Temperature variation in pulp chamber after external dental bleaching

Objective: This study evaluated the temperature variation in pulp chamber of teeth submitted to external bleaching with 38% hydrogen peroxide (PH) and 35% carbamide peroxide (PC) followed by photopolymerization with LED-laser system or halogen light.

Methods: Eighty superior central incisors had their 2-mm apical portion sectioned and the radicular spaces prepared with largo burs. A k-type thermocouple was introduced through the apex until the central portion of pulp chamber. The specimens were randomly distributed into 8 groups (n=10) according to the bleaching agent and light-curing source: GI- Halogen light + 38% PH, GII- Halogen light solely, GIII- Halogen light + 35% PC, GIV- LED solely, GV- LED + 35% PC, GVI- LED + 38% PH, GVII- 38% PH, GVIII- 35% PC. The specimens were fixed in an acrylic device and bleaching agents were applied in the vestibular surface of the crown, following by photopolymerization for 20 s and removal of the bleaching agent. This procedure was repeated 6 times, in a single session. The alterations were obtained by the difference between the highest and initial temperature.

Results:The halogen light solely (GII) and combined to the 38% PH (GI) were statistically similar between themselves (1.10±0.24 and 1.15±0.30, respectively). There was also no significant difference among groups III, IV, V and VI (p<0.01). GVII (0.19±0.10) and GVIII (0.13±0.07) had the inferior temperature increments and were statistically similar among themselves and to GV and GVI.

Conclusion: The highest temperature variations in pulp chamber were displayed by the halogen light and its association with 38% hydrogen peroxide, however, all values were below the maximum critical threshold of 5.6°C.