Residual monomer content determination in some acrylic denture base materials and possibilities of its reduction

Abstract

Background/Aim. Polymethyl methacrylate is used for producing a denture basis. It is a material made by the polymerization process of methyl methacrylate. Despite of the polymerization type, there is a certain amount of free methyl methacrylate (residual monomer) incorporated in the denture, which can cause irritation of the oral mucosa. The aim of this study was to determine the amount of residual monomer in four different denture base acrylic resins by liquid chromatography and the possibility of its reduction. Methods. After the polymerization, a postpolymerization treatment was performed in three different ways: in boiling water for thirty minutes, with 500 W microwaves for three minutes and in steam bath at 22? C for one to thirty days. Results. The obtained results showed that the amount of residual monomer is significantly higher in cold polymerizing acrylates (9.1-11%). The amount of residual monomer after hot polymerization was in the tolerance range (0.59- 0.86%). Conclusion. The obtained results denote a low content of residual monomer in the samples which have undergone postpolymerization treatment. A lower percent of residual monomer is established in samples undergone a hot polymerization.Uvod/Cilj. Za izradu baze zubne proteze koristi se akrilat, materijal koji nastaje polimerizacijom metil-metakrilata. Bez obzira na tip polimerizacije, u protezi zaostaje izvesna kolicina slobodnog metil-metakrilata, tzv. rezidualni monomer (RM), koji moze delovati iritirajuce na sluzokozu usne duplje u toku upotrebe proteze. Cilj rada bio je da se odredi kolicina rezidualnog monomera u cetiri razlicita akrilata za bazu proteze, kao i mogucnost njegove redukcije. Metode. Kolicina rezidualnog monomera odredjivana je metodom tecne hromatografije. Nakon polimerizacije obavljen je postpolimerizacioni tretman na tri razlicita nacina: u kljucaloj vodi trideset minuta, mikrotalasima 500 W tri minuta i odlaganjem u vodeno kupatilo na 22? C u trajanju od jedan do trideset dana. Rezultati. Dobijeni rezultati ukazuju na znatno vece vrednosti RM kod hladnopolimerizujucih akrilata. Vrednosti koncentracije RM nakon tople polimerizacije kretale su se u granicama tolerancije (0,59-0,86%), dok su te vrednosti kod hladnopolimerizujucih akrilata znatno vise (9,1-11%). Zakljucak: Dobijeni rezultati pokazuju nizak sadrzaj rezidualnog monomera u uzorcima podvrgnutim postpolimerizacionom tretmanu. Manji procenat rezidualnog monomera zapazen je u uzorcima podvrgnutim toploj polimerizaciji.