Identification of microrganisms and quantification of endotoxins in root canals from teeth with failure endodontic treatment with periapical lesion

Author(s)

Marcos Sergio Endo

• Document type: Master's Dissertation
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2011-07-02

Examining board members

Brenda Paula Figueiredo de Almeida Gomes; Mitsue Fujimaki Hayacibara; Caio Cezar Randi Ferraz

• Advisor: Brenda Paula Figueiredo de Almeida Gomes

Abstract

This clinical study was conducted to investigate the microbiota and bacteria endotoxin of root canal from teeth with posttreatment apical periodontitis (PAP) by culture and polymerase chain reaction (PCR) before and after chemomechanical preparation (CMP) and after the use of intracanal medications (ICM). Furthermore this work aimed to quantify endotoxin and cultivable bacteria in root canals with PAP correlating their levels with the presence of clinical and radiographic features. Fifteen single root-filled teeth with PAP were sampled. Culture techniques were used to determine the colony-forming unit (CFU). Microrganisms were identified by biochemichal tests and PCR. Limulus amebocyte lysate (LAL, turbidimetric Pyrogent 5000) was used to quantify endotoxins before (S1) and after (S2) CMP and after the use of ICM. The bacterial species most frequently isolated were Gemella morbillorum, Haemophilus aphrophilus, Enterococcus faecalis and Actinomyces naeslundii; while Parvimonas micra, Prevotella nigrescens, Fusobacterium nucleatum and Gemella morbillorum were frequently detected by PCR. Endotoxin was always detected at S1 and S2. At S1, endotoxin and bacteria were detected in a median value of 3.96 EU/mL and 2.57 x 102 CFU/mL, respectively. A positive correlation was found between the endotoxin and radiolucency area (>5 mm). CMP was effective in reducing bacteria (99.93%) and endotoxin (60.6%) (both p<0.05), and it was responsible for the majority of the microbial reduction when compared with ICM. In conclusion the microbiota of root-filled canals with PAP is predominantly facultative Gram-positive even though fastidious Gram-negative bacteria were detected by PCR. Gram-negative bacterial endotoxins play a role in the PAP and are associated with periapical bone-destruction. Moreover CMP with 2% CHX gel + 17% EDTA was effective in reducing but not complete removing endotoxin and cultivable bacteria from persistent root canal infection. (AU)