Methods: With IRB approval, human molars and canines were prepared for intrapulpal temperature measurements. A 2.5 mm opening from the apex to the pulp chamber was made to accommodate a precision thermistor with a diameter of 2.4 mm (Omega PN 44008, Omega, CT). The tooth was submerged to its cervical line in 37˚C water to simulate an oral environment. Due to fluctuations of +/-1˚C in the thermostat, an identical second thermistor was used to measure the water temperature. Thus a precise differential temperature measurement assessed the rise induced only by the photo-activation light (Zoom Light, Philips Oral Healthcare, WA). The tooth was also optically isolated except for the buccal surface which was treated with a bleaching compound (Philips Zoom White Speed, Philips Oral Healthcare, WA). The spectrum and irradiance of the photo-activation light were recorded using a laboratory metrology system (MARC® Resin Calibrator, BlueLight Analytics, NS).
Results: The average intrapulpal temperature increase over the course of each light activation treatment cycle was measured to be 0.7˚+/-0.1˚C. The temperature was observed to rise slowly over the course of each 15min treatment and then to drop rapidly (about 60-70 sec) back to pretreatment temperatures after light deactivation. Spectral characteristics of the photo-activation light showed a peak at 454+/-1 nm with a spectral width of 20+/-1 nm. The irradiance of the light was measured to be 251+/-3mW/cm2, which is lower than the typical 700-1000mW/cm2 irradiance of typical halogen curing lights.
Conclusions: The photo-activation light measured was shown to have minimal intrapulpal temperature rise under conditions approximating the oral thermal environment. Additionally, irradiance of the light was shown to be lower than that of typical curing lights.
Keywords: Bleach, Esthetics, Photoactivation and Pulp
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Signed on 10/10/2013 by R.S. KURTI
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