The aim of this study was to describe the shaping ability of a rotary nickel-titanium instrument in combination with different torque-controlled endodontic devices in severely curved root canals of extracted human teeth. Sixty human molars with curvatures ranging from 25° to 69° were embedded in a muffle system and portioned into five horizontal sections (thickness 1.2 mm), starting from the apex. Canals were divided into three groups (n = 20 for each) and were prepared with either a cordless endodontic handpiece (SiroNiti) or two conventional devices (E-MasterTM and Endo IT control) using FlexMaster® instruments and a crown-down preparation technique. We evaluated the frequency of instrument failure, preparation time, loss of working length and differences between pre- and postoperative instrumentation of root canal cross-sections. The root canal area before and after the intervention was determined using area-measuring software. The data were analyzed statistically using a one-way ANOVA followed by a Kruskal-Wallis multiple-comparison Z-test. Significantly higher values for preparation time and instrument failures were observed when using the cordless endodontic handpiece, while using the Endo IT control device resulted in significantly higher values for loss of working length (0.6 mm). Specimens treated with the SiroNiti device showed the greatest significant change from preoperative cross-sections. Preparing root canals using the described devices lead to various problems. The cordless endodontic handpiece produced unsatisfactory results for three of the four parameters analyzed. Thus within the limitations of our study, the SiroNiti device can only partially be recommended for treating curved canals.

Background: To evaluate the clinical efficacy of an in-office desensitizing paste containing 8% arginine and calcium carbonate relative to that of a commercially-available pumice prophylaxis paste when applied pre-procedurally to a dental scaling procedure (dental prophylaxis). Methods: This was a parallel group, randomized, double-blind, trial study conducted in 130 subjects who presented a tactile hypersensitivity score of 2 or 3 (Orchardson và Collins Tactile Sensitivity Scale) and an air blast hypersensitivity score of 2 or 3 (Schiff Cold Air Sensitivity Scale) and randomly assigned to one of two treatment groups. The two treatment groups were: (1) a Test paste, a desensitizing paste containing 8% arginine and calcium carbonate; and (2) a Control paste, Nupro pumice prophylaxis paste. Subjects had their assigned paste applied immediately before receiving dental scaling procedure. Record tactile and air blast hypersensitivity examinations score immediately after paste application and after the completion of the dental scaling procedure following the same methodology employed for the baseline hypersensitivity examinations. Results: At the final hypersensitivity examinations, the Test Paste and Control Paste groups were not statistically significant differences from baseline scores. Immediately following product application and after the completion of the dental scaling procedure, subjects assigned to the Test Paste group exhibited statistically significant improvements from baseline with respect to baselineadjusted mean air blast (38.9% and 37.4% respectively) and mean tactile hypersensitivity scores (40.2% and 42.4% respectively). At the same time points, subjects assigned to the Control Paste group exhibited statistically significant improvements from baseline with respect to baseline- adjusted mean air blast (16.0% and 17.8% respectively) and mean tactile hypersensitivity scores (14.6% and 16.4% respectively). Conclusion: The desensitizing paste containing 8% arginine and calcium carbonate provides reduction in dentin hypersensitivity immediately following product application and after the completion of the dental scaling procedure when applied as a single treatment before dental prophylaxis.

Dental transposition is a form of ectopic eruption with change in position of normal adjacent teeth. Its prevalence is very low in general population and could be frequently missed on oral examination. This article reports a case of early orthodontic treatment of a rare unilateral mandibular right lateral incisor – canine transposition.