In the cast restoration, cusp protection is mandatory when:

Indications: If the width of the lesion is 1/3 to 1/2 the intercuspal distance - cuspal protection is to be considered. If the width of the lesion exceeds 1/2 the intercuspal distance - cuspal protection is mandatory. If the length:width of the cusp is more than 1:1, but not exceeding 2:1 - cuspal protection is to be considered. If the length:width of the cusp is more than 2:1 - cuspal protection is mandatory. When there is a need to change the dimension, shape and interrelationship of the occluding tooth surfaces. MDS Prep Bytes( Cast Restoration – Onlay)