Antimicrobial effect of Citrus aurantifolia extract on Enterococcus faecalis within the dentinal tubules in the presence of smear layer

Instrumentation of the root canals results in formation of smear layer which covers the dentinal tubules. In infected teeth, it is ideal to achieve a material that has the ability to remove the smear layer besides antimicrobial activity. Therefore, this study was designed to evaluate the antimicrobial effect of Citrus aurantifolia extracts (lime juice and rind extract) on Enterococcus faecalis within dentinal tubules in the presence of smear layer. One-hundred and forty dentin tubes were prepared from bovine incisors. After removal the smear layer, the specimens were infected with Enterococcus faecalis. Then, the smear layer was reformed. Test solutions were used as the irrigants in study roups as follows: group 1: 5.25% NaOCl; group 2: 17% EDTA; group 3: NaOCl+EDTA; group 4: Lime juice; group 5: ethanolic rind extract of C.aurantifolia; group 6: 96% ethanol. Dentin chips were collected from inner and outer layers of dentinal walls and optical density was measured. The data were analyzed using one-way ANOVA and Tamhane tests. In outer layer of dentin, the efficacy of rind extract was less than that of NaOCl+EDTA (P<0.05). Also Lime juice was less effective than EDTA, NaOCl and NaOCl+EDTA (P<0.05). In inner layer of dentin, Lime juice was significantly less effective than NaOCl and NaOCl+EDTA (P<0.05). The efficacy of rind extract was less than that of NaOCl+EDTA (P<0.05). In the presence of smear layer, the antimicrobial activity of Lime juice was less than that of NaOCl but the efficacy of rind extract was similar to that of NaOCl.