tooth prepration presentation

1. Good Morning

2. Tooth Preparation for
Full Veneer Crowns

3. CONTENTS
Introduction and history of full veneer crowns
Terminologies
Rotary Instruments used for tooth preparation
Preparation for full veneer crowns
a. Complete cast metal crown
b. Anterior metal ceramic crown
c. Posterior metal ceramic crown
d. Porcelain jacket crown
e. Cast ceramic crown
Conclusion

4. Tooth preparation is a far more important phase of
fixed partial denture prosthesis treatment although
some practitioners never realize this.
It must be done with skill and meticulous attention to
detail, for everything that follows – pulpal vitality,
periodontal health, a good esthetic result, proper
occlusion, protection of remaining tooth structure, and
the longevity of the restoration itself – will depend on
it.
INTRODUCTION

5. Although fixed prosthodontic crown and bridge work
dates to as back as 300 to 400 BC where in one of the oldest
tombs of Sidon, a Phoenician specimen was found consisting
of gold wire fastened around six anterior teeth, two of them
being pontics.
But crown and bridge fixed partial prosthesis was
indeed in a crude state of development till as late as 1850.
The early crown were not fabricated by casting. It was
made by flowing solder over gold foil that had been adapted to
the tooth preparation, with wrought wire staples in the
preparation grooves.
Inlays were made in a similar fashion by flowing solder into a
foil matrix adapted to the cavity preparation.
HISTORY

6. A major step in this direction was the development of the
porcelain jacket crown by Land in 1886 when low-fusing
porcelain fused in a gold matrix made its appearance.
In 1907 William H. Taggart announced his method of
making gold castings, using a disappearing wax pattern.
Lost Wax technique
This application of an old method revolutionized the technical
aspect of restorative dentistry. It made possible exceptional
refinements in the construction of fixed partial prosthetic
appliances.

7. BIOLOGIC
Conservation of tooth
structure
Avoidance of over contouring
Supra gingival margins
Harmonious occlusion
Protection against tooth
fracture
MECHANICAL
Retention form
Resistance form
Deformation
ESTHETIC
Minimum display of metal
Maximum thickness of
porcelain
Porcelain occlusal
surfaces
Subgingival margins
PRINCIPLES OF TOOTH PREPARATION
(According to Rosenstiel)
Optimal restoration

8. PRINCIPLES OF TOOTH PREPARATION
According to Shillingburg, the design of a preparation for a cast
restorations and the execution of that design are governed by five
principles:
1. Preservation of tooth structure
2. Retention and resistance
3. Structural durability
4. Marginal integrity
5. Preservation of the periodontium.

9. TERMINOLOGIES
Tooth preparation: is defined as the mechanical treatment of dental
disease or injury to hard tissues that restores a tooth to original form.
(Tylman)
The process of of removal of diseased and / or healthy enamel and
dentin and cementum to shape a tooth to receive a restoration. GPT- 8
Crown / artificial crown: a metal, plastic, or ceramic restoration that
covers three or more axial surfaces and the occlusal surface or incisal edge
of a tooth (GPT)
Full veneer crown / Complete crown: A restoration that covers all the
coronal tooth surfaces ( mesial, distal, facial, lingual and occlusal )
Chamfer Finish line: A finish line design for tooth preparation in which the
gingival aspect meets the external axial surface at an obtuse angle
Shoulder finish line : A finish line design for tooth preparation in which the
gingival floor meets the external axial surfaces at approximately a right
angle(GPT)

10. Retention form : The feature of a tooth preparation that resists
dislodgement of crown in a vertical direction or along the path of
placement (GPT)
Resistance form : The features of a tooth preparation that enhance the
stability of a restoration and resist dislodgement along an axis other
than the path of placement
Bevel : The process of slanting the finish line and curve of a tooth
preparation (GPT)

11. ROTARY INSTRUMENTS USED FOR
FULL VENEER PREPARATIONS
Shape Use
Round end tapered
diamond
1.Depth orientation grooves
2.Occlusal reduction
3.Functional cusp
Torpedo diamond 1.Axial reduction
2.Chamfer finish line
Short needle 1.Initial interproximal axial
reduction in posterior teeth
Long needle 1.Initial proximal axial
reduction in anterior teeth

12. Small wheel diamond 1. Lingual reduction in anterior
teeth
Tapered fissure bur
(171L)
1.Seating groove
2.Proximal groove (posterior
teeth
3.Smoothing and finishing
4.Occlusal and incisal bevels

13. End cutting bur Conventional shoulder finishing
Torpedo bur 1.Axial wall finishing
2.Chamfer finishing
Flame bur 1. Flare and bevel finishing
Tapered fissure burs
(169L & 170L)
1.Initial groove alignment
2.Angles of proximal boxes
3.Smoothing and finishing
4.Occlusal and incisal bevels

14. FULL VENEER CROWNS
COMPLETE CAST
CROWN
ALL CERAMIC CROWN
METAL CERAMIC

15. COMPLETE CAST METAL CROWNS
Complete cast metal crowns can be used where the
break down of tooth structure is severe, to the extent that is
has been described in operative dentistry as “the final
attempt to preserve the tooth”.
The terms “full crown”, “full cast crown” and “complete
crown” can be used interchangeably with full veneer crown
to describe a restoration entirely made of cast metal.

