EVALUATION OF PHYSICAL PROPERTIES OF DENTURE BASE RESIN IN TWO DIFFERENT MEDIA BY USING THERMAL GRAVIMETRIC ANALYSIS AND DIFFERENTIAL THERMAL ANALYSIS.

Abstract

Aim: The aim was to evaluate the physical properties of denture base resin in two different media such as artificial saliva and chlorinated water by using thermal gravimetric analysis (TGA) & differential thermal analysis (DTA).

Materials and Methods: 40 samples divided into 2 groups of 20 samples each. One group was stored in artificial saliva the other group was stored in chlorinated water of 3ppm concentration. Total number of 40 acrylic blocks was grouped as Group I & II. Scrapings were taken from the blocks of both the Group I & II. Samples of artificial saliva and chlorinated water were subjected to thermal behavior by TGA and DTA.

Results: TGA Thermograph of Group I shows broad endothermic peak at 282.9⁰C to 357.7⁰C and exothermic peak at 535.4⁰C to 602.2⁰C. TGA Thermograph of Group II shows broad endothermic peak at 336.2⁰C to 362.2⁰C and exothermic peak at 535.6⁰C to 643.9⁰C. The phase change corresponding to the weight change is shown in DTA thermograph. The thermograph of TGA/DTA shows changes in thermal behavior in both the medium.

Conclusion: Changes in the physical properties of denture base resin such as transition temperature and phase changes were evaluated by thermal analysis. Chlorine being highly reactive will react with the double bonds of polymethylmethacrylate (PMMA). Blocking of double bond can affect the physical properties of denture base resin.

Keywords: Polymethylmethacrylate, Differential thermal analysis, Thermal analysis, Denture base resin.