finish lines (3) final

1MOHD.SIBGHATULLAH KHATIB

1ST PG STUDENT

GOOD MORNINGSUCCESS is not just a measure of how

big you can DREAM…It is also a measure of how much you can DO

2

FINISH LINE

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Contents

• Introduction • Definition • Principles of tooth

preparation• Finish lines for

Extracoronal restorationsFull veneer crown

Complete cast crownMetal - ceramic crownAll-ceramic crown

– Porcelain veneer crown

Partial veneer crown Onlays• Finish lines for

Intracoronal restorationsInlays AmalgamDirect filling goldCompositesGlass ionomer cement

• Conclusion

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• One of the basic tenets of restorative dentistry is to conserve as much tooth structure as possible consistent with the mechanical and esthetic principles of tooth preparation.

Introduction

Contemporary Fixed Prosthodontics 3rd edition

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Introduction

• Restoration can survive in the biologic environment of the oral cavity only if the margins are closely adapted to the finish line of the preparation


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According to Schwartz

• Refers to the border of the preparation where the prepared tooth structure meets the unprepared surface of the tooth.

According to Rosenstiel

1. A line of demarcation 2. The peripheral extension of a tooth preparation 3. The planned junction of different materials4. The terminal portion of the prepared tooth.

Definition

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Principles of tooth preparation1. Preservation of tooth structure2. Retention and resistance3. Structural durability – Marginal geometry4. Marginal integrity – Marginal adaptation5. Preservation of the periodontium – Margin placement

Herbert T. Shillingburg 3rd edition

8

Preservation of tooth structure

• Avoide excessive destruction

• Design restoration to reinforce and protect remaining enamel and dentin


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Retention & Resistance

• Retention prevents removal of the restoration along the path of insertion or long axis .

• Resistance prevents dislodgement of the restoration by an apical/oblique forces


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Taper

Freedom of displacement


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Length

Substitution of internal feature

Path of insertion


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Structural durability

• Adequate space created by tooth preparation

Occlusal reduction Axial reduction

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Marginal integrity

• Margins of restoration must be closely adapted to finish line of preparation

• Configuration of the preparation finish line dictates the shape of restorative material in the margin of the restoration

To bevel….. ….Not to bevel


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Finish line in extracoronal restoration

Chamfer

Heavy chamfer

Shoulder

Sloping shoulder

Radial shoulder

Shoulder with bevel

Knife edge/ Feather edge

Chisel edgeContemporary Fixed Prosthodontics 3rd edition

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Extracoronal restorations - Finish line configurations

• Finish line classification according to width

Marginal width less than 0.3mm - Knife-edge/ feather edge

Marginal width upto 0.3mm – Chamfer

Marginal width greater than 0.3mm - Shoulder

A.J. Hunter JPD 1990;64

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Chamfer

• GPT- A Finish line design for tooth preparation in which the gingival aspect meets the external axial surface at an obtuse angle.

• TYLMANN (1965): Concave extra coronal finish line that provides greater angulation than a knife-edge and less width than a shoulder.

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Advantage Disadvantage Indication

•Distinct margin•Adequate bulk•Easier control

•Care needed to avoid unsupported lip of enamel

•Cast metal restoration•Lingual margin of metal ceramic

Bur

Round end taper Round end taper

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Heavy chamfer

Provides 90 degrees cavosurface angle with a large radius rounded internal angle.

A bevel can be added to the heavy chamfer for use with metal restoation.


19Round end taper

Bur

Advantage Disadvantage Indication•Better support for a ceramic crown

•Unskilled operator can create an undesirable fragile “lip” of enamel at cavosurface

•Ceramic crown•With bevel metal crown

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Finish line of choice for all-ceramic crown

Wide ledge provides resistance to occlusal forces

Produce the space for healthy restoration contours and maximum esthtetic

Shoulder


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• Advantage • Disadvantage • Indication•Bulk of restorative material

•Less conservative of tooth structure

•Stress concentration at 90 degree internal angle of the finish line, hence conducive to coronal fracture

•Facial magin of metal ceramic crowns

•Complete ceramic crown

Flat end taper

Bur

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Modification of shoulder finish line Support for ceramic restoration is good


Radial shoulder

• Advantage • Disadvantage • Indication•Stress concentration lesser than the classic shoulder

