RESUMO
PURPOSE: The aim of this study was to evaluate the osseous response to laser bio-stimulation clinically and histologically during distraction osteogenesis (DO) induced in the mandibles of mongrel dogs. MATERIALS AND METHODS: Thirty dogs were divided into 3 groups of 10 (5 with and 5 without laser treatment) according to sacrifice periods (2, 4, and 8 weeks after distraction). DO was performed between the mandibular second and third premolars using an internal linear distractor. After a 7-day latency period, the distractor was activated at the rate of 1 mm per day for 10 days followed by a consolidation period during which the right mandibular side was irradiated with a diode laser (wavelength [λ], 970 nm; power, 2 W; spot size, 320 µm; total energy [E], 840 J), whereas the control group was not irradiated, after distraction. Histologic specimens were prepared and histomorphometric analysis of specimens was performed. RESULTS: Clinical examinations showed that the low-intensity laser diode had a pronounced effect on the quality and quantity of newly formed bone in the DO regenerate in the laser groups compared with the control groups. Histopathologic sections from laser groups I, II, and III displayed the bio-stimulatory effect of laser on new bone through an increased rate of osteoblast proliferation and differentiation, an accelerated rate of intramembranous ossification, and increased neoangiogenesis compared with the control groups. Moreover, the histomorphometric results showed that mean bone trabecular size, bone trabecular total area, and bony area fraction of the regenerate were larger and statistically significant (P < .05) especially in laser groups I and II (early stages of bone formation) compared with the control groups. CONCLUSION: The low-level diode laser had a positive role as a potential bio-stimulator and local inducer in enhancing bone formation during DO and resulted in early stability of the bone regenerate, a shorter total treatment time, and improved new bone quality and quantity.
