An in vitro comparative evaluation of the antibacterial efficacy of 10% metronidazole gel, 2% chlorhexidine gel, and a combination of calcium hydroxide and 2% chlorhexidine gel against Enterococcus faecalis

Abstract

Background and Objectives: A major objective in endodontic therapy is to disinfect the root canal system prior to obturation. This is because the residual root canal infection can sustain persistent or recurrent periapical disease. Hence, the use of an intracanal medicament between appointments helps in the elimination of bacteria that remain even after cleaning and shaping. The objective of this in vitro study is to compare the antibacterial efficacy of 10% metronidazole gel, 2% chlorhexidine (CHX) gel, and a combination of calcium hydroxide and 2% CHX gel against Enterococcus faecalis (E. faecalis) using a culture technique. Materials and Methods: The study included 40 single-rooted, human permanent teeth, ­extracted for periodontal or other reasons. Conventional access to the root canals was obtained using access preparation burs in a high speed handpiece. The working length was determined using the Ingle's radiographic method and the canals were instrumented using a Step-back technique with K-files, up to size 40, at the apex and irrigated with 1 ml of 2.5% Sodium hypochlorite and Ethylenediaminetetraacetic acid gel. The root canals were filled with a sterile Casein Soya meal peptone solution (CSL) and autoclaved twice for 30 minutes at 121°C. An inoculum of E. faecalis was injected into the canals using a sterile syringe and it was incubated aerobically at 37°C for nine days. The specimens were then randomly divided into three experimental groups (10% metronidazole gel, 2% CHX gel, and a combination of calcium hydroxide and 2% CHX gel) and one control group, each containing 10 samples. Following this, the canals were cleaned using an ultrasonically activated No.15 K-file, along with sodium ­hypochlorite irrigation. After medicament removal, each root canal was prepared manually with a new size 40 hedstrom file. The colony forming units per millimeter were determined by the standard laboratory methods. The obtained data was subjected to statistical analysis using the Mann-Whitney test and the χ2 test. Results: In our study, Group II (2% CHX gel) showed significant reduction of E. faecalis. Group I (10% metronidazole gel) showed minimal ­reduction, and Group III (2% CHX gel with calcium hydroxide) showed moderate ­reduction. There was no ­reduction in observed in Group IV (control group) patients. Conclusion: Our study ­signifies that 2% CHX gel showed substantial antimicrobial activity against E. faecalis. The ­combination of calcium hydroxide and 2% CHX gel also showed good ­antimicrobial activity. Hence, the efficacy of 2% CHX gel was greater than its ­combination with ­calcium hydroxide. The least effective drug against the microbes was metronidazole.