•Less conservative of tooth structure

•Facial magin of metal ceramic crowns•Complete ceramic crown

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Flat end taper End cutting carbide finishing bur

Modified bine-angle chisel

Bur

24Herbert T. Shillingburg 3rd edition

Shoulder with bevel

• Advantage • Disadvantage • Indication•Bulk of material •Less conservative,

extend peraparation apically

•Facial magin of posterior metal ceramic crowns with supragingival margin

Uses – • Gingival finish line on the proximal box of inlays and onlays• Occlusal shoulder of onlays and mandibular three-quarter crowns• Finish line for extremely short walls• More destruction of tooth - NOT USED routinely for full veneer

restorations

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A 120-degree sloped shoulder margin used as an alternative to the 90-degree shoulder for the facial margin of a metal-ceramic crown.

Reduces the possibility of leaving unsupported enamel

Provides sufficient bulk to allow thinning of the metal framework to a knife-edge for acceptable esthetics.

Sloping shoulder

• Advantage • Disadvantage • Indication•Bulk of material •Less conservative of

tooth sturcture•Facial magin of metal ceramic crowns


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The ultimate finish line that permit an acute margin of metal

Uses –• Lingual surface of mandibular posteroior teeth• Very convex axial surfaces• Surface towards which tooth is tilted

Disadvantage – • Axial reduction may fade out • Thin margins difficult to wax and cast• Overcontoured restorations


Knife edge/ Feather edge

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Chisel edge

• A variation of the featheredge, • Formed when there is a larger angle between

the axial surfaces and the unprepared tooth structure.

• Associated with an excessively tapered preparation


28A. Featheredge, B. Chisel, C. Chamfer, D. Bevel, E. Shoulder, F. Sloped Shoulder, G. Beveled shoulder Contemporary Fixed Prosthodontics 3rd edition

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• Shoulder margins provide good seat but a comparatively wider marginal seal

• Chamfer, long chamfer and feather edge margin provide superior sealing of the margins despite poor seat.

Journal of Clinical and Diagnostic Research. 2015 Aug, Vol-9(8 )

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• Both ZZ and E copings presented better marginal fit on shoulder preparations than chamfer preparations.

European Journal of Dentistry April 2012 - Vol.6

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Preservation of the periodontium

• Margins as smooth as possible • Kept clean by the patient • Supragingival placement of finish lines whenever

possible! • Subgingival finish lines 2.0 mm from alveolar crest


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• The biologic width is defined as the dimension of the soft tissue, which is attached to the portion of the tooth coronal to the crest of the alveolar bone

• Biologic width (EA + CTA) dimensions -– Anterior teeth 1.75mm– Premolars 1.97mm– Molars 2.08mm

Biologic width

J Clin Periodontol 2003; 30: 379–385

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Margin placement

Supragingival margin Equigingival margins Subgingival marginPlaced in non-esthetic area

At the crest of the marginal gingiva

Below the gingiva

Least impact on periodontium

More impact on the periodontium

Greatest biologic risk

More plaque retentive May violate gingival attachment apparatus

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Margin placement guidelines

If the sulcus probes 1.5mm or less, place the margin 0.5mm below the gingival crest

If probing depth more than 1.5mm – place the margin half the depth of the sulcus below the crest

If probing depth more than 2.0 mm – Gingivectomy is advocated

Indian Journal of Clinical Practice, Vol. 23, No. 11, April 2013

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Orkin et al

Silness

Indian Journal of Clinical Practice, Vol. 23, No. 11, April 2013

Subgingival restorations

Bleeding

Gingival recession

Supragingival position of the crown margin

Margins below the gingival margin

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Finish line exposure

• Mechanical– Copper tube/band– Rubber dam

• Chemomechanical (retraction cord)– Caustic chemicals – sulfuric acid, trichloracetic acid,

negatol, zinc chloride– Racemic epinephrine– Aluminium chloride, alum, aluminium sulfate, ferric sulfate

• Rotary curettage/ gingettage • Electrosurgery


1ST PG STUDENT

GOOD MORNINGBeginning well is a momentary thing;

finishing well is a life long thing.

40

Extracoronal restoration - Full veneer crowns

All ceramic crown

Full metal crown Metal ceramic crown

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Full veneer crownsFull metal

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Metal ceramic crown

Full veneer crown

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Metal ceramic crown

Full veneer crown

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Full veneer crown ALL CERAMIC CROWN

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Partial veneer crowns

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Porcelain laminate veneers

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A conservative method of restoring the -Discolored

Pitted

Fractured anterior teeth.

