To investigate the prevalence of tooth wear and associated factors in adults from the 1982 Pelotas Birth Cohort. A subsample of the 5,914 individuals from the 1982 Pelotas Birth Cohort was randomly selected to be interviewed and clinically examined at the age of 31. Tooth wear was evaluated using a simplified version of the Tooth Wear Index (TWI), considering the absence or presence of tooth wear in dentin of first molars and anterior teeth (incisors and canines). Independent variables were socioeconomic, demographic, unhealthy behavior, and mental health. Crude and adjusted Poisson regression models were employed. A significant level of P ≤ 0.05 was adopted. A total of 537 individuals were evaluated. A tooth wear prevalence of 61.6% was observed. Females presented a statistically significant lower tooth wear in dentin prevalence ratio (PR) compared to males in the adjusted analysis (PR 0.76; 95% CI: 0.67–0.86). Acid beverage consumption (PR 1.22; 95% CI: 1.01–1.49) and consumption of alcoholic beverages (PR 1.19; 95% CI: 1.04–1.35) were positively associated with tooth wear. Almost 2/3 of the surveyed individuals presented tooth wear in dentin. Being a male, higher consumption of alcohol and acidic beverages were factors associated with tooth wear. : There was a high prevalence of tooth wear in dentin in the adult population. Data has also shown the etiological complexity of tooth wear, reinforcing the importance of an early diagnosis and the establishment of preventive measures to decrease the potentially hazardous effect of tooth wear over time.