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1. CAST METAL RESTORATIONS
(CLASS II INLAY CAVITY
PREPARATION)
PRESENTED BY:-
• DR. ADITEE AGRAWAL
• PG 2nd YEAR
• DEPT. OF CONSERVATIVE DENTISTRY AND ENDODONTICS.

2. CONTENTS:-
• INTRODUCTION
• DEFINITIONS
• CAST METAL RESTORATION:-
 INDICATIONS AND CONTRAINDICATIONS
ADVANTAGES AND DISADVANTAGES
PREOPERATIVE CONSIDERATIONS
• PRINCIPALS OF CAVITY PREPARATION FOR CAST
RESTORATIONS
• TYPES AND DESIGN FEATURES OF OCCLUSAL AND
GINGIVAL BEVELS
• FUNCTIONS OF OCCLUSAL AND GINGIVAL BEVELS

3. • TYPES AND DESIGN FEATURES OF FACIAL AND
LINGUAL FLARES
• PREPARATION FEATURES OF CIRCUMFERENTIAL
TIE
• TOOTH PREPARATION FOR CLASS II CAST METAL
INLAYS
• MODIFICATIONS IN INLAY TOOTH PREPARATION
• MODIFICATIONS OF PROXIMAL CAVITY DESIGN
• TOOTH PREPARATION WITH SURFACE
EXTENSION

4. INTRODUCTION
• Dr. PHILL BROOK in 1897, was the first to
introduce inlay in dentistry who gave the
concept of forming an investment around wax
pattern, eliminating the wax and filling the
resultant mold with a gold alloy.
• In 1907 Taggart changed the practice of
restorative dentistry by introducing his
technique for cast gold restorations.
• It was most certainly Taggart who recognized the
significance of cast gold restorations.

5. MATERIALS FOR CAST METAL
RESTORATIONS
• Until recently gold based alloys have been the
only ones used for cast dental restorations. The
ADA sp # 5 still requires 75% of gold- plus-
platinum group metals to be present in alloys for
cast restorations.
• According to Sturdevant’s there are four distinct
groups of alloys:
The traditional high gold alloys
Low gold alloys
Palladium- silver alloys
Base metal alloys

6. According to Marzouk:
• Class I: gold and platinum group based alloys
• Class II : low gold alloys
• Class III: non- gold palladium based alloys
• Class IV: nicklel chromium based alloys
• Castable moldable ceramics.

11. DEFINTION
• Inlay:-
A fixed intracoronal restoration,a dental
restoration made outside of tooth to
correspond to the form of the prepared
cavity , which is then luted into the tooth.

12. • Onlay:-
A restoration that restores one or more
cusps and adjoining occlusal surfaces or the
entire occlusal surface and is retained by
mechnical or adhesive means.

13. INDICATIONS
• Large restorations:
Better strength
Control of contours and contacts
Better alternative to a crown to teeth that have
been greatly weakened by caries or by a large
failing restoration, but facial and lingual
surfaces are unaffected by disease/injury.
For such a weakened teeth , the superior
physical properties of the casting alloys are
desirable to withstand occlusal loads placed on
the restorations.

14. • Endodontically treated teeth:
Molars and premolars with endodontic
treatment can be restored with cast metal
onlay.
• Teeth at risk for frature:-
Teeth with extensive restoration, fracture line in
enamel and dentin must be recognized as
cleavage planes for future tooth fracture.

15. • Dental rehabilitation with cast metal alloy:
When cast metal restorations have already
been used to restore adjacent or opposite teeth,
the continue use of same metal to avoid
electrical or corrosive activity that may occur if
the dissimilar metals are used.
• Removable prosthodontic abutment:
Teeth that are to serve as abutment for a
removable partial denture can be restored with
cast metal restoration.

16. CONTRAINDICATION:-
 High caries rate:
Facial and lingual tooth surface must be free
of caries or previous restorations.
If present, the tooth must be restored with
full crown.
 Young patients:-
Amalgam or composite are the restorative
materials for Class I and Class II restorations
unless the tooth is severely broken down or
endodontically restored.

