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

Objective

The purpose of this study was to evaluate the efficacy of auxiliary chemicalsubstances and intracanal medications on Escherichia coli and its endotoxin inroot canals.

Material and Methods

Teeth were contaminated with a suspension of E. coli for 14 daysand divided into 3 groups according to the auxiliary chemical substance used: G1)2.5% sodium hypochlorite (NaOCl); G2) 2% chlorhexidine gel (CLX); G3) pyrogen-freesolution. After, these groups were subdivided according to the intracanalmedication (ICM): A) Calcium hydroxide paste (Calen®), B) polymyxin B, and C)Calcium hydroxide paste+2% CLX gel. For the control group (G4), pyrogen-freesaline solution was used without application of intracanal medication. Samples ofthe root canal content were collected immediately after biomechanical preparation(BMP), at 7 days after BMP, after 14 days of intracanal medication activity, and 7days after removal of intracanal medication. The following aspects were evaluatedfor all collections: a) antimicrobial activity; b) quantification of endotoxin bythe Limulus Amebocyte Lysate test (LAL). Results were analyzed by theKruskal-Wallis and Dunn’s tests at 5% significance level.

Results

The 2.5% NaOCl and CLX were able to eliminate E. coli from rootcanal lumen and reduced the amount of endotoxin compared to saline.

Conclusions

It was concluded that 2.5% NaOCl and CLX were effective in eliminating E.coli. Only the studied intracanal medications were to reduce theamount of endotoxin present in the root canals, regardless of the irrigantused.