instrumentation for crown and bridge prep

depth guide (reducing) burs, cutting instruments, finish line guiding stone/burs, polishing burs, tissue trimmers

rotary instruments classification according to function

flat end straight, round end straight, flat end tapered, round end tapered, flame shaped, long and short needle

rotary instruments classification according to shape

1.5-2 mm

amount of reduction in the incisal/occlusal surface

1.1.5 mm

amount of reduction on proximal surface

1.2-1.5 mm

amount of reduction on the labial/buccal surface

1-1.2 mm

amount of reduction on lingual surface

shoulder, 90*

cervical finish line modification on the labial

chamfer, 135*

cervical finish line modification on lingual

iatrogenic damage, excessive tooth reduction, unnecessary tipping/undesirable angulation of instrument

common errors in tooth preparation