An evaluation of the CO2 laser for endodontic disinfection

The goal of this study was to evaluate the bactericidal action of the CO, l aser on animal teeth infected with an endodontic bacterial species. After i nstrumentation, 24 freshly extracted incisors were inoculated with a known concentration of Actinomyces odontolyticus and incubated anaerobically for 18 h, The incisors were separated into three groups: group 1 - untreated co ntrol teeth; group 2 - teeth treated with 3% NaOCl; and group 3 - teeth las ed with a CO2 laser at 5 W using three successive 9.9 s irradiation periods with 10 s between treatments. For each of the three groups, 60 mu l sample s were removed using gel loading capillary pipette tips, and the diluted sa mples were plated in triplicate on Columbia agar plates. After a 5- to 6-da y incubation, the colony-forming units were counted, and the quantitative r esults were subjected to an analysis of variance. The results of this analy sis indicated an average 85% decrease in the colony-forming units in the la ser-treated group, compared with the control group. According to Fisher and Scheffe tests, the differences in the averages between the control and las er groups were statistically significant (p < 0.05). The NaOCl treatment wa s statistically superior to the CO2 laser treatment.