Genotoxic Effect of Methyl Methacrylate and Nickelcobalt-Chromium in Dental Lab Technicians: A Micronuclei and Cytomorphometric Study of Buccal Mucosal Cells

Abstract

Dental laboratory technicians are exposed routinely to non precious metal alloys such as chromium, cobalt, nickel, and methyl methacrylate (MMA). These chemicals are considered potentially toxic substances and are known to cause chromosomal damage and nuclear alterations. Buccal mucosa cells are very sensitive to toxicity as they readily form micronuclei (MN), in response to toxic exposure. Thus, the present study was conducted to evaluate MN frequency and analyze the cellular alterations, if any, using quantitative cytomorphometric analysis in the buccal mucosal cells of dental lab technicians. The study comprised 28 dental lab technicians who were exposed to acrylic (MMA) and metal (nickel, cobalt, and chromium) for a minimum of 5 years with 8h daily exposure. Twenty"‘eight individuals with no known exposure were selected as control group. For MN frequency, cytosmears were prepared from both study subjects and control group and were stained with Feulgen reaction. Cytosmears were made and stained by Papanicolaou's stain, and cytomorphometric analysis was done using Caliper Pro4.2 Image Analysis Software. The MN frequency and cytoplasmic area (CA)/nuclear area (NA) was compared using one"‘way ANOVA among dental lab technicians who were categorized into three groups, i.e., exposed only to acrylic (MMA), exposed only to metal (nickel, cobalt, and chromium) and exposed to both metal and acrylic. The mean occurrence of MN frequency was significantly higher (P < 0.05) in the study individuals when compared to the control group. When individual exposure was considered, subjects exposed to both acrylic and metals showed an increased mean frequency of MN, which was not statistically significant (P > 0.05). Quantitative analysis showed a definite increase in the NA and CA/NA (P < 0.05) and decrease in CA (P < 0.05) in study subjects when compared to the control group. Comparison of these cellular and nuclear parameters in the three divided groups did not show any significant changes. The findings of the present study signify that exposure to nickel, chromium, cobalt, and MMA induce genotoxic effect in exfoliated buccal epithelial cells, in addition, the significant quantitative cellular alterations are also seen which indicate a potential health risk for dental lab technicians. Therefore, to ensure maximum occupational safety, biomonitoring is of great value for assessing the risk for dental lab technicians.