Effect of Photobiomodulation Therapy Associated With Biphasic Phosphate Calcium on Bone Repair: A Histomorphometric Study in Rats

Background: This study aimed to investigate the effects of photobiomodulation therapy associate with biphasic calcium phosphate on calvaria critical defects in rats. Methods: Forty-eight (90days old) adult male rats (Rattus norvegicus, Albinus variation, Wistar) received critical defects with 5 mm in diameter were made on their skull and were randomly assigned into the groups: C-blood clot, B-biphasic calcium phosphate, L-photobiomodulation therapy and B+L-biphasic calcium phosphate+photobiomodulation therapy. A low-level GaAlAs was applied in a single dose tran-surgically, in a wavelength 660 nm, total dense energy density of 45 J/cm2. At 30 and 60 days, animals from each group were euthanized. Histological and histomorphometric analyzes were performed.  Results: In 30 days, almost all specimens (C, L, B and B+L) showed bone neoformation areas in regions near the borders of the surgical defect. In 60 days, in many specimens (C, L, B, B+L), it was possible to see a narrow neoformed bone structure along almost the whole extension of the surgical defect, though being thinner than the original calvary bone.  Data were recorded as mean ± standard deviation, after normality was tested, suitable statistical test was applied (α= 5%). At 60 days, there was a statistically significant difference when comparing the proportion of neoformation area between group L (0.52%±0.13) and B+L (0.20%±0.08). Group L showed a difference compared with all the groups when comparing the remaining distance between de edges of neoformed bone (C×L, p=0.0431; B×L, p=0.0386; L×B+L, p=0.0352), demonstrating a great defect closure.  Conclusions: Our findings suggest that photobiomodulation therapy applied at 45 J/cm² resulted in the highest percentage of bone neoformation area after 60 days, although biphasic calcium phosphate exerts some osteogenic activity during bone repair, photobiomodulation therapy is not able to modulate this process