Abstract
The rotational path of insertion differs substantially from the conventional path or the straight path of insertion. In the use of the rotational path, one segment of the partial denture is seated first, then the remainder of the prosthesis is rotated into position. One segment of this system is the rigid retentive component with long rest and the other the conventional clasp.
This study examined the influence of point and direction of displacing force and the proximal undercut of rigid retainer on retention of this system. Then this system was applied in clinical field. The following results were obtained:
1) Retention of denture is the smallest when displacing force was applied at the conventional clasp part.
2) Direction of displacing force (± 10deg;) has no significant effect on the retention.
3) The value of retention showed a tendency to increase in order when proximal undercut of rigid retainer was 0.3, 0.7 and 1.0 mm respectively.
4) The effects of the point and direction of displacing force on retention of mesio-disto rests and reciprocal arms design are similar to those of original long rest design.
5) When a severly tilted posterior tooth is used as an abutment tooth, this system could provide adequate retention.
