Effect of GaAlAs laser on reactional dentinogenesis induction in human teeth

Objective: This study investigated the biomodulatory effect of the gallium- aluminum-arsenate laser (GaAlAs) in pulp cells on reactional dentinogenesis, and on the expression of collagen type III (Col HI), tenascin (TN), and fibronectin (FN) in irradiated dental tissues and controls (not irradiated). Background Data: Several studies suggest a biomodulatory influence of low-intensity laser radiation in the inflammatory and reparative processes of biological tissues. Methods: Sixteen human premolar teeth were selected (after extraction due to orthodontal reasons) and divided into irradiated and control groups. Black class V cavity preparations were accomplished in both groups. For the irradiated group, GaAlAs laser (670 run, 50 mW) with an energy density of 4 J/cm(2) was used. Soon after, the cavities were restored with a glass ionomer and the extractions made after 14 and 42 days. Results: Histological changes were observed by light microscopy; less intense inflammatory reaction in the irradiated group was found when compared to the controls. Only the irradiated group of 42 days exhibited an area associated with reactional dentinogenesis. After immunohistochemical analysis by the streptoavidin-biotin complex (SABC) method, the expression of Col III, TN, and FN was greater in the irradiated groups. Conclusion: Our results suggest that a GaAlAs laser with energy density of 4 J/cm(2) and wavelength of 670 nm caused biomodulation in pulp cells and expression of collagen, but not collagen of the extracellular matrix, after preparation of a cavity.