持续性高正加速度重复作用对咀嚼肌的影响分析

目的 观察持续性高正加速度重复作用对大鼠咀嚼肌的影响。方法 雄性Wistar大鼠48只随机分成4组，每组12只。A组为空白对照；B组地面固定5min；C组固定于离心机转臂上，俯卧位，头向轴心，＋1Gz离心5min；D组体位同C组，＋10Gz离心30s,间隔时＋1Gz离心60s，连续每日5次，每周4d，共3周。观察咬肌、颞肌、翼外肌的组织形态学改变。结果 A组、B组和C组咬肌、颞肌、翼外肌肌纤维排列整齐，粗细均匀，肌节完整，肌横纹清晰，线粒体正常。D组咬肌、颞肌、翼外肌肌血管扩张，组织充血，部分肌纤维扭曲、断裂、横纹消失、翼外肌甚至出现肌纤维溶解。部分肌原纤维溶解，线粒体肿胀，糖原减少。结论 持续性高正加速度重复作用可引起咀嚼肌不同程度的损伤。     

牙齿重度磨耗患者咀嚼肌肌电的实验研究

目的 :研究重度牙齿磨耗 (TW )患者咀嚼肌的肌电活动 ,探讨不同类型牙合磨耗患者咀嚼肌受损的肌电表现。方法 :以 15例中老年重度牙齿磨耗患者为研究对象 ,通过肌电图仪 (EMG)测试下颌姿势位和牙尖交错位最大紧咬时颞肌前束 (TA)、咬肌 (MM )、二腹肌前腹 (DA )的肌电幅值 ;并以 8例正常牙合患者的咀嚼肌肌电幅值作为对照。结果 :姿势位时 ,磨耗Ⅰ、Ⅱ、Ⅲ组患者TA、MM、DA的平均肌电幅值高于对照组 ,TA、MM的肌电幅值增高显著大于对照组 (P <0 .0 1) ;ICP最大紧咬时 ,Ⅰ、Ⅱ、Ⅲ组患者TA、MM、DA平均肌电幅值降低 ,MM、DA肌电幅值与对照组比较有显著性差异 (分别为P <0 .0 1,P <0 .0 5 )。结论 :牙齿磨耗患者有肌紧张存在 ,Ⅲ型磨耗导致的不均匀接触对咬肌的损伤较大     

功能性矫治器打开大鼠下颌对咀嚼肌生物力学特性的影响

目的探讨功能性矫治器对咀嚼肌生物力学特性的影响及其临床意义。方法选用３０只生长期Ｗｉｓｔａｒ雄性大鼠，戴功能性上颌平面导板活动矫治器４周后，应用力学的测试方法对其嚼肌、二腹肌前腹及翼外肌生物力学特性的改变进行定量分析。结果咀嚼肌收缩性质发生了明显变化：嚼肌收缩速度加快，收缩张力增强；二腹肌前腹收缩速度变慢，收缩张力增强；翼外肌的收缩张力明显减弱。结论本项实验表明，功能性矫治器是通过改变咀嚼肌及二腹肌的生物力学特性来促进颌骨的生长改建，达到功能性颌骨矫形目的     

Histological changes in masticatory muscles of mdx mice

Objective

Duchenne muscular dystrophy (DMD) patients have distorted dentofacial morphology that could be a result of changed force balance of masticatory muscles due to unequal dystrophic changes in various masticatory muscles. Skeletal muscles of DMD patients and those of murine model of DMD - mdx mice - are both characterized by Ca²⁺ induced muscle damage, muscle weakness and characteristic histological changes. Therefore, to determine the pathological changes in this animal model of DMD, we examined the masticatory muscles of the mdx mice for histological abnormalities including nuclei localization, fibre diameters, and collagen expression.

Design

Muscle sections from masseter (MAS), temporal (TEM), tongue (TON) and soleus (SOL) of mdx and control normal mice were stained with hemalaun/eosin or with Sirius Red and morphometrically analysed. Levels of collagen staining in normal and mdx muscles were measured using image analysis and the mean optical density (mod) was determined.

