发育性偏颌畸形对咀嚼运动的影响

目的　研究发育性偏颌畸形 (DLJD)患者咀嚼运动的特点 ,探讨偏颌畸形对咀嚼运动的影响。方法　采用下颌运动轨迹描记仪采集 35名咬合正常者及 2 8例DLJD患者左右侧咀嚼口香糖时的下颌运动信号。用配对t检验和独立样本t检验分别对咀嚼速度、幅度等特征值做组内及组间的差异显著性检验。结果　①DLJD患者左右侧咀嚼运动不对称 ,运动轨迹一致率为 6 5 8%～78 73% ,较咬合正常者 (91 93% )低 (P <0 0 1) ,其咀嚼环在冠状面内有 9例分布异常 ,7例咀嚼顺序反向。②偏颌者的下颌最大后退幅度及平均咀嚼速度显著大于对照组 (P <0 0 1) ,总位移、水平面内及咬合接触时的平均咀嚼速度也大于对照组 (P <0 0 5 )。结论　偏颌畸形使下颌咀嚼运动型及水平面内的咀嚼速度和位移异常     

肌位咬合板对颅颌功能紊乱者下颌运动影响的研究

研究肌位咬合板对颅颌功能紊乱患者下颌运动的影响。方法：采用下颌运动轨迹描记信，记录99例患者戴板前和即刻置入咬合板后自姿势位（MPP）至牙尖交错（ICO）、自然张闭口及最大最快张闭口运动；孪-吞个月后复查（不戴板）。结果：戴板后87．8％CMD患者由MPP闭合至ICO侧后移消失，自然张闭口轨迹一致率由戴板前4％提高到78.8％，最大最快张闭口运动轨迹规则度由15.2％提高至89.9％,速度也显著增加（P＜0.05）.复查显示:咬合正常者MPP至ICP侧后消失,张闭口轨迹一致,速度轨迹规则,速度增加,咬合异常者下颌运动与治疗前相比无变化.结论:肌位咬合板对CMD治疗机理之一是调整异常的下颌运动.     

偏侧咀嚼对张闭口运动的影响

目的:分析偏侧咀嚼患者在最大张闭口运动中的下颌运动轨迹特征。方法:通过下颌运动轨迹描记检测技术,比较偏侧咀嚼和正常咀嚼人群在大张口运动中的运动轨迹,进行统计分析。结果:1)偏侧咀嚼组在大张口运动时开闭口轨迹多数分离,开口型与与双侧咀嚼组相比差异有统计学意义(P<0.05)。2)偏侧咀嚼组张闭口运动时垂直向和矢状向位移显著低于双侧咀嚼组(P<0.01)。结论:最大张闭口运动中偏侧咀嚼组开口型多数偏向工作侧,50%的人群开闭口轨迹分离,开口度减小,说明长期偏侧咀嚼会导致张闭口运动轨迹的异常。     

个别正常[牙合]人下颌语音运动的研究

目的探讨个别正常[牙合]人的下颌语音运动轨迹参数及特征,为口颌功能状况的诊断提供一定的依据。方法32名个别正常[牙合]人,运用BioEGN下颌运动轨迹描记仪记录受试者语音运动时的下颌运动轨迹情况,对收集的轨迹信号进行处理分析。结果下颌语音运动最大开、闭口速度分别为（96.19±38.66）mm/s和（86.89±31.96）mm/s;最大开口、前伸、后退、左侧、右侧运动位移分别为（9.93±3.85）mm、（1.09±0.76）mm、（5.24±2.23）mm、（1.58±0.93）mm、（1.65±0.94）mm。下颌语音运动轨迹参数之间存在一定相关关系,其中,下颌最大开口速度与最大闭口速度之间成显著正相关关系（r=0.880,P=0.000）;最大开、闭口速度与轨迹冠状面最大垂直开口位移、矢状面最大后退位移、最大斜行位移、水平面最大左侧位移、水平面最大右侧位移之间成一定正相关关系（P〈0.05）。结论个别正常[牙合]人的下颌语音运动轨迹形态相似,为连续、平滑、流畅的曲线。下颌语音运动为一种功能运动,其特征为：矢状面上前伸运动幅度小于后退运动幅度;冠状面上近似垂直向下运动,垂直向运动幅度大于水平向运动幅度;水平面上左、右侧方运动基本对称。     

