Structural Durability :-


i. Functional cusp bevel -2 mm* for structural durability
ii. Proper oclusal / incisal clearance
iii. Incisal edge — 2 mm *
iv. labial — 1.5 mm

METAL CROWNS
 All surface reduction of 0.5 (max-1.0mm)
 Sharp line angles are okay

METAL-CERAMIC CROWN
- 1.5 (max-2MM) PREP (0.5 FOR METAL, 1-1.5 FOR CERAMIC)
- FUNCTIONAL CUSP / INCISAL – 2MM REDUCTION
- WALLS -6 DEGREE TAPER, NOT MORE THAT 10DEGREE
- CHAMFER FINISH LINE
- ALL MARGINS PLACED SUPRAGINGIVALLY
- Can have sharpline angles

ALL CERAMIC CROWN
 SAME CONFIGURATIONS 1.5-2mm
 At incisal / cuspa – 2mm for any type of preparation
 Shoulder finish lines
 ALL line angles SHOULD BE ROUNDED, NO SHARP ANGLES
 THIS IS TO AVOID PORCELAIN FRACTURE

Q. For onlays preparation reduction of functional cusp 1.5 mm.
Q. The amount of reduction in all ceramic crown 1 – 1.5 mm.
Q. The amount of reduction in PFM crown 1.5 – 2 mm.
Q. The incisal reduction for a metal ceramic restoration should be 2 mm.
Q. The amount of reduction in metallic crown 0.5 mm.

*Minimum thickness of metal — 0.5 mm required, thus gives adequate strength
*Bevel all functional cusp — to give thick material at the region and thus resist
occlusal forces


Maryland / Resin bonded bridge
i. Indication
a. maxillary lateral incisors *
b. poor oral hygiene
ii. Advantage
a. better hygiene maintainability
b. conserve tooth structure.
iii. Disadvantage — weak bond — poor retention of resin and metal