MARGINAL INTEGRITY,CIRCUMFERENTIAL TIE AND FINISH LINES.pptx

1. MARGINAL INTEGRITY,CIRCUMFERENTIAL TIE
AND FINISH LINES

2. CONTENTS
• INTRODUCTION
• PRINCIPLES OF TOOTH PREPARATION
• FINISH LINES
• MARGINAL INTEGRITY
• MARGIN PLACEMENT GUIDELINES
• FINISH LINES IN EXTRA CORONAL
RESTORATIONS
• FINISH LINE EXPOSURES
• CAVOSURFACE MARGINS IN DIRECT
RESTORATIONS
• MARGIN CONFIGURATION FOR DIRECT
RESTORATIONS
• CIRCUMFERENTIAL TIE
• FINISH LINES IN INTRA CORONAL
RESTORATIONS
• CONCLUSION

3. 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
INTRODUCTION

4. • The selection of an appropriate restorative material with its proper
clinical technique is essential for the success of the restorative
treatment.
• An adequate seating and specific adaption of the restorative
material to the preparation margins contribute to its success.
• This margin between the restoration and the tooth structure, which
is one of the weakest links in the tooth restoration complex.

5. 1. Preservation of tooth structure
2. Retention and resistance
3. Structural durability – Marginal geometry
4. Marginal integrity – Marginal adaptation
5. Preservation of the periodontium – Margin placement
Herbert T. Shillingburg 3rd edition
RULES FOR PREPARING TEETH

6. • Avoid excessive destruction
• Design restoration to reinforce and protect remaining enamel and
dentin
Herbert T. Shillingburg 3rd edition
PRESERVATION OF TOOTH STRUCTURE
Preservation of tooth structure in some cases may
require that limited amounts of sound tooth
structure be removed to prevent subsequent
uncontrolled loss of larger quantities of tooth
structure.

7. • 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
Retention & Resistance
No cements that are compatible
with living tooth structure and the
biologic environment of the oral
cavity possess adequate adhesive
properties to hold a restoration in
place solely through adhesion

9. FACTORS AFFECTING RETENTION
TAPER
FREEDOM OF
DISPLACEMENT
LENGTH
SUBSTITUTION
OF INTERNAL
FEATURES
PATH OF
INSERTION

10. Taper
ANGLE OF CONVERGENCE ANGLE OF DIVERGENCE

12. FREEDOM OF
DISPLACEMENT
By limiting the paths of withdrawal, retention is improved. (b) A preparation with
unlimited freedom of displacement is much less retentive

13. The preparation with longer walls (a) interferes
with the tipping displacement of the restoration
better than the short preparation (b)
A preparation on a tooth with a smaller
diameter (a) resists pivoting movements better
than a preparation of equal length on a tooth
of larger diameter (b).
The resistance of a short preparation (a) can be improved
by adding grooves (b)
LENGTH

14. SUBSTITUTION OF
INTERNAL FEATURES

15. To examine a
preparation for
undercuts, one eye
should be closed.
Preparations in the mouth are viewed through a mouth
mirror using one eye

16. • Adequate space created by tooth preparation
STRUCTURAL
DURABILITY
Occlusal
reduction Axial reduction
Functional cusp bevel

17. • For metal alloys, there should be 1.5 mm
clearance on the functional cusps, and
around 1 mm on the nonfunctional cusps.
• Metal-ceramic crowns will require 1.5–2 mm
on the functional cusps and 1–1.5 mm on the
nonfunctional cusps.
• There should be 2 mm clearance on
preparations for all-ceramic restorations.
• For malposed teeth, only minimal
preparation may be required to obtain
clearance.
OCCLUSAL
REDUCTION

18. • The average functional cusp bevel is at a 45° angle and is
approximately 1.5 mm wide.

19. Axial reduction
Inadequate axial reduction can cause thin walls and a weak
restoration (a) or a bulbous, overcontoured restoration (b).

20. MARGINS
- The outer edge of a crown ,inlay onlay or
other restorations
FINISHLINES
- Terminal portion/peripheral extension of
the prepared tooth’.
(GPT8).