17. • Esthetics:-
Their use restricted to the tooth surfaces that are
not visible at conversational distance.
• Small restorations:-
Amalgam and composite serves as a better
option.

18. ADVANTAGES
• Strength
• Biocompatibilty
• Low wear
• Control of contacts and contours.

19. DISADVANTAGES
• Number of appointments and more chair time.
• Extensive tooth preparation
• Cost and temporary restoration requirement
• Technique sensitive
• Spliting forces

20. Preoperative considerations
• Occlusion :-
 Occlusion contacts must be evaluated
It must be decided that occlusal relationships can
be improved with a cast metal restoration.
The pattern of occlusal contacts influences the
preparation design, the selection of interocclusal
records, and the type of articulator.

21. • Anaesthesia:-
Eliminates pain, reduces salivation.
• Considerations for temporary restorations:-
An index can be fabricated preoperatively
using elastomeric impression or alginate.

22. TECHINQUES
1. Direct technique
2. Indirect technique

23. • DIRECT TECHIQUE:-
Where inlay wax is inserted into the prepared
cavity , carved, contacts made and taken out of
the cavity.
The lab procedure than follow.

25. • Indirect technique:
 When an impression of the prepared cavity is
taken and all the procedures are followed in the
model in the lab.

27. GENERAL PRINCIPLES
• Greater surface extension in outline form
than amalgam.
• This facilitates support and efficient marginal
manipulation.
• More extensive surface involvement to
compensate for the cariogenically weak
joints of cast/cement/tooth interface.

28. • The design for a cast restoration is governed by
5 principles:-
1. Preservation of the tooth structure
2. Retention and resistance
3. Structure durability
4. Marginal integrity
5. Preservation of the periodontium.

29. • Preservation of tooth structure:-
In addition to replacing the lost tooth structure,
the cast restoration must preserve the
remaining structure.
Preservation of tooth structure may involve
limited amounts of the tooth being prepared.

30. • Retention and resistance :-
 Retention prevents removal of the restoration
along the path of insertion or long axis of the
tooth preparation.
Resistance prevents dislodgment of the
restorations by forces in an apical or oblique
direction and prevents any movement of the
restoration under occlusal forces.

31. • Besides applying the general principles of tooth
and cavity preparation, cast restoration
preparations should have the following
features:-
A) Preparation path:-
 Preparation should have a “Single Insertion
Path”
 Path is parallel to the long axis of tooth crown.
 Helps in retention and decreases the micro
movements of restoration during function.

33. B)Apico- occlusal
taper:-
 For maximum retention,
opposing walls and axial
surfaces should be
perfectly parallel to
each other.
 Slight divergence of
opposing walls in Intracoraonal .
 Slight convergence of axial walls
in Extracoronal.
 Taper should be 2-5°
from path of preparation.

34. C) Circumferential tie:-
The peripheral marginal anatomy of the
preparation is called as the “ Circumferential Tie”
Should fulfill the requirements advocated by Noy:
If the preparation ends on enamel, enamel must
supported by sound dentin.
Enamel rods forming the cavosurface margin
should be continous with sound dentin.
Enamel rods forming the cavosurface margin
should be covered by restorative material.
Angular cavosurface angle should be trimmed.

35. • Structural durability:-
Occlusal reduction
Functional cusp bevel
Axial reduction

36. • Marginal integrity( Bevels):-
Bevels are defined as “ flexible extensions” of
cavity preparation, allowing the inclusion of
surface defects, supplementary grooves and
other areas on the tooth surface.
Two types of bevels:-
1. Occlusal bevel
2. Gingival bevel

37. Types and design features of occlusal
and gingival bevels
• Partial bevel:
Involves part of
the enamel only,
Not exceeding 2/3rd its
Dimension.
 Not used in cast
restoration, except
to trim weak enamel
rods.

38. • Short bevel :-
Includes entire enamel wall but not dentin, it is
used with Class I alloys specially for type 1 & 2 (
Gold platinum based alloys).

39. • Long bevel:-
 Includes all enamel and upto ½ of the dentinal
wall, its major advantage is that it preserves the
internal boxed up resistance
Most frequently used bevel for cast materials.

