Evidence for Reduced Fatigue Resistance of Contemporary Rotary Instruments Exposed to Body Temperature.

INTRODUCTION: The purpose of this study was to evaluate the effect of 2 different temperatures (20°C and 37°C) on the cyclic fatigue life of rotary instruments and correlate the results with martensitic transformation temperatures. METHODS: Contemporary nickel-titanium rotary instruments (n = 20 each and tip size #25, including Hyflex CM [Coltene, Cuyahoga Falls, OH], TRUShape [Dentsply Tulsa Dental Specialties, Tulsa, OK], Vortex Blue [Dentsply Tulsa Dental Specialties], and ProTaper Universal [Dentsply Tulsa Dental Specialties]) were tested for cyclic fatigue at room temperature (20°C ± 1°C) and at body temperature (37°C ± 1°C). Instruments were rotated until fracture occurred in a simulated canal with an angle curvature of about 60° and a radius curvature of 3 mm; the center of the curvature was 4.5 mm from the instrument tip. The number of cycles to fracture was measured. Phase transformation temperatures for 2 instruments of each brand were analyzed by differential scanning calorimetry. Data were analyzed using the t test and 1-way analysis of variance with the significance level set at 0.05. RESULTS: For the tested size and at 20°C, Hyflex CM showed the highest resistance to fracture; no significant difference was found between TRUShape and Vortex Blue, whereas ProTaper Universal showed the lowest resistance to fracture. At 37°C, resistance to fatigue fracture was significantly reduced, up to 85%, for the tested instruments (P < .001); at that temperature, Hyflex CM and Vortex Blue had similar and higher fatigue resistance compared with TRUShape and ProTaper Universal. CONCLUSIONS: Under the conditions of this study, using a novel testing design, immersion in water at simulated body temperature was associated with a marked decrease in the fatigue life of all rotary instruments tested.

Reliability of circulatory and neurologic examination by telemedicine in a pediatric intensive care unit.

OBJECTIVE: To test the hypothesis that telemedicine can reliably be used for many aspects of circulatory and neurologic examinations of children admitted to a pediatric intensive care unit (PICU). STUDY DESIGN: A prospective, randomized study in a 14-bed PICU in a tertiary care, academic-affiliated institution. Eligible patients were >2 months or <19 years of age, not involved in a concurrent study, had parents/guardian able to sign an informed consent form, were not at end-of-life, and had an attending who not only deemed them medically stable, but also felt that the study would not interrupt their care. Other than the Principal Investigator, 6 pediatric intensivists and 7 pediatric critical care fellows were eligible study providers. Two physician providers were randomly assigned to perform circulatory and neurologic examinations according to the American Heart Association/Pediatric Advanced Life Support guidelines in-person and via telemedicine. Findings were recorded on a standardized data collection form and compared. RESULTS: One hundred ten data collection forms were completed. For many aspects of the circulatory and neurologic examinations, outcomes showed substantial to perfect agreement between the in-person and telemedical care providers (kappa = 0.64-1.00). However, assessments of muscle tone had a kappa = 0.23, with a kappa = 0.37 for skin color. CONCLUSIONS: Telemedicine can reliably identify normal and abnormal findings of many aspects of circulatory and neurologic examinations in PICU patients. This finding opens the door to further studies on the use of telemedicine across other disciplines.