口腔解剖生理学

口腔内冷刺激的脑功能成像;建立数字化颅颌运动系统的初步研究;咬合恢复对偏侧咀嚼大鼠咀嚼肌影响的实验研究;下颌第三磨牙的解剖形态观察;正常人群下颌运动轨迹的研究     

前伸咬合对可复性关节盘移位患者关节振动的作用

目的:研究前伸咬合对可复性关节盘移位患者颞下颌关节振动的影响。方法:30例可复性关节盘前移位者分别作正常开闭口运动(正中颌位开始的最大开闭口运动)以及前伸开闭口运动(下颌前伸至切对切开始的最大开闭口运动),运用关节振动分析仪收集2种下颌运动方式下的关节振动信号,结合Joint-3D技术记录并分析开口度、开口型的变化,并对数据结果进行统计分析。结果:前伸开闭口组关节振动的振动总能量TI、频率小于300 Hz的振动能量A、频率大于300 Hz的振动能量B、峰振幅PA明显小于正中颌位最大开闭口运动组(P<0.01)。2种运动产生振动的峰频率PF以及频率大于300 Hz的振动能量与频率小于300 Hz的振动能量之比B/A 没有差异。2种运动方式下,开口度无明显变化,而37.4%的可复性关节盘移位患者前伸开闭口的下颌偏离中线距离比正常开闭口运动小。结论:下颌前伸至切对切可降低可复性关节盘移位患者的颞下颌关节区振动的强度但不改变其频率特性,部分患者可以改善开口型。本研究从定量化的角度为调整下颌前伸的再定位咬合板治疗可复性关节盘移位的可行性及有效性提供了佐证。     

第三磨牙伸长者咀嚼运动轨迹的研究

目的：探讨对颌第二磨牙远中有密切接触的,伸长的第三磨牙对咀嚼运动轨迹的影响。方法：应用K6－I型下颌运动轨迹描记仪,分别记录11名第三磨牙伸长者和12名正常He者用左、右侧咀嚼口香糖的运动轨迹。结果：（1）正常He者冠状面和水平面咀嚼运动呈规则环形,He期轨迹明显,矢状面开闭口He期轨迹多数重合。（2）63．6％的第三磨牙伸长者冠状面He期轨迹出现内外向约0．2－1．0mm的平台,50％的水平面轨迹有前后向约0．2－0．5mm的台阶,72．7％的矢状面开闭口He期轨迹不重合,冠状面出现平台与矢状面不重合及水平面出现台阶的异常轨迹明显相关。（3）第三磨牙伸长者咀嚼运动中向后运动的幅度及咀嚼速度均明显增大。结论：第三磨牙伸长对咬合运动形式与咀嚼的幅度、速度有明显影响。     

正常颞下颌关节音与其相应下颌位置的研究

目的 研究正常颞下颌关节音的特点及关节音产生时相应下颌位置,探讨正常关节音产生的机理.方法 按照纳入标准从中山大学光华口腔医学院选取26名个别正常青年人,应用BioPAK口颌分析系统(BioJVA颞下颌关节振动分析仪和BioEGN下颌运动轨迹描记仪)对最大开闭口运动时产生的关节音与产生关节音时下颌所处运动轨迹中的相应位置进行记录分析.结果 个别正常青年人的颞下颌关节音频谱图呈单峰,振幅和频率四分数位区间分别为0.40 ～ 1.08 Pa和48 ～ 91 Hz,左右侧颞下颌音振幅和频率的差异无统计学意义.个别正常受试者行开闭口运动产生关节音时下颌多处于开口阶段,相应下颌位置比值为74% ± 15%,显示正常颞下颌关节音产生于下颌运动矢状面开口轨迹距牙尖交错位74% ± 15%最大开口距离处.结论 正常颞下颌关节音振幅和频率呈偏态分布,双侧无明显差异,正常颞下颌关节音产生时下颌处于开口运动轨迹的中下段.     

