RPD Review Questions

Answer to Question #135


The correct answer is

Incorrect. Because the abutments tilt mesially, the distal guide plates will pre-empt the mesial rests and act like distal rests on inclined planes. Physiologic relief would create a space between the guide plates and the abutments. Thus, it is best to switch to disal rests. Once that decision is made, one must also change the type of retentive arms.

Incorrect. With very few exceptions, WW I-bars should be avoided. It is difficult to position them properly, especially in relation to the soft tissues. They are also prone to accidental bending. The other problem here is that, because the abutments are tilted mesially, the guide plates will pre-empt the mesial rests. Thus, distal rests should be selected.

Incorrect. Same reasoning as #3.

Correct. Because the abutments tilt mesially, the distal guide plates would pre-empt the mesial rests and act like distal rests on inclined planes. Physiologic relief would create a space between the guide plates and the abutments. Thus, it is best to use distal rests. Once that decision is made, one must also change the type of retentive arms to WW circumferential clasps. Fortunately, when teeth are tilted mesially, there are almost always mesiofacial undercuts appropriate for WW circumferential retentive arms.