Orofacial Physiotherapy after Radiotherapy in the Head and Neck Region

Because a so-called mandibular whiplash injury requires the absence of short-latency jaw-closing reflexes in order to explain the postulated mechanism of injury (excessive jaw opening), the authors studied the presence and absence and, more importantly, the kinematics (duration, displacement, velocity, acceleration) of monosynaptic and, possibly, polysynaptic myotatic (stretch) reflexes in the jaw elevator muscles. In six healthy adults jaw jerk maneuvers were elicited through a brisk tap on the chin, and surface electromyography identified elevator reflexes while translational electrognathography identified the kinematics of the reflexes. The maneuvers were done while maintaining the rest position (3% MVC) and moderate clenching of the teeth (30% MVC). Electromyography was also used to identify phasic elevator excitations during a passive brisk neck extension maneuver. A sudden and unexpected elongation of the jaw elevators released autogenic reflex responses that, in conjunction with augmented tissue elasticity (stiffness), elevated the mandible into centric occlusion within approximately 150 milliseconds. In 86% of trials, the responses occurred regardless of the prevailing resting and clenching contractile activities. There was no evidence of a depressor force that consistently would and could anchor the mandible in a position of extreme or moderate depression, the theoretical linchpin of the mandibular whiplash injury. It was concluded that the mandibular locomotor system is very efficient in maintaining the rest and intercuspal positions of the mandible. This study found no evidence corroborating the mechanism claimed to release a so-called mandibular whiplash injury.     

健康人下颌运动时头颈肩部肌电活动的研究

目的　研究健康人的下颌息止位及运动时头颈肩部肌的协同活动。方法　用肌电积分值记录分析的方法调查 1 0名健康成人的下颌息止位和各种运动时颞肌前后腹、胸锁乳突肌和斜方肌的肌电活动。结果　无论在下颌息止位还是下颌运动中 ,胸锁乳突肌和斜方肌均有相应活动 ,胸锁乳突肌活动的增加倍数与颞肌前后腹活动的增加倍数有密切的正相关关系。斜方肌在不伴咬合的各种下颌运动时活动增加 ,而在大力咬牙和咀嚼时活动趋于停止。下颌不发生偏斜时 ,同一肌的左右两侧肌的活动有密切的正相关关系。结论　颞肌前后腹、胸锁乳突肌和斜方肌均参与维持下颌息止位及下颌运动。下颌功能和头颈肩部肌功能有密切关系     

一侧下颌角受力对双侧关节盘及髁突软骨的影响

目的:利用三维有限元分析法,从生物力学角度探讨一侧下颌角受力瞬间双侧颞下颌关节(TMJ)关节盘及髁突软骨的相应变化及其与临床实际的关系。方法:建立下颌骨和TMJ共5个不同开口度(闭口位及1、2、3、4cm开口位)的三维有限元数字模型;于左侧下颌角下缘向上,施以与眶耳平面垂直的1000N压力。获取受力后双侧关节盘和髁突软骨产生的平均主应力的分布及其峰值大小。结果:(1)闭口位时,双侧关节盘和髁突软骨的平均主应力(EQV应力)峰值明显较小;(2)在不同开口位,关节盘EQV应力峰值多位于后带,髁突软骨则多位于前斜面;(3)关节盘EQV应力峰值始终是左侧大于右侧,而髁突软骨在闭口位及1、4cm开口位时左侧EQV应力峰值大于右侧,2、3cm开口位时则是右侧大于左侧;(4)双侧关节盘和髁突软骨的EQV应力峰值出现的部位基本对称。结论:(1)本组模型较精确地反映了实物,并且实验结果与临床实际相接近,解决了以往实验中遇到的一些问题,为TMJ的生物力学研究提供了新的途径。(2)稳定的咬合关系可以明显减小TMJ的间接损伤。(3)关节盘后带病变及髁突器质性病变可能由下颌骨一次性暴力创伤后造成的TMJ间接损伤引起;受力侧关节盘比对侧更易受损伤,而双侧髁突软骨都有受到严重损伤的可能。     

The effects of a single intercuspal interference on electromyographic characteristics of human masticatory muscles during maximal voluntary teeth clenching

In 13 healthy subjects (eight men and five women, mean age, 22 years), an aluminum intercuspal interference (height, 0.25 mm) was placed on the maxillary right first premolar to study its effect on the contractile symmetry of the right and left masseter and anterior temporalis muscles when measured through a Percentage Overlapping Coefficient (POC), derived from surface electromyographic recordings of maximum voluntary teeth clenching. Additionally, and to estimate the potential of the experimental intercuspal interference to induce lateral displacement of the mandible, a Torque Coefficient (TC) was derived from surface electromyographic recordings. The conclusion was that the experimental occlusal interference gave rise to asymmetric contractile activity in the studied mandibular elevator muscles as well as a potential to displace the mandible in a lateral direction.     

