Low-level laser therapy enhances the number of osteocytes in calvaria bone defects of ovariectomized rats.
Background
Osteoporosis can make bone repair difficult. Low-level laser therapy (LLLT) has been shown to be a promising tool for bone neoformation. This study aimed to analyze the effect of LLLT on calvaria bone defects of ovariectomized rats using stereology.


Methods
Fifty-four Wistar rats were subjected to bilateral ovariectomy, and bone defects were created in calvaria after 150 days. The animals were divided into nine groups (n =  6 per group), and 24 hours after the bone defects were created they received 3, 6 or 12 sessions of LLLT at 0, 20 or 30 J/cm2, using a 780-nm low-intensity GaAlAs laser. One-way ANOVA followed by Tukey's post hoc test was used for data processing. A difference of P < 0.05 was considered statistically significant. The parameters evaluated were osteocyte density (Nv ost), total osteocyte number (Nto ost), trabecular surface density (Sv t), and trabecular surface area (Sa t).


Results
Data obtained showed that Nto ost, Sv t, and Sa t in group G2 rats were significantly different from G1 (0 J/cm2) (P < 0.05). Compared to group G4, G5 presented higher values for the parameters Sv t and Sa t, and G6 presented significantly higher values for almost all the analyzed parameters (Nv ost, Nto ost, Sv t, and Sa t) (P < 0.05). Compared to group G7, G8 showed a higher value only for the parameter Sa t, and G9 showed significantly higher values for parameters Nv ost, Nto ost, Sv t, and Sa t.


Conclusion
We conclude that LLLT stimulated bone neoformation and contributed to an increase in the total number of osteocytes, especially with a laser energy density of 30 J/cm2 given for 6 and 12 sessions.
['Scalize|Priscilla Hakime|PH|', 'de Sousa|Luiz Gustavo|LG|', 'Gonçalves|Lígia Maria Napolitano|LMN|', 'Pitol|Dimitrius Leonardo|DL|', 'Palinkas|Marcelo|M|', 'Coppi|Antônio Augusto|AA|', 'Righeti|Mariah Acioli|MA|', 'Ricardo|Vitória|V|', 'Bombonato-Prado|Karina Fittipaldi|KF|', 'Regalo|Simone Cecílio Hallak|SCH|', 'Siessere|Selma|S|https://orcid.org/0000-0001-9756-3771']
osteocytes bone osteoporosis low‐level laser therapy