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According to sturdavent

– PLV can be classified into1. Partial veneers2. Full veneers

a) Window preparationb) Incisal lapping

Windows Feather Bevel Incisal overlap

Four basic preparation designs for the incisal edge reduction.........

Incisal edge reduction

Walls et al. Crowns and other extra-coronal restorations: Porcelain laminate veneers :British dental journal 2002;193 : 2:73-81

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Cervical finish line

Long chamfer with about a 0.4 mm maximum depth.

• Proximal finish line– Incisal third of the tooth - not to extend beyond the

contact point

Walls et al. Crowns and other extra-coronal restorations: Porcelain laminate veneers :British dental journal 2002;193 : 2:73-81

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Finish lines for intracoronal restorations

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Enamel pattern Occlusal surface Axial surface

Clincal significance

Cavity wall angulation

ConvergentDepending upon the

buccolingual width

Divergent

Parallel

Cavity prepared

Amalgam

Bevels Cast gold

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Noy’s criteria

1. Enamel must be supported by sound dentin

2. The enamel rod which form the cavosurface angle must

have their inner end resting on sound dentin

3. Enamel rods forming cavosurface angle should be

covered with restorative material4. Angular cavosurface angles should be trimmed

M.A Marzouk

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Cavosurface margin Cavosurface angle Cirumferential tie

Terminologies

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Bevels

Plane of a cavity wall/ floor directed away from the cavity preparation

Any angle other than 90o between a tooth cut and a cavity wall in the preparation of the tooth cavity

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Classification

1. Partial bevel 2. Short bevel3. Long bevel4. Full bevel5. Counter bevel6. Hollow ground (concave) bevel

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Partial bevel • Not more than two third the thickness of enamel• Used to trim weak enamel rods at the margins

Short bevel• Entire enamel wall but not dentin• Used for class I alloys – type I and II alloys

Long bevel• Entire enamel+1/2 of dentinal wall• Used for first three classes of cast alloys• Preserves internal box form of resistance and

retention featureFull bevel• Entire enamel and dentin• Resistance and retention form hampered• All classes of cast alloys

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Hollow ground (concave) bevel• Concave form• For base metal alloys and castable ceramics• Improves castability• Provides bulk

Cusp capping Opposite to axial cavity wall on facial or lingual surfaces

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Bevel with different restoration

• Amalgam ………..

• Composite …..

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Amalgam

Cavosurface angle Gingival margin

Cavosurface Margins in Direct restorations

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Margins in Direct tooth coloured restorations

• General concepts1. Minimal extension2. Pulpal and/or axial walls of varying depth3. Enamel bevel4. Butt joint on root surfaces5. Tooth preparation walls must be rough

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Direct tooth coloured restoration• Five designs of tooth preparations for composite restorations are..........

1. Conventional • Similar to amalgam cavity preparation designs

2. Beveled conventional • Similar to conventional but bevels given

3. Modified • Scooped out design

4. Box only • Proximal caries

5. Slot preparation designs.

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Anterior composite restoration

Class III composite

Beveled conventional class III design

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Anterior composite restoration

Bevelled conventionalClass IV restoration

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Anterior composite restorations

According to Albers• Class IV cavity preparations– Chamfer design – Bevelled margins

1. Chamfer design– 1mm long or half the length of fracture– Most durable restorative margins– Stair stepping – better esthetics

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• Bevelled margins– Alternative to stair step chamfer– 2-3mm bevel– Better esthetics – Bevels in a curve better than scalloped margins– Drawback• Margins not as durable as chamfer• Chipping

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68


Class V restoration

Conventional Bevelled conventional

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Posterior composite restorationEnamel margin design

90 degree exit 45 degree bevel

Concave bevel (chamfer)

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• Internal bevel at the cervical cavosurface of class 2 composite restoration reduced marginal microleakge as compared to conventional butt joint

JIOH, October 2010, Volume 2 (Issue 3)

71

Margins in direct gold restoration

• Cavosurface margin bevel – Partial bevelWidth – not more than 0.2mm30-40 degrees metal marginGingival margin bevelled if on enamelShould include atleast 1/4th enamel wallWedelstaedt chisel used

• Allows coverage of the enamel margin with the restorative material


1ST PG STUDENT

GOOD MORNINGDon’t stop when you are tired.

