Evaluation of Microbial Reduction in Root Canals Instrumented with Reciprocating and Rotary Systems

Objective

This in vitro study aimed to evaluate the efficacy of the disinfection of root canal systems carried out with Reciproc^TM and ProTaper Universal^TM systems using 1% sodium hypochlorite (NaOCl).

Methods

Forty human single-rooted mandibular premolars were infected with Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans, and twenty were not infected. The specimens were randomly divided into 6 groups (n = 10): Group 1: ProTaper Universal^TM + 1% NaOCl; Group 2 (positive control): ProTaper Universal^TM + saline; Group 3 (negative control without microorganisms): ProTaper Universal^TM + saline; Group 4: Reciproc^TM + 1% NaOCl; Group 5 (positive control): Reciproc^TM + saline; Group 6 (negative control without microorganisms): Reciproc^TM + saline. Samples were collected before and after the completion of specific treatments, and plated in specific media cultures. The Fisher exact test was used for the statistical analysis of differences in terms of presence or absence of microbial growth among groups. For all tested pathogens, significant differences (p < 0.001) were verified between the instrumentation systems used.

Results

ProTaper Universal^TM associated with 1% NaOCl completely eliminated all microorganisms. Microbial growth, however, was observed when Reciproc^TM was used associated with 1% NaOCl.

Conclusion

According to the protocol executed for this study, the Reciproc^TM system associated with 1% NaOCl was not able to completely eliminate E. faecalis, P. aeruginosa, S. aureus and C. albicans from the root canal systems.Key words: endodontic treatment, Enterococcus faecalis, single-file instrumentation, sodium hypochlorite     

Switch movements and the myosin crossbridge stroke

The myosin II motor from Dictyostelium discoideum has been engineered to contain single tryptophan residues at strategic locations to probe movements of switch 1 and switch 2. The tryptophan residue at W501 probes movement of the relay helix and indirectly reports on switch 2 movement. This probe suggests that there is an equilibrium between the switch 2 open- and closed-states when the γ-phosphate position is occupied. Actin does not appear to greatly affect this equilibrium directly, but has indirect influence via switch 1. The latter region has been probed by introducing tryptophan residues at positions 239 and 242. The kinetics of the actomyosin ATPase in solution is discussed with respect to recent crossbridge models based on high-resolution crystal structures. To whom correspondence should be addressed: Tel.: +44-(0)-116-229-7048; Fax: +44-(0)-116-229-7018; E-mail: crb5@le.ac.uk     

Pseudomonas spp. ISOLATED FROM THE ORAL CAVITY OF HEALTHCARE WORKERS FROM AN ONCOLOGY HOSPITAL IN MIDWESTERN BRAZIL

This cross-sectional study, performed in an oncology hospital in Goiania, aimed to characterize the prevalence of oral colonization and antimicrobial susceptibility of Pseudomonas spp. isolated from the saliva of healthcare workers. Microorganisms were subjected to biochemical tests, susceptibility profile, and phenotypic detection. Of 76 participants colonized with Gram negative bacilli, 12 (15.8%) harbored Pseudomonas spp. Of all isolates, P. aeruginosa (75.0%), P. stutzeri (16.7%), and P. fluorescens (8.3%), were resistant to cefoxitin, and therefore likely to be AmpC producers. The results are clinically relevant and emphasize the importance of surveillance to minimize bacterial dissemination and multiresistance.