Intraoral periapical radiographs are made usingImaging modalities


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Intraoral periapical radiographs, are made usingparalleling technique . Periapical radiography used to

rule out the presence of pathosis, location of anatomicstructures in relation to implant site . It also determinesvertical height, architecture and bone quality [density,amount of cortical bone and amount of trabecular bone]


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Digital Radiography:


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Direct digital intraoral imaging is an emerging

and alternative technique to film radiography. Itallows rapid acquisition of intraoral images andtheir enhancement, their storage, retrieval, andtransmission to remote sites.

The future utility of digital imaging may restwith the operators ability to manipulate imagedensity and contrast and to measure bonedensity at specific sites .

electronic or CCD imaging


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With charge coupled devices (CCDs) presurgical implantassessment of single sites becomes precise. CCDs allowaccurate measurement of implant sites preoperatively andprovide more information about osseointegrationpostoperatively than with film.

The use of wire grids helps in site selection and bone heightdetermination. Multiple images of a site allow two and threedimensional reconstruction of the proposed site and allowviewing the information on a video monitor prior to

placement .

g gtechniques:

Occlusal Rad iog raphs


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Occlusal radiographs are used for the edentulousmandible/maxilla to obtain information regardingbucco-lingual width and contour .

Applications: Individual implant sites and mapping formultidirectional tomography.

g p

Cephalometr icradiography


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Cephalometric radiographs with lateral, posteroanteriorand oblique views of the jaws will provide pertinentinformation like angulation, thickness and vertical boneheight in the midline, inter-jaw skeletal relationshipsand the soft tissue profile .

Together with regional periapical radiographs,quantitative spatial information is available todemonstrate the geometry of implant site and the spatialrelationship between implant site and critical structures such

as the floor of nasal cavity, the anter ior recess of maxi l lary

sinus and the nasal palatine canal.

radiography

Panoram ic rad iog raphy


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Panoramic radiographs are used for the longitudinalassessment of the success of the implant. Panoramicimages provide a broader visualization of the jaws andadjoining anatomic structures.

These are widely available and can be used as screeningradiograph. They are also used to assess the crestalalveolar bone and cortical boundaries of the mandibularcanal, maxillary sinus and nasal fossa .


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Zonography:

Recently, a modification of the panoramic x-ray machine has beendeveloped that has the capability of making a cross-sectional image of the

jaws. These devices employ limited angle linear tomography (zonography)and a means for positioning the patient.

This technique enables the appreciation of spatial relationship between thecritical structures and implant site and quantification of geometry ofimplant site.

It has limited usefulness, especially in the anterior regions. Thetomographic layers are relatively thick and have adjacent structures thatare blurred and superimposed on the image, limiting the usefulness of thistechnique for individual sites, especially in the anterior regions where the

geometry of alveolous changes relatively rapidly. This technique is not useful for determining the differences in most bone

densities or identifying disease at implant site .

Cross Sectional Imaging


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Cross sectional imaging include

- Conventional tomography. - Computed tomography (CT).

- Magnetic resonance imaging (MRI).


Conventional tomography:


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Conventional film- based tomography is designed to

obtain clear images of structures lying within a planeof interest . It used for accurate assessment ofalveolar bone height, width and inclination. It canassess both the quality and quantity of the bone. Itgives information regarding the spatial relationshipof vital structures .

g y

Computed tomography (CT):


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CT was first applied successfully in implantology in the 1980s .

In CT implant imaging, multiple thin axial slices are obtainedthrough jaws and then the data are reformatted with specialsoftware packages to produce cross-sectional and panoramicviews.

Computer software programs are available to analyze thereformatted images and aid in planning implant placementwith electronically simulated fixtures, measure the distancefrom the alveolar crest to vital structures .

Computer assisted tomography has become popular in implantand temporomandibular joint imaging with the advent ofprecise positioning techniques controlled by computer workstations.

p g p y


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The complex motion tomographic machines

incorporates most of the complex motions oftomography like circular, trispiral, elliptical,hypocycloidal .


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Principle-


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The tomogram is obtained by moving the source of x-rays in one

direction and the receptor (film or digital sensor) in the oppositedirection around the object in the focal plane.

This sharpens the object in the rotation centre as it is always in the

same place on the sensor, and blurs/hides the structures that arenot in the focal plane as they are projected in different parts of thesensor during the movement.

Objects that are situated before the slice are blurred and smaller,objects behind the slice are blurred and larger.

