Microbial distribution in the root canal system after periapical lesion induction using different methods

Mario Roberto Leonardo,Mário Tanomaru-Filho,Juliane Maria Guerreiro Tanomaru,Léa Assed Bezerra Da Silva,Izabel Yoko Ito

doi:10.1590/s0103-64402008000200007

Mario Roberto Leonardo, Mário Tanomaru-Filho + Show 3 more

Open Access

https://doi.org/10.1590/s0103-64402008000200007

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Abstract

The aim of this study was to evaluate the microbial distribution in the root canal system after periapical lesion induction in dogs' teeth using different methods. Fifty-two root canals were assigned to 4 groups (n=13). Groups I and II: root canals were exposed to the oral cavity for 180 days; groups III and IV: root canals were exposed for 7 days and then the coronal openings were sealed for 53 days. The root apices of groups I and III were perforated, while those of groups II and IV remained intact. After the experimental periods, the animals were euthanized and the anatomic pieces containing the roots were processed and stained with the Brown & Brenn method to assess the presence and distribution of microorganisms. The incidence of microorganisms at different sites of the roots and periapical lesions was analyzed statistically by the chi-square test at 5% significance level. All groups presented microorganisms in the entire root canal system. A larger number of microorganisms was observed on the root canal walls, apical delta and dentinal tubules (p<0.05), followed by cementum and cemental resorption areas. In spite of the different periods of exposure to the oral environment, the methods used for induction of periapical periodontitis yielded similar distribution of microorganisms in the root canal system.

Highlights

The biological effects of root canal filling materials and substances employed in the different phases of the root canal treatment may be investigated by ‘usage tests’, which is the ANSI/ADA denomination for evaluation methods that reproduce in primates and dogs the clinical conditions of usage of dental materials [1].Regarding teeth with apical periodontitis, the presence of bacteria after pulp necrosis is fundamental for the establishment of periapical pathosis [2]
Given that microbial diffusion into the root canal system and apical cementum is an important factor for reproducing the conditions of teeth with periapical lesion, the aim of this study was to evaluate the microbial distribution in the root canal system after periapical lesion induction in dogs’ teeth using different methods
The topographical distribution of microorganisms in the apical 3 mm of the root canal system and periapical region of the 4 groups is given on Table 1

Summary

Introduction

Regarding teeth with apical periodontitis, the presence of bacteria after pulp necrosis is fundamental for the establishment of periapical pathosis [2]. In teeth with necrotic pulp, bacteria are initially restricted to the root canal system. The dentinal tubules and canal ramifications [3] are important areas of propagation, contributing to the establishment of a large number of bacterial morphotypes. The methods for induction of periapical periodontitis used in endodontic research should reproduce the microbiological conditions of the root canal system. In this way, the use of these experimental models and the correct interpretation of the results shall provide evidence-based results that will contribute to the improvement of endodontic treatment

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