Rapid Maxillary Expansion Associated With Lasertherapy Improves Early Bone Remodeling

Objectives: The aim of this study was to evaluate in vivo the effects of low-level laser therapy (LLLT) on bone healing after rapid maxillary expansion (RME). Materials and Methods: One hundred young rats were assigned to three groups: Control (n=10) without treatment (no RME and no LLLT); Experimental I (n=45) with RME without LLLT: 25 animals were euthanized at days 1, 2, 3, 7 and 10 after RME for real time reverse transcriptase polymerase chain reaction (qRT-PCR) analysis and 20 animals were euthanized at days 1, 7, 14 and 21 after RME for histological and micro-CT evaluation; Experimental II (n=45) with RME and LLLT: animals were euthanized at the same periods described for Experimental I. Bone healing in the mid-palatal suture was investigated using micro-CT scan, histological evaluation and qRT-PCR for RUNX2 gene expression. Data were analyzed using one-way ANOVA followed by Tukey test (alpha = 0.05). Results: RME significantly increased newly mineralized bone formation compared with immediate expansion (day 1). LLLT improved bone formation, with higher bone volume at days 7 and 14, compared to RME without LLLT (p < 0.05), although at 21 days there was no difference between groups with or without LLLT (p > 0.05), indicating that LLLT accelerated bone healing. RUNX2 gene expression was increased in RME groups, compared to the control group, mainly at the initial periods of healing. LLLT stimulated RUNX2  gene expression to higher levels than RME without LLLT (p < 0.05). Conclusions: Our results demonstrate that LLLT improves bone formation after RME probably due to an early and increased expression of RUNX2.