Okazaki Kanako, Nakatani Ayaka, Kunimatsu Ryo, Kado Isamu, Sakata Shuzo, Kiridoshi Hirotaka, Tanimoto Kotaro
Department of Orthodontics and Craniofacial Development Biology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan.
Int J Mol Sci. 2025 Jul 31;26(15):7404. doi: 10.3390/ijms26157404.
Pain following orthodontic treatment is the chief complaint of patients undergoing this form of treatment. Although the use of diode lasers has been suggested for pain reduction, the mechanism of laser-induced analgesic effects remains unclear. Neuropeptides, such as substance P (SP) and calcitonin gene-related peptide (CGRP), contribute to the transmission and maintenance of inflammatory pain. Heat shock protein (HSP) 70 plays a protective role against various stresses, including orthodontic forces. This study aimed to examine the effects of diode laser irradiation on neuropeptides and HSP 70 expression in periodontal tissues induced by experimental tooth movement (ETM). For inducing ETM for 24 h, 50 g of orthodontic force was applied using a nickel-titanium closed-coil spring to the upper left first molar and the incisors of 20 male Sprague Dawley rats (7 weeks old). The right side without ETM treatment was considered the untreated control group. In 10 rats, diode laser irradiation was performed on the buccal and palatal sides of the first molar for 90 s with a total energy of 100.8 J/cm. A near-infrared (NIR) laser with a 808 nm wavelength, 7 W peak power, 560 W average power, and 20 ms pulse width was used for the experiment. We measured the number of facial groomings and vacuous chewing movements (VCMs) in the ETM and ETM + laser groups. Immunohistochemical staining of the periodontal tissue with SP, CGRP, and HSP 70 was performed. The number of facial grooming and VCM periods significantly decreased in the ETM + laser group compared to the ETM group. Moreover, the ETM + laser group demonstrated significant suppression of SP, CGRP, and HSP 70 expression. These results suggest that the diode laser demonstrated analgesic effects on ETM-induced pain by inhibiting SP and CGRP expression, and decreased HSP 70 expression shows alleviation of cell damage. Thus, although further validation is warranted for human applications, an NIR diode laser can be used for reducing pain and neuropeptide markers during orthodontic tooth movement.
正畸治疗后的疼痛是接受这种治疗形式的患者的主要诉求。尽管有人建议使用二极管激光来减轻疼痛，但激光诱导镇痛作用的机制仍不清楚。神经肽，如P物质（SP）和降钙素基因相关肽（CGRP），参与炎症性疼痛的传递和维持。热休克蛋白（HSP）70对包括正畸力在内的各种应激起保护作用。本研究旨在探讨二极管激光照射对实验性牙齿移动（ETM）诱导的牙周组织中神经肽和HSP 70表达的影响。为诱导ETM 24小时，使用镍钛闭合螺旋弹簧对20只7周龄雄性Sprague Dawley大鼠的左上第一磨牙和切牙施加50 g正畸力。右侧未经ETM处理的作为未处理对照组。在10只大鼠中，对第一磨牙的颊侧和腭侧进行二极管激光照射90秒，总能量为100.8 J/cm²。实验使用波长808 nm、峰值功率7 W、平均功率560 W和脉冲宽度20 ms的近红外（NIR）激光。我们测量了ETM组和ETM+激光组的面部梳理次数和空嚼运动（VCMs）。对牙周组织进行SP、CGRP和HSP 70的免疫组织化学染色。与ETM组相比，ETM+激光组的面部梳理次数和VCMs时间显著减少。此外，ETM+激光组显示出对SP、CGRP和HSP 70表达的显著抑制。这些结果表明，二极管激光通过抑制SP和CGRP表达对ETM诱导的疼痛具有镇痛作用，而HSP 70表达的降低表明细胞损伤得到缓解。因此，尽管在人体应用中需要进一步验证，但近红外二极管激光可用于在正畸牙齿移动过程中减轻疼痛和神经肽标志物。
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