Optical density of the mandibular head in cases of TMJ dysfunction and asymmetry of masticatory muscles activity

There was an examination of 20 patients (12 women and 8 men), aged 30 to 50, with TMJ dysfunction and with partial absence and abrasion of teeth with decrease in the height of the lower facial part and distal mandible shift, and of 12 people (7 women and 5 men), aged 20 to 40, with intact dentitions using electromyography of masticatory muscles and computer tomography, followed by evaluation of the optical density of mandibular head. Analysis of the results enabled to determine the presence of disorders of the balanced activity of masticatory muscles and enables to determine alterations in the optical density of mandibular head. It is necessary to consider the obtained data in planning the prosthetic treatment and preparation of the mouth for prosthetics of patients with TMJ pathology.     

Quantification of translational and gliding components in human temporomandibular joint during mouth opening

OBJECTIVE: In humans, the opening movement of the mouth requires a complex combination of rotation in the lower temporomandibular joint compartment and of translation in the upper compartment. The aim of the current study was to quantitatively assess the percentage contribution of rotation and translation movements of the mandible at maximum mouth opening in normal, healthy individuals. DESIGN: Free, habitual movements of mouth opening were recorded in 12 men and 15 women aged 19-30 years using an optoelectronic three-dimensional motion analyser. All subjects had a sound, complete, permanent dentitions with Angle Class I jaw relationships, without cast restorations or cuspal coverage, TMJ or craniocervical disorders. For each subject, the mandibular movements at the interincisor point (occlusal plane) were reconstructed, and, using suitable mathematical algorithms, divided into their rotation and gliding components. The relative contribution of the two components to the total movement was calculated for each frame of motion. In particular, the situation at maximum opening was assessed. RESULTS: At maximum mouth opening, on average, men had significantly larger displacement of the mandibular interincisor point (56 mm versus 46 mm) and angle of rotation (34 degrees versus 32 degrees), than women. The percentage of mandibular movement explained by rotation at maximum mouth opening (77%) was not influenced by sex. The degree of rotation was significantly related to the displacement of the interincisor point: in women r2 = 87%, in men, r2 = 45%. CONCLUSIONS: Overall, in normal subjects with a healthy stomatognathic apparatus, mouth opening was more determined by mandibular rotation than by translation.     

Effects of the newly developed mandibular retraction system in a rat

Authors have developed a mandibular retraction system in a rat that was constructed by arms having a metal mesh, an incisor metal cap, a pair of closed coil springs and a soft plastic collar. The merit of this system is that the anchor is very stable because it is made on the parietal bones, and the direction and load of the traction are invariable regardless of head position of the rat compared to the previous methods in which the anchor was made on the neck collar of a rat. Seventy of 8-week-old male Wistar rats were divided into five groups that were intact, collar, sham operation, straight-pull and high-pull. The anchor was implanted with a metal mesh into the subperiosteal space of the parietal bones just in front of the lambda suture of a rat. The coil spring attached on the sliding hook on the arm was connected with a hook soldered with an incisor metal cap. Therefore, the mandible was retracted in the TMJ direction (straight-pull) and some were 20 degrees upper than TMJ (high-pull) for 15 days at a tension of 10 g. All operations except for traction by the coil springs were performed on a rat in the sham operation group. Only the plastic collar was set on the neck in the collar group. Mandibular retraction for 15 days showed significant inhibition of the sagittal growth of the mandible in both high- and straight-pull groups. No inhibition of sagittal cranial growth was observed according to morphometrical and microscopical investigations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Deep circumflex iliac artery flap combined with a costochondral graft for mandibular reconstruction

Our aim was to use the deep circumflex iliac artery (DCIA) flap together with a costochondral graft as a safe and reliable bone flap for routine reconstruction of the mandibular body and the temporomandibular joint (TMJ). Five patients with benign tumours of the mandible had segmental mandibulectomy including the condyle, and this was reconstructed in one stage using the DCIA combined with a constochondral graft. The rib was inserted into the iliac crest as a whole transplant, and fixed to the proximal stump of the mandible with a prebent reconstruction plate according to a computer-aided design. The grafts healed uneventfully, and dental implants were inserted in 4 cases. During the 2-year follow-up these patients had good mandibular function, including mouth opening, force of bite, and occlusion. The radiographs showed good bony consolidation between the graft and the stump of the mandible and function of the TMJ.A DCIA flap combined with a costochondral graft is a safe and reliable way to provide not only a large bulk of bone to suit the mandible, but also good function of the TMJ in the absence of radiotherapy.     

