Effect of ultrasound streaming on the disinfection of flattened root canals prepared by rotary and reciprocating systems

Abstract New technical and scientific developments have been advocated to promote the success of the endodontic treatment. In addition to rotary and reciprocating systems, irrigating solution agitation has been suggested and passive ultrasonic irrigation (PUI) is the most used. Objective: To evaluate, in vitro, the effect of ultrasound streaming (US) in the disinfection of flattened root canal systems prepared by the ProTaper, BioRaCe and Reciproc systems, utilizing the microbiological culture. Methodology: Extracted human mandibular incisors (n=84) were used. Suspensions of Enterococcus faecalis (ATCC 29212) were standardized and inserted along with the teeth immersed in brain-heart infusion (BHI) broth. The contamination was made following a protocol during 5 days. The teeth were randomly divided into six groups: G1, ProTaper Universal; G2, ProTaper Universal with US; G3, BioRaCe; G4, BioRaCe with US; G5, Reciproc; and G6, Reciproc with US. Irrigation was performed with saline solution. After biomechanical preparation, microbiological samples were performed with sterilized paper points, which were diluted and spread on BHI agar; after 48 h, the colony forming units (CFU/mL) were counted for each sample. Results: Groups using ultrasonic agitation presented a greater antibacterial effect than the other ones, even using saline solution as irrigant. The ProTaper Universal system showed the best antibacterial activity of the tested systems (median of 0 CFU/mL with and without surfactant or ultrasonic activation [PUI]). Even with PUI, Reciproc (median of 2.5 CFU/mL with PUI and 5 without it) could not reduce as many colonies as ProTaper Universal without US. The BioRaCe system had greater bacterial reduction when using US (median of 0 CFU/mL with PUI and 30 without it). Conclusions: US promoted greater reduction in the number of bacteria in the flattened root canals prepared with nickel-titanium mechanized systems. Regarding the instruments used, the ProTaper Universal system was the most effective in reducing the bacterial number.

Ex vivo Analysis of Three Electronic Apex Locators Accuracy with Different Settings.

Aims: The correct determination of a root canal length is a fundamental step for an adequate chemical-mechanical preparation and consequently, for a successful endodontic treatment. Electronic apex locators (EAL) were developed to provide fast and reliable working lengths. The aim of the present study was to analyze the accuracy of the Root ZX II, RomiApex A-15, and SmarPex EAL’s to determine the location of apical constriction, with and without the instructions recommended by the manufacturers. Methodology: Fifteen mandibular premolars were randomly selected and root canals were accessed. The real canal length was determined by introducing a #15 K-file until the tip was visualized in the apical foramen, using 40x magnification of an operative microscope. In the sequence, the teeth were inserted in plastic flasks containing floral foam soaked in 0.9% saline solution. The root canals were filled with 1% sodium hypochlorite and the electronic measures were obtained with the selected devices until the “0.0” or the last green bar mark, as showed in devices display, and as per the manufacturers settings recommendation. The data were submitted to statistical analysis with the Friedman and Wilcoxon tests with a 0.05% significance level (p < 0.05). Results: All devices were similar (p > 0.05) and showed precise and acceptable measurements at both times. Without manufacturers setting recommendation, the Root ZX II was the EAL that presented the greater percentage of coincidences with the real teeth length measures (73.33%), followed by the RomiApex A-15 (66.66%) and the SmarPex (40%). After performing the recommended settings the Root ZX II and the SmarPex presented 86.66% of coincidence with the real length, however, only the SmarPex device enhanced the mean precision with the real length (p < 0.05). Conclusion: Considering a clinically acceptable average error of ±0.5 mm, all devices were effective in determining the measurement until the apical constriction. Although, there were no statistical significant difference with and without manufacturers instruction, for Root ZX II, the performance was better when manufacturer instructions were followed.