21. • 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 materials
4. The terminal portion of the prepared tooth.
FINISH
LINES/MARGINS

22. • 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
Marginal integrity

23. THE INTEGRITY OF THE MARGIN IS
DETERMINED BY:
Margin
placemen
t
Margin
geometry
Margin
adaptatio
n

24. Supragingival
margin
Placed in non-
esthetic area
Least impact on
periodontium
Equigingival
margins
At the crest of the
marginal gingiva
More impact on
peridontium
More plaque
retentive
Subgingival margin
Below the gingiva
Greatest biologic
risk May violate
gingival
apparatus
Margin
placement

25. Improved bonding with no
crevicular seepage
Preservation of cervical
tooth structure maintains
structural integrity of the
abutment
A dental dam could be
used if indicated
They can be easily finished
without associated soft
tissue trauma
They are more easily kept
plaque free
Impressions are more easily
made, with less potential
for soft tissue damage
Restorations can be easily
evaluated at the time of
placement and at recall
appointments
Elevation of the restorative
margin eliminates potential
risks of chronic periodontal
complications contributed
by restorative dentistry
Advantages of supragingival
margins

26. Dental caries, cervical erosion,
or restorations extend
subgingivally, and a crown-
lengthening procedure is
contraindicated
The proximal contact area
extends apically to the level of
the gingival crest
Additional retention,
resistance, or both are needed
The margin of an esthetic
restoration is to be hidden
behind the labiogingival crest
Root sensitivity cannot be
controlled by more
conservative procedures, such
as the application of dentin
bonding agents or connective
tissue grafts to cover exposed
root structure.
INDICATION FOR SUB GINGIVAL
MARGINS

28. • 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
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
Margin placement guidelines

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

30. MARGIN GEOMETRY
• The shape or configuration of the prepared finish line ’
• It should possess
• Ease of preparation
• Ease of identification
• Distinct boundary
• Sufficient strength
• Conservation of tooth structures

31. FINISH LINE IN EXTRACORONAL
RESTORATION
Contemporary Fixed Prosthodontics 3rd edition
Chamfer
Heavy chamfer
Shoulder
Sloping shoulder
Radial shoulder
Shoulder with bevel
Knife edge/ Feather edge
Chisel edge

32. 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
Extracoronal restorations - Finish line
configurations

33. • GPT- A Finish line design for tooth preparation in which the
gingival aspect meets the external axial surface at an obtuse
• TYLMANN (1965): Concave extra coronal finish line that provides
greater angulation than a knife-edge and less width than a
shoulder.
Chamfer

34. ADVANTAGES
• Distinct margin
• Adequate bulk
• Easier control
DISADVANTAGES
•Care needed to
avoid unsupported
lip of enamel
INDICATION
•Cast metal
restoration
• Lingual margin of
metal ceramic

35. BURS

36. • 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
restoration.
Heavy chamfer
a) Deep chamfer on a preparation for an all-ceramic
crown. (b) Ninetydegree finish line formation.

38. Advantage
•Better support for
a ceramic crown
Disadvantage
•Unskilled
can create an
undesirable
“lip” of enamel at
cavosurface
Indication
•Ceramic crown
•With bevel- metal
crown

39. • 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

40. Bur

41. Advantage
•Bulk of restorative material
Disadvantage
•Less conservative of tooth structure
•Stress concentration at 90 degree internal angle of the
finish line, hence conducive to coronal fracture
Indication
•Facial magin of metal ceramic crowns
•Complete ceramic crown

42. Shoulder with bevel
(A) Shoulder with bevel. (B) Metal on the bevelled portion
is placed subgingivally in metal-ceramic restorations.