One-stage microvascular mandible reconstruction and alloplastic TMJ prosthesis

Severely deformed or absent temporomandibular joints (TMJ) benefit from total alloplastic joint replacement and large mandibular defects from revascularized free tissue transfer for reconstruction. However no cases of their combined one-stage placement with outcomes can be found in the literature. We present two cases with different indications and reconstruction.The first patient required mandibular body and ascending ramus reconstruction after previous sarcoma resection. This was with a condyle-bearing reconstruction plate which resulted in significant dysfunction, leaving the patient unable to open her mouth. A one-stage vascularized iliac crest free flap and alloplastic TMJ prosthesis was used to reconstruct the mandible. Subsequently, metal removal, soft tissue augmentation by lipotransfer and dental implant placement were performed. At 63 months follow-up patient was pain-free, with mouth opening, protrusion and lateral excursion back to normal.The second patient required mandibular body, ascending ramus and joint reconstruction, performed by transoral vascularized fibula free flap with temporal vessel anastomosis. The traumatic deep bite and posterior facial height were corrected, additional submandibular scars avoided by transoral placement of the fibula transplant and a miniaturized TMJ prosthesis along with the vascularised free flap with 28 months follow-up.A miniaturized TMJ prosthesis may become placed transorally for reconstruction of the TMJ, together with a vascularized free flap for mandibular reconstruction and promises good long-term stability with normal function above all for protrusion and lateral excursion.     

Condylar Hyperplasia Associated to Synovial Chondromatosis of the Temporomandibular Joint: A Case Report

Condylar hyperplasia is a slowly developing malformation of the mandible, with elongation of the mandibular neck, that generally results in facial asymmetry. Synovial chondromatosis is a benign chronic disorder characterized by the formation of multiple small nodules of hyaline cartilage as a result of metaplasia of the synovial connective tissue. It affects mostly the large joints, particularly the knee, hip, elbow and ankle. The temporomandibular joint (TMJ) is rarely affected. The case of a 42-year-old male with a history of left preauricular pain and swelling and deviation of the mandible to the left upon opening the mouth is presented. Computed tomography disclosed hyperplasia of the left condyle with loose radiopaque bodies within the joint cavity. The left TMJ was subject to open surgery, which included resection of four loose bodies and a remodeling condylectomy. The histopathological study confirmed the diagnosis of condylar hyperplasia and chondromatosis of the left TMJ.     

Condylar hyperplasia associated to synovial chondromatosis of the temporomandibular joint: a case report

Condylar hyperplasia is a slowly developing malformation of the mandible, with elongation of the mandibular neck, that generally results in facial asymmetry. Synovial chondromatosis is a benign chronic disorder characterized by the formation of multiple small nodules of hyaline cartilage as a result of metaplasia of the synovial connective tissue. It affects mostly the large joints, particularly the knee, hip, elbow and ankle. The temporomandibular joint (TMJ) is rarely affected. The case of a 42-year-old male with a history of left preauricular pain and swelling and deviation of the mandible to the left upon opening the mouth is presented. Computed tomography disclosed hyperplasia of the left condyle with loose radiopaque bodies within the joint cavity. The left TMJ was subject to open surgery, which included resection of four loose bodies and a remodeling condylectomy. The histopathological study confirmed the diagnosis of condylar hyperplasia and chondromatosis of the left TMJ.     

Mandible protrusion and decrease of TMJ sounds: an electrovibratographic examination

This study quantified by, electrovibratography, the amount of mandible protrusion required to decrease significantly temporomandibular joint (TMJ) vibratory energy as an aid in the diagnosis of the recapture of anteriorly displaced disk. Eighteen patients diagnosed as having anterior disk displacement with reduction and TMJ clicking were submitted to electrovibratographic examination at the first appointment and treated with a stabilizing appliance and anterior positioning appliance with 1 to 5 mm protrusion. Vibratory energy was checked in each of these positions. Baseline data were used as control. At the first appointment, the patients had vibrations with more elevated intensities at the middle and late phases of the mouth opening cycle. At only one clinical step, mandible protrusion was obtained with the anterior repositioning appliance, ranging from 1 to 5 mm protusion. At each new position, a new electrovibratographic exam was made. After the 5-mm mandibular projection, only 2 patients presented vibration, with means between 0.6 and 2.8 Hz. Data were analyzed statistically by ANOVA and Tukey's test (alpha=0.05). The outcomes of this study indicate that 3 mm is the minimum amount of mandible protrusion to significantly decrease the TMJ vibratory energy and to recapture the displaced articular disk.     

