Evaluation of single-use rotary nickel-titanium instruments.

The purpose of this study was to analyze the number and types of defects observed in single-use, rotary nickel-titanium instruments. Every ProFile Series 29.04 taper nickel-titanium instrument used during a 4-week period in an endodontic specialty practice was collected. All instruments were new and were used by experienced clinicians during a single patient visit. The instruments were routinely used in a crown-down manner with RC Prep lubrication and copious irrigation. The instruments were used in a MicroMega 324 air motor in a 6:1 gear reduction contra-angle at 333 rpm. The instruments were collected, ultrasonically cleaned, sterilized, and inspected at x16 magnification. Torsional, flexural, and fracture defects were recorded and statistical analysis was performed using the Kruskal-Wallis one-way analysis of variance. A total of 786 ProFile Series 29 nickel-titanium rotary instruments were evaluated; 115 (14.63%) showed some type of defect after one clinical use. Size 3 instruments had the highest defect rate (22.66%) followed by size 5 (17.30%), size 2 (17.24%), and size 4 instruments (16.10%). However, there was no statistically significant difference. The size 6 and size 7 instruments showed minimal defects (2.38% and 4.76%, respectfully). Seven of 786 files had fractured (0.891%). There was no statistically significant difference in the type of failure seen within each file size. This study does show that defects can occur even with new files in the hands of experienced endodontists, and for absolute safety a single-use approach should be followed.

Non-surgical post perforation repair with mineral trioxide aggregate: a case report.

Mineral trioxide aggregate, or MTA, is a biocompatible material that has demonstrated numerous clinical applications in endodontics. It appears to be an improvement over other materials for use in procedures that involve root repair and bone healing, as it has consistently demonstrated the ability to promote regeneration of the original tissues when it is placed in contact with the periradicular tissues. This article describes the use of MTA for the successful non-surgical repair of an iatrogenic post perforation.

The influence of sodium hypochlorite irrigation on the accuracy of the Root ZX electronic apex locator.

The purpose of this in vitro investigation was to determine whether the presence of sodium hypochlorite influences the accuracy of the Root ZX electronic apex locator. Forty, extracted, human teeth were mounted in an experimental apparatus. After achieving ideal access, working length measurements were obtained using the Root ZX. The canals were flushed with 2.125% sodium hypochlorite and measurements were again made with the electronic apex locator. Before measuring a third time, 5.25% sodium hypochlorite was then administered to each canal. Finally, the tooth was removed from the apparatus and the actual canal length was determined by measuring a file brought to the apical constriction (verified by direct visualization). No significant differences were found between the experimental groups. Overall, Root ZX measurements were within 0.5 mm of the actual length 83% of the time. The results of this study indicate that the Root ZX is not adversely affected by the presence of sodium hypochlorite.

Lateral condensation in canals prepared with nickel titanium rotary instruments: an evaluation of the use of three different master cones.

Forty-five single-rooted teeth were instrumented with ProFile ISO .06 nickel-titanium rotary instruments and obturated with lateral condensation using three different master cones: an ISO-standardized gutta-percha cone (group A), a Dia-ISO(GT).06 gutta-percha cone (group B), and a size medium gutta-percha cone (group C). Obturation efficiency in each group was evaluated by recording the number of accessory cones utilized. To evaluate obturation quality in the three groups, a cross-sectional observation of the ability of the gutta-percha in each group to obliterate the prepared canal space was carried out. Results showed that obturation efficiency was significantly greater in groups B and C than in group A. There was no significant difference in obturation quality between any of the three groups.

Root-end fracture during retropreparation: a comparison between zirconium nitride-coated and stainless steel microsurgical ultrasonic instruments.

The purpose of this study was to evaluate a stainless steel (CT-5) and zirconium nitride coated (KiS) microsurgical ultrasonic instrument with regard to possible root-end fracture production during retropreparation. Forty extracted human central incisors were prepared in a crown-down fashion. Canals were obturated with gutta-percha by lateral condensation. Root-ends were resected. Teeth were placed in methylene blue for 48 h and evaluated by three independent evaluators under microscope. Teeth with existing fractures were eliminated from the study. The remaining teeth were randomly divided into two equal groups. Group A was prepared with the CT-5 tip and Group B with the KiS tip. Preparation time was recorded for all roots. The teeth were again immersed in methylene blue for 48 h and reevaluated. No root-end fractures were produced by either the KiS or CT-5 microsurgical ultrasonic instruments.