Resorption of incisors after ectopic eruption of maxillary canines: A CT study

The purpose of the study was to analyze the extent and prevalence of resorp tion of maxillary incisors after ectopic eruption of the maxillary canines in a sample of subjects referred to an orthodontic specialist clinic for co nsultation. The subjects consisted of 107 children, 39 boys and 68 girls, b etween 9 and 15 years of age (mean 12.5 years), with 156 ectopically and 58 normally erupting maxillary canines. All children were subjected to a basi c clinical and intraoral radiographic investigation. These radiographs were supplemented with computerized tomography (CT) of the upper alveolar bones in order to get more precise information on the positions and relationship s between the maxillary canines and adjacent incisors and to evaluate resor ptions on the roots of the incisors. The results showed that, relative to t he roots of the adjacent incisors, the crowns of 21% the ectopically positi oned canines were located to the buccal, 18% to the distobuccal, 27% to the lingual, 23% to the distolingual, 5% apically and 6% between the central a nd lateral incisors. Ninety-three percent of the ectopically positioned can ines were in contact with the roots of the adjacent lateral incisor and 198 were in contact with the central incisor. The corresponding figures for th e normally erupting canines were 49%. Resorptions on the roots of the incis ors adjacent to the ectopically positioned canine occurred in 38% of the la terals and in 9% of the centrals. The resorptions were graded and tended to be extensive. Among the 58 resorbed lateral incisors, resorptions were sli ght in 31%, moderate in 9%, and severe with pulpal involvement in 60%. The corresponding figures for the 14 resorbed centrals were 36%, 21%, and 43%, respectively. About 60% of the resorptions involved the middle and apical t hirds, the tip of the apex not included. On the sides with normally eruptin g canines, 3 lateral maxillary incisors were slightly or moderately resorbe d distally. In all, 51 of the 107 subjects with ectopically erupting maxill ary canines (48%) had resorbed maxillary incisors during the eruption of th e maxillary canines. There were statistically significant correlations betw een ectopic eruption of the maxillary canine, contacts between the teeth an d resorptions on the adjacent incisors. It was concluded that resorption on maxillary incisors after ectopic eruption of the maxillary canines is a mo re common phenomenon than previously reported and has to be considered in a ll cases with seriously diverging eruption of maxillary canines. It was als o concluded that the resorptions of the roots of the incisors were caused b y pressure during the eruption of the adjacent, aberrant canine. Finally, i t was shown that CT scanning substantially increased the detection of root resorptions on incisors adjacent to ectopically erupting maxillary canines (about 50%). The sensitivity of intraoral films was low when diagnosing the resorptions, being calculated to 0.68. (Angle Orthod 2000;70:000-000.).