40. • Full bevel:-
Includes all of the enamel and dentinal walls of
the cavity wall and floor. Its use should be
avoided except in cases where it is impossible to
use any other form of bevel.

41. • Counter bevel:-
When capping cusps these protect and support
them.
Given opposite to an axial wall on the facial and
lingual surface.

42. • Hollow ground (concave bevel):-
Allows more space for cast material bulk.
Used to improve retention and resistance to
stresses.

43. • Functions of occlusal and gingival bevel:-
 Bevels create an obtuse angles marginal tooth
structure (strong tooth anatomy)
Produce an acute angled marginal cast alloy(
most amenable finishing and burnishing).
Makes it possible to decrease the cement line
by bringing cast alloy closer to the tooth.
They are also part of one of the major retention
form of cast restorations.

44. • PRINCIPLES OF CAVITY DESIGN FOR CAST INLAY
RESTORATIONS:-
• The class II inlay involves the occlusal and
proximal surfaces of a posterior tooth and may
cap one cusps but not all of the cusps.

45. • Indications:-
Cavity width not to exceed 1/3 of intercuspal
distance.
Strong, self resistant cusps.
Indicated teeth have minimal or no occlusal
facets.
Tooth is not be used as an abutment in FPD or
RPD.
Occlusion or occluding surface are not be
changed by restorative procedure.

46. • Steps for class II cast metal inlays:-
 initial preparation
Occlusal step
Proximal box
Resistance and retention form
Final preparation
Removal of infected caries and pulpal
protection
Preparation of bevels and flares
Modification

47. Initial preparation :-
ARMANTERIUM:-
 BURS:-
 Burs used are no. 271, 169L & no. 8862
Sides and the end surface of the bur meet in a
rounded manner to prevent sharp internal angles.
Burs are “plane cut” so that vertical walls are
smooth.

49. Outline form
• Occlusal part consist of an dovetail form and a
proximal box.

50. • Occlusal step:-
Initial entry is made in the central fossa/ pit
with a tapered fissure bur no. 271 to establish
the pulpal floor (punch out ) to a depth of 1.5
mm
The depth is determined by extent of existing
carious lesions or restorations or the need for
additional retention.

53. • The occlusal outline is
extended mesiodistally
along the central groove
and stopped just short of
the marginal ridge. The is
kept in vertical position in
the long axis of the tooth
through out the preparation
so that its taper provides the
3-5°divergence to the facial
and lingual walls (total
divergence of 6- 10° )

54. • Primary resistance form:-
 Use of box shape
Preservation of cusps and marginal
ridges
Slight rounding of internal line angles
Capping weakened cusps
Adequate thickness of restorative material.

56. Preserving dentin support

57. Shallow enamel fault less than 1/3rd
the thickness of enamel can be
removed by enameloplasty

58. Final extension in the facial and lingual
triangular grooves with 169L bur
forming the dovetail

59. Dovetail aids in additional retention as it
fits in the preparation only in occlusal to
gingival direction

60. Extending the margin distally into distal
marginal ridge to expose the proximal
dentino-enamel junction

61. Cutting the proximal ditch with no.
271 bur

62. Extension of proximal ditch facially and
lingually beyond the caries and which
should clear the adjacent tooth by 0.2-

63. Penetration of enamel by side of bur at
its gingival end, followed by breaking
of the isolated enamel

65. Planning the walls

68. Removing caries on the axial wall

69. Removing the remaining infected
dentin with no. 2 or 4 round bur

70. Insertion of suitable base and
completed base

71. • Preparation of the bevels and flares:-
The slender flame shaped fine grit diamond is
used to bevel the occlusal and gingival margins
and to apply the secondary flare on the proximal
facial and lingual walls.
It will result in 30-40° marginal metal and 140-
150° cavosurface margin.

