release of residual monomeric methyl methacrylate in human saliva after using acrylic dentures

ABSTRACT

Autopolymerized and heat polymerized acrylic resins are widely used in dentistry for various purposes, Despite the polymerization method, the conversion of monomer into polymer is not complete and varying amounts of free or unreacted monomer [residual monomer] remain in the polymerized resin. The aim of this study was to determine the residual monomeric methyl metacrylate content in the saliva of patients using acrylic dentures, at different time intervals. Informed consents were obtained from 25 patients with complete dentures, ranging in age from 35 to 65 years. 1 mL samples of whole saliva were collected upon insertion of the dentures and l day, 1 week and 1 month after wearing them. Methyl methacrylate [MMA] levels were measured by use of gas chromatography. Data were analyzed by repeated measurement ANOVA and paired sample T-tests. The maximum concentration of monomer released into saliva was detected one day after insertion of the dentures. The Mean [SD] MMA content in saliva was 0.4 +/- 0.12 [ng/ml] upon insertion, and 0.7 +/- 0.16 [ng/ml], 0.5 +/- 0.13 [ng/ml], and 0.38 +/- 0.1 [ng/ml] on the 1st day, 1st week and 1st month post-insertion, respectively. The maximum amount of monomer released by heat-polymerized poly-MMA was observed on the first day after insertion, which, while not a toxic or primary irritant dose, could sensitize patients or elicit an allergic reaction. For minimization of the adverse effects, patients could be advised not to wear their dentures overnight, 24 hours after delivery