THE COMPLETE CAST PREPARATION

CONTENTS
1. INTRODUCTION—SELECTION, WHY???
2. INDICATION & CONTRAINDICATION
3. ADVANTAGES & DISADVANTAGES
4. SPECIAL CONSIDERATIONS
5. ARMAMENTARIUM
6. TECHNIQUE
7. EVALUATION

WHY FULL COVERAGE OVER PARTIAL
COVERAGE ???
laboratory studies by Lorey and Meyers , Reisbick and Shillingburg ,
and Potts et al

CONTRAINDICATIONS
1. If less than maximum retention and
resistance is necessary
2. If high esthetics need exists (anterior
teeth)
3. Intact buccal/lingual wall exists
4. If treatment objectives can be met with
more conservative restoration.
5. Mouths with uncontrolled caries
INDICATIONS
1. Extensive coronal destruction from
caries/trauma
2. Endodontically treated teeth
3. Existing restoration
4. Necessity for max retention & strength
5. Enameloplasty
6. Correct minor malinclinations
7. Correction of occlusal plane
Rosensteil 5th edition The Complete Cast Crown Preparation ;Page209

ADVANTAGES
1. Strong
2. High retention & resistance form
3. easy to obtain adequate resistance form
4. Option to modify form & occlusion -
especially for supraerupted teeth
5. Less easily to deform
DISADVANTAGES
1. Removal of large amount of tooth
structure
2. Adverse effects on pulp &
periodontium
3. Vitality test cannot be done
4. Display of metal, may be restricted to
max molars/mand molars/premolars
Rosensteil 5th edition The Complete Cast Crown Preparation ;Page209-210

SPECIAL CONSIDERATIONS
. 1 BEVEL:
 A wide bevel -- placed on the functional cusp ---
round-end tapered diamond
 angled flatter than external surface
 At 45' to long axis
Failure to place this bevel can produce :
 thin casting or poor morphology.
 to prevent overcontoured restoration
2. CHAMFER WIDTH :
 common error – increasing faciolingual width---
---lead to periodontal disease
 min 0.5mm is adequate-- to develop optimum
axial contour
 on premolars, make slightly narrower chamfer--
to conserve tooth struc & retention form

ARMAMENTARIUM
Shillinburg 4th edition Preparations for Full Coverage page 347

T
• GUIDING GROOVES FOR OCCLUSAL REDUCTION
E
• OCCLUSAL REDUCTION & BEVEL
C
• ALIGNMENT GROOVES FOR AXIAL REDUCTION
H
• AXIAL REDUCTION
N
• FINISHING
Q
• EVALUATION

1. GUIDING GROOVES FOR OCCLUSAL
REDUCTION
1. Round end tapered diamond
2. Position --- central & dev grooves & cusp tips &
triangular ridges of each cusp
3. Depth & Angulation :
Non-func cusp & central groove: 0.8mm--- intend the
cuspal inclination
Func-cusp : 1.3mm---should be angled slightly flatter --to
ensure additional clearence of func cup
4. Functn.: ensure occlusal reduction follows anatomic
configuration-- minimizes the loss of tooth structure
5. Periodontal probe to measure extent of reduction.

2) OCCLUSAL REDUCTION
1. Remove the tooth structure that remains between
grooves
Preserving occlusal morphology
2. Round-end tapered diamond
3. Technique:
 first, reduce half of occlusal surface- other half
will act as reference
 then reduce the other half
4 . Func cusps : 1.5mm & Non-func cusps : 1mm

3. FUNCTIONAL CUSP BEVEL

4. VERIFYING THE REDUCTION/CLEARANCE ;
 Ask patient to close on utility wax in –MI---- evaluate wax for thin spots----measured with wax
caliper
 place again in patient's mouth ----ask to move his mandible into potrusion & excursive positions
 remove again from mouth------measure the thickness of the utility wax
 alternative way : use Occlusal reduction gauge

5) ALIGNMENT GROOVES FOR
AXIAL REDUCTION
1. Place 3 alignment grooves in each buccal & lingual
wall--- 1 is placed at center, 1 in mesial & distal
transitional line angle
2. Round end tapered diamond
3. Shank of the diamond must // to p.o.p of restoration
--- will automatically produce a convergence to the
prep. Wall--- identical to the taper of the diamond (6'
taper)
4. Diamond shouldn’t cut tooth beyond its
midpoint---creation of enamel lip(unsupported
enamel)
5. use periodontal probe to asses the parallelism of
alignment grooves with one another

6. FACIAL & LINGUAL WALLS
 Place cervical chamfer concurrently with axial
reduction
-width : 0.5mm – allow adequate bulk of metal at the
margin
-must be smooth & continuos mesiodistally
 remove unsupported enamel

7 . PROXIMAL REDUCTION
Initial proxmal reduction: thinner, tapered
diamond (needle diamond)------Prevent unintentional
damage to adjacent teeth
 Enamel lip is maintained between the diamond &
adjacent tooth
Place metal matrix band to protect the adjacent
teeth- ----if damage, polish with white stones,
silicone points, prophylaxis paste
Secondly--- use torpedo diamond in proximal area-
- to produce chamfer finish line & increase the axial
depth of reduction

Chamfer finishing: torpedo bur .
8. FINISHING
1. Functions –
 to facilitate impression making, waxing investing, casting
 to enhance retention & resistance form
2. Use fine-grit diamond/carbide bur, with reduced speed handpiece
3 . Margin must be glassy smooth, line angles should be round , finish line should be smooth &
continuous.

9. ADDITIONAL RETENTIVE FEATURES
(RETENTIVE GROOVES/BOXES)
Tapered carbide bur & slow handpiece
Prevent --- rotational tendencies during
cementation & guide the casting into place
Site: axial surface with the greatest BulK
•facial surface of mand. ,
•palatal surface of maxillary.

10) EVALUATION
1. Detect the common errors that can reduce the
retention--overtapered & undercuts
2. Correct errors by-- upright the overtapered axial walls ,
use grooves/boxes/pinholes
3. Tip of diamond should rest on the chamfer while making
the axial reduction
4. Assess any probs and correct before making interim
restoration & impression

FIG: The features of a full veneer crown preparation and the function served by each .

THE COMPLETE CAST PREPARATION

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