Traumatic injuries to upper permanent incisors related to age and incisal overjet. A retrospective study.

The relationship between traumatic injuries to upper permanent incisors and incisal overjet, with special reference to the age at which the trauma occurred, was studied in a sample of 1437 orthodontically untreated children aged 7--16 years. Traumatic injuries to hard dental tissues and exarticulations of teeth were recorded. Before 10 years of age, the increase of the prevalence rates was most rapid in the extreme (greater than 6 mm) overjet group in both sexes; the ratios between the extreme and normal (0--3 mm) overjet groups being 6.5/1 in girls and 5.0/1 in boys. According to the estimate, about 50% of the girls and 70% of the boys in this overjet group with injuries were affected before the age of 10 years.