43. • Bulk of material
ADVANTAGES
• Less conservative, extend
peraparation apically
DISADVANTAGES
• Facial magin of posterior
metal ceramic crowns
with supragingival
margin
INDICATIONS 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

44. • Modification of shoulder finish line
• Support for ceramic restoration is good
Advantages
• Stress
concentration
lesser than the
classic
shoulder
Disadvantages
• Less
conservative
tooth structure
Indication
• Facial magin
metal ceramic
crowns
•Complete
ceramic crown
RADIAL SHOULDER

45. BURS

46.  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
SLOPING SHOULDER
• Bulk of material
ADVANTAGES
• Less conservative of
tooth sturcture
DISADVANTAGES
• Facial magin of metal
ceramic crowns
INDICATIONS

48. • The ultimate finish line that permit an acute margin of metal
KNIFE EDGE / FEATHER
EDGE
• Lingual surface of mandibular
posterior teeth
• Very convex axial surfaces
• Surface towards which tooth is
tilted
USES
• Axial reduction may fade out
• Thin margins difficult to wax and
cast
• Overcontoured restorations
DISADVANTAGES

49. 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

52. •
• 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 )

53. Presented better marginal fit on shoulder preparations than chamfer
preparations.
European Journal of Dentistry April 2012 - Vol.6

54. MARGIN ADAPTATION
• The interface between a restoration and the tooth is
always a potential site for recurrent caries because of
dissolution of the luting agent and inherent surface
roughness.
• The more precisely the restoration is adapted to the
tooth, the lower is the risk for recurrent caries or
periodontal disease

55. IMPORTANCE OF MARGINAL FIT
• Well adapted margins to finish lines of preparation
provide longevity to the restoration serving marginal
integrity.
• Configuration of finish line decides the shape and bulk
of marginal metal, affects the marginal adaptation and
degree of seating.
• The junction between a cemented restoration and the
tooth is a potential site for recurrent caries.

56. • Metal casting fits within 10 μm, whereas the
porcelain margin fits within 50 μm.
• Clinically acceptable marginal gap must be less
than 120 μm.
• Improperly adapted margins act as an area of
plaque accumulation, increase cement dissolution,
and are correlated with the severity of
inflammation. It may make the tooth surface
susceptible to caries.

58. • Clinically acceptable marginal gap is 10 microns for cast metal and upto 50
microns for ceramic restorations.
• The discrepancy in adaptation can have a horizontal and vertical
component
Vertical and horizontal margin opening.

59. • 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
Preservation of the periodontium

60. • 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
Biologic Width

61. BIOLOGIC WIDTH VIOLATION
The signs of biologic width violation are:
• Chronic progressive gingival inflammation around the restoration
• bleeding on probing
• localized gingival hyperplasia with minimal bone loss
• gingival recession
• pocket formation
• clinical attachment loss and alveolar bone loss.

62. 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

63. CAVOSURFACE MARGINS IN DIRECT
RESTORATIONS

65. CAVOSURFACE ANGLE
1.The cavosurface angle is the angle of
tooth structure formed by the junction of
a prepared wall and the external surface
of the tooth.

66. FACTORS TO BE CONSIDERED IN
PREPARING CAVOSURFACE MARGIN
Direction of
enamel rods
Noy’s criteria
Type of
restorative
material
The location
of margins

67. DIRECTION OF ENAMEL RODS
• Theoretically, the enamel rods radiate from
DEJ to the external surface of the enamel
and are perpendicular to the tooth surface.
• All rods extend full length from DEJ toward
concave enamel surfaces and diverge
outwardly towards the convex surface.

68. NOY’S CRITERIA
 Enamel must be supported by sound dentin
 Enamel rods forming the cavosurface margin should be
continuous with sound dentin.
 Enamel rods forming the cavosurface margin should be
covered with the restorative material.
 Angular cavosurface angles should be trimmed.

70. BUTT JOINT
• 90–100º cavosurface angle produces a butt joint.
• Butt joint is usually given for brittle materials which
have low edge strength.
Direct Filling
Gold
restorations
Glass
ionomer
restorations.
Amalgam.

71. AMALGAM RESTORATIONS
The location of the margin for amalgam is determined by its
property of high compressive strength and weak tensile
strength.
 Occlusal margins should be located on smooth surfaces,
inclined cuspal planes, marginal ridges, and crossing ridges.
 Enamel cavosurface margins of 90°- 110° (butt joint) prevent
enamel fracture and help marginal amalgam tolerate
masticatory forces.

