AN INVESTIGATION OF THE ASSOCIATION BETWEEN OVERJET SIZE, LIP COVERAGE, AND TRAUMATIC INJURY TO MAXILLARY INCISORS

This study investigated the association between overjet size and lip c overage when assessing the likelihood of traumatic injury to maxillary incisors. Eleven-hundred-and-thirty-seven 11- and 12-year-olds were e xamined in school for traumatic injury to their maxillary incisors. Th e size of overjet and the adequacy of lip coverage of the maxillary in cisors was assessed for each child. One-hundred-and-sixty-seven (15 pe r cent) had experienced traumatic injury to their maxillary incisors. Both increased overjet and inadequate lip coverage of the maxillary in cisors were found to be significant risk factors. However, inadequate lip coverage was the single most important independent predictor of tr aumatic injury (P<0.001), with a relative odds ratio of 2.62. The resu lts suggest that much of the predictive value of increased overjet may be explained by inadequate lip coverage.