In vitro effectiveness of auxiliary chemical substances and intracanal medications on microorganisms and endotoxin in root canals

Author(s)

Ana Carolina Mascarenhas Oliveira

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2013-06-03

Examining board members

Brenda Paula Figueiredo de Almeida Gomes; Lourdes Aparecida Martins dos Santos Pinto; Maria Cristina Borsatto; Flaviana Bombarda de Andrade Ferreira; Izabel Cristina Froner

• Advisor: Brenda Paula Figueiredo de Almeida Gomes

Abstract

The aim of this study was to evaluate in vitro the effectiveness of the auxiliary chemical substances and intracanal medications on microorganisms and endotoxins in root canals. Single-rooted extracted human teeth (n=520) were scraped and sectioned, and their crowns discarded. The roots were standarded at 15 mm and stored in sterile saline at -20ºC until use. They (n=520) were externally waterproof, endodontically instrumented, included in microtiter plates, sterilized by ethylene oxide gas and inoculated with E. faecalis, E. coli, and C. albicans for 28 days. Among the 520 roots, 400 were used for microbiological assay (phenotypic/molecular identification) and endotoxin assay by LAL test (Limulus amebocyte Lysate). Samples were collected at different times on CMP and intracanal medication: 7, 14 and 30 days. Four hundred roots were randomly divided into groups and instrumented according to the auxiliary chemical substances used during chemomechanical preparation (CMP) with (n=360) or without (n=40) 17% EDTA, respectively: 5.25% sodium hypochlorite (NaOCl) (n=90/10); 2% chlorhexidine gel (CLG) (n=90/10); 5.25% NaOCl and final irrigation with 2% CLL (n=90/10); and saline (control) (n=90/10). The roots irrigated with 17% EDTA were divided into subgroups according to intracanal medication: 2% CLG (n=90); calcium hydroxide (CH) plus 2% CLG (n=90); CH plus saline (9:1) (n=90); and saline (control) (n=90). Another roots (n=120) were submitted to different auxiliary chemical substances and intracanal medications and analyzed by confocal microscopy regarding microbial viability. The results were statistically analyzed at 5% significance level. CMP with 2% CLG, 5.25% NaOCl, and 5.25% NaOCl plus 2% CLL promoted reduction of E. coli, E. faecalis, C. albicans and endotoxin levels. Seven days after CMP, the root canals were re-infected. 2% CLG, 5.25% NaOCl, 5.25% NaOCl plus 2% CLL, CH, and CH plus 2% CLG showed no ability on endotoxin elimination. It was concluded that 2% CLG, 5.25% NaOCl, 5.25% NaOCl plus 2% CLL, CH, and CH plus 2% CLG was effective on reducing E. coli, E. faecalis, and C. albicans. Lower microbial reduction occurred in the dentinal tubules compared to the root canal. No substance was able to eliminate endotoxin (AU)

• FAPESP's process: 09/17707-4 - In vitro evaluation of the effectiveness of irrigating solutions and intracanal medications on microorganisms and endotoxin in root canals.
• Grantee: Ana Carolina Mascarenhas Oliveira
• Support Opportunities: Scholarships in Brazil - Doctorate