72. • For class II restorations, the finished gingival margins
should be located in the gingival sulcus' occlusal portion.
• If it is gingival to the CEJ, the gingival cavosurface angle of
90° to the external root surface is needed.
• Proximal clearance of 0.5 mm should be given; since it
compensates for setting the amalgam. 20° declination
gingivally is given; if the gingival seat is in enamel.
• The bevel should not be given if the gingival margin is
to the CEJ and primary teeth..

73. GINGIVAL BEVELS IN AMALGAM
• In enamel – gingival cavosurface bevel
(15- 20 degrees)
- It should follow enamel rod direction
- To remove unsupported enamel

74. GLASS IONOMER RESTORATIONS:
• Glass ionomers show good adhesive property with the tooth
structure due to ionic bonding.
• Advances like resin-modified GIC has superior properties like
marginal adaptation and esthetics for restoring non-carious
cervical lesions.
• Therefore, bevelling of the margins is usually not
recommended.

75. MARGINS IN DIRECT TOOTH
COLOURED RESTORATIONS
• General concepts
1. Minimal extension
2. Pulpal and/or axial walls of varying depth
3. Enamel bevel
4. Butt joint on root surfaces
5. Tooth preparation walls must be rough

76. 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

77. CONVENTIONAL
(a) Butt joint marginal configuration.
(b) Used in areas when margins are located in nonenamel areas such
as root surface.
An inverted cone diamond stone or carbide bur is used to prepare
the tooth
(c) Not a preferred cavity design.

78. BEVELED CONVENTIONAL PREPARATION
(a) Bevel is given on enamel margins.
(c) Bevel width – 0.25-0.5mm.
(d) In class IV, bevel width is 0.25-2mm.

79. THE ADVANTAGE OF AN ENAMEL BEVEL FOR
A COMPOSITE TOOTH PREPARATION
• The ends of the enamel rods (exposed by beveling) are more
effectively etched than otherwise occurs when only the sides of the
enamel rods are exposed to the acid etchant
• The increase in etched surface area results in a stronger enamel-to-
resin bond
• Incorporation of a cavosurface bevel may enable the restoration to
blend more esthetically with the coloration of the surrounding tooth
structure

80. Ends of enamel rods (A) are more effectively etched,
producing deeper microundercuts than when only the
sides of enamel rods are etched

81. Etching patterns of tooth enamel. A, Etching pattern characterized by
removal of prism core. B, Etching pattern showing loss of prism periphery. C,
Both etching patterns are evident

82. MODIFIED PREPARATION
• Modified tooth preparations for composite restorations have neither
specified wall configurations nor specified pulpal or axial depths;
preferably, they have enamel margins.
• Round burs or diamond stones may be used for this type of
preparation, resulting in a marginal design similar to a beveled
preparation; however, less tooth structure is removed in the internal
portions of the preparation.

83. Modified preparation designs for Class III (A and B), Class IV (C and D), and
Class V (E and F) restorations.

84. BOX -ONLY
• This design is indicated when only the
proximal surface is faulty, with no lesions
present on the occlusal surface.
• A proximal box is prepared with an inverted
cone or round diamond stone or bur held
parallel to the long axis of the tooth crown
• Neither beveling nor secondary retention is
usually indicated

85. SLOT PREPARATION
• In this case, a lesion is detected on the
proximal surface, but the operator believes
that access to the lesion can be obtained
from either a facial or a lingual direction,
rather than through the marginal ridge from
an occlusal direction.
• Usually a small round diamond stone or
is used to gain access to the lesion.

86. • In slot preparations, the occlusal, facial, and gingival
cavosurface margins of 90˚ or greater should be placed.
• For a vital asymptomatic extensively carious tooth, bevel
placement is not required on occlusal cavosurface margin
unless there are unsupported enamel rods.

87. • In class III and class IV, starburst
bevel camouflages the restoration
margin; thus, providing superior
esthetics and removal of unsupported
and frail enamel structure .
• Preservation of enamel margin on
gingival seat is of utmost importance
as it is critical for bonding.