The thickness of the slice has an influence on the image: a thin sliceprovides more details by better removing the objects outside thefocal plane, but reduces the contrast.The thickness of the slice is determined by the angle of the slice; awide angle (long trajectory) will give a finer slice. A zonography isa tomography with a slice thickness superior to 5mm.

Principle-

Figure 2: Conventional tomogram showingclear plastic overlay used to visualize and


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determine desired length of implant placement

(11).

Figure 3: Axial CT view of the mandibleshowing the potential crosssectional


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slices that can be reformatted by

Dentascan (18).

Cone Beam Computed


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Cone beam CT is a relatively newer modality,

specifically designed for maxillofacial imagingintroduced in the late 1990s.

It is characterized by true volumetric dataacquisition obtained simultaneously during onerotation of the x-ray source.

It produces a 3-D image volume that can bereformatted using software for customizedvisualization of the anatomy. It gives all theinformation of CT at 1/8th the radiation dose and ata lower cost (17).

Tomography

Tuned Aperture ComputedTomography (TACT)


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TACT is a new and promising method for dentoalveolar

imaging based on optical aperture theory. This techniqueuses information collected by passing a radiograph beamthrough an object from several different angles. A prototypedeveloped for dental applications has a cluster of smallradiograph tubes that can be fired in close sequence.

The relationship of the source and the object can be used todetermine projection geometry after the exposure is complete.TACT can map the incrementally collected data into a single3- dimensional matrix. It can isolate the images of desired

structures limited to certain depths. It has the ability toaccommodate patients motion between exposures. It hasconsiderable flexibility to adjust contrast and resolution .

Tomography (TACT)


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Accurate distance determinations between

horizontally aligned structures such as the


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y g

mandibular canal and a vertically aligned structure

such as a Dental Implant Using TACT

Magnetic resonance imaging


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Magnetic resonance imaging (MRI) is based on the

phenomenon of nuclear magnetic resonance (NMRI). Firstdescribed in 1946, its application in implantology is however of

recent origin . MRI with a 0.2 Tesla low field scanner, has shown definite

potential as a future replacement for CT imaging with theobvious advantages that it delivers no ionizing radiation .

MRI is used in implant imaging as a secondary imagingtechnique when primary imaging techniques fail.

MRI visualizes the fat in trabecular bone and differentiates theinferior alveolar canal and neurovascular bundle from theadjacent trabecular bone .

(MRI):


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Oriented MRI imaging of the posterior mandible is

dimensionally quantitative and enables spatialdifferentiation between critical structures and the

proposed implant site.

MRI is not useful in characterizing bonemineralization or a high-yield technique foridentifying bone or dental disease .

Figure 4: A transaxial image showing the markerindicating the potential implant site (arrow). The


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g p p ( )lines show the planned position of a set of images

at right-angles to the maxilla at the site (20)


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Advantages: MRI can sharply delineate soft

and hard tissues, differentiate between cortical and

cancellous bones, zero radiation dose, flexibility of planeacquisition, gives good soft tissue details and lessartifacts.

Disadvantages: Expensive, no specialsoftware is available for specific use in implantology, anexpert radiologist is required to interpret and itsapplication in implantology is still in its experimentalphase

Diagnostic imaging forpreoperative planning


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Periapical radiographs may be supplemental when highdetailed images are indicated. To assess the suitability ofan implant site i.e. to assess the mesial/distal view, apanoramic radiograph is appropriate because it providesthe view of both jaws. Imaging information from

panoramic, cephalometric and intra-oral films alone isinadequate to evaluate the bony architecture of anyimplant site completely.

preoperative planning


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The AAOMR recommends that evaluation of any

potential implant site include cross sectional imagingorthogonal to the site of interest.

This information is best acquired with tomography,either conventional or CT. Conventional filmtomographic views are most useful when complexmotions are used such as spiral or hypocycloidalpatterns, instead of linear movement.

CT is most appropriate for patients who are beingconsidered for many implants [8-10 or more]

Surgical and


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Surgical and interventional imaging involves

imaging the patient during and immediately aftersurgery and during the placement of the prosthesis.

The purpose of surgical imaging is to evaluate thedepth of implant placement, the position andorientationof implants/osteotomies, and to evaluatedonor or graft sites. Because most implant surgeries

are performed in the doctor's office rather than ahospital, the modalities are usually limited toperiapical and panoramic radiography

interventional imaging

Di it l i i l i t bl i t ll

D g ta per ap caradiography


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Digital periapical image receptors enable virtuallyinstantaneous image acquisition, produce image qualitysimilar to that of dental film, and enable the surgicalprocedure to proceed without undue delay.

radiography


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Image enhancement and the digital measuring

techniques, can help the surgeon in establishing theoptimum depth and orientation of the implants .

