Authors : Ehab A. Elsaih
Volume : 61
Issue : 1
Year : 2015
Page No : 1937-1942
Purpose: This invitro study investigated and compared the effect of different retainer design on load transmission to abutments in asymmetrical distal extension removable partial denture (RPD) cases to verify the null hypothesis that; the use of different clasps in asymmetrical design has no effect on abutment teeth. Materials and methods: A simulated Mandibular arch model with six-anterior teeth, two-first premolars and a left-second-premolar was fabricated. Six RPDs were constructed as follows; three RPDs designed with RPI clasp (mesial occlusal rest, proximal plate and I-bar retainer arm) on both sides (Group I) and the other three RPDs designed with RPI clasp on the longer side and a distal half T clasp (mesial occlusal rest, proximal plate and half T-bar retainer arm) on the shorter side. Linea strain gauges were bonded buccal, lingual and distal to the abutment teeth. Unilateral and central loading was applied and micro strains readings were collected, tabulated, and statistically analyzed Results: The use of a distal half T clasp retainer decreases the micro strains on abutment of the shorter saddle in asymmetrical distal extension partial edentulous model. The use of RPI clasp in the shorter saddle increase strain of abutments (especially distal) upon central loading. Also thi increase strain of abutments (especially lingual) upon unilateral loading of longer RPD saddle. Conclusion: The RPI clasp assembly was found to increase micro-strain versus the distal half T clasp under unilateral load and central loading conditions of asymmetrical bilateral distal extension RDPs.