深覆与颅颌功能紊乱

为探讨深覆的致病机理,对56例伴深覆的颅颌功能紊乱患者从临床,X线摄影。下颌运动及治疗等方面进行了研究,得出结果:①弹响以开口初、闭口末居多(75.61％);髁突以后位居多(76.79％);②有31例临床上表现牙位与肌位不一致;③下颌运动轨迹描记,深覆(牙合)患者自然开闭口及由姿势位闭合至ICO时下颌向后运动的人数显著多于非深覆(牙合)患者,但戴咬合板由姿势位闭合至ICO下颌则呈前上方向运动;④经肌位咬合板治疗,患者症状消失,但牙位与肌位仍不一致.结果提示深覆(牙合)的主要致病机理:①切道斜度大,下颌运动受限、下颌后退导致髁突后位,盘突关系不协调;②导致牙位与肌位不一致,造成关节内微小创伤。肌位咬合板可消除或减轻症状。     

下颌偏斜患者颌面结构及其颈椎姿势生长变化的研究

目的：研究下颌偏斜患者颌面结构及颈椎姿势的生长变化趋势。方法：对20例儿童下颌偏斜患者，20例成人下颌偏斜患者及20例儿童正常咬合者，20例成人正常咬合者拍摄头颅定位侧位片，进行头影测量分析及统计学分析。结果：下颌偏斜患者成人组的咬合平面、下颌平面倾斜度及颈椎弯曲度大于儿童组而颈椎的倾斜度小于儿童组，患者头颈呈前倾，前伸位。结论：随着年龄的增大，偏颌畸形可能逐渐影响颌面形态及颈椎姿势。下颌偏斜患者应尽早矫治，在矫治颌面畸形的同时还应矫正异常的颈椎姿势。     

Disparate osteogenic response of mandible and iliac crest bone marrow stromal cells to pamidronate

Objective:  Long-term administration of intravenous bisphosphonates like pamidronate is associated with jaw osteonecrosis but axial and appendicular bones remain unaffected. Pathogenesis of bisphosphonate-associated jaw osteonecrosis may relate to skeletal site-specific effects of bisphosphonates on osteogenic differentiation of bone marrow stromal cells (BMSCs) of orofacial and axial / appendicular bones. This study evaluated and compared skeletal site-specific osteogenic response of mandible (orofacial bone) and iliac crest (axial bone) human BMSCs to pamidronate.
Materials and methods:  Mandible and iliac crest BMSCs from six normal healthy volunteers were established in culture and tested with pamidronate to evaluate and compare cell survival, osteogenic marker alkaline phosphatase, osteoclast differentiation in co-cultures with CD34⁺ hematopoietic stem cells, gene expression of receptor activator of NFκB ligand (RANKL) and osteoprotegerin, and in vivo bone regeneration.
Results:  Mandible BMSCs were more susceptible to pamidronate than iliac crest BMSCs based on decreased cell survival, lower alkaline phosphatase production, and structurally less organized in vivo bone regeneration. Pamidronate promoted higher RANKL gene expression and osteoclast recruitment by mandible BMSCs.
Conclusion:  Mandible and iliac crest BMSC survival and osteogenic differentiation are disparately affected by pamidronate to favor dysregulated mandible bone homeostasis.     

Medial pterygoid muscle activity during chewing and clenching

Specific activity of the human medial pterygoid muscle in relation to jaw movements and occlusion during mastication and clenching tasks is unclear. EMG activity of the medial pterygoid, masseter, anterior, and posterior temporal muscles was recorded simultaneously with three dimensional incisor point movement of the mandible. Data were sampled and analyzed by an on-line computer system. Patterns of medial pterygoid muscle activity were consistent for ipsilateral chewing and demonstrated activity of the muscle on the chewing side that peaked near the onset of intercuspation. The muscle on the contralateral side was active at the onset of intercuspation for subjects with a chopping stroke and inactive for those with a more lateral stroke guided into intercuspation on cuspal inclines. Activity in the early part of the closing phase was associated with a marked jaw movement toward the chewing side. There was generally less activity in protrusive than intercuspal clenching when occlusion was normal but more activity if marked incisal wear was present or multiple tooth contacts could be attained on protrusion. Intercuspal clenching initiated less activity when force was directed posteriorly and more activity when directed anteriorly than vertical intercuspal clenching.     

