RPD Review Questions

Answer to Question #71

The correct answer is

Incorrect. While teeth numbers 21 and 28 could be plated, there is nothing in the stem of the question indicating that this is necessary. Answer #1 is not the BEST answer.

Correct. As shown, the plating ends at the tooth tissue junction---essentially in the sulcus. Plating must extend to the contacts interproximally and must cover the cinguli. When possible, rest seats should be prepared on the incisor teeth and must be prepared at least on the canines.

Incorrect. Assuming the undercuts are appropriate for I-bars and there is no contraindication to infrabulge retainers, the mesial rest, I-bar, distal guide plate is the preferred clasp assembly. Simply changing the rests to the distal would place the I-bars (which are cast clasps) in front of the axis of rotation.

Incorrect. Mesial rests, distal guide plates, and cast circumferential clasps compose the clasp assembly called the "RPA". This is not the recommended design because the rigid originating portion of the cast clasp often lies above the height of contour and acts like a rest on an inclined plane.