State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of Oral Anatomy and Physiology and TMD, School of Stomatology, The Fourth Military Medical University, Xi'an, China.
State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of Oral Anatomy and Physiology and TMD, School of Stomatology, The Fourth Military Medical University, Xi'an, China.
Arch Oral Biol. 2017 Oct;82:147-152. doi: 10.1016/j.archoralbio.2017.06.012. Epub 2017 Jun 15.
To clarify whether over-eruption of the mandibular third molar can disturb chewing movement.
Eighteen patients with a unilateral mandibular over-erupted third molar confirmed by both study cast observation and T-scan occlusal detection were selected from a sample of patients with complaints of temporomandibular disorder (TMD) symptoms. A unilateral gum-chewing trace was recorded separately for left and right side chewing by an electrognathography system. The average chewing pattern (ACP) was created based on segments from the recorded chewing trace to represent the chewing movement characteristics of each individual. Two factors, the TMD symptomatic side and the over-eruption side, were analysed for their effects on values of difference in the parameters (Δvalue) regarding the ACP between chewing with right and left side. Three-dimensional amplitudes of ACP and the cross point value of ACP with the vertical axis (termed the cross zero point value) which described the turning point of the chewing cycle from the balancing side to the working side, were compared between sides.
The over-eruption side had an effect on the Δvalue of the medial amplitude, the lateral amplitude, and the cross zero point (P<0.05), but the symptomatic side didn't (P>0.05). When chewing on the over-eruption side, the medial amplitude was shorter, the lateral amplitude was larger, and the cross zero point value was smaller than those when chewing on the other side (P<0.05).
The present data indicate an effect of the over-erupted mandibular third molar on the chewing pattern while that from the symptom(s) is limited.
阐明下颌第三磨牙过度萌出是否会干扰咀嚼运动。
从颞下颌关节紊乱症（TMD）患者样本中选择 18 名单侧下颌第三磨牙过度萌出的患者，通过研究模型观察和 T-scan 咬合检测均证实存在该情况。使用肌电图系统分别记录单侧咀嚼的咀嚼痕迹。根据记录的咀嚼痕迹中的片段创建平均咀嚼模式（ACP），以代表每个个体的咀嚼运动特征。分析 TMD 症状侧和过度萌出侧两个因素对 ACP 左右侧咀嚼参数差异值（Δ 值）的影响。比较 ACP 的三维幅度和 ACP 与垂直轴的交叉点值（称为交叉零点值），以描述咀嚼周期从平衡侧到工作侧的转折点。
过度萌出侧对内侧幅度、外侧幅度和交叉零点的 Δ 值有影响（P<0.05），但症状侧没有影响（P>0.05）。在过度萌出侧咀嚼时，内侧幅度较短，外侧幅度较大，交叉零点值较小（P<0.05）。
本研究数据表明下颌第三磨牙过度萌出对咀嚼模式有影响，而症状的影响则较为有限。
