A complete slide for general dentist who is in need for a perfect slide for complete cast crown preparation

1. COMPLETE CAST
CROWN
PROSTHODONTICS – FPD DR. SIDDHARTHA ROY RGUHS 2020
Contemporary Fixed Prosthodontics
ROSENSTIEL | Land | Fujimoto

2. All metal complete cast crown should always be used
for restorations for badly damaged posterior teeth.
Longevity of complete cast crown is superior to that
of all other fixed restorations. As its name implies, it
covers all axial walls and the occlusal surface of the
tooth.
INTRODUCTION

3. ADVANTAGES
• Greater retention – as all the axial surfaces of the tooth are
included in the preparation.
• Greater resistance – complete cast crown has greater resistance
than partial coverage restoration.
• Strength – is superior than other restoration.
• Cylindrical configuration – helps in encircling the tooth. O-shaped
configuration resists deformation than partial veneer configuration.
• It is possible to allow improved access for oral hygiene for teeth
with furcation involvement . This is sometimes referred to as fluting
or barreling.

4. Fluting of the buccal wall of the complete cast crown on the
maxillary tooth - enables better access to furcation for plaque
control to improve long term prognosis of the restorations.
Fluting of the buccal wall of the complete
cast crown on the mandibular tooth
FLUTING or BARRELLING

5. DISADVANTAGES
• Tooth structure is extensively removed so it can have
adverse side effects on the pulp and periodontium.
• Inflammation – because of proximity of the margin to
the gingiva, inflammation of the gingival tissues is very
likely.
• Esthetic – most cast crown are of not tooth colour so
they should be used strictly to maxillary molars,
mandibular molars and premolars.
Fig: Gingival inflammation around the cast metal crown.

6. CONTRAINDICATIONS
• Complete cast crown is contraindicated if treatment
objectives can be met with a more conservative
restoration.
• Anterior teeth – Esthetic need is high at anterior region so
ccc is contraindicated at anterior region. For anterior,
Zirconia crowns are indicated.
Fig: Zirconia crowns for anterior tooth
restoration

7. Some points
• Clearance – it is the amount of space between the completed
preparation and the opposing tooth.
• Minimum recommended clearance – 1 mm for non-
functional [non-centric] cusps and 1.5 mm on functional
[centric] cusps.
• Reduction – is the amount of tooth structure that is removed to
establish the desired clearance.
• The chamfer margin should allow for approximately 0.5 mm of metal
thickness at the margin.
- Occlusal reduction should generally follow normal anatomic contours
- Axial reduction should parallel the long axis of the tooth but allow 6
degree taper.
- Preparation should have a chamfer configuration and its ideal
location is supra-gingival.

8. Functional cusp bevel – it is a type of bevel which is placed
on the functional cusp i. e the cusp having an opposing
cusp.
On most posterior teeth, the functional cusp bevel is placed
at an angle of approximately 45 degrees to the long axis of
the prepared tooth.
Non – functional cusp bevel – it is a type of bevel which is
placed on the non-functional cusp i.e which has no
opposing cusp present on it.
Functional cusp
45 degree

9. Without such two-plane buccal reduction, the result can
be either a restoration that is too thin or, more likely, an
over-contoured restoration that does not follow normal
anatomic form.
Fig: over-contoured restoration
over-contoured restoration

10. PREPARATION – the clinical tooth preparation of complete
cast crown consists of following steps:
• Occlusal depth grooves
• Occlusal reduction and functional cusp bevel
• Axial alignment grooves
• Axial reduction
• Finishing and evaluation
Step-by-Step Procedure

