What should be the depth of grooves placed in occlusal surface of the tooth during tooth preparation?
Guiding grooves for occlusal reduction
A tapered carbide or a narrow, tapered diamond is recommended for placing the guiding grooves for occlusal reduction:

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 guiding grooves in the buccal and lingual developmental grooves and in each triangular ridge extending from the cusp tip to the center of its base.

Key Concept:
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.
At least 1.0 mm
At least 2.0 mm
At least 1.5 mm
At least 1.2 mm