This study aims to investigate the toxic effects of metals, which dental technicians are exposed to, on the oral mucosa cells in dental prosthesis laboratories (DPL). To monitor cytotoxic effects, mutations of pyknosis, Karyolysis Karyorrhexis, binucleus, micronucleus, and broken-egg were evaluated. Experimental group comprised of a total of 30 volunteer DPL employees from various DPLs, and 30 teachers and office workers were volunteered to be a part of the control group. Age range of DPL employees and whether they consume alcohol or smoke cigarettes were also considered as sub-variables. Peripheral smear technique was applied by taking samples from the oral mucosa of the experimental group and the control group. Anomalies determined between technicians and control group were statistically significant (p < .05). However, our findings revealed that the sub-variables (ie, age range, alcohol, and smoking) did not significantly affect the anomalies.