Temporomandibular joint condyle changes after surgically induced non-reducing disk displacement in rabbits: a macroscopic and microscopic study

Experimentally induced displacement of the temporomandibular joint (TMJ) disk has previously been shown to induce shortening of the mandibular ramus on the ipsilateral side. The aim of this investigation was to reveal whether this shortening develops due to primary influence on condyle growth or by secondary loss of condyle mass due to degenerative tissue breakdown. Disk displacement was created in the right TMJ in seven 3-month-old rabbits, the posterior disk attachment kept intact. Seven rabbits underwent surgical opening of the TMJ without disk intervention. Seven additional animals served as references. After a 3-month experimental period, the animals were sacrificed. Previous analysis revealed shortening of mandibular height and length caused by ipsilateral TMJ disk displacement. The condyles were examined macroscopically and by histologic sectioning or scanning electron microscopy. All condyles were covered with smooth articulating soft tissue and without visible signs of degenerative changes. Four condyles from joints with disk displacement demonstrated substantial regressive remodeling resulting in a change of condyle shape with forward/downward rotation of an enlarged articulating surface. It was concluded that TMJ disk displacement in a growing individual can induce reduction of mandibular height and length before a stage where visible osteoarthrotic changes develop. It implies a primary adverse effect on condyle growth.     

Mandibular skeletal growth and modelling between 10 and 15 years of age

This study pertains to a random sample of untreated French-Canadian adolescents (79 females and 107 males) evaluated at 10 and again at 15 years of age. Superimpositions on natural reference structures were performed to describe condylar growth and modelling of 11 mandibular landmarks. Superimpositions on natural cranial/cranial base reference structures were performed to describe mandibular displacement and true rotation. The results showed significant superior and posterior growth/modelling of the condyle and ramus. Males underwent significantly (P < 0.01) greater condylar growth and ramus modelling than females. With the exception of point B, which showed significant superior drift, modelling changes for the corpus landmarks were small and variable. The mandible rotated forward 2-3.3 degrees and was displaced 9.6-12.7 mm inferiorly and 1.9-2.7 mm anteriorly. Individual differences in ramus growth and modelling, both amount and direction, can be explained by mandibular rotation and displacements. Multivariate assessments revealed that superior condylar growth and ramus modelling were most closely associated with forward rotation and inferior mandibular displacement. Posterior growth and modelling were most closely correlated with anterior mandibular displacement and forward rotation. Modelling of the lower anterior border was independent of rotation and displacement.     

A longitudinal radiographic study of the periosteal migration along the growing rabbit mandible.

In the present study, the role of the periosteum in mandibular growth was investigated. The orientation of the superficial bony spicules of rabbit mandibles was determined on dry skulls after perfusion of the animals with an India ink solution. The spicular orientation in the ramus area appeared to be toward the condyle, rostrally toward the incisors, and caudally toward the angular region. The behavior, during growth, of the periosteum in the caudal mandibular half was studied by implantation of metal periosteal and bone markers. A series of cephalograms revealed the migration pattern of the periosteal markers, and by that the migration pattern of the periosteum. It can be concluded that both the pattern of the superficial bony spicules and the periosteal migration pattern suggest a possible influence of the periosteum on mandibular growth.     

Mandibular growth changes and cervical vertebral maturation. a cephalometric implant study

OBJECTIVE: To evaluate mandibular dimensional changes and regional remodeling occurring during five intervals of circumpubertal growth. MATERIALS AND METHODS: This investigation evaluated a unique sample of subjects in whom tantalum implants were placed into the craniofacial complex during childhood. The sample was obtained from the Mathews and Ware implant study originally conducted at the University of California San Francisco in the 1970s, with longitudinal cephalometric records of 20 subjects (13 female, 7 male) available for evaluation. Cephalograms at six consecutive stages of cervical vertebral maturation (CS1 through CS6) were analyzed. RESULTS: Peak mandibular growth was noted during the interval from CS3 to CS4. Forward rotation of the mandible was due to greater mandibular growth posteriorly than anteriorly. Progressive closure of the condylar-ramus-occlusal (CRO) angle resulted in a forward and upward orientation of the ramus relative to the corpus of the mandible due to increased vertical growth of the condyle. CONCLUSIONS: A peak in mandibular growth at puberty was substantiated. Mandibular remodeling and condylar rotation continue to occur after the growth spurt.     

