Aim: To investigate the content of Copper, Iron, and Manganese in the saliva and blood of patients affected by generalized periodontitis who have been working in harmful industries for an extended period. Materials and Methods: The study enrolled 133 employees of the Burshtyn Thermal Power Plant (TPP). A comprehensive examination was conducted in 125 individuals with chronic generalized periodontitis of I and II degrees by clinical and biochemical methods. The study also enrolled 30 people not working at the Burshtyn TPP, examined with intact periodontium (controls). We investigated the content of Copper, Iron, and Manganese in biological materials using spectral analysis in 110 patients with chronic generalized periodontitis and 27 controls. Results: The conducted examination indicated a disturbance in the content of Copper, Iron, and Manganese in the blood and mixed saliva of patients with generalized periodontitis who were employees of the Burshtyn TPP. We observed a decrease in the level of Manganese and Iron and an increase in Copper’s content in patients with generalized periodontitis (vs. controls), which may indicate a violated metabolism of trace elements upon chronic exposure to small doses of heavy metal salts. The changes in the content of trace elements (particularly Copper and Manganese) were associated with the severity of the disease. Conclusions: The changes in the level of particular trace elements in the saliva and blood of the examined individuals indicate their role in the development of generalized periodontitis.