The image can be manipulated to change the densityand contrast and to measure the bone density atspecific sites.

Panoramic Radiography


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For extensive implant procedures that may involve

the entire jaw, both jaws, large donor graft sites, orsinus graft augmentation, panoramic radiography

will provide a more global view of the patient'sanatomy.

Patient must generally leave the surgical site andstand or sit still for the panoramic procedure, less

resolution and shows magnification and distortion .

Panoramic Radiography

Postsurgical


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The purpose of post-prosthetic implant imaging is to

evaluate the status and prognosis of the dental implant.

The bone adjacent to the dental implant should be

evaluated for successful integration, fibrous tissueinterfaces, inflammation, or infection, loss of crestal boneadjacent to the dental implant, excessive functionalloading, or para functional loading.

Loss of cylindrical bone volume adjacent to the implant

surface may indicate excessive axial or shear loading,bone damage during implant placement, integrationfailure with an epithelial bone implant interface,inflammation, and/or infection .

assessment


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Loss of cylindrical bone volume adjacent to the implant

surface may indicate excessive axial or shear loading, bonedamage during implant placement, integration failure withan epithelial bone implant interface,inflammation, and/orinfection .

Figure 5: Periapical radiograph showingmoderate bone loss (saucerization type)


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( yp )cervical region (11).

Marginal bone loss of approximately 1.2 mm in the firstyear and 0.1mm is subsequent years is generally


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considered acceptable. Conventional intraoral and

panoramic radiography are most widely used for postsurgical assessment and in most cases, are adequate forthis task.

The short- and long-term evaluation of crestal bone loss

around implants is best evaluated with Bite-wingradiographs. In these images, the superior one third ofthe implant is the region of interest . Cross-sectionalimaging is usually not required for routine post-surgicalevaluation of implants. However, it may be of benefit in

certain cases to evaluate potential complications


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The short- and long-term evaluation of crestal bone

loss around implants is best evaluated with Bite-wing radiographs. In these images, the superior one

third of the implant is the region of interest . Cross-sectional imaging is usually not required for routinepost-surgical evaluation of implants. However, itmay be of benefit in certain cases to evaluate

potential complications

Processed stent withmetal cylinders marking


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metal cylinders marking

the implant sites


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The value of imaging may be enhanced with the use

of an imaging stent. The intended implant sites areidentified by markers made of radiopaque spheres or

rods (metal, composite resin, and gutta-percha)retained within an acrylic stent which the patientwears during imaging procedure .

Diagnostic dentures coated with barium paste maybe used during imaging. Only nonmetallic

radiopaque markers are (gutta-percha, compositeresin) used in CT imaging because metal markersproduce image artifacts

-used to create a pilot hole

th h th d t t th


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through the denture toothon the cast.

pilot hole on the cast to

verify position and


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verify position and

angulation.

-placed on the guide pin

ith th t ti b k t


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with the retentive bracket

toward the lingual.

gel is carried over the

i i l d t t


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incisal edge to create

stability of the stent to theadjacent teeth.

The surgical stent is shown

i t ll


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intraorally.


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Summary andl i


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Many radiographic projections are available for implantimaging.

Intraoral, panoramic and cephalometric radiography may beused best during initial phase of patient evaluation.

Once the decision for implant placement has been made, theproposed site must be further evaluated using conventionaltomography or CT.

Film tomography is the most cost effective technique forevaluating single sites or several sites within the same quadrant

multiple sites several quadrants in dentate patients or multiplesites in edentulous patents may be more effectively studied byCT. MRI is not commonly used for implant imaging becausebony detail cannot be readily appreciated.

conclusions

A 2-mm osteotomy drill isbeing used through the


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g g

surgical stent intraorally.


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placed using the surgicalstent demonstrates final


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positioningrelative to thestents sleeve.

open Guide Right sleeve

for placement of a lower


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for placement of a lower

first molar.

Osteotomy drill being usedin an open sleeve Guide


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p

Right surgical stent.

achieved using the open

sleeve Guide Right


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sleeve Guide Right

surgical stent.


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. Stents facilitate the application of bone measurements

from the radiograph to the clinical scenario. Stents alsomay be designed to evaluate the path of insertion and

axial inclination of the anticipated implant and theemergence profile of the implant.

