Effects of an in-office bleaching system (ZOOM) on pulp chamber temperature in vitro.

AIM: Several new techniques and materials for in-office bleaching have been introduced recently. The aim of this in vitro study was to measure the temperature increase in the pulp chamber of extracted teeth produced by the Zoom! in-office bleaching system and to investigate the influence of this light in conjunction with the bleaching gel on pulp temperature rise. METHODS AND MATERIALS: Ten extracted, caries-free, unrestored human maxillary central incisor teeth were used for the study. The root of each tooth was cut approximately 2-3 mm apical to the cementoenamel junction (CEJ), and the apical orifice of the root canal was enlarged. The remaining pulp tissue was removed and the empty pulp chamber was filled with a heat sink compound. A thin K-type thermocouple was inserted into the pulp chamber through the cut root area. The root surfaces of the teeth were partially submerged in a water bath during the testing procedure at 37 degrees C. A whitening gel containing 25% hydrogen peroxide was applied to the buccal surfaces of all ten teeth and exposed to a Zoom! activation light for twenty minutes for three times; this was designated as Group I. The same teeth were then exposed with the Zoom! light for the same time period without the application of the bleaching gel and designated as Group II. The intrapulpal temperature pre-treatment (baseline) and the temperature increase during treatment was measured for both treatment groups. RESULTS: There was a statistically significant difference between the two groups (p=0.003). Application of the Zoom! light in conjuction with the application of bleaching gel produced a greater temperature rise than did the light alone. The mean temperature rise for Group I (light and bleaching gel) was 1.11 degrees C (0.18 degrees C) and 1.01 degrees C (0.12 degrees C) for Group II (light alone) at the end of a five-minute exposure. CONCLUSION: The Zoom! light either used with or without bleaching gel showed no significant increase in the intrapulpal temperature of teeth when used for the recommended exposure time.