单侧最大紧咬软硬物对咬合力和咀嚼肌的影响

 目的 研究单侧最大紧咬不同硬度物质对咬合力和咬肌、颞肌前束的肌电值的影响。方法 在受试者一侧下颌第2前磨牙与第1磨牙上放置聚氯乙烯(polyvinyl chloride,PVC)软片,对侧同名牙放置面团期丙烯酸树脂(acrylic resin, AR),最大紧咬时制取丙烯酸树脂片为硬物;使用T-ScanⅢ咬合分析仪和Bio-Pak肌电图仪测量受试者在牙尖交错位(intercuspal position, ICP)和单侧咬合软硬物下双侧最大紧咬时的咬合力和咬肌(masseter muscle, MA)、颞肌前束(temporalis-anterior muscle, TA)的肌电值。结果 (1)ICP最大紧咬时,双侧MA肌电值、双侧TA肌电值均无明显差异 (P>0.05); (2)单侧最大紧咬时,咬合侧与咬合对侧MA肌电值无明显差异(P>0.05);而咬合侧TA肌电值分别为(147.75±31.37)μν、(145.70±35.08)μν,均明显大于咬合对侧(115.87±24.08)μν、(121.24±22.78)μν,差异均有统计学意义(P<0.05); (3)单侧最大紧咬时,MA肌电值与ICP最大紧咬时相比差异无明显统计学意义,咬合对侧TA肌电值(147.75±31.37)μν和(145.70±35.08)μν均明显小于ICP最大紧咬时的TA肌电值(136.88±29.54)μν,差异有统计学意义(P<0.05);(4)单侧咬合时,所有受试者(20/20例)均出现了咬合对侧接触现象。单侧最大紧咬时软物的咬合力为(9174.60±955.29)raw,明显大于硬物的咬合力(6156.70±979.27)raw,差异有统计学意义(P<0.05);但软物最大紧咬时的MA和TA肌电值分别与硬物比较差异无统计学意义。结论 与硬物相比,软物对咬合力的影响相对较小,但不同硬度咬合物对咀嚼肌肌电值无明显影响。

The influence of soft and hard bolus on bite force and masticatory muscles during unilateral maxmal biting

Objective To investigate the influence of different hardness bolus on bite force and the functional characteristics of masseter and temporalis-anterior muscle during unilateral maxmal biting. Methods PVC film was placed on the surface of mandibular second premolar and the first molar on one side of the subject, the contralateral same teeth were placed in doughy acrylic. Then the acrylic resin piece was made by maxmal biting.Using T - Scan Ⅲ bite analyzer and Bio-Pak EMG the bilateral maximum bite force and masseter and temporalis-anterior muscle activity were measured under ICP and unilateral biting. Results (1)During ICP maxmal biting,no differences was found in EMG activity between bilateral temporalis-anterior muscles or between bilateral masseters.(2) During unilateral maxmal bitting , bilateral side of masseter muscle activity had no obvious difference (P>0.05), but EMG activity of the temporalis-anterior muscle on the biting-side(147.75±31.37)μν,(145.70±35.08)μν were higher than that of the contralateral side(115.87±24.08)μν,(121.24±22.78)μν (P<0.05).(3)During unilateral maxmal biting, masseter muscle activity had no obvious statistically significance when compared with ICP maximal biting(P>0.05), but the contralateral temporalis-anterior muscle values(147.75±31.37)μν and (145.70±35.08)μν were much smaller than that of ICP maxmal biting(136.88±29.54)μν, the difference was statistically significant (P<0.05). (4)Unlateral occlusion, all the subjects (20/20) had the contralateral occlusal contact phenomenon. The bite force of soft bolus (9174.60±955.29)raw was bigger than that of he hard bolus(6156.70±979.27)raw (P<0.05). But the masseter and temporalis-anterior muscle activity in soft bolus had no obvious difference when compared with hard bolus (P>0.05). Conclusions Compared with hard bolus, the bite force of soft bolus is relatively smaller than that of hard bolus, the influence of different hardness of occlusal bolus has no significant effect on masticatory muscle.