Denture Base Polymer Biodegradation: In Vitro Study

Abstract

Abstract Introduction Acrylic resins are the most frequently used materials for the bases of prostheses, and are also used in the re-optimization and the repair of prostheses. The aim of our study was to investigate whether direct contact with the resin causes decomposition of methyl methacrylate and formation of ketone bodies in the oral cavity. Material and methods The in vitro study included 12 samples of autopolymerized polymethyl methacrylate and 8 samples of thermopolymerized polymethyl methacrylate. Some of the resin samples were intentionally prepared incorrectly, with modified powder to liquid ratios or thermal regime, to be able to compare them with samples prepared according to the manufacturer’s instructions. Some of the samples were immersed in gastric juice or alcohol for 48 h at 37 °C in a thermostatic bath to simulate the environment and temperature of the oral cavity, while others were kept at room temperature. The Legal reaction was used to identify the presence of ketone bodies in the solutions. Results The samples that were prepared incorrectly and were kept at 37 °C were the most affected. The presence of ketone bodies was demonstrated by the formation of a precipitate on the bottom of the test tube and the color change of the solution. Samples that were kept at room temperature were less affected, both from a spectrophotometric and biochemical point of view. Conclusion The quality of polymethyl methacrylate can be improved by respecting the manufacturer’s instructions and work protocols, and by avoiding substances that are considered aggressive, such as gastric juice, alcohol, and local factors in the oral cavity.