Objective: The purpose of this research was to investigate the effect per se of two shaping and cleaning techniques on the reduction of an in vitro multispecies biofilm.
Materials and methods: A total of 39 freshly extracted monoradicular teeth for periodontal reason were decoronated. Roots were sectioned longitudinally. After autoclaving, a specific stressed biofilm was grown on the root halves that were subsequently reassembled in a silicone index. Two treatments (n = 9 each)-RaCe (Schottlander; Letchworth Garden City, United Kingdom) and ProTaper Gold ( PTG; Dentsply Maillefer, Baillagues, Switzerland)-were tested; three noninstrumented samples served as a control group and three were rinsed with saline. Posttreatment samples were taken at three different levels of the root. Colony-forming units were counted after incubations. Additionally, three treatments (n = 5 each)-RaCe, PTG, and saline only-were evaluated under a confocal laser scanning microscope (CLSM).
Statistical analysis: Statistical analysis was conducted using Tukey's test and analysis of variance to evaluate the post-instrumentation bioburden.
Results: Both instrumentations were able to reduce the biofilm; however, differences were not present between them (p > 0.05). CLSM showed biofilm killing and disruption through mechanical shaping alone.
Conclusions: Intraradicular biofilm is reduced with mechanical shaping. There was no difference between RaCe and PTG systems in biofilm reduction despite differences in design, file sequence, and rotational speed.