Effects of overdenture retention designs and implant orientations on load transfer characteristics.

Various approaches have been used for the retention and stabilization of implant-supported overdentures. This study examined photoelastically the simulated load transfer characteristics of a resilient cap attachment with moderately atrophied mandibular plastic models with two implant orientations. Comparison was made with overdentures supported by a splinting bar and a bar with distal resilient cap attachments. Stress patterns developed by simulated occlusal loading demonstrated little cross-arch load sharing and more uniform stress distribution with noninclined implants for all retention designs. The most equitable simulated occlusal force transfer was provided by the resilient cap attachments direct to the implants.