Abstract
To investigate the effects of coping designs on the abutment teeth displacementsunder the overdentures, we constructed a test model simulated a partially edentulous mandible with only two canines and fabricated an experimental overdenture like an occlusal rim. We measured the displacements of the right canine with six different designs of copings respectively under the overdenture in two kinds of vertical load applications as follows:(1) in height 2 mm (short type) and 4 mm (long type);(2) in buccolingually vertical section the dome configuration and three types of square configurations consisting of the monoplane as primary contour and the unilaterally and bilaterally inclined planes made by grinding the buccal and lingual top contour of the monoplane;(3) the bilateral load (5 kg) and the unilateral load (2 kg).
The results are as follows.
The magnitude and direction of the abutment tooth displacement were influenced by the degree of crown-root ratio, the presence of line angle and inclined plane, and the soat of load application.
The short and dome shaped coping transmitted the least stress to the abutment tooth under the unilateral load.
