Avivi-Arber L, Lee J-C, Sessle B J
Department of Oral Physiology, Faculty of Dentistry, University of Toronto, Toronto, Canada Department of Prosthodontics, Faculty of Dentistry, University of Toronto, Toronto, Canada
Department of Oral Physiology, Faculty of Dentistry, University of Toronto, Toronto, Canada.
J Dent Res. 2015 Dec;94(12):1757-64. doi: 10.1177/0022034515602478. Epub 2015 Aug 26.
Modification to the dental occlusion may alter oral sensorimotor functions. Restorative treatments aim to restore sensorimotor functions; however, it is unclear why some patients fail to adapt to the restoration and remain with sensorimotor complaints. The face primary motor cortex (face-M1) is involved in the generation and control of orofacial movements. Altered sensory inputs or motor function can induce face-M1 neuroplasticity. We took advantage of the continuous eruption of the incisors in Sprague-Dawley rats and used intracortical microstimulation (ICMS) to map the jaw and tongue motor representations in face-M1. Specifically, we tested the hypothesis that multiple trimming of the right mandibular incisor, to keep it out of occlusal contacts for 7 d, and subsequent incisor eruption and restoration of occlusal contacts, can alter the ICMS-defined features of jaw and tongue motor representations (i.e., neuroplasticity). On days 1, 3, 5, and 7, the trim and trim-recovered groups had 1 to 2 mm of incisal trimming of the incisor; a sham trim group had buccal surface trimming with no occlusal changes; and a naive group had no treatment. Systematic mapping was performed on day 8 in the naive, trim, and sham trim groups and on day 14 in the trim-recovered group. In the trim group, the tongue onset latency was shorter in the left face-M1 than in the right face-M1 (P < .001). In the trim-recovered group, the number of tongue sites and jaw/tongue overlapping sites was greater in the left face-M1 than in the right face-M1 (P = 0.0032, 0.0016, respectively), and the center of gravity was deeper in the left than in the right face-M1 (P = 0.026). Therefore, incisor trimming and subsequent restoration of occlusal contacts induced face-M1 neuroplasticity, reflected in significant disparities between the left and right face-M1 in some ICMS-defined features of the tongue motor representations. Such neuroplasticity may reflect or contribute to subjects' ability to adapt their oral sensorimotor functions to an altered dental occlusion.
牙合的改变可能会改变口腔感觉运动功能。修复治疗旨在恢复感觉运动功能；然而，尚不清楚为什么有些患者无法适应修复体，仍存在感觉运动方面的不适。面部初级运动皮层（face-M1）参与口面部运动的产生和控制。感觉输入或运动功能的改变可诱导face-M1神经可塑性。我们利用Sprague-Dawley大鼠切牙的持续萌出，采用皮层内微刺激（ICMS）来绘制face-M1中下颌和舌的运动代表区。具体而言，我们检验了以下假设：多次修剪右侧下颌切牙，使其在7天内不发生咬合接触，随后切牙萌出并恢复咬合接触，可改变ICMS定义的下颌和舌运动代表区的特征（即神经可塑性）。在第1、3、5和7天，修剪组和修剪恢复组对切牙进行1至2毫米的切牙修剪；假修剪组对颊面进行修剪，咬合无变化；未处理组不进行任何处理。在第8天对未处理组、修剪组和假修剪组进行系统绘图，在第14天对修剪恢复组进行系统绘图。在修剪组中，左侧face-M1的舌起始潜伏期比右侧face-M1短（P <.001）。在修剪恢复组中，左侧face-M1的舌位点数量和下颌/舌重叠位点数量比右侧face-M1多（分别为P = 0.0032和0.0016），并且左侧face-M1的重心比右侧face-M1深（P = 0.026）。因此，切牙修剪及随后咬合接触的恢复诱导了face-M1神经可塑性，这在舌运动代表区的一些ICMS定义特征中表现为左右face-M1之间的显著差异。这种神经可塑性可能反映了受试者使口腔感觉运动功能适应改变的牙合的能力，或对此能力有贡献。
