하악 편측 유리단 가철성 국소의치의 설계에 따른 광탄성 응력 분석

Abstract

The purpose of this study was to compare and evaluate the magnitude and distribution of stress around the abutment teeth and on the residual ridge produced by four kinds of the mandibular unilateral free-end removable partial dentures. For this study, a three-dimensional photoelastic stress analysis method was used. Mandibular photoelastic epoxy models missing right the 1st and the 2nd molars and unilateral free-end removable partial dentures were fabricated using clasp(C-URPD), Konus crown(K-URPD), resilient attachment(ReA-URPD), and flexible resin(F-URPD). Unilateral free-end removable partial dentures were positioned on the photoelastic epoxy resin models, and the vertical load of 6kg was applied on the central fossa of mandibular right the 1st molar artificial tooth of the every removable partial dentures. After photoelastic epoxy resin models with applied stress were frozen in a stress freezing furnace according to the stress freezing cycle, these models were sliced mesio-distally to a thickness of 6㎜. The sliced specimens were examined with the polariscope and transmission photoelastic device to observe the distribution of stress. The results were as follows : 1. In all of the sliced specimens, Only the compressive stress were observed. 2. The isochromatic maximum fringe order number was in the decreasing order of F-URPD, C-URPD, ReA-URPD, and K-URPD, and the location of maximum stress concentration was different from each other. 3. On the residual ridge just below the loading point, the fringe order number was in the decreasing order of F-URPD, C-URPD, ReA-URPD, and K-URPD. 4. On the root apex of the 2nd premolar, the fringe order number was in the decreasing order of C-URPD, F-URPD, K-URPD, and ReA-URPD. 5. K-URPD showed the most equalized transmission of the vertical loads to the supporting alveolar bone of abutment teeth and residual ridge. In conclusion, in view of the stress distribution on the supporting structures under the vertical loading, K-URPD was the most favorable design of the four unilateral free-end removable partial dentures tested. And the other hand, even though F-URPD showed much higher stress concentration on the residual ridge than on alveolar bone surrounding abutment tooth, F-URPD can be considerable clinically because of the advantage without tooth reduction.