Prevalence and Types of Ectopic Eruption of First Permanent Molars in Children in Talca, Chile

Abstract

Introduction: The lateral zone of the temporal dental arch, formed by the canine and temporal molars, is important for the consolidation of a correct definitive occlusion. However, its integrity can be altered by the ectopic eruption (EE) of the first permanent molar (1MP), so it is important to know its epidemiology. Objective: To determine prevalence and location of the different types of 1MP EE, in patients from 4 to 7 years old, treated at the Dental Clinical Center of the University of Talca, Chile. Materials and methods: Observational, analytical and cross-sectional study. We evaluated 474 orthopantomographies, determining frequency and distribution of ectopic eruption (EE) of 1MP in its different types, by dental quadrant. The association was determined between affected subjects and sex, and the difference in proportions between maxillary/jaw, uniarch/biarch, unilateral/bilateral. Results: Of 474 orthopantomographies, the distribution of patients with and without EE was 34.6% and 65.4% respectively. At the age of 4 years, no patients were found with EE of 1MP, but this was found to increase up to 42.1% at 7 years. Of the total, patients with EE of 1MP in maxilla were 31.2% and in mandible 5.1%. The EE of 1MP was uniarch in 96.3% and biarch in 3.7%. In the maxilla and in the mandible, it was mostly unilateral with 55% and 60.9% respectively. Conclusions: prevalence of EE of 1MP was approximately one third of the population studied, with no sex predilection. EE of 1MP was diagnosed since 5 years old. EE of 1MP was found to be significantly more prevalent in maxilla than in mandible. The frequency of reversible EE was the lowest, compared to patients without EE and those with irreversible EE. EE of 1MP occurred significantly more frequently in maxilla than in mandible.