STOP when you are DONE……

73

Margins in Indirect restorations

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Advantage Indication •Large restoration•Endodontically treated teeth•Teeth at risk for fracture•Removable prosthodontic abutment

•Strength•Biocompatibility•Low wear•Control of contour and contact

Contraindication •High caries rate•Young patient •Esthetics•Small restoration

Disadvantage •Number of appointment•Temoprary •Cost •Technquie sensitive •Splitting force

75

Cast metal inlay

• It is as intracoronal cast restoration replacing one or more, but not all of the cusps fabricated extrorally using direct or indirect wax pattern.

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Cast metal inlay Bevel

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• Basic part of circumferential tie

• Similar to long bevel

• Angulations of 45 degrees to inner dentinal wall

Flare Primary

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• Function -Same as bevelsBrings facial and lingual margins to self –

cleansable areas• Indication -

Normal contacts Minimum extension of caries in the buccolingual dimension

80

• Flat plane superimposed peripherally to a primary flare

• Prepared solely in enamel, sometimes includes dentin

• No definite angulation – depends on involvement and extent

• 40 degrees marginal metal and 140 degrees marginal enamel desirable

Flare Secondary

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Indications Indirect wax pattern Broad contact areasWide extension of caries buccolinguallyOvercome undercuts in the cervical aspect of facial and lingual proximal walls in ovoid teeth

Extends margins into embrasuresStronger enamel margin produced40 degree marginal metal

Function

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• Secondary flare omitted in mesiofacial proximal wall of –

Maxillary premolarsMaxillary molars

• Burs No. 8862/ 169 L / paper discs

84

Tooth coloured inlays

• Ceramic and Composite inlays– Facial, lingual, and gingival margins of the

proximal boxes - clear the adjacent tooth by at least 0.5 mm

– 90-degree cavosurface margin desired–Minimal gingival margin extension - margins in

enamel preferred for bonding and impression

85

Margins for onlay

86

Onlay

• According to sturdavent– The cast metal onlay by definition caps all of the

cusps of a posterior tooth and can be designed to help strengthen a tooth that has been weakened by caries or previous restorative experiences.

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OnlayCounter bevel

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Onlay

CollarSkirt

89

Summary

Extracoronal restoration

Intracoronal restoration

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Restoration Finish line design

Finish Line dimension

Purpose

Full metal Chamfer, knife-edge, shoulder

with bevel

0-1mm Marginal integrity, structural durability

91



Purpose

Metal ceramic Labiallyshoulder,

shoulder with bevel, sloping

shoulder

Lingually Chamfer

Labially 1.2mm

Lingually 0.5mm

Removes unsupported

enamel, structural durability,

marginal integrity

92



Purpose

All ceramic Shoulder, heavy

chamfer, rounded shoulder

0.7 - 1mm Marginal integrityStructural durabilityEsthetic

93

Restoration Finish line design Finish Line dimension

Purpose

Partial veneer crown

Chamfer 0-1mm Marginal integrity, Structural durability

Proximal flare Marginal integrityOcclusal/incisal offset

Structural durability

Buccal/incisal bevel

Marginal integrity, Remove unsupported enamel

Occlusal shoulder 1mm Structural durability

94



Purpose

Porcelain laminate veneer

Long chamfer 0.3-0.5mm Marginal integrity, conserves tooth structure, better

etching

95

Restoration Cavosurface margin design

Margin features

purpose

Amalgam

Butt joint 90 degrees Strongest margin for amalgam

Gingival finish line

At Gingival third- beveled

At Middle third/root surface – no bevel

15-20 degrees Remove unsupported enamel

96


Margin features Purpose

Anterior Direct

Composite Restoration

Conventional – no bevel

90 degrees margin

Lesion on root- no enamel to bevel

Bevelled conventional

(partial , long)

45 degrees0.25-0.5mm

Increased surface area for etching and bonding

According to Sturdavent

97



Anterior direct

composite restoration

Chamfer

1mm or half the length of defect

Half the depth of enamel

Durability

Bevelled (scalloped) 2-3mm Esthetics

According to Albers

98


Margin features

purpose

Occlusal Butt joint

Bevel (partial, long)