下颌骨创伤致慢性颞下颌关节创伤性关节炎相关因素的初步分析

目的 初步探讨下颌骨骨折后颞下颌关节发生慢性创伤性关节炎的相关因素。方法 对下颌骨骨折后37例颞下颌关节慢性创伤性关节炎病例(A组)和83例无关节症状病例(B组)的临床资料进行比较分析。结果 A组较B组女性及成人比例多；颌间结扎时间长，开口练习执行情况差；髁突骨折病例多，经保守治疗的髁突脱位骨折病例多。结论 下颌骨骨折引起的颞下颌关节慢性创伤性关节炎易发于颌间结扎时间长、未能进行完善开口练习的患者，且成年及女性患者多见；髁突骨折是引起该病的主要创伤类型，其中保守治疗的髁突脱位骨折患者更易发生慢性创伤性关节炎；下颌骨其它部位骨折者也可引起慢性创伤性关节炎，应引起临床工作者重视。     

间接创伤对幼年大白鼠颞下颌关节血供的影响

目的　探讨间接创伤对幼年鼠颞下颌关节的影响。方法　Wistar幼年大白鼠颞下颌关节间接创伤后,应用放射性同位素测定方法对其关节区进行动态观察。结果　与正常组比较,随着创伤后对颞下颌关节区不同时间段同位素测定,创伤后颞下颌关节区放射性强度随时间增加,两周达高峰,1月时放射性强度仍比正常对照组高,在任何时间段,创伤侧都较非创伤侧颞下颌关节区放射性强度高。结论　间接创伤可以引起幼年鼠颞下颌关节局部血流变化     

颞下颌关节上腔封闭-扩张联合灌洗及粘弹补充治疗不可复性关节盘前移位

目的评价颞下颌关节上腔封闭-扩张术联合灌洗及粘弹补充疗法治疗不可复性关节盘前移位的临床效果.方法对29例不可复性关节盘前移位患者行关节上腔封闭-扩张治疗,3～5d后行灌洗术,结束时注入1%透明质酸钠1ml.在治疗的同时配合被动张口训练.以配对t检验对数据进行处理.结果封闭-扩张术后张口度及健侧侧向运动度较治疗前、灌洗及粘弹补充治疗术后张口度及健侧侧向运动度较灌洗术前均有显著增加(P＜0.01),疼痛基本消失.治疗过程中有5例患者出现健侧关节疼痛,经用封闭-扩张治疗后疼痛消失,张口度相应增加3～5mm.结论(1)颞下颌关节上腔封闭-扩张联合灌洗及粘弹补充疗法能有效改善不可复性关节盘前移位患者的张口度及侧向运动度,缓解关节疼痛.(2)封闭-扩张术与灌洗及粘弹补充疗法两者有互补及累加作用.(3)及时发现对侧关节的隐匿病变并进行治疗,能提高整体疗效.     

Biomechanical evaluation of Chinese customized three-dimensionally printed total temporomandibular joint prostheses: A finite element analysis

Purpose

This work aims to evaluate the biomechanical behavior of Chinese customized three-dimensional (3D)?printing total temporomandibular joint (TMJ) prostheses by means of finite element analysis.

前方牵引反作用力对颞下颌关节区受力状况影响的有限元研究

目的：建立并使用颅颌面三维有限元模型,研究前方牵引反作用力对颞下颌关节区以及整个下颌骨的应力分布和位移变化状况的影响。方法：选择1例健康成年男性志愿者,采用薄层螺旋CT扫描获取其颅颌面复合体二维图像原始DICOM数据,利用Mimics、Magics、MSC．Marc等图像处理软件建立颅颌面复合体三维有限元模型。利用AN-SYSIO．0软件,在下颌骨颏顶点处施加与耠平面成37。角,大小为5N的力并分析其受力状况。结果：①获得了精确细致的颅颌面复合体三维几何模型,其网格划分准确合理,与重建生物模型的形态相似性好,力学特性体现准确性高。②下颌骨的应力集中区域位于髁突顶部及颈部,髁突表面最大受力区域位于髁突前斜面。上颌骨表面应力集中区域位于关节窝,其中关节窝表面受力最大区域位于关节结节后斜面。③下颌骨的位移图显示位移大小从颏部至髁突逐级递减,其方向与施力方向一致。下颌骨位移变化最大处位于节点力加载部位,髁突部位位移变化量最小。结论：成功建立了包括颞下颌关节在内的颅颌面三维有限元模型,该模型具有很高的精确性,可用于前方牵引反作用力的相关研究。前方牵引反作用力会对颞下颌关节区以及下颌骨的应力分布和位移状况产生影响,但其是否会造成颞下颌关节紊乱还有待进一步研究。     

