Evaluation of carbon dioxide laser irradiation associated with calcium hydroxide in the treatment of dentinal hypersensitivity. A preliminary study

Attempts have been made to treat dentinal hypersensitivity by sealing exposed dentinal tubules, and the carbon dioxide (CO₂) laser has been shown to have a sealing effect on dentinal surfaces. The purpose of this study was to analyze the morphological ultra-structure and temperature change after CO₂ laser irradiation of dentin. Fourteen human third molars were selected and cleaned. An area was delimited, and the samples were randomly divided into seven groups: Group 1 (G1): control; G2, calcium hydroxide paste (CA) + CO₂ laser (L) (0.5 W/63,69 W/cm²); G3, CA + L (1 W/125,38 W/cm²); G4, CA + L (1.5 W/191,08 W/cm²); G5, L (0.5 W); G6, L (1 W); G7, L (1.5 W). All irradiation was performed in unfocused mode. The electron micrographs were analyzed by three observers. For temperature analysis, a thermocouple was used. Data were subjected to statistical analysis. The Kruskal–Wallis non-parametric test showed statistical differences between the groups (P < 0.05). For the two by two comparisons, all groups treated with calcium hydroxide paste presented significantly higher mean scores. In the groups treated by CO₂ laser only, fusion, re-crystallization, cracks and carbonization were observed. A change of 1 ± 5°C was noted in the temperature. Under the limitation of an in vitro study, and with the protocols used, we concluded that CO₂ laser is safe to use for the establishment of partial fusion and re-solidification of the dentinal surface.