90 degrees

45-70 degrees0.25 – 0.5mm

Enamel rod ends exposed

Conserves tooth structureBetter sealing

Proximal Long bevel 0.5mm wide45 degrees

1. Increased surfacearea for etching andbonding2. Margins placed in accessible areas3. Reduced marginal leakage

Posterior direct composite restoration

99


Margin features

purpose

Gingival

Partial bevel

Butt joint .... close to CEJ

1/3rd – ½ the enamel wall

90 degrees

Better sealing

Exposes enamel rod ends internallyBetter sealing than butt joint

Direct gold restoration

Partial bevel <0.2mm 30-40 degrees metal margin

Posterior direct composite restoration

100

Cast metal inlay

Bevel

Occlusally

Gingivally

Flare

Primary Secondary

Partial bevel

101



Cast metal inlay

Occlusally – • partial bevel

• Steep cusp – no bevel

Width – 1/4th the depth of respective

wall140-150 degrees

cavosurface margin

• 30-40 degrees marginal metal – burnishible, lap

joint• Strongest cavosurface

margin

INDIRECT RESTORATION

102


Margin features purpose

Cast metal inlay

Gingivally –

• Partial bevel

• Reverse bevel – sufficient gingival

floor width

Width - 0.5-1mm150 degrees cavosurface

margin

• 30-40 degrees marginal metal –

burnishable

• Minimizes cement line

• Strongest cavosurface margin

• Removes unsupported enamel

• Resistance to dislodgement against

occlusal forces


103



Cast metal inlay

Primary flare 45 degrees to inner dentinal

wall

similar to long bevel

30-40 degrees marginal metal

• Increases retention• Self-cleansable

areas

Secondary flare Placed entirely in enamel

sometimes dentin

No particular angulation

• Acute marginal metal

• Strong enamel margins

• Extends margins to embrasures


105



Tooth coloured

inlay

Bevels and flares – hollow

ground

90 degrees butt joint

• Material bulk

• Better Resistance to stresses

Gingival margin -

hollow groundOr no bevel –

middle third/cementum

90 degrees butt joint

• Removes unsupported

enamel

• Material bulk

• Better Resistance to

stresses


106

Restoration Margin design Margin features purpose

Cast metal onlay

Counter bevel

Facial and lingual margin of reduced

cusp

Structural durability, marginal integrity,

retention, stress distribution 30-40 degrees marginal

metal

Just gingival to tip and ridge crests

Flat sometimes partial bevel given if unsupported enamel

remains

Increased resistance and retention

Conservation of tooth structure

Gingival bevel and secondary flares similar to inlay


107

Restoration Margin design Margin features purpose

Tooth coloured onlays

Cusp protection – capping

Exaggerated hollowground counterbevel –

occlusal table to facial termination of the preparation

Shoulder – 1mm

Increased retentionStructural durability

Gingival margins and proximal

margins – same as tooth coloured

inlays


108

Conclusion...

• While choosing a configuration of finish line for extracoronal restoration one must consider the advantages and disadvantages of various finish lines

• While deciding about the placement of the finish line , periodontal health and esthetics have to be equally weighed

• For the intracoronal restoration, type of restorative material being used and the enamel pattern play an important role

109

Conclusion...

• For the restorative materials with low tensile strength like amalgam and ceramics, butt joint is preferred

• Bevels and flares are used for metals because of their property of burnishability

• Angle and width of bevels and flares also require careful placement

110

Conclusion...

“We shall neither fail nor falter , we shall not weaken or tire, give us the tools and we will finish the job”

- Winston Churchill• Hence every effort should be made to design

and prepare the marginal peripheries to create the most favourable relationship with the restoring casting and luting cement.....

111

References • Contemporary Fixed Prosthodontics 3rd edition• Herbert T. Shillingburg 3rd edition• A.J. Hunter JPD 1990;64 • Journal of Clinical and Diagnostic Research. 2015 Aug, Vol-

9(8 )• European Journal of Dentistry April 2012 - Vol.6• Indian Journal of Clinical Practice, Vol. 23, No. 11, April 2013 • Walls et al. Crowns and other extra-coronal restorations:

Porcelain laminate veneers :British dental journal 2002;193 : 2:73-81

• Sturdavent 4th edition• JIOH, October 2010, Volume 2 (Issue 3)• J Appl Oral Sci. 2012;20(2):174-9

finish lines (3) final

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