Orthodontics and Craniofacial Research, 2026 (SCI-Expanded, Scopus)
Objectives: This study aims to investigate the effects of low-level laser therapies (LLLTs) with four different wavelengths (532, 650, 810 and 940 nm) on new bone regeneration during inter-premaxillary suture expansion in rats. Materials and Methods: Sixty rats were divided into five groups (n = 12): control (Group A) and four laser groups (Group B: 940 nm, Group C: 810 nm, Group D: 650 nm and Group E: 532 nm). Each group was further divided into two subgroups (n = 6) based on the sacrifice day: Day 7 and Day 14. The upper incisors of the rats were drilled, and a 30-g force expansion appliance was inserted. The study lasted 14 days, with 7 days of expansion and 7 days of retention. LLLT was administered at 48-h intervals in groups other than the control group. Bone regeneration in the suture was assessed using micro-computed tomography and immunohistochemistry. Trabecular number (Tb.N), trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp) were measured by using micro-computed tomography. Alkaline phosphatase (ALP), bone morphogenetic protein 2 (BMP-2) and tartrate-resistant acid phosphatase (TRAP) immunoreactivity intensities were calculated in the immunohistochemically stained upper jaw sections. Results: In Group B (940 nm), ALP was significantly higher on the 7th day (p < 0.001); ALP and BMP-2 were significantly higher (p = 0.002; p = 0.013, respectively), and Tb.Sp was significantly lower on the 14th day (p = 0.034) compared with the control group. Conclusions: The results show that 940 nm low-level laser therapy accelerates bone regeneration more effectively in the expanded inter-premaxillary suture.