Most imaging stents can be converted to surgical guidesfor use in the surgical phase of implant treatment to orientthe insertion angle of the guide bur and the angle of the

implant. For optimal visualization the width of themarkers should be less than the thickness of conventionaltomographic image layer .

Dosimetry


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Definitions


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Radiographic template: Acrylic resin guide used by

the surgeon to direct the placement of an implantinto its proper position.

It uses information from 2D panoramic radiographsand 3D CT or digital volume tomography (DVT)scans to achieve optimal implant body placementwithin the available bone and to preserve vital

structures.


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Image guidance: General technique of using pre-

operative diagnostic imaging with computer-based

planning tools to facilitate surgical and restorative

plans and procedures.


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Imaging guide: Scan to determine bone volume,

inclination, and shape of the alveolar process, andbone height and width used at a surgical site.


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Surgical navigation: Computer-aided, intra-

operative navigation of surgical instruments at theoperation site using real-time matching to the

patient's anatomy.During surgical navigation, deviations from the

preoperative plan can be immediately observed onthe monitor.


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Computer-aided navigation: Intra-operative

navigation computer systems provide the surgeonwith current positions of the instruments and the

operation site on a 3D reconstructed image of thepatient that is displayed on a monitor intheoperating room.

System aims to transfer pre-operative planning on

radiographs or CT scans of the patient in real timeand independent of the position of the patients head.


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Surgical template (surgical guide): Laboratory-

fabricated guide based on ideal prosthetic

positioning of implants used during surgery.


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Stereolithographic guide: Surgical guides that assist

placement of implants in vivo in the same locationand direction as those in a planned simulation.

Stereolithography (3D layering and 3D printing) is atechnique that is used to create solid plastic 3Dobjects from CAD drawings by selectivelysolidifying an ultraviolet-sensitive liquid resin

(photopolymer) using a laser beam.


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Use of


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StereolithographicTemplates for

Surgical and ProsthodonticImplant Planningand Placement.


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There were working and nonworking sideinterferences in the molar region resulting in arestricted range of mandibular movement.

The prostheses had open margins with resultantsecondary caries in the abutment teeth.


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The porcelain had fractured off in

several places resulting in the exposure

of metal substructure and unacceptableocclusion.

Periodontal charting revealed probing

depths between 6 and 9 mm, andsignificant bleeding was observed onprobing.


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Radiographic examination revealed periapical

lesions around all the abutment teeth with significant

bone loss.


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The diagnostic casts were articulated on a

semiadjustable articulator using facebow transfer

and a centric relation interocclusal record.

A comprehensive treatment plan was presented

to the patient based on clinical and radiographic

findings, articulated diagnostic casts, diagnostic wax-

up, and, to some extent, the patients desires.

After consultation with the endodontist and the periodontist, it was


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determined that the mandibular posterior teeth had a poor

prognosis.

The existing fixed partial dentures were removed and the teeth were

extracted to eliminate the periodontal pathology.

Diagnostic Wax-Up/RadiographicTemplate


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A diagnostic wax-up was done, and a Broaderick

occlusal plane analyzer was used to develop an

ideal plane of occlusion. The diagnostic waxup

was duplicated in the form of a radiographic

template using resin.


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Gutta-percha markers were placed in the mesio-distal

centers of the buccal aspect of the teeth in the resintemplate.

(It might have been better to have used barium sulphate

denture teeth, for the radiographic template for more

precise planning).


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The barium teeth are a more accurate representation


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of the intended restoration as they appear on the

reformatted CT data.

This would prevent the possibility of deviating

from the confines of the intended restoration while

moving the simulated implants or using angulation

correcting abutments.


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Denture teeth of molds identical to the barium teeth

may then be used for fabricating a fixed or

removable interim prosthesis using a vinylsiloxane

index made from the radiographic template.

Scanning Procedure


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The patient was sent for a spiral CT scan with1 mm slice intervals and a 0 gantry tilt. The

raw data were sent electronically for reformatting into avirtual 3D model along with parasagittal views of thebone.

12 shows 0 degreeGantry tilt


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3D Computer Simulation


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The implant simulation was carried out usingSurgicase software with the 3D model andparasagittal views The surgeon finalized the length

and diameter of each implant along with theiroptimal spatial positioning within the bone.

On the right side,the two distal implants were keptshorter due to proximity to the inferior dental

alveolar canal.


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The abutments were also selected at this stagebased on the angulations of the implant as they

related to the 3D representations of the guttapercha

markers used in the radiographic template.

