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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
3
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
4
• 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
5
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
Contemporary Fixed Prosthodontics 3rd edition
6
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
7
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
Herbert T. Shillingburg 3rd edition
9
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
Herbert T. Shillingburg 3rd edition
10
Taper
Freedom of displacement
Herbert T. Shillingburg 3rd edition
11
Length
Substitution of internal feature
Path of insertion
Herbert T. Shillingburg 3rd edition
12
Structural durability
• Adequate space created by tooth preparation
Occlusal reduction Axial reduction
13
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
Herbert T. Shillingburg 3rd edition
14
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
15
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
16
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.
17
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
18
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.
Herbert T. Shillingburg 3rd edition
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
20
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
Herbert T. Shillingburg 3rd edition
21
• 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
22
Modification of shoulder finish line Support for ceramic restoration is good
Herbert T. Shillingburg 3rd edition
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
23
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
25
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
Contemporary Fixed Prosthodontics 3rd edition
26
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
Herbert T. Shillingburg 3rd edition
Knife edge/ Feather edge
27
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
Contemporary Fixed Prosthodontics 3rd edition
28A. Featheredge, B. Chisel, C. Chamfer, D. Bevel, E. Shoulder, F. Sloped Shoulder, G. Beveled shoulder Contemporary Fixed Prosthodontics 3rd edition
30
• 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 )
31
• Both ZZ and E copings presented better marginal fit on shoulder preparations than chamfer preparations.
European Journal of Dentistry April 2012 - Vol.6
32
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
Herbert T. Shillingburg 3rd edition
33
• 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
35
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
36
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
37
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
38
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
39MOHD.SIBGHATULLAH KHATIB
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
41
Full veneer crownsFull metal
42
Metal ceramic crown
Full veneer crown
43
Metal ceramic crown
Full veneer crown
44
Full veneer crown ALL CERAMIC CROWN
45
Partial veneer crowns
46
Porcelain laminate veneers
47
A conservative method of restoring the -Discolored
Pitted
Fractured anterior teeth.
48
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
50
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
51
Finish lines for intracoronal restorations
52
Enamel pattern Occlusal surface Axial surface
Clincal significance
Cavity wall angulation
ConvergentDepending upon the
buccolingual width
Divergent
Parallel
Cavity prepared
Amalgam
Bevels Cast gold
53
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
54
Cavosurface margin Cavosurface angle Cirumferential tie
Terminologies
55
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
56
Classification
1. Partial bevel 2. Short bevel3. Long bevel4. Full bevel5. Counter bevel6. Hollow ground (concave) bevel
57
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
58
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
59
Bevel with different restoration
• Amalgam ………..
• Composite …..
60
Amalgam
Cavosurface angle Gingival margin
Cavosurface Margins in Direct restorations
61
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
62
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.
63
Anterior composite restoration
Class III composite
Beveled conventional class III design
64
Anterior composite restoration
Bevelled conventionalClass IV restoration
65
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
66
Anterior composite restorations
• 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
67
Anterior composite restorations
68
Anterior composite restorations
Class V restoration
Conventional Bevelled conventional
69
Posterior composite restorationEnamel margin design
90 degree exit 45 degree bevel
Concave bevel (chamfer)
70
• 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
72MOHD.SIBGHATULLAH KHATIB
1ST PG STUDENT
GOOD MORNINGDon’t stop when you are tired.
STOP when you are DONE……
73
Margins in Indirect restorations
74
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.
76
77
Cast metal inlay Bevel
78
• Basic part of circumferential tie
• Similar to long bevel
• Angulations of 45 degrees to inner dentinal wall
Flare Primary
79
• 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
81
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
82
• 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.
87
OnlayCounter bevel
88
Onlay
CollarSkirt
89
Summary
Extracoronal restoration
Intracoronal restoration
90
Restoration Finish line design
Finish Line dimension
Purpose
Full metal Chamfer, knife-edge, shoulder
with bevel
0-1mm Marginal integrity, structural durability
91
Restoration Finish line design
Finish Line dimension
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
Restoration Finish line design
Finish Line dimension
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
Restoration Finish line design
Finish Line dimension
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
Restoration Cavosurface margin design
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
Restoration Cavosurface margin design
Margin features Purpose
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
Restoration Cavosurface margin design
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
Restoration Cavosurface margin design
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
Restoration Cavosurface margin design
Margin features Purpose
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
Restoration Cavosurface margin design
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
INDIRECT RESTORATION
103
Restoration Cavosurface margin design
Margin features Purpose
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
INDIRECT RESTORATION
105
Restoration Cavosurface margin design
Margin features Purpose
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
INDIRECT RESTORATION
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
INDIRECT RESTORATION
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
INDIRECT RESTORATION
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
112