An assessment of bactericidal effect of two different types of lasers on enterococcus faecalis: An in vitro study

Aim and Objective: To evaluate the bactericidal efficacy of the Nd:YAG laser and the Diode laser at different parameters to that of calcium hydroxide, and to know the effect of increase in lasing time on degree of disinfection. Materials and Methods: Fifty human single-rooted teeth were taken and were kept in 3% NaOCl for 15 mins and access cavities were prepared, the apical third of these roots was gradually enlarged until reaching the ISO 40- K file. Later the teeth were autoclaved and mounted on 2.5 ml eppendorf tubes filled with BHI medium which was autoclaved again. The teeth were inoculated with a standard strain of Enterococcus faecalis and incubated for one week. They were randomly divided into five groups and treated as follows, G-I: - Negative control. G-II:- 980 nm diode laser irradiation for five seconds and five cycles at 2W power, 10 Hz frequency and pulsed mode. G-III:- 980 nm diode laser irradiation for 10 seconds and five cycles at 2W power, 10 Hz frequency and pulsed mode. G-IV:- Nd:YAG laser irradiation for five seconds and five cycles at 2 W power, 15 Hz frequency and pulsed mode. G-V:- Nd:YAG laser irradiation for 10 seconds and five cycles at 2 W power, 15 Hz frequency and pulsed mode. The dentin dust was collected from superficial and deep dentin of coronal and apical halves of all the samples and CFU/ ml were evaluated after three days. Results: The results were calculated and statistical analysis was done using Kruskal Wallis ANOVA test by ranks and Mann Whitney's U test. Comparisons were done between the superficial and deep dentin of different groups and between the groups. Conclusion: Under the parameters of the samples tested Nd:YAG laser provided the best results for disinfection compared to Diode laser. However, both the Nd:YAG and Diode lasers provided clinically acceptable disinfection.