Results

Dystrophin deficient masticatory muscles contained 11-75% fibres with centralised nuclei. In mdx mice an increased mean fibre diameter was observed as compared to the age-matched control muscles (control vs. mdx; MAS: 33.44 ± 0.49 μm vs. 37.76 ± 0.68 μm, p < 0.005; TEM: 32.93 ± 0.4 μm vs. 42.93 ± 0.68 μm, p < 0.005; SOL: 33.15 ± 0.29 μm vs. 40.62 ± 0.55 μm, p < 0.005; TON: 13.44 ± 0.68 μm vs. 15.63 ± 0.18 μm, p < 0.005). Increased expression of collagen was found in MAS (mod control vs. mdx: 1.34 vs. 3.99, p < 0.005), TEM (mod control vs. mdx: 3.11 vs. 4.73, p < 0.01) and SOL (mod control vs. mdx: 2.36 vs. 3.49, p < 0.01).

Conclusion

Our findings revealed that mdx masticatory muscles are unequally affected by the disease process. The masticatory muscles of the mdx mice could present a useful model for further investigating the influence of dystrophin deficiency on muscles function.     

自体喙突移植重建下颌髁突的实验研究

目的:研究运用自体喙突移植重建髁突的可行性及其整复效果。方法:选取12只成年雄性山羊,手术截除右侧髁突与关节盘,取同侧喙突以L型钛板固定在下颌升支。分别在术后第4、12、24周各处死4只动物。通过大体观察、三维CT分析和组织学检查等方法评价自体喙突移植后的形态学和组织学变化。结果:所有动物术后咬合基本正常。术后4周可见喙突再生,术后24周时自体喙突形态基本接近正常髁突。新生髁突表面有较厚的致密纤维结缔组织覆盖,其下方的组织结构类似正常髁突表面的关节软骨。结论:自体喙突移植可以重建一个形态和功能都基本接近正常的髁突,因此这种技术可以作为一种整复TMJ缺损的新方法。     

功能性矫治器引导下颌前伸对其咀嚼肌生物力学特性的影响

目的：探讨在功能性颌骨矫形过程中，咀嚼肌生物力学特性变化的规律。方法：选用３０只４周龄Ｗｉｓｔａｒ雄性大鼠，多为实验组和对照组，实验组每日戴功能矫治器１０ｈ～１２ｈ，对照组不戴。４周后应用力学测试方法对嚼肌、二腹肌前腹、翼外肌生物力学特性的变化进行定量分析。结果：咀嚼肌收缩性质发生明显变化，翼外肌收缩张力增强，收缩速度减慢，二腹肌前腹收缩张力减弱，收缩速度加快。结论：表明功能性矫治器是通过改变翼外肌、二腹肌等口颌系统肌肉的功能活动，促进颌骨生长改建，从而达到功能性颌骨矫形目的。     

自体冠突移植在颞下颌关节强直关节重建术中的应用

目的：探讨自体冠突移植在颞下颌关节强直关节重建术中的应用及效果。方法：对2008年9月—2010年9月期间收治的9例颞下颌关节强直患者应用自体冠突移植关节重建术式治疗,间隙插补物采用自体关节盘或口腔生物膜,比较术前、术后开口度、咬合情况和锥形束CT检查结果。结果：术后随访12～24个月,术后最大开口度得到明显改善,咬合关系无改变,在随访期内, 所有患者无复发。锥形束CT显示,移植冠突与下颌支骨性愈合,移植的冠突顶端变圆钝,向髁突形态转变。结论：自体冠突移植关节重建术是治疗颞下颌关节强直的有效术式。     

A型肉毒毒素治疗咀嚼肌群痉挛的远期疗效分析

目的 分析A型肉毒毒素治疗咀嚼肌群痉挛的远期疗效.方法 对17例经保守治疗无效的咀嚼肌群痉挛患者进行A型肉毒毒素肌肉注射治疗.受累咬肌和颞肌注射剂量分别为1ml(50U)和0.5ml(25U),未受累咬肌和颞肌注射剂量分别为0.5ml(25U)和0.25ml(12.5U).观察治疗前后不同时期患者最大张口度和并发症发生情况.结果 治疗后不同时期患者最大张口度明显大于治疗前(P＜0.001),而治疗后不同时期患者最大张口度相差不大(P＞0.05).平均随访时间4～9年(6.5±1.6),患者无严重并发症发生.结论 A型肉毒毒素治疗咀嚼肌群痉挛安全有效,可明显改善咀嚼肌功能,增大张口度.     

Comparison of dynamic electromyographic analysis of masticatory capsules with materials of different textures

The aim of this study was to compare the mastication electromyographic indexes of capsules used for the masticatory efficiency evaluation “ME-mastig” and of materials of different textures (gum, raisins, and peanuts).

