[Effect of stress distribution of support tissues using attachment prostheses with different number of abutment].

Purpose: The purpose is to evaluate the effect of the stress distribution of support tissues when using the hinge extracoronal attachment for distal-extension prosthesis with different number of abutment.
Methods: Hinge extracoronal attachment was used for retention in distal-extension prosthesis. The 3-D photoelastic models of attachment of the denture of single abutment with the first molar or double abutments with the first molar and the second premolar were fabricated. Photoelastic analysis was adopted to compare the stress patterns generated around the support tissues with different number of abutment.
Results: Under central occlusion, most stress of the attachment of the denture with single abutment was concentrated at the edentulous ridge, the distal and mesial apex of the abutment. The results were similar with double abutments.
Conclusions: In choosing attachment prostheses to restore the second molar distal-extension defects, we can choose only one tooth as abutment. The number of the abutment has no significant effect on the stress distribution in the supporting tissue under central occlusion,and there is an evenly stress distribution at the edentulous ridge and in the abutment. The attachment is suitable for cases with better alveolar membrane without high demand for abutment teeth. Supported by Development Fund of Science and Technology of Shanghai Municipality (Grant No. 004119075).