Solubility Of An Acrylic Resin Used For Occlusal Splint Adjustment

Objectives: The aim of this in vitro study was to assess the leakage of a self curing methyl methacrylate resin (Steady Resin) made occlusal splint before and after an adjustment with the same resin at the dental chair. Methods: ten samples of a standard occlusal bite were prepared with the tested resin on the basis of the manufacturer instructions. Each sample was merged in artificial saliva for 72 hours and at the end of this period of time a chemical analysis of each solution was made in order to determine the concentration of free monomer in solution. After this a simulation of an adjustment was realized applying a layer of 1 mm of thickness of resin on the 50% of the occlusal splint surface, leaving the resin to harden in the open air without any other treatment. When the resin cool down after the heating due to the curing reaction, the samples were again merged for 72 hours and the chemical analysis repeated. Results: The data were analysed with 1-way ANOVA and the Bonferroni-Dunn multiple comparisons post hoc analysis. The comparison made between the data obtained before and after the adjustment with the same acrylic resin showed a significant (P < 0.05) difference: the concentration of free monomers was 83.2 +/- 3.4% higher in the solution used after the specimen adjustment. Conclusion: The results we have obtained show that occlusal splint adjustment with a self curing methyl methacrylate resin, as is sometimes performed during the clinical treatment of a patient with TMD, causes an increase in the amount of free monomer delivered in the saliva. As the biocompatibility and the in vivo effect of methyl methacrylate monomer are longtime been studied, it seems worth finding a method to minimize this leakage increase of the acrylic resin made occlusal splints.