Methods: Thirty young, healthy, adult subjects, with an average age of 23.46?years old, with no symptoms of temporomandibular dysfunction (TMD), confirmed by the clinical exam, RDC/TMD, and the static test of electromyography (EMG) were chosen. Afterward, dynamic tests were performed (bilateral mastication of the compounds) to determine number of chewing cycles (CYCLES); masticatory frequency (FREQ); SMI (symmetrical masticatory index – corresponding to the value of neuromuscular coordination during mastication); and IMPACT (corresponding to impact – total electromyographic activity performed by the system during chewing).

Results: Cycle and frequency were similar. Regarding SMI and IMPACT, the raisin, the capsule, and the peanut were similar between each other, and different from the gum.

Conclusions: Masticatory capsules and the natural foods with different textures had similar results regarding EMG indexes.     

Occlusal force, electromyographic activity of masticatory muscles and mandibular flexure of subjects with different facial types

Objective

The aim of this study was to evaluate whether vertical facial patterns influence maximal occlusal force (MOF), masticatory muscle electromyographic (EMG) activity, and medial mandibular flexure (MMF).

Material and Methods

Seventy-eight dentate subjects were divided into 3 groups by Ricketts''s analysis: brachyfacial, mesofacial and dolychofacial. Maximum occlusal force in the molar region was bilaterally measured with a force transducer. The electromyographic activities of the masseter and anterior temporal muscles were recorded during maximal voluntary clenching. Medial mandibular flexure was calculated by subtracting the intermolar distance of maximum opening or protrusion from the distance in the rest position. The data were analyzed using ANOVA followed by Tukey''s HSD test. The significance level was set at 5%.

Results

Data on maximum occlusal force showed that shorter faces had higher occlusal forces (P<0.0001). Brachyfacial subjects presented higher levels of masseter electromyographic activity and medial mandibular flexure, followed by the mesofacial and dolychofacial groups. Additionally, dolychofacial subjects showed significantly lower electromyographic temporalis activities (P<0.05).

Conclusion

Within the limitations of the study, it may be concluded that maximum occlusal force, masticatory muscle activity and medial mandibular flexure were influenced by the vertical facial pattern.     

Effect of third molar absence on development of masticatory muscles in EL mice

We investigated the effect of the lack of the third molar on synaptogenesis at the neuromuscular junction of masticatory muscles in EL/ Sea (Sea) mice, in which tooth bud of all third molars disappears in the process of development. We analyzed the mRNA expression levels of the nicotinic acetylcholine receptor (nAChR) α, ε, and γ subunits at 3, 6, and 12 weeks of age in the masseter and temporalis muscles of Sea mice, and in the control strain EL/Kwl (Kwl) mice, using real-time PCR. In the Sea, no third molars erupted over the oral mucous membrane during the experimental period. In the Kwl, at 3 weeks of age, no third molars had erupted over the oral mucous membrane, but they partially had emerged over the maxilla and mandible and, after 3 weeks of age, completely erupted over the oral mucous membrane. In the masseter, the expression levels of the α, ε, and γ subunit mRNAs in the Sea mice were 92% (P< 0.05), 100% (P< 0.05), and 91% (not significant) higher than in the Kwl mice at 3 weeks of age, but steadily decreased until 12 weeks of age. The expression levels in the Kwl mice were stable throughout the experimental period. In the temporalis and gastrocnemius, there were no significant differences in the expression levels of any of the subunits studied between the Sea and Kwl mice. This result suggests that the difference in the expression of nAChR subunits in the masseter muscle between the Sea and Kwl mice is associated with the eruption of the third molars, and that the absence of the third molars has different effects between the masseter and temporalis.     

颞肌筋膜瓣联合冠突移植治疗颞下颌关节强直

目的:应用带蒂颞肌筋膜瓣联合冠突移植治疗颞下颌关节真性强直,评价其重建颞下颌关节的效果。方法:对6例颞下颌关节真性强直患者切除病变区骨质,形成骨间隙,采用带蒂颞肌筋膜瓣转移充填骨间隙和冠突切取植入构造新的“髁突”,重建颞下颌关节。手术后常规随访,评价其疗效。结果:全部病例术后随访4～28个月,开口度3.1～3.8cm,平均开口度3.5cm,效果满意。结论:带蒂颞肌筋膜瓣联合冠突移植治疗颞下颌关节真性强直具有多方面优势,是防止颞下颌关节术后复发的有效手术治疗方法。     

Assessment of thickness and function of masticatory and cervical muscles in adults with and without temporomandibular disorders

Objective

The aim of this study was to evaluate the maximal bite force (MBF), electromyographic (EMG) activity and thickness of the masseter, anterior part of the temporalis and sternocleidomastoid (SCM) muscles in a group of young adults with and without temporomandibular disorders (TMDs).

