IN-VIVO ASSESSMENT OF METHYL-METHACRYLATE METABOLISM AND TOXICITY

Methyl methacrylate (MM), a widely used monomer in industry and medicine has been reported to cause abnormalities or lesions in several organs. However, to our knowledge no general complications were reported in patients carrying acrylic dentures nor in technicians or physicians involved in preparation of acrylic resine for dentures or acrylic bone cement and therefore exposed to MM. The purpose of this study was to determine whether MM released to the gastrointestinal tract from acrylic dentures is able to damage the liver or other internal organs. Experiments were conducted by exposing rats to MM administrated by stomach tube. Methacrylic acid-a product of MM degradation was found in rat serum 5 min after a single dose of MM. The maximum accumulation of this compound in serum was observed between 10 and 15 min after MM administration. Then the methacrylic acid concentration declined steadily, reaching a very low level after 1 hr. It was found that MM is hydrolysed both in human and rat serum due to serum nonspecific carboxylesterase. No histopathologic changes were found in Liver, kidney, heart, spleen, brain, lung and intestine as well as in serum activity of enzymes: aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and gamma glutamyltransferase in rats intoxicated with MM. These results suggest that relatively low toxicity of orally administered MM is a consequence of rapid hydrolysis, of the ester by serum nonspecific carboxylesterase with subsequent very fast uptake and degradation of methacrylic acid to less toxic compounds.