Histologic analysis of costochondral and sternoclavicular grafts in the TMJ of the juvenile monkey

Variability in growth response of the mandible after replacement of the mandibular condyle with the costochondral junction of a rib (CCJ) is common. Other donor graft sites that are more similar to the mandibular condyle might be more suitable for mandibular condylar replacement. Previous studies have shown the histomorphologic and developmental similarities between the sternoclavicular joint (SCJ) and temporomandibular joint (TMJ). The purpose of this study was to evaluate histologically short-term adaptations within the TMJ after replacement of the mandibular condyle with the autogenous sternal head of the clavicle, and to compare these adaptations with autogenous CCJ and mandibular condyle (surgical control) transplants. Bilateral vertical ramus osteotomies were performed in 12 juvenile Macaca mulatta with the left condyle being immediately replaced and the right condyle removed and replaced with either the sternal head of the clavicle or costochondral junction of a rib. All grafts were stabilized with maxillomandibular fixation for five weeks. Two animals in each group were killed at five, 11, and 17 weeks postsurgery and prepared for histologic analysis. The results indicate that: 1) incorporation of all grafts into the recipient site occurred and all animals had good mandibular function and occlusion throughout the follow-up period; 2) the clavicular and mandibular condylar grafts were incorporated sooner than the CCJ grafts; 3) clavicular graft changes resembled those of the condylar grafts histologically while the costal grafts remained inert and unchanged; and 4) a new condylar process with cartilage similar to that of a normal mandibular condyle regenerated in the costal graft animals from cells presumably contributed by the periosteum of the mandibular ramus and TMJ capsule.(ABSTRACT TRUNCATED AT 250 WORDS)     

Three-dimensional finite element analysis of the mandible and temporomandibular joint during vertical ramus elongation by distraction osteogenesis

Distraction osteogenesis has been accepted as an alternative treatment modality for hypoplastic mandibles. Knowledge about the changes occurring in the temporomandibular joint region during mandibular distraction osteogenesis is, however, limited and controversial. Stress distribution in the temporomandibular joint region during unilateral vertical mandibular ramus distraction was studied using a finite element model. The finite element model was based on computed tomography scans and magnetic resonance imaging scans of a patient with unilateral hypoplasia of the right mandibular ramus caused by juvenile idiopathic arthritis. The character of stress distribution in the temporomandibular joint and mandible was analyzed quantitatively at different intervals of the vertical mandibular ramus elongation. During the distraction phase, the condyles, articular disks, and glenoid fossa regions were loaded with a differentiated stress pattern. The affected right condyle, disk, and fossa were submitted to increasing loads with increasing elongation compared with the contralateral temporomandibular joint. Loading on the unaffected left side shifted posteriorly and slightly laterally, because the left condyle was the center of rotation. The loading of the temporomandibular joint regions was low during the active distraction phase, although local areas were subjected to elevated peak stresses.     

下颌骨缺损整复后颞下颌关节的变化

目的 :观察单侧或部分下颌骨缺损重建术后升支高度和下颌骨髁状突运动的变化。材料和方法 :30例患者按手术方式的不同分为两组 ,A组为保留髁状突的下颌骨部分切除、自体骨移植或病变骨冷冻再植整复组 ,B组为未保留髁状突组 ,术后通过X线检查评价结果。结果 :所有患者手术后都表现有不同程度的髁状突运动障碍。主要有升支高度降低、髁状突水平运动和转动能力降低 ,且A、B两组间存在明显差别 ,B组改变大于A组。结论 :下颌骨缺损重建对颞下颌关节结构和功能具有一定的影响 ,保留髁状突时所受影响要明显小于未保留髁状突组。因此保留髁状突有利于获得较好的术后功能效果     

双颌手术升支截骨后退术后下颌稳定性及与关节关系的研究

目的　探讨升支矢状劈开截骨术(BSSRO)小钛板坚固内固定与口内入路升支垂直截骨术(BIVRO)下颌后退术后颌稳定性的不同规律,了解导致复发的有关因素特别是髁状突移位在不同手术后复发过程中的意义。方法　升支截骨手术后退下颌的患者共38例,皆为双颌手术,其中下颌BSSRO19例,BIVRO后退术19例。于手术前1周(T1),手术后1周(T2),3个月(T3)及1年(T4)分别拍摄定位头颅侧位片及定位颞下颌关节薛氏位片用于测量下颌移动幅度及关节髁状突的手术后移位。结果　双颌手术下颌升支截骨后退术后,BSSRO坚固内固定组1年时的复发率为25%,而BIVRO组大部分患者1年时下颌发生了与手术目的相同的移动,两组的不稳定主要发生在术后3个月内。结论　手术使髁状突移位术后位置的调整可导致BIVRO术后的下颌继续后移而不稳定,而髁状突近心骨段术中向后旋转术后位置的调整可导致BSSRO术后的下颌骨继续向前而不稳定     

The inter-relationship between mandibular autorotation and maxillary LeFort I impaction osteotomies