16. Indications
 Extensive destruction from caries or trauma.
 Endodontically treated teeth.
 Existing restoration that needs the use of a more conservative
restoration
 Necessity for maximum retention and strength.
 To provide contours to receive a removable appliance.
 Other re-contouring of axial surfaces (minor corrections of
malinclinations).
 Correction of occlusal plane.
Contraindications
 Should not be used in mouths with uncontrolled caries
 Less than maximum retention necessary.
 Esthetics.

17. Advantages
 Strong.
 High retentive qualities.
 Usually easy to obtain adequate resistance form.
 Option to modify form and occlusion.
 Contact areas can be conveniently developed.
 Embrasure areas can be enhanced for periodontally
compromised dentition.
Disadvantages
 Removal of large amount of tooth structure.
 Adverse effects on tissue.
 Vitality testing not readily feasible.
 Display of metal.

18. Planar occlusal reduction is done
using round end tapered diamond and
no: 171 bur.
Depth orientation grooves are made on
the triangular ridges and primary
developmental grooves.
The depth orientation grooves should be
1.5mm deep on functional cusps and
1mm deep on non-functional cusps. The
tooth structures between the orientation
grooves are removed following cuspal
contours.
TOOTH PREPARATION FOR COMPLETE CAST CROWN

19. Functional cusp bevel is done using
round end tapered diamond and no:
171 bur.
Depth orientation grooves are placed
across the facial occlusal line angle
of the mandibular molar.
The bevel should parallel the inward
facing inclines of the cusps of the
opposing tooth, at a depth of 1.5 mm
usually forming a 45 angle with the
axial wall.

20. Facial and lingual axial
reduction is done with a torpedo
diamond producing a definite
chamfer finish line at the same
time.
The facial and lingual reduction
are carried as far as possible
into the interproximal
embrasures without nicking the
adjacent teeth.

21. Mesial and distal axial reduction.
A short thin tapered diamond is
placed against the facial surface of
the remaining interproximal tooth
structure.
It is held upright and moved up and
down, directing it lingually with light
pressure.
Once sufficient space has been
produced, sweep the short thin
diamond back and forth planning the
surface to smoothness.

22. Chamfer finishing.
Torpedo bur is used to produce a
distinct finish line and to round of
the angles of the preparation.

23. Seating groove is made on the axial
surface using no: 171 bur. The groove
should be cut to the full diameter and it
should extend gingivally to a point 0.5
mm above the chamfer.

24. Features of full veneer crown preparation and
the function served by each

25. METAL CERAMIC
RESTORATION

26. The use of porcelain fused to metal restorations has grown from the
development of the first commercially successful porcelain/ gold alloy
restoration by Weinstein et al in 1950’s.
While a porcelain-fused to metal crown can serve as a strong and
esthetic restorations, patients too often receive this type of restoration
for minor irregularities that could have been better handled by
conservative treatment or none at all.

27. Indications
• Esthetics
• Need to incorporate occlusal or cingulum rests
• If porcelain jacket crown is contraindicated.
Contraindications
• Large pulp chamber.
• Intact buccal wall.
• When more conservative retainer is technically feasible.
ANTERIOR METAL-CERAMIC CROWN

28. Advantages
• Superior esthetics as compared to cast gold restoration.
• Retentive qualities are excellent
Disadvantages
• Removal of substantial tooth structure.
• Subject to fracture because porcelain is brittle.
• Difficult to obtain accurate occlusion in glazed porcelain.
• Shade selection can be difficult
• Inferior esthetics compared to porcelain jacket crown.
• Expensive.

29. Depth orientation grooves: A flat end
tapered diamond is first aligned with the
incisal portion of the facial surface and
two vertical cuts are made to the full
diameter of the diamond fading out at
the “break” where the curvature of the
facial is the greatest.
Three similar grooves are made
maintaining the same instrument
parallel to the gingival segment of the
facial surface. Two incisal orientation
grooves 2.0 mm deep are made.
ANTERIOR PORCELAIN FUSED TO METAL CROWN
PREPARATION

30. Incisal reduction: A flat end tapered
diamond is used to reduce the
incisal edge by 2.0 mm keeping the
plane of the reduced surface parallel
to the former incisal edge. A round
wheel diamond may also be used
for incisal reduction.

