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.
CO2 laser Calcium hydroxide Dentin hypersensitivity
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The authors wish to express their gratitude to the Special Laboratory of Lasers in Dentistry (LELO) at the University of São Paulo, Brazil. They thank the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) for financial support, the Mestrado Profissionalizante de Lasers em Odontologia (MPLO; Professional Master’s Course in Lasers in Dentistry) and Fundação para o Desenvolvimento Científico e Tecnológico da Odontologia (FUNDECTO; Foundation for the Scientific and Technological Development of Dentistry) for the use of the CO2 laser.
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