73. For the facial and lingual proximal walls in an
inlay cavity preparation for castings flares are
used, which are the flat or concave pheripheral
portions of the facial and lingual walls.
There are two types of flares:-
A) Primary flare
B) Secondary flare

74. • The Primary Flare:
Is the conventional and basic part of the cavity
facially and lingually for an intracoronal
preparation.
It is very similar to a long bevel formed of
enamel and part of the dentin on the facial or
lingual wall. Primary flare also have a specific
angualation i.e 45° to the inner dentinal wall
proper.

75. Functions and indications:-
 These design fearures perform the same function
as bevels.
They can bring the facial and lingual margins of the
cavity preparation to cleansable finishable areas.
They are indicated for any facial or lingual proximal
wall of an intracoronal cavity preparation.

76. Secondary flare:-
It is almost always a flat plane superimposed
peripherally to a primary flare. It is usually
prepared solely in enamel. unlike primary flares,
secondary flares have different angulations,
involvement and extent depending on their
function.
Functions and indication of secondary flare:-
 lesions with wide bucco-lingual extension.
Contact areas too broad.

78. Bevelling gingival margin

80. After completion of the gingival bevel
facial secondary flare is made

82. Bevelling axio-pulpal line angle
and mesial marginal ridge

83. Completed preparation

84. Modifications of class II inlay cavity preparation:-
For esthetics:
Absence of
secondary
flare on facial
proximal
surface

85. Facial and lingual groove extension

86. Extension gingivally to extend root
surface lesion

87. Capping cusps:-
When the occlusal outline is extended up the
cusp slopes more than half the distance from
primary groove, capping the cusp should be
considered.
If it is extended two thirds or more, capping is
necessary.

89. MODIFICATIONS OF PROXIMAL CAVITY DESIGN:-
Box preparation
Slice preparation
Auxillary slice preparation
Modified flare

90. Box preparation:-
 Introduced by Dr. G. V Black in which the
proximal cavities are prepared box shaped with
and buccal and lingual walls and a definite
gingival floor.
Advantages:-
 it has its own retention and resistance form .
Direct wax pattern can be made.
The outline form of proximal surfaces can be
made on all types of teeth.

92. Slice preparation:-
 A slice is referred to the placement of extra
coronal taper using a disk of adequate diameter
to contact nearly the entire proximal surface.
This form of cavity is modified so that the
proximal surface is flat without definite side
walls.
These slices are generally placed on the buccal
and lingual proximal surfaces independently.
The slice may extend to the cervical floor, or
more frequently will terminate at some point
occlusal floor.

93. • Slice preparation involves
conservative disking of the
proximal surface to establish
the buccal and lingual
extent of finish lines and
provide a lap joint for
finishing.

94. Auxillary slice preparation:-
 Wraps partially around the proximal line
angles, thus providing additional tooth support.
 Resistance form is enhanced.
 Provide external retention form.

95. • Modified flare:-
• The modified flare preparation is a hybrid
between the box and slice preparations.
• Buccal and lingual proximal walls initially
formed with minimal extension, then disked in a
plane that only slightly reduces the proximal
wall dimension.

97. Tooth preparation for cast restoration with
surface extension:-
Reverse Secondary Flare:-
This is a surface extension of the basic
intracoronal inlay or onlay cavity preparation.
The reverse secondary flare is in the form of
partial bevel. It involves only enamel, with its
maximum depth at its junction with the main
cavity preparation.

98. • It ends on the facial or lingual surface with a
knife edge finishing line, and its extent
should not exceed the height of contour of
the facial or lingual surface in the mesio-
distal direction, nor should include the tip of
the cusp.

99. Indications:-
1. Surface extensions are required to include
facial and lingual defects beyond the axial
angle of the tooth.
2. A surface extension is needed to eradicate
severe peripheral marginal undercuts.
3. A surface extension is needed to add to the
retentive capability of the restoration
proximally.
Contraindications:-
This type of surface extension is contraindicated
for Class IV and Class V cast materials.

101. REFERNCES
Art and Science of Operative Dentistry-
Sturdevant’s. fifth edition.
Fundamentals of Operative Dentistry- Marzouk.
Operative dentistry- Summit
Principles and Practice Operative Dentistry.
Third edition. Gerald T. Charbeneau.

102. THANK U