The purpose of this study was to identify the possibility of using a micronucleus test to assess the impact of harmful chemicals on the condition of periodontal tissues of employees of a mining and processing plant. Material and methods. Dental examination was conducted for 40 employees of the mining and processing plant, exposed to harmful substances with an experience of more than 10 years, 36 employees of the plant with a contact time of not more than 10 years, and 46 people with a healthy periodontium. The analysis of buccal epithelial cells for the presence of chromosomal aberrations using the micronucleus test. Results. The prevalence of inflammatory diseases of periodontal tissues in the groups of workers of the plant was 100%. A statistically significant difference was found in the frequency of cells with micronuclei and protrusions of the nucleus in the group of internship workers compared with other groups (p = 0.001). The frequency of cells with two nuclei in the workers of the plant in the groups was at the same level and significantly exceeded the value of the index for a group of people with a healthy periodontium (p = 0.002 and p = 0.006). The frequency of occurrence of cells with vacuolization of the nucleus in a group of workers with an experience of more than 10 years more than doubles that of a group of individuals with a healthy periodontium (p = 0.009). Conclusion. Occupational factors have a significant impact on the development and course of inflammatory periodontal diseases in mining and processing complex employees. Studies using the micronuclear test indicate a negative impact of a complex of harmful substances on the development and course of inflammatory periodontal diseases.