Guiding planes in cast partial denture:

 # Guiding planes in cast partial denture:

A. Should be perpendicular to the path of insertions

B. They must always face each other

C. Should be prepared always on the proximal surface of the abutment teeth

D. Should be parallel to the path of insertion

The correct answer is D. Should be parallel to the path of insertion.

Guiding planes or guide planes are defined as “Two or more vertically parallel surfaces of abutment teeth so oriented as to direct the path of placement and removal of removable partial dentures” -GPT. They are prepared on the proximal and axial surfaces of primary and secondary abutment teeth.

Structure

Guide planes are usually 2-3 mm in occlusogingival height parallel to the path of insertion. The guide planes should be flat and contain no undercuts. Guide planes do not occur naturally on the abutment teeth, instead they should be prepared by the clinician during prosthetic mouth preparation. They are prepared by selective grinding of teeth (enameloplasty) or by appropriate shaping of wax patterns, crowns or cast restorations on the abutment teeth.

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