Dental injury among Brazilian schoolchildren in the state of São Paulo.

To describe the distribution of dental trauma in Brazilian schoolchildren and its association with demographic, environmental and clinical factors. A random sample of 73 243 schoolchildren's oral examination records from private and public units, selected from 131 cities within the state of São Paulo, Brazil, was analysed. Trauma was assessed based on international methodological standards prescribed by the World Health Organization for Oral Health Surveys (1997). Proportions obtained were compared between urban and rural schools, as well as between private and public units. Oral health status indices were estimated based on the decayed, missing and filled teeth (DMFT) index - the average number of decayed, missing and filled teeth; the proportion of caries-free 5-year-old schoolchildren and anterior maxillary overjet among 12-year-old schoolchildren. The prevalence of dental trauma in anterior dentition was of 2.4, enrolling average 1.2 teeth per child. A rate of 2.4 impaired anterior teeth per thousand was obtained, upper central incisors being those that were most affected - 7.7 in every 10. Among 8- to 11-year-old children, the rates grew regularly. The proportion of dental trauma was significantly higher in boys than in girls (P < 0.01), and gender prevalence ratio was of 1.58 for boys. The results showed positive associations between dental trauma and caries-free 5-year-old schoolchildren (P = 0.003), anterior maxillary overjet > or =3 mm (P < 0.001), and private school as a socio-economic proxy indicator (P = 0.048).