31. Facial reduction, incisal half: A flat
end tapered diamond is used to
remove the tooth structure
remaining between the orientation
groove in the incisal portion of the
facial surface.

32. Facial reduction, gingival half: A flat
end tapered diamond is used to
reduce the gingival segment and
extend well into the proximal surface.
1.2 mm to 1.4 mm is the accepted
reduction for a porcelain fused to
metal restoration. If there is sound
tooth structure interproximaly a
vertical wall or “wing” of it, is left
standing in each interproximal area
lingual to the proximal contact.

33. Lingual reduction: A small
round diamond with a head 1.4
mm in diameter is used to
make four depth orientation
cuts. A small round wheel
diamond is used create a
concave surface over the
lingual surface of the tooth
incisal to the cingulum.

34. Lingual axial reduction
is done with a torpedo diamond
producing a definite chamfer finish
line at the same time.
If there is limited space between the
facio proximal angle of the wing and
the proximal surface of the adjacent
tooth, use a long needle diamond to
reduce the axial wall lingual to the
wing.
The lingual axial wall should be
parallel with the cervical one third of
the facial surface.

35. Facial axial finishing: No: 171 bur
is used to smooth the entire facial
surface and round over any sharp
angles on the incisal angle or
along the edges.

36. Shoulder finishing:
No: 957 bur or end cutting bur is used to finish the shoulder.

37. The features of an anterior porcelain fused to metal crowns
preparation on an anterior tooth

38. POSTERIOR PORCELAIN FUSED TO METAL
CROWN PREPARATION

39. Appearance zone
Maxillary - premolars
- first molars
Mandibular – first premolar

40. POSTERIOR PORCELAIN FUSED TO METAL
CROWN PREPARATION
Planar occlusal reduction is done
using round and tapered diamond
and no: 171 bur.
Depth orientation grooves are
made on the triangular ridges and
primary developmental grooves.
The depth orientation grooves
should be 1.5 to 2.0 mm in
occlusal areas where porcelain
coverage is required.
The tooth structures between the
orientation grooves are removed
following cuspal contours.

41. Functional cusp bevel is done
using round end tapered
diamond and no: 171 bur.
Depth orientation grooves are
placed across the lingual incline
of the maxillary lingual cusp.
The bevel should parallel the
inward facing inclines of the
cusps of the opposing tooth, at a
depth of 1.5 mm usually forming
a 45 angle with the axial wall.

42. Depth orientation grooves
A flat end tapered diamond is first aligned
with the occlusal portion of the facial
surface and three vertical cuts are made to
the full diameter of the diamond, fading out
at the “break” where the curvature of the
facial surface is the greatest.
Two similar grooves are made maintaining
the same instrument parallel to the
gingival segment of the facial surface. A
single depth orientation groove may also
be used.

43. Facial reduction, occlusal half: A flat end tapered diamond is used
to remove the tooth structure remaining between the orientation
groove in the occlusal portion of the facial surface.

44. Facial reduction, gingival half: A flat
end tapered diamond is used to
reduce the gingival segment and
extend well into the proximal surface.
1.2 mm to 1.4 mm is the accepted
reduction for a porcelain fused to
metal restoration.

45. Proximal axial reduction:
Short needle diamond facilities interproximal reduction with out nicking
the adjacent tooth. Once separation between the teeth is achieved the
needle diamond is used to plane the proximal axial wall.

46. Lingual axial reduction: A torpedo diamond is used for lingual
axial reduction and to round over the corner created at the line
angle with the proximal surfaces.

47. Axial finishing: All axial surfaces
to be veneered with metal are
finished using a torpedo finishing
bur producing the chamfer finish
line. The facial surface and those
areas of the proximal surfaces to be
veneered with porcelain are
smoothened with the no: 171 bur.
Lingual to the proximal contact, the
transition from the deeper facial
reduction to the relatively shallower
lingual axial reduction result in a
vertical wall or “wing” of tooth
structure.

48. Shoulder finishing: No: 957 bur is used to finish the shoulder
and is planed with a sharp 1.0 m wide chisel.
Gingival bevel: Flame diamond and finishing bur are used to
produce a narrow bevel, no wider than 0.3 mm.

49. The features of a posterior porcelain fused to metal
crown preparations for a porcelain fused to metal crown
on an posterior tooth and the function served by each.

