[Prevalence of dental erosion caused by sulfuric acid fumes in a smelter in Japan].

The effect of occupational sulfuric acid exposure and other factors on teeth was explored in a cross-sectional study with blind dental examinations. Among 350 male workers in a copper-smelter in Japan, 28 had mild dental erosion with silky-glazed opaque appearance of the enamel and/or shallow concavities on the enamel. While opaqueness was observed in 20 and concavities found in 11 workers, only 3 had both signs, suggesting that the concave lesions were often accompanied with enough remineralization to keep the dental surface gloss, possibly due to acid exposure at a low level. The cases had a history of working in an electrolytic refining plant (36%), significantly more than in the non-cases (14%, p < 0.05). Some significant differences were found between the cases and the non-cases: the cases were older, had less dental plaque, less gingivitis, and more frequent toothbrushing habits. No significant differences were observed in possibly related dietary habits such as several types of acidic drinks. It was concluded that the present cases with dental erosion were most probably associated with occupational acid exposure. The risk ratio of cross-sectional prevalence of dental erosion for those with a history of electrolytic refining plant work was 3.0 (95% CI: 1.3-6.7) compared with those without a history of acid exposure. Whether the present work environment can still develop new cases of dental erosion remains to be studied.