Constancy of clinical signs in patients with mandibular dysfunction

Repeated clinical examinations were performed 6 weeks apart on 34 patients with mandibular dysfunction to estimate the consistancy of clinical signs. The clinical examination of the patients included the masticatory muscles, the temporomandibular joint (TMJ) and the mandibular movement capacity. The clinical dysfunction index (Di) was calculated as a measure of the degree of mandibular dysfunction. The highest agreement between examinations was found for maximal mouth opening and protrusion. The agreement for palpation tenderness of the masticatory muscles and TMJ, limited movement of the TMJ, TMJ sounds, and pain during movement was considerably lower. The lowest agreement within 6 weeks was found for the clinical dysfunction index. No statistically significant difference could be detected between the two examinations for any of the clinical signs, as a result of given information and counseling before the 6-week period. It was concluded that all clinical signs, except maximal mouth opening and maximal protrusion, showed low consistancy.     

Whiplash injuries of the temporomandibular joint in motor vehicle accidents: Speculations and facts

Summary Referring to the temporomandibular joint (TMJ) of the human mandibular locomotor system, it has been asserted that displacement of the TMJ disc and inflammation of TMJ tissues are the results of acute and indirect trauma to the TMJ; on occasion this is allegedly experienced in motor vehicle accidents and commonly known as a TMJ whiplash injury. It is postulated that the TMJ whiplash injury is released in the occupant or occupants of a target vehicle when its rear end is impacted by the front end of a bullet vehicle. On the basis of detailed analyses of TMJ trauma/pain histories and TMJ magnetic resonance images, presented as circumstantial evidence in favour of the postulated TMJ whiplash injury, and detailed analyses of the mathematical biophysics of the mandibular locomotor system as well as direct experimental evidence, it is concluded that the postulated TMJ whiplash injury does not exist as a single and independent disease entity caused by motor vehicle accidents. If TMJ disc displacement and inflammation are present, they are expressions of an insidious and progressive pre—existing (pre—accident) disease entity that is comprised of TMJ synovitis/osteoarthritis (phase of inflammation with presence of immune system cells), TMJ internal derangement (phase of disc displacement and deformation with presence of proteinases), and TMJ osteoarthrosis (phase of degeneration with absence of immune system cells). For the asserted TMJ whiplash manoeuvre and ensuing injury to occur as postulated, the laws of physics and biology would have to be suspended.     

Sound analysis of temporomandibular joint internal derangements with phonographic recordings

STATEMENT OF PROBLEM: Temporomandibular joint (TMJ) sound recordings could be analyzed to assess the state of TMJ internal derangements. PURPOSE: The aim of the study was to assess the value of sound analysis in the diagnosis of the type of the TMJ internal derangements. MATERIAL AND METHODS: After clinical and radiologic examinations, phonographic sound recordings on mandibular excursions were obtained in 52 patients with TMJ internal derangements and 12 control individuals. Sound correlations were made on the basis of opening-closing, protrusive-retrusive, and lateral excursions of the mandible. RESULTS: Clicking was a consistent finding of anterior disc displacement with reduction, whereas crepitation was found in varying degrees in anterior disc displacement and osteodegenerative arthritis. Silent TMJs were the feature of normal TMJs, except for the situations of acute lock. Although in 29 TMJs opening click was followed by a closing click (reciprocal clicking), 46 TMJs with opening click also had clicking on protrusion. On the other hand, 19 TMJs with opening click also had clicking on ipsilateral motion, and 40 TMJs with opening click had clicking on contralateral motion of the mandible. The sound patterns were found to be similar in opening-protrusive clicks and opening-contralateral clicks. The lack of protrusive clicking in the presence of opening click was considered an indication of late disc reduction on opening. Crepitation was observed in advanced cases of TMJ internal derangements. CONCLUSION: Within the limitations of this study, the results suggest that TMJ sound analysis on mandibular excursions was indicative for diagnosis and establishment of severity of TMJ internal derangements. Clicking and crepitation may be looked on as signs of abnormal joint disorder, clicking indicating anterior disc displacement with reduction, and crepitation, indicating progression from anterior disc displacement without reduction to osteodegenerative arthritis.