88. • Extensive class III and class IV preparations might need additional
bevel on the enamel walls for adequate retention.
• If the preparation extends gingivally onto the root surface, a 90˚
cavosurface margin should be provided in class III and class IV
preparations.
• Flame shaped or round diamond instrument can be used to create a
bevel of 45˚ angle to the external surface with a width ranging from
0.5–2 mm.

89. ACCORDING TO ALBERS
• Class IV cavity preparations
-
– Chamfer design
– Bevelled margins
Chamfer design
– 1mm long or half the length of fracture
– Most durable restorative margins
– Stair stepping
– better esthetics

90. • 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

91. • For class V restorations, there is no need for enamel bevel for
prevention of microleakage.
• In maxillary incisors, bevel on lingual aspect may be
contraindicated if it would cause the restoration marginal interface
to be placed at the incisal contact area

92. CLASS V RESTORATIONS

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

94. MARGINS IN DIRECT GOLD
RESTORATION
• Cavosurface margin bevel
Partial bevel
Width – not more than 0.2mm
30-40 degrees metal margin
Gingival margin bevelled if on enamel
Should include atleast 1/4th enamel wall
Wedelstaedt chisel used
• Allows coverage of the enamel margin with the
restorative material

95. Extracoronal restoration

96. FULL VENEER
CROWN
FULL
METAL

97. ARMAMENTARIUM FOR THE METAL-CERAMIC
CROWN PREPARATION

98. METAL CERAMIC CROWN

100. ALL CERAMIC CROWN

101. PARTIAL VENEER
CROWN

102. LITHIUMDISILICATE CROWN
PREPARATION
in vitro study was to evaluate the marginal and
internal fit of CAD-CAM ceramic crowns made from
lithium disilicate based on 3 different finish lines
(rounded shoulder, chamfer, feather-edge).
All 3 finish lines produced marginal gaps within the
range of clinically accep table values. Lithium
disilicate CAD crowns with a rounded shoulder finish
line had the best marginal fit but the poorest internal
fit, and lithium disilicate CAD crowns with a feather-
edge finish line had the best internal fit but the
poorest marginal fit.

103. • A conservative method of restoring the –
Discolored
Pitted
Fractured anterior teeth
PORCELAIN LAMINATE VENEER

104. • According to sturdavent –
• PLV can be classified into
1. Partial veneers
2. Full veneers
a) Window preparation
b) Incisal lapping

105. • Four basic preparation designs for the incisal edge reduction.........
Walls et al. Crowns and other extra-coronal restorations: Porcelain laminate veneers :British dental journal 2002;193 : 2:73-8
INCISAL EDGE
REDUCTION

106. BASIS OF NEW VENEER CLASSIFICATION SYSTEM (DENTIN EXPOSED )

108. • The influence of preparation design and material type on the success of dental veneers is
controversial..
• Nevertheless, veneers with incisal coverage seem to have better aesthetic and more
predictable outcomes, while having a chamfer finish line palatable seems to be unnecessary
and limiting the preparation to a butt-join finish line is more sensible.
• According to multiple clinical studies, porcelain veneers have excellent aesthetic results, the
longevity of the treatment and patient’s satisfaction; the most critical factors to ensure a
successful treatment are to obtain bonding to enamel and absence of parafunctional habits.
• Respectively, composite veneers provide good aesthetic outcome and patient’s satisfaction;
however, due to its physical properties and to the bonding strength when compared to
porcelain veneers, composite veneers tend to fail significantly faster than porcelain veneers

109. VERTICAL PREPARATION
• A preparation without a finish line is a less-
invasive substitute to a horizontal margin,
allowing enamel preservation in the cervical area.
• It is indicated when periodontally compromised
teeth are used as abutments for fixed prostheses.
This is referred to as the biologically oriented
preparation technique (BOPT).
• A Batt-Bur, which is a round-ended tapered
diamond bur with a non-cutting end, is used.

