Assessment of Antibacterial Activity of Four Endodontic Sealers against Enterococcus Faecalis by a Direct Contact Test: An In-Vitro Study

Antibiotic activity of endodontic sealers can improve the success rate of endodontic treatment provided the physical properties are not compromised. The dentin adhesive sealers are superior in case of manipulation, radio opacity, setting time, and excellent adaptation to canal walls, but the antibacterial activity of the Urethane dimethacrylate resin based and Polydimethyl siloxane based sealers is questionable. An in-vitro experimental study was formulated to evaluate the antibacterial activity of four endodontic sealers on Enterococcus faecalis by a Direct Contact Test. The study materials grouped and selected were Group I, Calcium- hydroxide based sealer (Sealapex), Group II, Polydimethyl siloxane based (RoekoSeal), Group III ,Urethane dimethacrylate resin based sealer (Endo Rez), Group IV Zinc Oxide Eugenol based sealer (Tubli-Seal EWT). The sealers were mixed in strict compliance with the manufacturer's recommendations. The direct contact test was performed based on turbidometric determination of bacterial growth in 96 well microtiter plates. The kinetics of the outgrowth in each well was monitored at 600 nm at 370C. Side walls of the microtiter plate wells were coated with freshly mixed tested material and a 10 μL bacterial suspension was placed. After 1 hr of incubation at 37°C which ensured direct contact between bacteria and tested material, Brain Heart Infusion broth (245 μL) was added to each of these wells and gently mixed for 2 min. These were designated as ‘A’ wells. 15 μL were then transferred from these A wells to an adjacent set of 4 wells containing fresh medium (215 μL) which were designated as ‘B’ wells. The bacterial outgrowth was monitored both in the presence (A wells) and in the absence of the tested material (B wells). The recordings were based on the reading of the transmittance values in the spectrophotometer. Higher the transmittance value, the higher was the antimicrobial activity (i.e. less microbial growth).The microbial growth was recorded every 1 hour using a spectrophotometer for 7 hours at time intervals of 20mts, 1 day and 7 days. The results obtained were subjected to statistical analysis by Kruskal Wallis One way Anova and Mann –Whitney ‘U’ test. CONCLUSION: Under the limitations of this study, the following conclusions were inferred: 1. Endodontic root canal sealers had different inhibitory effects on Enterococcus faecalis during the growth period. 2. Calcium hydroxide based sealer (Sealapex) had an initial antibacterial activity for 10 hours, which slowly reduced with time. 3. Polydimethyl siloxane based (RoekoSeal) endodontic sealer underwent a brisk decrease in antibacterial activity after 3 hours followed by a decrease in its antibacterial activity at 1day and 7 days. 4. Urethane dimethacrylate resin (EndoRez) based sealer had no antimicrobial property. 5. Zinc oxide Eugenol based sealer (Tubli-Seal EWT) was the most effective and Urethane dimethacrylate resin based sealer (EndoRez) was the least effective against Enterococcus faecalis