Inferior alveolar nerve (IAN) injuries may occur during various dental routine procedures, especially in the removal of impacted lower third molars, and nerve recovery in these cases is a great challenge in dentistry. Here, the IAN crush injury model was used to assess the efficacy of photobiomodulation (PBM) in the recovery of the IAN in rats following crushing injury (a partial lesion). Rats were divided into four experimental groups: without any procedure, IAN crush injury, and IAN crush injury with PBM and sham group with PBM. Treatment was started 2 days after surgery, above the site of injury, and was performed every other day, totaling 10 sessions. Rats were irradiated with GaAs Laser (Gallium Arsenide, Laserpulse, Ibramed Brazil) emitting a wavelength of 904 nm, an output power of 70 mWpk, beam spot size at target ∼0.1 cm2, a frequency of 9500 Hz, a pulse time 60 ns, and an energy density of 6 J/cm2. Nerve recovery was investigated by measuring the morphometric data of the IAN using TEM and by the expression of laminin, neurofilaments (NFs), and myelin protein zero (MPZ) using Western blot analysis. We found that IAN-injured rats which received PBM had a significant improvement of IAN morphometry when compared to IAN-injured rats without PBM. In parallel, all MPZ, laminin, and NFs exhibited a decrease after PBM. The results of this study indicate that the correlation between the peripheral nerve ultrastructure and the associated protein expression shows the beneficial effects of PBM.
Molecular changes Alveolar inferior nerve Photobiomodulation Myelin sheath Rat
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The authors are grateful to Sônia Regina Yokomizo for her valuable help.
All authors made substantial contributions to the following tasks of research: initial conception (Martins D.O., Britto L.R.G., Lemos J.B.D., Chacur M.), design (Martins D.O., Britto L.R.G., Lemos J.B.D., Chacur M), provision of resources (Chacur M), collection of data (Martins D.O, Santos F.M.,, Ciena A.P., Watanabe I.), analysis and interpretation of data (Martins D.O., Chacur M., Ciena A.P., Watanabe I.), writing the first draft of the paper or important intellectual content (Martins D.O, Santos F.M.), and revision of paper (Martins D.O., Chacur M., Britto L.R.G.).
Compliance with ethical standards
Ethics approval and consent to participate
All procedures were approved by the Institutional Animal Care Committee of the University of São Paulo (protocol number 150/2010) and performed in accordance with the guidelines for the ethical use of conscious animals in pain study published by the international association for the study of pain.
The authors declare that they have no competing interests.
FAPESP 2010/20026-6; 2012/05840-4; 2014/24533-0
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