The Effect of N-acetylcysteine Addition on the Polymerization Behavior of PMMA Bone Cement

Abstract

Wearing dental acrylic prosthesis may cause adverse reactions to oral tissues due to bioactive leaches from resins such as residual methyl methacrylate (MMA). N-Acetylcysteine (NAC), a well-known thiol-containing antioxidant, may alleviate the toxicity of polymethyl methacrylate (PMMA) bone cement through the inactivation of the monomer components in the cement by its sulfhydryl moiety. This study aimed to reveal the effects of NAC on the polymerization heat, degree of conversion (DC), mechanical properties, and residual monomer release of PMMA bone cement by adding 0.25, 0.50, 0.75, and 1.00 wt. % NAC to PMMA powder. Measurements were performed 5 times per experimental groups and averaged. The data were analyzed with One-way ANOVA and Tukey test with p<0.05 as significance level. 1.The peak temperature of PMMA cements during polymerization (Tmax) was significantly reduced and setting time (tset) was steadily delayed with the increasing NAC percentage. 2.The DC of all experimental PMMA bone cements reached as high as 91% after 7 days of incubation, as determined by Fourier-transform infrared spectroscopy (FTIR). 3.The experimental groups showed steady declines in flexural strength and surface hardness as a fraction of increasing NAC. Meanwhile, the mechanical properties of the experimental groups were improved with time. 4.The amount of MMA leached into deionized water was analyzed using high performance liquid chromatography (HPLC). It was found to increase with immersion time up to 24 hours, after which no significant change was observed. 5.Results showed a linear correlation between thermal characteristics, mechanical properties and the released MMA amount with the DC of the experimental groups. The potential usefulness of NAC in developing more biocompatible PMMA bone cement for increased working performance was highlighted in this study.