Masticatory mandibular movements for different foods textures related to onomatopoetic words

This study aimed to investigate the effects of different sensory-evaluated food textures on masticatory movements, and to identify meaningful factors that correspond to different food textures. Masticatory movements of three healthy subjects were evaluated with a jaw movement tracking device using five different test foods: almond, hard and light rice crackers, apple, and chewing gum. The movements of the incisor point, working and non-working condyle and the entire mandible at the occlusal phase in the horizontal plane were analyzed. For harder foods, the incisor entered the intercuspal position from a rear and lateral, the working condyle showed anterior and noticeable medial movements as the entire mandible translated posteriorly and medially. For soft foods, the incisor movements were nearly coincidental with the lateral border movements, and the mandible rotated towards the inner side near the working condyle. Although the overall paths of the mandibular movements are individually different, it appeared that jaw movement at the final closure is particular to the food texture. From the standpoint of mandibular movements, it is suggested that masticatory movements during the occlusal phase in the horizontal plane is useful for revealing the relationship between mandibular movements and food textures that were evaluated with onomatopoetic words.     

Masseter and temporalis surface electromyography in patients wearing complete dentures comparing anterior and posterior occlusal concepts — A pilot study

The activity of jaw elevator muscles (masseter and anterior temporal muscle) was studied by surface electromyography in 17 patients wearing complete dentures with anterior-canine guidance.
Baseline electromyography was recorded with the dentures and compared to recordings obtained with two different splints adapted to the upper denture, one providing anterior guidance leading to immediate disclusion of the posterior teeth during any jaw movement, the other providing posterior guidance buccally on the working side and lingually on the non-working side (bilaterally balanced occlusion).
Recordings were obtained during a sequence of different jaw movements: postural position, maximal tooth contact in intercuspal position, protrusive movement of the mandible (under tooth contact) and during lateral excursions, also carried out under tooth contact.
Muscle activity was not significantly different as recorded with dentures only versus with the splints providing anterior guidance. However, a significant increase in activity was observed with bilaterally balanced occlusion.
The results of this study in edentulous people are similar to those found in patients with natural teeth.     

Influence of maximum bite force on jaw movement during gummy jelly mastication

It is known that maximum bite force has various influences on chewing function; however, there have not been studies in which the relationships between maximum bite force and masticatory jaw movement have been clarified. The aim of this study was to investigate the effect of maximum bite force on masticatory jaw movement in subjects with normal occlusion. Thirty young adults (22 men and 8 women; mean age, 22·6 years) with good occlusion were divided into two groups based on whether they had a relatively high or low maximum bite force according to the median. The maximum bite force was determined according to the Dental Prescale System using pressure‐sensitive sheets. Jaw movement during mastication of hard gummy jelly (each 5·5 g) on the preferred chewing side was recorded using a six degrees of freedom jaw movement recording system. The motion of the lower incisal point of the mandible was computed, and the mean values of 10 cycles (cycles 2–11) were calculated. A masticatory performance test was conducted using gummy jelly. Subjects with a lower maximum bite force showed increased maximum lateral amplitude, closing distance, width and closing angle; wider masticatory jaw movement; and significantly lower masticatory performance. However, no differences in the maximum vertical or maximum anteroposterior amplitudes were observed between the groups. Although other factors, such as individual morphology, may influence masticatory jaw movement, our results suggest that subjects with a lower maximum bite force show increased lateral jaw motion during mastication.     

Movement of the lateral and medial poles of the working condyle during mastication in patients with unilateral posterior crossbite.

