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Failure to control infection in the root canal system has an adverse impact on outcome. Clinicians should be aware of anatomical variations in the teeth they are managing, and should never assume that canal systems are simple. The majority of mandibular canines have one root and root canal, but 15% may have two canals, and a smaller number may have two distinct roots.

The aim of this study was to evaluate the efficacy of the Pumped Diodium-Nd:YAG laser in sterilizing contaminated root canals. After hand instrumentation, 30 teeth were inoculated with Actinomyces naeslundii CH-12 and 30 teeth with Pseudomonas aeruginosa ATCC 27853 and incubated for 24 h. The teeth were divided into three subgroups: subgroup A received no treatment; subgroup B was irradiated with laser (5 Hz for 15 s or 10 Hz for 15 s); and subgroup C was irrigated with 5.25% NaOCl. The number of viable bacteria in each group was evaluated by using the surface-spread plate technique. The results indicated an average of 34.0% decrease in colony-forming units for A. naeslundii CH-12 and 15.7% for P. aeruginosa ATCC 27853 with the 5 Hz/15 s laser treatment, and for the 10 Hz laser frequency, a decrease of the 77.4% for A. naeslundii CH-12 and 85.8% for P. aeruginosa ATCC 27853. No bacteria were detected in the canals treated with 5.25% NaOCl. The results show an antibacterial effect of the Pumped Diodium Nd:YAG laser, depending on the radiation frequency. However, 5.25% NaOCl was more effective than either laser application.

This paper reports two clinical aids for the removal of broken instruments in root canals using a combination of hand instrumentation and ultrasonic devices. This technique is based on two phases: hand instrumentation with stainless-steel K-file instruments for bypassing the fragments, and K-files mounted on an ultrasonic handpiece for loosening and retrieval of the broken instruments. This method offers the following advantages: conservation of the remaining dentin wall of the root canal and elimination of the necessity for surgical treatment.