Design

Nineteen individuals comprised the TMD group (6 males/13 females, aged 25.4 ± 3.8 years), classified based on the Research Diagnostic Criteria for TMD (RDC/TMD), and 19 comprised the control group (6 males/13 females, aged 24.1 ± 3.6 years). The MBF was determined with a transducer placed between the dental arches at the first molars level (N). The muscles were evaluated bilaterally at rest and during maximal voluntary clenching (MVC) by assessing EMG activity and performing ultrasonography (USG). The mean values of these measures for both sides of the mouth were used. The normality of the distributions was assessed by the Shapiro–Wilks test. Variables between groups and genders were compared using two-way factorial ANOVA test and correlated using the Spearman coefficient (α = 0.05). Unpaired t test was used to compare variables between TMD subgroups. Logistic regression analysis was used to identify the variables associated with the presence of TMD.

Results

MBF, EMG and USG data were similar among clinical groups and among TMD subgroups. The thickness of masseter and SCM muscles in the relaxed and clenching states were significantly higher in males than females. On the other hand, the EMG of the temporalis muscle in the rest state was significantly higher in females than males. Additionally, the MBF was positively correlated with the USG characteristics of masseter and SCM muscles, as well as with the EMG activity of masseter and temporalis muscles in the TMD group. In this group, there was also a positive correlation between the thickness of the masseter muscle and its activity. On the other hand, the thickness of the SCM muscle was negatively correlated with its activity. A lower MBF was independently associated with the presence of TMD.

Conclusions

Subjects with TMD exhibited similar values of MBF, thickness and electrical activity of masticatory and cervical muscles when compared with controls; positive correlations observed between these variables may suggest a muscular alteration in TMD patients and a co-activation of masticatory and cervical muscles during mandibular movement. This fact may also be confirmed by the negative association between bite forces and presence of TMD.     

正畸与正颌联合治疗成人骨性反后咀嚼肌肌电变化

目的 :检查对比分析成人骨性反牙合正畸与正颌手术联合矫治前后的主要咀嚼肌肌电 ,揭示正畸与正颌手术联合矫治后咀嚼肌功能的变化规律。方法 :2 0名正畸与正颌手术联合治疗的成人骨性反牙合患者 ,利用肌电图仪测试治疗前后咬肌、颞肌前束、二腹肌前腹在功能活动中肌电变化。结果 :正畸与正颌手术联合矫治对咬肌、颞肌前束、二腹肌前腹的功能活动均有不同程度的影响 ,其中对咬肌的功能影响最明显。结论 :正畸与正颌手术联合治疗成人骨性反牙合 ,咀嚼肌的异常肌张力多数得到纠正 ,但咀嚼肌的功能未能得到满意的恢复 ,咀嚼肌的功能恢复是一个复杂而长期的过程 ,还需要较长的功能锻炼恢复期     

自体喙突移植重建下颌髁突对下颌骨生长发育的影响

目的探讨自体喙突移植重建下颌髁突对下颌骨生长发育的影响。方法18只幼年雄性山羊随机分成A（n=10）和B（n=8）两组,所有动物均手术切除右侧髁突,取同侧喙突移植重建下颌髁突。术后48周时处死所有A组动物,对下颌骨及重建髁突形态进行大体观察与测量。术后24和48周各处死B组4只实验动物进行组织学检查,左侧下颌骨作为正常对照组。结果术后48周时双侧升支高度、下颌骨高度以及下颌骨长度无明显差异,手术侧重建髁突明显增大,同时升支宽度较正常侧缩小;重建髁突表面有再生的关节软骨,其组织学结构与正常关节软骨类似。结论自体喙突移植重建髁突未对下颌骨生长发育产生明显影响,其中功能刺激是促进下颌骨继续生长发育的主要原因。     