50. ALL-CERAMIC CROWNS

51. The all ceramic crown differs from other ceramic veneer restorations
because it’s not cast in gold or some other metal
It is capable of producing the best cosmetic effect of all dental
restoration. However since it is entirely made of ceramic, a brittle
substance, it is more susceptible to fracture.
For many years the only type of all ceramic crown was the porcelain
jacket crown, which was built up in increments over a matrix or shell
formed by thin platinum foil adapted to a cast or die of the prepared
tooth. A lot of recent advances have improved the properties of
dental porcelain.
However more than any other restoration all ceramic crown depends
for its very survival on the tooth preparation beneath. Tooth support
is more critical for fracture resistance of the restoration than is the
bulk of porcelain.

52. Indications
• High esthetic requirement.
• Considerable proximal caries.
• Incisal edge reasonably intact.
• Endodontically treated teeth with post-and –cores.
• Favourable distribution of occlusal load.
Contraindications
• When superior strength is warranted and metal-ceramic crown is
more appropriate.
• Significant caries with insufficient coronal tooth structure for
support.
• Thin teeth faciolingually.
• Unfavourable distribution of occlusal load.

53. Advantages
• Excellent esthetics
• Good tissue response even for subgingival margins.
• Slightly more conservative of facial wall than metal ceramic
• Brittle nature of material.
• Can be used as single restoration only.
Disadvantages:
• Reduced strength compared to metal ceramic crown.
• Proper preparation extremely critical
• Among least conservative preparations
• Brittle nature of material
• Can be used as single restoration only

54. PORCELAIN JACKET CROWN PREPARATION
Depth orientation grooves:
A flat end tapered diamond is first aligned
with the incisal portion of the facial
surface and two vertical cuts are made to
the full diameter of the diamond, fading
out at the “break” where the curvature of
the facial surface is the greatest.
Three similar grooves are made maintaining
the same instrument parallel to the
gingival segment of the facial surface.
Two incisal orientation grooves 2.0 mm deep
are made.

55. Incisal reduction: A flat end
tapered diamond is used to
reduce the incisal edge by
2.0 mm keeping the plane of
the reduced surface parallel
to the former incisal edge. A
round wheel diamond may
also be used for incisal
reduction.

56. Facial reduction, incisal half: A flat
end tapered diamond is used to
remove the tooth structure remaining
between the orientation groove in the
incisal portion of the facial surface.

57. Facial reduction, gingival half:
A flat end tapered diamond is used to
reduce the gingival segment and
extend well into the proximal
surface.
Extend the facial reduction through the
proximal surfaces with the flat end
tapered diamond producing a
shoulder in the process.

58. Lingual reduction:
A small round diamond with a
head 1.4 mm in diameter is
used to make four depth
orientation cuts.
A small round wheel diamond is
used to create a concave
surface over the lingual
surface of the tooth incisal to
the cingulum.

59. Lingual axial reduction: A flat
end tapered diamond is
employed for axial reduction to
prepare the vertical lingual wall.
Blend the reduction of each axial
surface with that on the adjacent
axial surface.

60. Axial finishing: No: 171 bur is
used to smooth the axial surfaces
and to round all distinct positive
angles on the preparation.

61. Shoulder finishing: No: 957 bur is
used for preparing a smoothly cut
shoulder perpendicular to the line of
force or to the long axis of the tooth.

62. The features of all ceramic crowns preparation for a
porcelain jacket crown on an anterior tooth and the
function served by each.

63. POSTERIOR ALL CERAMIC CROWN PREPARATION
Occlusal reduction: A large round end
tapered diamond is used to place depth
orientation grooves on triangular ridges
and major grooves.
The final occlusal reduction should be 1.5
mm to 2.0 mm deep. Remove the tooth
structure remaining between the depth-
orientation grooves with the large round-
end tapered diamond.

64. Functional cusp bevel: The large
round end tapered diamond is used to
produce depth orientation grooves in
the facial incline of the facial cusp. A
minimum of 1.5 mm of clearance is
necessary.

65. Facial and lingual axial reduction:
The large round end tapered diamond is
used to obtain axial reduction ranging
from 1.0 to 1.5 mm by making depth
orientation grooves and removing the
tooth structure between them. The axial
reductions are carried out as far as
possible into the proximal embrasures.

66. Complete axial reduction: A short needle diamond is used to begin the
proximal axial reduction without touching the adjacent tooth. The axial
reduction interproximally is complete by running the round end tapered
diamond.

67. Preparation finishing: round end tapered carbide bur is used to
finish the axial surfaces and the functional cusp bevel.

68. The features of a cast ceramic crown preparation for an all
ceramic crown on a posterior tooth and the function
served by each.

69. THANK YOU