Influence of reciprocating single-file and rotary instrumentation on bacterial reduction on infected root canals.

AIM To compare the bacterial reduction achieved with reciprocating and rotary systems during root canal preparation. METHODOLOGY Sixty distobuccal root canals of maxillary molars were contaminated with Enterococcus faecalis broth culture. After an incubation period of 21 days, bacterial samples were collected and cultured on m-Enterococcus agar plates. The root canals were divided into five groups, according to the system used for instrumentation: WaveOne, Reciproc, ProTaper, Mtwo and manual instrumentation. The negative controls consisted of five uncontaminated root canals that were subjected to the same instrumentations as each of the experimental groups. Bacterial samples were collected immediately and 7 days after instrumentation. Statistical analysis was performed by paired t-tests and anova tests. RESULTS Compared with the samples before instrumentation, the bacterial count was significantly reduced after instrumentation in all groups, with no significant difference in bacterial count reduction amongst the reciprocating, rotary and manual techniques. However, the samples tested 7 days after instrumentation showed significantly higher bacterial counts than the samples tested immediately after instrumentation. CONCLUSIONS All systems tested reduced bacterial counts to a similar level.