This study investigated risk factors for tooth injuries in individuals from a dental clinical reference service for patients with special needs in Belo Horizonte, MG, Brazil. This is a retrospective cohort study that evaluated 493 dental charts of individuals with or without tooth injuries at their first dental appointment. The dependent variable was the time of occurrence of new dental traumatic injuries and was measured in months. Gender, age, International Code of Diseases, mother's education, mouth breathing, hyperkinesis, pacifier use, thumb sucking, psychotropic drug use, tooth injuries at the first dental examination, involuntary movements, open bite, having one or more siblings and reports of seizures were the covariates. The Cox proportional hazards regression model was used to estimate the unadjusted and adjusted hazard ratios and their respective 95% confidence intervals. The average time that individuals remained free of dental traumatism was 170.78 months (95% CI, 157.89-183.66) with median of 216 months. The incidence of new events was 11.88%. The covariate associated with an increased risk of dental traumatism was a history of tooth injuries at the first dental appointment. The increase in dental trauma risk was 3.59 (95% CI, 1.94-6.65). A history of traumatic dental injury was the risk factor for the dental trauma found in this group of individuals with developmental disabilities.