Ectopic Eruption of Permanent First Molars

Ectopic eruption may be defined as the eruption of a permanent tooth that takes place in such a manner that a partial or a total resorption of the root(s) of an adjacent primary tooth occurs and can be noted during routine dental radiographic evaluation. It is a common case in mixed dentition and is usually diagnosed by a pediatric dentist. This retrospective study aimed to determine the prevalence and related factors of the ectopic eruption of permanent first molars(PFM). This retrospective study was performed using the panoramic radiographs of 11,924 child patients aged 6-10 years with at least one ectopically erupted PFM were included. The total prevalence of ectopic eruption, type, age, gender, jaw distribution, and bilateral versus unilateral occurrence were determined. The angulation of PFM, mesialization ratio of PFM, and degree of adjacent primary second molar(PSM) tooth root resorption were also assessed. The chi-square test, ANOVA was used for statistical analysis. A total of 76 ectopic eruptions were detected in the maxilla, 6 in the mandible, and 2 in both the maxilla and the mandible. In terms of the eruption status of cases with ectopic eruption, 27 were self-corrected, 51 remained impacted, and 6 were both. The impaction rate of the right upper PFMs was higher than that of others. No significant relationship was found between eruption status and degree of resorption. As a conclusion, small impaction of the PFM does not mean that the PSM lesion is also small. With substantial displacements, a proportionally diminutive lesion can exist, and vice versa.