Background CPAP is the gold standard treatment for OSA and was conceived to be applied through a nasal interface. This study was designed to determine the acute effects of changing the nasal CPAP ...route to oronasal and oral in upper airway patency during sleep in patients with OSA. We hypothesized that the oronasal route may compromise CPAP’s effectiveness in treating OSA. Methods Eighteen patients (mean ± SD age, 44 ± 9 years; BMI, 33.8 ± 4.7 kg/m2 ; apnea-hypopnea index, 49.0 ± 39.1 events/hour) slept with a customized oronasal mask with nasal and oral sealed compartments connected to a multidirectional valve. Sleep was monitored by using full polysomnography and induced by low doses of midazolam. Nasal CPAP was titrated up to holding pressure. Flow route was acutely changed to the oronasal (n = 18) and oral route (n = 16) during sleep. Retroglossal area was continuously observed by using nasoendoscopy. Results Nasal CPAP (14.8 ± 4.1 cm H2 O) was able to stabilize breathing in all patients. In contrast, CPAP delivered by the oronasal and oral routes promoted obstructive events in 12 (66.7%) and 14 (87.5%) patients, respectively. Compared with stable breathing during the nasal route, there was a significant and progressive reduction in the distance between the epiglottis and tongue base and the retroglossal area when CPAP was delivered by the oronasal and oral routes. Conclusions CPAP delivered through the oronasal route may compromise CPAP’s effectiveness in treating OSA.
Abstract 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.
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