Principles and Technique of Tooth Preparation of a Maxillary Central Incisor to Receive a Porcelain Fused to Metal Crown

1. TOOTH PREPARATION IN FPD
FOR ANTERIOR PFM CROWN
DR. AAMIR GODIL
DEPARTMENT OF PROSTHODONTICS
M.A.R.D.C.

2. PRINCIPLES OF TOOTH PREPARATION
The principles of tooth preparation may be
divided into three broad categories:
1. Biologic considerations:
which affect the health of the oral tissues
2. Mechanical considerations:
which affect the integrity and durability of
the restoration
3. Esthetic considerations:
which affect the appearance of the patient
Contemporary fixed prosthodontics. Stephen Rosenstiel, Martin Land, Junhei Fujimoto- 5th edition (2015)

3. MARGIN GEOMETRY
Chamfer Shoulder Sloped Shoulder
Knife EdgeFeather Edge
Radial Shoulder
Shoulder with Bevel

4. PORCELAIN FUSED TO
METAL CROWN
TOOTH PREPARATION FOR INCISOR

5. PFM CROWNS

6. OVERVIEW

7. BIOMECHANICAL CONSIDERATIONS
BIOLOGICAL CONSIDERATIONS
1. Prevention of damage
 Pulp
 Periodontium
2. Conservative preparation
 PFM restoration
 Minimal taper
 Avoidance of over contour
3.
Margin placement and
adaptation
 Supragingival
X Subgingival
 Well flushed
4. Harmonious occlusion and prevention of tooth fracture

8. BIOMECHANICAL CONSIDERATIONS
MECHANICAL CONSIDERATIONS
1. Retention form
 Taper: ~6 degrees
 Prevention of undercuts
 Optimal surface area of preparation
 Retentive luting agent
2. Resistance form
 Adequate taper and height: width ratio
 Pinholes/ grooves/ boxes
 Choice of luting agent
3.
Prevention of
deformation
 Adequate tooth preparation
 Alloy selection: Noble/ base metal
 Margin placement and geometry

9. BIOMECHANICAL CONSIDERATIONS
ESTHETIC CONSIDERATIONS
1. PFM/ all ceramic  Compromised esthetics
2. Acrylic facing/ porcelain facing X Less conservative
3. Partial coverage X Not applicable

10. PREPARATION DESIGN
PFMPREPARATION
Margin geometry: labially shoulder, palatally chamfer
Margin placement: supra-gingival/ equi-gingival/ sub-
gingival
Incisal reduction
Incisal edge: 1.5 – 2.0 mm
Axial reduction
Labial: 1.2 – 1.5 mm
Lingual: 1.0 – 1.5 mm
Retentive features
Wings, grooves, pinholes, boxes

11. MARGIN GEOMETRIES
Chamfer
Shoulder
Shoulder with bevel

12. ARMAMENTARIUM
Armamentarium for the PFM preparation
Flatended,tapered:diamond
Roundended,tapered:diamond
Twelvefluted:carbide
Round:diamond
Oblong(football):diamond
Roundwheel(donut):diamond

13. ARMAMENTARIUM

14. OVERVIEW

15. STEPS IN TOOTH PREPARATION
Guiding grooves Labial shoulder
margin
Blending with guiding
grooves
Labial reduction Palatal reduction

16. WINGED VS WINGLESS PREPARATION
The “wingless” variation does not exhibit the defined transition from chamfer margin
to shoulder margin. Rather, the shoulder margin gradually narrows toward the lingual
side.
An even chamfer margin width and a smooth transition between lingual and axial
surfaces.The chamfer margin is distinct and blends smoothly into the facial
shoulder margin.

17. PUTTY INDEX
Facial index Mid-sagittal index

18. DEPTH GROOVES
Labial grooves Incisal grooves

19. INCISAL REDUCTION
1.5 – 2.0 mm incisal reduction

20. FACIAL REDUCTION
Facial reduction
1.0 – 1.5 mm
Proximal lip
For breaking adjacent
tooth contact

21. LINGUAL REDUCTION: CINGULUM
0.7 mm depth demarcation
with round bur
Cingulum reduction
with wheel bur

22. AXIAL REDUCTION (PROXIMAL)
Proximal reduction and rounding off line angles

23. FINISHING
Axial and marginal
finishing
Final preparation

24. ASSESSMENT
Assessment of preparation using pre-operative putty index

25. FINAL PREPARATION
Schematic representation

26. REFERENCES

27. THANK YOU