Patients with unilateral posterior crossbite often show reverse sequential jaw movement patterns on the frontal view during mastication on the crossbite side. Recent studies show that such patients are prone to suffer from temporomandibular joint (TMJ) disc displacement, particularly the lateral portion. The purpose of this study was to examine the movement of the lateral and medial poles of the working condyle during mastication in such patients. Subjects were 12 consecutive patients with unilateral posterior crossbites and without TMJ disc displacements and 12 normal subjects. An optoelectronic jaw-tracking system with 6 degrees of freedom was used to record the motion of the lateral and medial poles of the working condyle during mastication of standardized hard, gummy jelly. The data from the first 10 cycles were analyzed. The lateral and medial poles of the condyle on the crossbite side moved more in the medial direction and less in the lateral direction during mastication in the crossbite patients than the condyle in the normal subjects. The lateral pole of the working condyle moved more in the posterior and inferior directions and less in the anterior direction than the medial pole in all subjects. These results suggest that these condylar movements in patients with unilateral posterior crossbites might be related to the susceptibility to TMJ disc displacement, particularly the lateral portion.     

Assessment of occlusal interferences

The variability in the assessment of occlusal variables was investigated in eight subjects by the repeated registrations of four observers. The following variables were investigated in three different ways: sliding between the RCP (retruded contact position) and the ICP (inter-cuspal contact position) in the sagittal, vertical and lateral plane. Interferences during lateral movements on the working and balancing sides as well as interferences causing deviation of the mandible during protrusive movements were recorded. The intra- and inter-observer error for the measurement of sagittal and vertical distance RCP-ICP was within acceptable limits. There was no significant difference between the three methods used. The intra- and inter-observer agreement between duplicate recordings of the lateral distance RCP-ICP was high and there were no differences between the different measurement modalities. The inter-observer agreement was lower than the intra-observer agreement concerning presence/absence of balancing side interferences, and positive inter-observer agreement was only found on lateral movement more than 3 mm from the RCP or the ICP. The observer error for the variable working side interferences should be acceptable for future research, while the observer error for measurement of lateral deviation of the mandible upon protrusion was somewhat larger.     

正颌外科患者术前的颞下颌关节功能评价

目的　了解正颌患者颞下颌关节 (TMJ)的功能状况 ,探讨牙颌面畸形与颞下颌关节之间的关系。方法正颌外科发育性牙颌面畸形 12 3例患者 ,平均年龄 2 3.8岁 ,男性 45例 ,女性 78例。颞下颌关节功能的检查方法采取问诊与检查相结合 ,颞下颌关节功能记分采取 Helkim o指数记分方法。结果　 (1)牙颌面畸形患者颞下颌关节紊乱病 (TMD)各种症状发生率明显高于对照组人群。(2 )男性患者弹响症状发生率高于女性 ,而女性患者关节触诊疼发生率高。(3) 16～ 2 5岁患者张口受限发生率较高 ,但大多数为轻度张口受限。(4 )不对称畸形 (下颌前突偏斜 )者弹响症状发生率较高 ,而且相应偏斜侧最大侧向移动度小。而下颌后缩组开口度明显小于其他各组 ,提示其关节功能受损较严重。结论　牙颌面畸形患者的颞下颌关节功能不同于正常人 ,部分下颌偏斜与后缩患者关节功能受损     

An electromyographic evaluation of the bilateral symmetry and nature of masticatory muscle activity in jaw deformity patients during normal daily activities

This study was designed to investigate the nature of masticatory muscle activity and the balance in the bilateral symmetry of the masticatory muscle activity in jaw deformity patients. Fifteen patients (19.9 +/- 5.3 years) with lateral shift of the mandible caused by transverse craniofacial deformity and 15 controls (28.6 +/- 1.9 years) were used as the subjects in this study. Surface electromyographic (EMG) activities were recorded from the bilateral masseter and anterior temporal muscles during daytime (142 min, including mealtime) and sleep (142 min). The averaged rectified EMG values were normalized with reference to the EMG amplitude induced by a 98-N bite force. Bilateral symmetry of masseter and anterior temporal muscle activities was examined using an asymmetry index (AI) for both the controls and the patients. The normalized activities of the masseter and anterior temporal muscles during normal daily activities were lower in patients than in the controls. Asymmetry indices in patients were significantly greater during usual daytime activities and sleep for the anterior temporal muscle and significantly smaller during sleep for the masseter muscle as compared with the controls. The results show that masticatory muscle activity is lower in these jaw deformity patients in association with more prominent asymmetry of anterior temporal muscle activity than in the controls. It is suggested that these findings are highly relevant to occlusal interference and instability because of malocclusion and lateral mandibular deviation.