Fractures of the mandibular coronoid process: A two centres study

The aim of this study was to assess the characteristics of patients with coronoid fractures treated in two European centres over 10 years and to briefly review the literature.This study is based on 2 systematic computer-assisted databases that have continuously recorded patients hospitalized with maxillofacial fractures and surgically treated in two European centres between 2001 and 2010.During the 10 years, 1818 patients and 523 patients with maxillofacial fractures were admitted to the two centres respectively: 21 patients (16 males, 5 females) were admitted with 21 coronoid fractures and 28 associated maxillofacial fractures.A mean age of 42.1 years was observed. The fractures were mainly the result of motor vehicle accidents, followed by assaults and falls. The most frequently observed associated maxillofacial fracture was a zygomatic fracture (13 fractures). In both centres, mandibular coronoid fractures are treated unless a severe dislocation of the fractured coronoid is observed or a functional mandibular impairment is encountered.Conservative treatment can be used, together with the open reduction and internal fixation of associated fractures. The crucial point is to prevent ankylosis, which may be prevented by correct and early postoperative physiotherapy and mandibular function.     

自体肋软骨和自体喙突移植在成人单侧颞颌关节强直治疗中的临床效果比较

目的：比较成人单侧颞颌关节强直髁突重建中自体喙突移植和肋软骨移植的临床效果。方法：选取32例自体喙突移植和28例自体肋软骨移植重建髁突的颞下颌关节强直病例,对其术前和术后的饮食分数、最大张口度、侧向运动、开口型偏斜、CT扫描影像学等方面进行评价。结果：两组患者的关节强直治疗均取得满意效果。在饮食分数、张口度、侧向运动、开口型偏斜和复发率等术前及术后的测量值中,两组间差异无统计学意义（P>0．05）,但两组病例中术后张口度、侧向运动及饮食分数均较术前有显著改善。肋软骨移植术中有3例患者出现了胸膜撕裂,6例患者出现了移植骨供区的暂时性疼痛。肋软骨移植及喙突移植术后分别有5例和3例患者的面神经颞支受到了损伤,3－6月内康复。喙突移植组中无关节强直复发,肋软骨移植组中有1例复发。结论：在颞下颌关节强直矫治中,自体喙突移植是一种较好的髁突重建骨移植材料。     

Retrospective comparison of autogenous cosotochondral graft and coronoid process graft in the management of unilateral ankylosis of the temporomandibular joint in adults

We retrospectively compared the clinical outcomes of autogenous coronoid process grafts (n = 32) and costochondral grafts (n = 28) in condylar reconstruction for the treatment of unilateral ankylosis of the temporomandibular joint (TMJ) in adults. Preoperative and postoperative assessments included diet scores, cone-beam computed tomography (CT), maximal interincisal opening, lateral excursion, and mandibular deviation on opening the mouth. There were no significant differences between the 2 groups in the measurements before and after the operation with respect to incisal opening, lateral excursion, mandibular deviation, diet scores, or recurrence rate, but in both the postoperative incisal opening, lateral excursion, and diet scores had improved significantly compared with preoperatively. After costochondral graft 3 patients developed intraoperative plural tears, and 6 had temporary pain at the donor site. The frontal branch of the facial nerve was temporarily affected in 5 patients after costochondral graft and 3 after coronoid process grafts, all of which recovered in 3–6 months. There was no recurrence after coronoid process grafting, and one after costochondral grafting. The clinical outcomes in both groups were satisfactory and comparable. Autogenous coronoid process grafting may therefore be a good alternative for condylar reconstruction in patients with ankylosis of the TMJ.     

Co-activation of jaw and neck muscles during submaximum clenching in the supine position

Objective

The purpose of this study was to test the hypothesis that jaw clenching induces co-contraction and low-level long-lasting tonic activation (LLTA) of neck muscles in the supine position.

Design

Ten healthy subjects developed various feedback-controlled submaximum bite forces in different bite-force directions in supine position. The electromyographic (EMG) activity of the semispinalis capitis, semispinalis cervicis, multifidi, splenius capitis, levator scapulae, trapezius, sternocleidomastoideus, masseter and infra/supra-hyoidal muscles was recorded. For normalization of EMG data, maximum-effort tasks of the neck muscles were performed.

Results

Co-contractions of the posterior neck muscles varied between 2% and 11% of their maximum voluntary contraction. Different bite forces and bite-force directions resulted in significant (p < .05) activity differences between the co-contraction levels of the neck muscles. In addition, LLTA of specific neck muscles, provoked by the jaw clenching tasks, was observed.

Conclusions

This study demonstrated for the first time moderate co-contractions of jaw and neck muscles in the supine position under controlled submaximum jaw clenching forces. LLTA of most neck muscles was observed, outlasting clenching episodes and indicating an additional neuromuscular interaction between the two muscle groups.