On the left side, use of angulated abutments wouldnot be necessary,as the long axes of the four implantsappeared to be emerging from the center of theocclusal surface of the intended definitiverestoration.


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The finalized 3D simulation was electronicallysent to lab. The stereolithographic models andtemplates (Surgiguides) were received after 2 weeks

(Fig 6).


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Prior to surgery, a second set of templates were


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used to drill holes in the stereolithographic modelto familiarize the surgeon with the system.

The mandibular nerve was selectively colored red and

the remaining osseous structure of the mandible

was made transparent in the stereolithographic

model.


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Following the trial drilling on the model, it was reassuring tosee that the drill sites were well away from the nerve andclosely resembled the 3D model of the computer simulation.

This model could be articulated with the cast of theopposing dentition and used to fabricate an interim

definitive prosthesis.

Surgical Procedure


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Since it was the first time the system was being

used by this team, implant placement was carried

out separately for the right and left sides.

A fullthickness mucoperiosteal flap was reflected

and the first template corresponding to the 2-mm

twist drill was seated. Care was taken to prevent the

free ends of the flap from interfering with the seating

of the template

Osteotomies with the 2-mm drill were completed

and then enlarged using the second templatecorresponding to the 3-mm twist drill


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corresponding to the 3 mm twist drill.

Implants were placed and conventional procedures

were followed for the two-stage procedure.

At this point, dimensions of all implants usedduring surgery were compared with those planned

preoperatively; they were identical for all eight

implants.


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Implants were allowed to integrate for a periodof 4 months during which time the patient was

wearing a removable partial interim prosthesis.


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ProsthodonticProcedure


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Following second-stage surgery, an implant-levelimpression was made using polyether impression

material (Impregum, 3M, St. Paul, MN) along

with a new centric relation record to articulate the

master casts.


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The previously selected abutments were orientedappropriately on the cast using a clear vacuum-formed template of the initial wax-up as a guide.

The metal framework was then fabricated alongwith an interim fixed prosthesis at the abutmentlevel. GC pattern resin (GC Corporation, Tokyo,

Japan) was used to connect the abutments together

in the form of an abutment transfer assembly to helptransfer them intraorally.


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The abutments were transferred to the implantsand hand tightened. The metal framework

was then tried in and radiographs were

made to verify the seating of the abutments and

framework.

The framework was removed, abutment screws

torqued, and the interim prosthesis secured in

place over the abutments.


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p

The prostheses were tried in the patients mouth andfunctionally equilibrated.


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. This was followed by the insertion of the definitiveprosthesis. All the abutments used were identical

to those planned and the resulting screwretained

definitive prosthesis displayed screw access holesoriented in the center of the occlusal surfaces of theteeth (Fig 8).

A posttreatment panoramic radiograph was made (Fig

9).


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In addition, the screw access holes for all eightimplants placed were predictably oriented near thecenter of the occlusal surface of the definitive

prosthesis. At the 18-month postinsertion follow-up, probing

depths were 3 to 4 mm and horizontal bitewingradiographs revealed stable bone levels

corresponding to the first thread of all the implants.


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That near ideal surgical and prosthodontic implantplacement can predictably be achieved usingstereolithographic templates (Figs 10 and 11).

The mucosally supported templates could make theprocedure less invasive and significantly reduce thetime required for comprehensive oral rehabilitationwith dental implants.

CONCLUSION


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The imaging modalities that exist today can enhancethe success and satisfaction with implant placement.Selection of projection should be made with

consideration to the type and number of implants,location and surrounding anatomy. As in the case ofall imaging, appropriate selection criteria must beapplied individually to each patient.

THANK YOU!


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Chapter FOUR


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STRESS TREATMENT

THEOREM FORIMPLANT DENTISTRY

The most common Implant related complications are

Most Common Implantrelated Complications.


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Biomechanical problems that occur after the Implant isloaded ( with in 18 months of initial Implant loading).

These early Implant loading failure occur mostly in Softest

bone type (16% failure) or the shortest Implant length (17%failure).

BiologicalBi

omechanical

Stress Treatment Theorem:Biological vs


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Biomechanical

Implant Failure Early LoadingFailure

Micromovement.

Surgical Failure. CellularBiomechanics.

Healing. Engineering.

Crestal Bone loss Bone Mechanics

Periosteal Reflection.

Osteotomy.

Autoimmune.

Biological Microgap.

Prosthetic Complications Mechanics Screw loosening. Attachment Wear

Component Fracture. AttachmentFracture

Implant Body Fracture. Denture ToothFracture.

Biomechanical


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