RPD Review Questions

Answer to Question #17

The answer is FALSE.

The guide surface - guide plate contacts DO NOT determine a definite path of insertion in this case. If the minor connectors to the rests on the mesial occlusal surfaces of the premolars are in intimate contact with the abutments, they may help to ensure a definite path of insertion/dislodgement. However, it is safest to place the tips of the I-bar retentive arms just in front of the greatest mesiodistal curvature of the facial surface of the abutments. If the tips are placed at or behind the greatest mesiodistal curvature, it would be possible for the RPD to move slightly upward and backward allowing the retentive arms to escape the undercuts without flexing. Under these circumstances, the RPD would not exhibit retention.