Pattern of Disinfection of Root Canal Dentin by Alternated Acid-Base Irrigating Regimen

Abstract

Objective. To quantifyEnterococcus faecalisdensity in root canal dentin after chemomechanical preparation (CMP) using alternated irrigating regimen.Methodology. Root canals (RC) were contaminated withE. faecalis(ATCC 19433) for 3 weeks and evident biofilms were obtained. After initial sampling (S1), the CMP was aided by irrigants: saline solution (control; n=12), a conventional regimen (CR) (group 1; n=12) using 5.25% NaOCl and a final rinse with 17% EDTA, and an alternating regimen (AR) of intercalated use of NaOCl and EDTA (group 2, n=12), followed by a second sampling (S2). After 2 weeks, S3 was obtained. Two roots were analyzed by scanning electron microscopy. Each root was divided into cervical, mild, and apical segments and sampling of the superficial (n=90) and deep (n=90) dentin layers was obtained using Gates-Glidden burs. TheE. faecalisdensity (CFU/mg) in log10was categorized as residual (0 > 0.2), moderate (0.2 ≥ 0.5), or elevated (> 0.5). The prevalence of positive samples in BHI and BHI-A was analyzed by Pearson’s chi-square test. The data were normalized by a log10transformation of CFU and were analyzed by one-way ANOVA and Tukey’s tests.Results. Biofilms were observed only in the control root canal walls. Topographically, the controls and CR showed similar distributions ofE. faecalisin the dentin. Microbiologically positive root canals harbored muchE. faecalisin the adjacent dentin (p< 0.05). Irrigating saline provided moderate density ofE. faecalisin the dentin while CR and AR resulted in a residual density of microorganisms (p< 0.05).Conclusions. TheEnterococcus faecalisdensity in dentin was influenced by the irrigating regimen and the microbiological status of the root canal. The CMP aided by the alternating regimen interfered with the recolonization of the root canal and topographic distribution ofEnterococcusin root dentin.