# Prevalence of lower second molar impaction on panoramic radiographs of Peruvian individuals. A cross-sectional study

## TL;DR

This study found a 6% prevalence of impacted lower second molars in Peruvian adults, with a higher occurrence in females and a common coronal impaction pattern.

## Contribution

The study provides new prevalence data on impacted second molars in a Peruvian population using panoramic radiographs.

## Key findings

- Impacted second molars were found in 6% of the Peruvian sample, with a higher frequency in females.
- The most common impaction level was coronal (78.8%), and the most frequent angulation was mesioangular (71.8%).
- Bilateral impaction occurred in 41.7% of cases, while unilateral impaction was more common on the left side.

## Abstract

To determine the prevalence and primary radiographic characteristics of impacted mandibular second molars in Peruvian individuals using panoramic radiographs.

Material and methods: This cross-sectional study examined 1,000 digital panoramic radiographs of young adults aged 15 to 40 years in Lima, Peru, conducted from 2022 to 2024. These radiographs were evaluated individually for each side, for a total of 2000 sides evaluated. Two trained evaluators performed the measurements. The selected radiographs included complete lower dentition and demonstrated good contrast and clarity. We evaluated the presence of second molar impaction and the level of impaction (coronal, cervical, or radicular). The direction of impaction was also assessed and categorized as vertical, mesioangular, distoangular, horizontal, inverted, or transverse. Additionally, the relationship between the third molar and whether the impaction was unilateral (right or left) or bilateral were evaluated. Data analysis was performed using IBM SPSS Statistics version 29.0, applying Fisher’s exact test, chi-square test, and logistic regression (p<0.05).

The sample consisted of 514 females (mean age, 26.79 ± 10.12 years) and 486 males (mean age, 26.26 ± 9.76 years). The prevalence of impaction was found to be 6%. Among the impacted cases, females represented the majority (61.67%) compared to males (28.33%). The most frequently observed level of impaction was coronal (78.8%), followed by cervical (16.5%) and radicular (4.7%). The predominant angulation was mesioangular (71.8%), followed by distoangular (16.5%), vertical (7.1%), and horizontal (4.7%). Unilateral impaction was fairly distributed between the right side (28.3%) and left side (30%), while bilateral impaction was observed in 41.7% of cases.

The prevalence of impacted second molars in our study was significant and has a considerable impact on orthodontic clinical practice. This issue was more common in females, with most cases occurring at the coronal level. The most frequent orientation of impaction was mesioangular, and unilateral cases were more common than bilateral ones.

Key words:Prevalence, Mandible, Tooth eruption, Panoramic radiograph, Molar tooth.