# Copaiba Oil–Resin Reduces the Alveolar Bone Damage Triggered by Apical Periodontitis in Rats

## TL;DR

Copaiba oil–resin helps reduce bone damage in rats with apical periodontitis, suggesting it could be a useful treatment for this condition.

## Contribution

The study demonstrates for the first time that copaiba oil–resin can reduce alveolar bone damage caused by apical periodontitis in rats.

## Key findings

- Copaiba oil–resin reduced lesion volume and space between bone trabeculae in rats with apical periodontitis.
- The resin preserved collagen fibers and reduced tissue damage around the lesion.
- Histopathological analysis confirmed significant alveolar bone preservation in treated rats.

## Abstract

This study aimed to investigate the effects of copaiba oil–resin on induced apical periodontitis in rats.

A total of 24 male Wistar rats were divided equally into three groups (eight animals each): control (C), apical periodontitis (AP) and apical periodontitis with copaiba administration (AP + COP). The AP was induced by exposing the pulp chambers of the mandibular first molars to the oral environment. The openings were maintained for 28 days to allow lesion development. The AP + COP group received systemic administration of 200 mg/kg of copaiba oil–resin via intragastric gavage during the final 7 days of the AP induction period. The rats were then euthanised, and their hemimandibles were subjected to histopathological analysis to assess tissue preservation, histochemical staining with picrosirius red to evaluate collagen content, and microcomputed tomography to assess lesion volume and bone quality parameters. Statistical analyses were performed using a one‐way ANOVA, followed by Tukey's post hoc test for parametric data and the Kruskal–Wallis test for nonparametric data. The results are expressed as mean and standard error of the mean for parametric tests, and median and interquartile deviation for the nonparametric test.

The findings showed that copaiba oil–resin reduced lesion volume compared to the untreated group (p = 0.0261), as well as reducing the space between the bone trabeculae found in the AP group (p = 0.0063). Additionally, copaiba oil–resin preserved the collagen fibres, which were more degraded in the untreated group (p = 0.0009). Histopathological analysis showed that copaiba oil–resin reduced tissue damage, preserving a significant area of alveolar bone surrounding the lesion.

These results indicate that copaiba oil resin has a promising adjunct therapeutic potential to reduce the bone loss caused by apical periodontitis and contribute to the maintenance of quality in the remaining bone.