111. CIRCUMFERENTIAL TIE
• The peripheral marginal anatomy of the preparation is called
circumferential tie

112. PREPARATION FEATURES OF THE CIRCUMFERENTIAL
TIE
NOY’S CRITERIA
 Enamel must be supported by sound dentin
 Enamel rods forming the cavosurface margin
should be continuous with sound dentin.
 Enamel rods forming the cavosurface margin
should be covered with the restorative material.
 Angular cavosurface angles should be trimmed.

113. CIRCUMFERENTIAL TIE FOR
INTRA CORONAL RESTORATION
• For the occlusal and gingival walls in intra-coronal
cavity preparation, the tooth circumferential tie will be
in the form of a bevel,which is a plane of a cavity wall
or floor directed away from the cavity preparation.

114. BEVELS
• Six types according to the shape and tissue involvement
A. Partial bevel
B. Short bevel
C. Long bevel
D. Full bevel
E. Counterbevel
F. Hollow ground / Concave bevel
A plane of a cavity wall or floor directed away from the cavity
preparation

118. TYPES OF BEVELS
They are classified according to surface they are
placed
1)Gingival bevel
2) Occlusal bevel
3) Functional cusp bevel

119. FUNCTION OF OCCLUSAL AND
GINGIVAL BEVEL
• Bevels are the flexible extensions of a
cavity preparation, allowing the inclusion
of surface defects, supplementary
grooves, or other areas on the tooth
surface.
• Bevels create obtuse angled marginal
tooth structure

120. • Bevels are major retention forms for cast
restorations.
• Reduce the error factor to three or more folds at
the margins.
• Some bevels like hollow ground and counter bevel,
are used for the resistance form of the tooth-
restoration complex, by encompassing cusps

121. OCCLUSAL CAVOSURFACE DESIGN
• The cavosurface line angles of the preparation in the
occlusal portion of the tooth should be finished with a
bevel to avoid a right angle “butt joint”.
• Depth of cavosurface bevel on occlusal margin should be
approximately ¼ depth of respective wall.
• This should result in 30-40° marginal metal on inlay which
in turn results in a strong enamel margin with an angle of
140-150°.

122. PURPOSE OF OCCLUSAL BEVEL
• Produces a stronger enamel margin.
• Permits marginal seal in slightly undersized casting.
• Provides marginal metal that is more easily burnished and adapted.
• Reduces the amount of cement line that will be exposed to oral fluids.
• Produces the bulk of metal on the edge of tooth structure which is helpful in
waxing the pattern and finishing the casting to maintain the seal of
restorations.

123. GINGIVAL BEVEL
• Weak enamel is removed.
• Bevel results in 30° angle at the gingival margin that is burnishable
because of its angular design

124. • A lap sliding fit is produced at the gingival
margin which help in improving the fit of casting
in this region

125. GINGIVAL CAVOSURFACE SEAL:
1.The gingivo-cavosurface angle is also in the form of bevel.
Usually, the angulation for gingival bevel is 30-40° which
results in 30 ° gingival marginal metal, which is ideal.
2.The gingival bevel should be 0.5 – 1 mm wide and should
be blend with lingual secondary flare.
3.If less than 30°, a thin and weak metal will be outcome

126. FACTORS AFFECTING BEVEL ANGLE
• Increased to bevel E.rods which inclines towards the cusps.
• Angle of bevel is decreased with increase in steepness of the
cusps
• Increased bevel angulations is necessary for a direct wax
patterns as more marginal bulk is required.
• Bevel angulations should be increased to include remotely
located defects, supplementary grooves or decalcifications on the
occlusal surface.

127. • In wider cavities and in deeper ones, they are extended to
improve the taper & reduce frictional components for easier
material manipulation.
• Bevel on the occluding surface of the tooth produces thin
feather edges in gold casting which are subject to injury by
attrition and excessive forces during mastication.

128. • As conditions require the occlusal width of the
preparation to be extended bucco lingually the degree
of the occlusal bevel must be increased.
• This increase will result in the forces of occlusion
driving the margin of the casting into closer apposition
to the tooth structure

129. FUNCTIONAL CUSP BEVEL
• It is additional removal of tooth structure in a cavity
preparation
• A wide bevel placed on the functional cusp provides space
for an adequate bulk of metal in an area of heavy occlusal
contact.

