Inhaling air filled with fine particles can harm the gums and the bone that supports teeth. In May 2026, a Brazilian research team described in Air Quality, Atmosphere & Health how these particles affect the mouth. The study was conducted by scientists at the University of São Paulo, who exposed mice to air from a very busy street. While pollution is commonly studied for its effects on the lungs and heart, research on its impact on oral tissues is rare. These fine particles might still damage the tissues that keep teeth in place. To examine these effects, the researchers divided forty male mice into four groups of ten each. Some mice breathed filtered air, while others were exposed to air from the street that had been concentrated twenty times more than normal. The exposure lasted thirty or sixty days, with levels exceeding those set by the World Health Organization. Mice that breathed the polluted air showed changes in their tongues and gums. Histological analysis revealed hyperkeratosis, a thickening of the skin-like layer composed of keratin, a hard protein also found in nails. Mast cells, which are immune cells that release inflammatory molecules, multiplied in both tissues. Four inflammation markers increased simultaneously, while enzymes that neutralize harmful oxidants weakened in both the tongue and the periodontium, the tissues that surround and support the teeth. The researchers then simulated an existing gum disease by damaging the periodontium of new mice. They injected a component of bacterial cell walls into the gums three times a week for four weeks, which triggers periodontitis, a condition that destroys the bone and fibers supporting the teeth. Using a high-resolution scanner, they compared the bone volume around the molars. Mice previously exposed to fine particles had significantly more bone loss than others. Their gums had more lymphocytes and osteoclasts, the cells responsible for breaking down bone. This suggests that polluted air may amplify an existing inflammation rather than cause it from scratch. The duration of exposure had little effect. Thirty days of exposure were enough to trigger the same level of inflammation as sixty days. The researchers noted a plateau effect, where inflammatory responses begin early and then stabilize. Possible compensatory mechanisms, such as increased antioxidant defenses in the mouth, might slow further damage. The mouth is a constant point of contact between the body and the outside world. Inhaled particles settle directly there, irritating the epithelial tissue. After passing through the lungs, these particles could contribute to a general inflammation that affects highly irrigated tissues like the gums. The authors suggest a connection between the lungs, the bloodstream, and the mouth. This study does not claim that pollution causes periodontitis. Bacteria in dental plaque are still considered the primary cause, while polluted air may only worsen the conditions that allow the disease to develop. The experiment only involved male mice, and the suspected molecular pathways have not been tested individually. In humans, there is currently no equivalent measurement of bone loss linked to inhaled air.