11. Guiding grooves for occlusal reduction:
• Once the desired reduction depth has been determined, a
tapered tungsten carbide or a narrow tapered or small
– ended diamond is recommended for placing the depth
grooves for occlusal reduction.
• Depth grooves are helpful in guiding occlusal reduction only if
the tooth is in good occlusal relationship before preparation.
• Place depth holes approximately 1 mm deep in the central,
mesial, and distal fossae, and connect them so that a channel
runs the length of the central groove and extends into the mesial
and distal marginal ridge.
• Place depth grooves in the buccal and lingual developmental
grooves and in each triangular ridge; they should extend
approximately from the cusp tip to the center of its base.
• NOTE : Guiding grooves are deeper on the functional cusp, and
for the functional cusp bevel. They diminish in depth from the
cusp tip to the cervical margin.
A- Guiding grooves are placed on the occlusal surface.
B - After the guiding grooves are placed, the occlusal
reduction is performed. Either the mesial or the distal half
is maintained initially as a reference to facilitate evaluation
of adequacy of the reduction.

12. Buccal developmental
groove
Lingual
developmental
groove
Triangular ridge
Central groove

14. • The depth grooves should follow anatomic configuration and thus minimizes the loss of tooth
structure while ensuring adequate clearance.
• The depth grooves must be placed with accuracy, the practitioner should concentrate on
position, depth and angulation of each groove.
• To achieve correct depth—0.8 mm for the central groove and nonfunctional cusps and 1.3
mm for the functional cusps (allowing approximately 0.2 mm for preparation finishing and
smoothing).
• The clinician must know the dimensions of the instruments being used. Memorizing the
diameters of the rotary instruments facilitates assessment of the adequacy of the reduction
during preparation.
• If necessary, a periodontal probe can be used to measure the extent of the reduction that has
been achieved.
• Correct groove angulation is necessary to ensure that the occlusal reduction will allow
appropriate crown form and thickness
Some points to remember:

15. OCCLUSAL REDUCTION:
Once the depth grooves have been placed, the remaining tooth
structure between the grooves is removed with the tungsten carbide or
the narrow, round-ended, tapered diamond.
Proper placement of the grooves automatically results in adequate
occlusal clearance.
• Complete the occlusal reduction in two stages:
 Half the occlusal surface is reduced first so that the other half
can be maintained as a reference.
 When the first half is reduced, the remaining half is then
removed.
 On completion, verify that a clearance of 1.5mm has been
established on functional cusps and at-least 1 mm on non-
functional cusps.
 if you are uncertain about the clearance then ask
the patient to bite many times on a utility wax in
maximum intercuspation.

16.  if you are uncertain about the clearance then ask the
patient to bite many times on a utility wax in
maximum intercuspation.
A. The patient closes the teeth into softened
wax.
B. After the wax has been removed from the
mouth, its thickness is assessed visually and
measured with a wax caliper.
A
B

17. Occlusal clearance can be judged intraorally with a
reduction gauge.
A. Reduction gauge
B. The instrument has two spherical tips: one that is 1.5
mm in diameter.
C. and one that is 1.0 mm in diameter.
REDUCTION GAUGE:

18. ALIGNMENT GROOVES FOR AXIAL REDUCTION
Once the occlusal reduction has been completed, alignment
grooves are placed in each buccal and lingual wall with a
narrow, round-ended tapered diamond.
On molars, one alignment groove may be placed in the center of
the wall, and one in each mesial and distal transitional line
angle.
Note: that the alignment grooves are deep occlusally but
shallower toward the cervical margin. When placing these
grooves, keep reduction to a minimum at the tip of the
diamond.
Fig: Alignment grooves. One buccal and one lingually
[on the walls] , one on each line angles. [ mesio-lingual,
mesio-buccal, disto-lingual, disto-buccal].

19. Fig: Alignment grooves. One buccal and one
lingually [on the walls] , one on each line angles. [
mesio-lingual, mesio-buccal, disto-lingual, disto-
buccal].
ALIGNMENT GROOVES FOR AXIAL REDUCTION
Once the occlusal reduction has been completed,
alignment grooves are placed in each buccal and
lingual wall with a narrow, round-ended tapered
diamond.
On molars, one alignment groove may be placed in
the center of the wall, and one in each mesial and
distal transitional line angle.
Buccal D. groove
M-B groove
D-B groove
Lingual
groove
D-L groove
M-L groove

20. As these alignment grooves are placed, ensure that
the shank of the diamond is parallel to the
proposed
path of placement of the restoration, [which is
typically the long axis of the tooth]. Such
positioning automatically produces a convergence
between the axial walls of the alignment
grooves that is identical to the taper of the
diamond.