130. • Functional cusp bevel increases the
thickness of thin occluso-axial junction of the
restoration.
Angulation-45 degree
USE- Provides additonal thickness for the
material which is necesaary because these are
the maximum load bearing areas. So, large
bevel is given which will help to bear excess
load without fracture

131. LOCATION
• Its prepared on the palatal
cusp of maxillary teeth.
• Buaccal cusps of mandibular
teeth.

132. TYPES AND DESIGN FEATURE OF FACIAL
AND LINGUAL FLARE
• There are 2 types of flares;-
• The Primary Flare-
• The Secondary Flare

133. • Basic part of circumferential tie
• Similar to long bevel
• Angulations of 45 degrees to inner dentinal wall
PRIMARY
FLARE

134. FUNCTION
Same as bevels
Brings facial and lingual margins to self –
cleansable areas
INDICATION
- Normal contacts
- Minimum extension of caries in the
buccolingual dimension

135. • 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
SECONDARY
FLARE

136. • Indirect wax pattern
• Broad contact areas
• Wide extension of caries buccolingually
• Overcome undercuts in the cervical aspect of facial and
lingual proximal walls in ovoid teeth
Extends margins into embrasures
Stronger enamel margin produced
40 degree marginal metal
INDICATION
S
FUNCTION
S

137. SECONDARY FLARE
In very widely
extended
lesions bucco-
lingually
In very broad
or malposed
contact areas
In ovoid teeth
with undercuts at
facial & lingual
peripheries
Surface defects /
decalcifications
Functions :

138. Occlusal bevel
Axial wall
Reverse flare

139. REVERSE FLARE
These are the extension of secondary flare.
INDICATIONS –
• Indicated to include facial or lingual defects beyond the axial
angle of the tooth.
• To eradicate severe peripheral marginal undercuts which
have not been removed by the maximum angulation & extent
of a secondary flare.

140. • Needed to add to the retentive capability of the
restoration proximally.
• Also to fulfill the objectives of secondary flares in
extremely wide cavities or contact areas.
• • For encompassing an axial angle for reinforcing and
supporting reasons.
• • Contraindicated in class IV & V cast materials.

141. Finish lines for intracoronal
restorations

142. MARGINS IN INDIRECT RESTORATIONS

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

147. – 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
TOOTH COLOURED
INLAYS
Ceramic and Composite
inlays

148. PREPARATION GUIDELINES FOR
MONOLITHIC CERAMIC RESTORATIONS

149. • Retention form is not as critical due to the bonded nature of the
restoration
• bevels are contraindicated.
• Cavosurface angles of 90°
• A minimum cervicoocclusal axial wall convergence of 10°–12°
• . Generally, a minimum of 1.5–2 mm of pulpal floor depth, 1–1.5 mm
of axial reduction, and 2 mm of isthmus width

150. DIRECT COMPOSITE INLAY
• The composite material is condensed into the cavity after
the separating medium is applied to the cavity. This
separating medium helps in easy removal of the inlay after
the initial intraoral curing.
• The restoration is then subjected to extraoral light or heat
tempering in an oven. DI-500® Oven or a Cerinate® Oven
(Den-Mat Corp) can be used at 110°C for 7 min

151. INDIRECT COMPOSITE INLAY
• The inlay is fabricated in a die.
• After the separating medium is applied to the die, composite material is
condensed in increments into the cavity and light cured for 40 sec for each
surface.
• The inlay is then removed and heat cured in an oven at 100°C for 15 min
(CRC-100 Curing Oven®, Kuraray).

152. MARGINS FOR ONLAY

153. • 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.
ONLAY

157. SKIRT
This is more extensive surface extension then the reverse
secondary flare.
INDICATIONS-
• To involve defects with more dimensions (depth) than those
that can be invovled in a reverse secondary flare.
• To impart resistance & retension on a cast restoration instead
of missing or shortened opposing facial or lingual walls.

