In vitro evaluation of the action of irrigating solutions associated with intracanal medications on Escherichia coli and its endotoxin in root canals

Abstract

ObjectiveThe purpose of this study was to evaluate the efficacy of auxiliary chemical substances and intracanal medications on Escherichia coli and its endotoxin in root canals.Material and MethodsTeeth were contaminated with a suspension of E. coli for 14 days and divided into 3 groups according to the auxiliary chemical substance used: G1) 2.5% sodium hypochlorite (NaOCl); G2) 2% chlorhexidine gel (CLX); G3) pyrogen-free solution. After, these groups were subdivided according to the intracanal medication (ICM): A) Calcium hydroxide paste (Calen®), B) polymyxin B, and C) Calcium hydroxide paste+2% CLX gel. For the control group (G4), pyrogen-free saline solution was used without application of intracanal medication. Samples of the root canal content were collected immediately after biomechanical preparation (BMP), at 7 days after BMP, after 14 days of intracanal medication activity, and 7 days after removal of intracanal medication. The following aspects were evaluated for all collections: a) antimicrobial activity; b) quantification of endotoxin by the Limulus Amebocyte Lysate test (LAL). Results were analyzed by the Kruskal-Wallis and Dunn’s tests at 5% significance level.ResultsThe 2.5% NaOCl and CLX were able to eliminate E. coli from root canal lumen and reduced the amount of endotoxin compared to saline.ConclusionsIt was concluded that 2.5% NaOCl and CLX were effective in eliminating E. coli. Only the studied intracanal medications were to reduce the amount of endotoxin present in the root canals, regardless of the irrigant used.

Efficacy of Endodontic Treatment for Endotoxin Reduction in Primarily Infected Root Canals and Evaluation of Cytotoxic Effects

“…The longer time of application (14 days) in the present study might have promoted a greater action of the intracanal medication deep within the dentinal tubules. The present in vivo results confirm previous in vitro studies in which application of the intracanal medication (chlorhexidine gel + calcium hydroxide) for 14 days neutralized most of the endotoxins that remained in the root canals after biomechanical preparation (22,26). The biological properties of LPS require the presence of ester-linked hydroxy fatty acids, and calcium hydroxide cleaves these bonds (27).…”

“…Sodium hypochlorite and chlorhexidine, which are used as auxiliary chemical solutions during biomechanical preparation, have shown an excellent antimicrobial activity, but little or no effect on LPS has been reported (12,15,(17)(18)(19)22). In an in vitro study (15), 2.5% and 5.25% sodium hypochlorite and 2% chlorhexidine were unable to inactivate LPS in root canals.…”

Ação antibacteriana de materiais restauradores ionoméricos contra Staphylococcus aureus e Escherichia coli

“…Há comprovação de que o Staphylococcus aureus pode constituir, de fato, parte da microbiota oral 4 . Já a Escherichia coli e a sua endotoxina 5 estão associadas a necroses pulpares de canais radiculares e lesão periapical crônica, por serem bactérias anaeróbias, especialmente gram-negativas.…”

Exopolysaccharide dispelled by calcium hydroxide with volatile vehicles related to bactericidal effect for root canal medication

“…Because of anatomical complexities that cannot be reached by instruments, it is still difficult to clean root canals mechanically. Thus, intracanal medication has been proposed as a component of instrumentation and irrigation to eliminate bacteria along with their by-products 15 .…”