21. Gingivally, the depth of the alignment grooves
should therefore be no more than half the
width of the tip of the diamond bur.
The diamond tip should not cut into the tooth
beyond its midpoint; otherwise, a “lip” of
tooth, enamel will be unsupported.
A. Normal chamfer margin B. lip of the tooth enamel is formed.
A B

22. AXIAL REDUCTION
The technique for axial reduction is similar to that of occlusal
reduction. The residual islands of tooth structure between the
alignment grooves are removed, and the chamfer margin is
simultaneously created and the same narrow, round-ended
diamond is used for the procedure.
The axial reduction may be performed for half the tooth,
while the other half is maintained as a reference to check how
much reduction has been done.

23. If axial reduction is completed first on either the
distal or the mesial half of the tooth, evaluation is
simplified because the remaining intact half of the
tooth can serve as a reference.
A. Note the alignment of the diamond as tooth
structure between the alignment grooves is
removed.
B. Axial reduction. The distobuccal axial reduction
has been completed.
A
B

24. When breaking interproximal contact, pay special
attention to prevent unintentional damage to the
adjacent teeth. This often results if the practitioner
attempts to force the diamond into the proximal
aspect too rapidly.
Sufficient time must be allowed for the cutting
instrument to create space for its passage.

25. Typically, if the proper cervical placement of the margin
has been selected with correct axial alignment of the
instrument, a “lip” of tooth enamel is maintained
between the diamond and the adjacent tooth, protecting
the adjacent tooth from iatrogenic damage.
If desired, protect the adjacent teeth by placing a
metal matrix band.

26. Cut into the proximal area from both sides until only a
few millimetres of interproximal island remain. If
necessary, this area can then be removed (and proximal
contact broken) by using thinner, tapered diamonds.

27. Place the cervical chamfer margin concurrently
with axial reduction. Finished chamfer margin width should be
approximately 0.5 mm, which allows for adequate bulk of
metal at the margin.
The chamfer margin must be smooth and continuous.
The chamfer margin must be at least 0.6 mm from the
proximal surface of the adjacent tooth.
Unsupported enamel cannot be tolerated on the chamfer
margin because it is likely to fracture when the restoration is
evaluated or cemented, which, if undetected, will result in an
open margin and premature restoration failure.

28. Unsupported enamel cannot be tolerated on the chamfer
margin because it is likely to fracture when the restoration is
evaluated or cemented, which, if undetected, will result in an
open margin and premature restoration failure.
open margin
Open margin can cause sensitivity when air is sucked by
mouth.

29. FINISHING
A smooth surface finish and continuity of all prepared
surfaces aid most phases of fabrication of the
restoration.
Smooth transitions blend occlusal and axial surfaces.
Use a fine-grit diamond or tungsten carbide rotary
instrument of slightly greater diameter to finish the
chamfer margin. This should be done as smoothly
as possible, with a high-speed handpiece operating
at reduced speed.
Some clinicians favor using a low-speed contra-
angle handpiece for the finishing steps. A properly
finished margin should be smooth as glass, as verified
with a touch by the tip of an explorer.

30. FINISHING & POLISHING

31. Place additional retentive features as needed (e.g.,
grooves or boxes) with the tapered tungsten carbide bur
and the slow-speed handpiece

32. During margin finishing, the use of air cooling alone
is recommended to improve visibility.
However, when only air cooling is used, a water
spray should be applied from time to time to
prevent the tooth from dehydrating, to avoid the
possible development of pulpal damage, and to
wash away debris.
The larger diamond is recommended because it will
eliminate any unwanted ripples that were created
during axial reduction

34. THE END
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