158. FEATURES –
• Prepared to include facial & lingual surfaces near the axial
angle to a depth of – 0.5-1mm- class I & II alloy 1.5-2mm-
III, IV,V
• Max. depth should be at the junction of the surface
with cavity preparation.
• Sometimes preferable to terminate skirt in mesially or
in a vertical groove

159. COLLAR
This type of extension involve more surface area and depth.
• 2 types
1. Cuspal collar
2. Tooth collar
• Cuspal collar- involves facial or lingual surfaces of one cusp
only in a multicusped tooth.
• Tooth collar- involve entire facial or lingual surfaces of the
tooth.

160. Indication-
• Help in retention and resistance when entire cusp is
lost prior to tooth preparation or when it is necessary to
remove it due to excessive undermining.
• Helps in retention in shortened teeth.
• Help in enhancing the support for endodontically
treated teeth

161. • used in places where pins are contraindicated.
• For cast material with low castability.
• Used for areas in a cast alloy restoration to be veneered by fused
porcelain, an collar can accommodate both porcelain and alloy and
facilitates marginal seating of castings cicumferential tie.
FEATURES
• With the depth of 1-2mm,collar ends gingivally in a bevelled
shoulder finish line.
• Class IV bevelled portion should be hollow ground & for ceramics
bevelled in rounded & exaggerated fashion or have no bevel.
• The interveining cusp should be should be preserved same as
with the skirt

162. TOOTH PREPARATION FOR ESTHETIC
ONLAY
• The principle For esthetic inlay or onlay restorations, bevels and
retention forms are not needed.
• Resistance form is generally not necessary but may be required in
very large onlay restorations.
• Cavity walls are flared 5 degrees to 15 degrees in total (10 degrees
to 12 degrees ideal), and the gingival floor can be prepared with a
butt joint.
• The internal line angles are rounded, the minimum isthmus width is
2 mm, and the minimum depth thickness is 1.5 mm

164. CIRCUMFERENTIAL TIE CONSTITUENTS
OF EXTRACORONAL PREPARATIONS
THE CHAMFER
FINISHLINES
THE KNIFE
EDGE
FINISHLINES
THE BEVELLED
SHOULDER
FINISH LINES
THE HOLLOW
GROUND
BEVEL

165. THE CHAMFER FINISH LINES
• Universally used design –class I II and III cast metals
• Bulk and definite termination for the preparation margin with little tooth
involvement
LIMITED BURNISHABILITY OF MARGINAL
CAST ALLOY
CONTRAINDICATED
FOR CLASS IV AND V
CAST MATERIALS

166. THE KNIFE EDGE FINISH LINES
• Least tooth structure involvement
• It should only be used to accommodate a very castable –burnishable
type of alloy .
• Minimal axial depth is required for biologic or anatomic purposes .
Technical
difficulty
Fracturing the
alloy part of
circumferential
tie

167. THE BEVELLED SHOULDER FINISH LINES
• Most tooth structure involvement
• Indicated when definite gingival floor with all its
components –resistance retention purpose
• When maximum bulk of cast is needed marginally
Ideal design for sub gingivally located margins

168. THE HOLLOW GROUND BEVEL
• Exaggerated chamfer or a concave bevelled shoulder
• Tooth involvement is greater than a chamfer and less than a
bevelled shoulder
• Ideal finish line for class IV and V cast materials.
•

169. CONCLUSION
• The success of a dental restoration largely depends on
the accurate margin placement, adaptation, and
integrity. The restorative margin placed plays an
essential role in the long-term prognosis and
outcome of the restoration. Thus, proper knowledge
of the gingival and periodontal response to the
restoration from a biomechanical perspective is
essential

170. 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
•

171. • Walls et al. Crowns and other extra-coronal restorations:
• Porcelain laminate veneers :British dental journal 2002;193 : 2:73-
81
• Sturdavent 4th edition
• Rangarajan – textbook of prosthodontics
• Deepak nallaswamy – textbook of prosthodontics
• JIOH, October 2010, Volume 2 (Issue 3)
• J Appl Oral Sci. 2012;20(2):174-9 111