The purposes of the present investigation were to: 1)locate the instantaneous rotation center of mandible autorotation during maxillary surgical impaction; 2) identify the discrepancies between the resultant mandibular position following by maxillary surgical impaction and presurgical predictions, which use the radiographic condylar center as the rotation center for mandibular autorotation; and 3)find the interrelation between the magnitude of maxillary surgical impaction and the sagittal change of mandible. Ten patients underwent maxillary LeFort I impaction without concomitant major mandibular ramus split osteotomies were included. The preoperative (T0) and postoperative (T1) lateral cephalograms were used to evaluate the surgical changes and locate the center of rotation of mandibular autorotation with Reuleaux method. Prediction errors were measured by comparing the predicted (Tp) and postoperative (T1) cephalometric tracings. The magnitude of the maxillary surgical impaction was compared to the positional changes of mandible after mandibular autorotation with correlation and regression analysis. The results demonstrated that the centers of mandibular autorotation located 2.5 mm behind and 19.6 mm below the radiographic condylar center of the mandible in average with large individual variations. By using the radiographic condylar center of the mandible to predict the mandibular autorotation would overestimate the horizontal position of chin by 2 mm and underestimate the vertical position of chin by 1.3 mm following an average of 5 mm surgical maxillary impaction. The magnitude of maxillary impaction was highly and positively correlated to the horizontal displacement of chin position. The rotation centers of mandibular autorotation following by maxillary LeFort I impaction osteotomies might not usually locate at the radiographic condylar center of the mandible also with large individual variations in their positions. Surgeons and orthodontists should be aware of the horizontal and vertical discrepancies of chin positions while planning a two-jaw surgery by using the radiographic center of mandibular condyle as the rotation center in mandibular autorotation.     

Spatial deviations of the temporomandibular joint after oncological mandibular reconstruction

Spatial deviations of the temporomandibular joint (TMJ) after oncological mandibular reconstruction are important to the aesthetic and functional rehabilitation. The aim of this study was to clarify whether and how three dimensionally (3D) printed patient-specific surgical plates, and the preservation of the condyle or ramus, affect spatial deviations of the TMJ. A total of 33 patients who underwent mandibular reconstruction via computer-assisted surgery were included. Regarding absolute deviations, patients in the 3D-printed plate group showed smaller TMJ deviations compared to those in the conventional plate group. There was no difference in absolute deviations of the TMJ regardless of whether the condyle or ramus was preserved. Regarding physiological deviations, the impact on the contralateral TMJ was smaller in the 3D-printed plate group. Patients with both the condyle and ramus removed had significantly higher deviations of the condyle and joint space. In summary, 3D-printed patient-specific surgical plates improved the spatial accuracy of the TMJ. Under physiological conditions, TMJ deviations on the operated side were mainly affected by the preservation of the condyle. Removal of both the condyle and ramus caused more severe spatial interference to the TMJ; this should be further confirmed.     

Experimental occlusal interferences. Part III. Mandibular rotations induced by a rigid interference

summary A rigid intercuspal interference (minimum mean height of 0.24 mm) was placed on either the right or left mandibular second premolar and first molar of 12 subjects. During brisk and forceful biting on the interference, rotational electrognathography measured maximum torque of the right and left mandibular condyles in the frontal and horizontal planes of orientation. All subjects showed frontal plane upward rotation (mean of 0.7 degrees) of the mandibular condyle contralateral to the interference. In 33% of the subjects there was no horizontal plane rotation. In 58% of the subjects there was horizontal plane backward rotation (mean of 0.5 degrees) of the mandibular condyle ipsilateral to the interference, and in one subject (8%) there was backward horizontal plane rotation (0.1 degree) of the mandibular condyle contralateral to the interference. It was inferred that the masseter muscle, ipsilateral to the interference, generated negative work in order to decelerate frontal plane'unseating'of the mandibular condyle ipsilateral to the interference. It was inferred that the masseter muscle, contralateral to the interference, produced positive work in order to accelerate frontal plane 'seating'of the mandibular condyle contralateral to the interference. Finally, it was speculated that the impact forces of frontal plane 'seating'of the mandibular condyle, contralateral to the interference, might lead to'vacuum sticking'of the temporomandibular joint disc because of the formation of negative hydrostatic pressures.     

口腔内入路行髁突高位骨折复位固定的临床治疗

目的:探讨应用定量截骨锯,行口腔内入路髁突高位骨折手术治疗的效果。方法:对13例14侧下颌骨髁突颈骨折患者采用口腔内入路,用定量截骨锯将下颌骨升支后缘垂直截骨,取出升支后缘骨块,将骨折的髁突游离后取出,体外直视下将骨折片与升支后缘骨块复位固定后再从口腔内原切口回植,行颞下颌关节重建。结果:术后6、12、24月复查全部患者的开口范围25～40mm,平均为37.2mm。除1例患侧后牙早接触,下切牙中线偏斜1mm;另1例张口约25mm,轻度受限外,其余患者咬合关系良好,无其他并发症。结论:口腔内入路具有无外部皮肤瘢痕,且不损伤面神经的优点。但操作视野较小,增加了操作的难度。     

Sliding reconstruction of the condyle using posterior border of mandibular ramus in patients with temporomandibular joint ankylosis

The traditional approach for ankylosis is gap arthroplasty or interpositional arthroplasty followed by reconstruction of the condyle using, for example, costochondral grafts. As these are non-pedicled grafts, there is eventual resorption with subsequent decrease in height of the ramus, facial asymmetry and deviated mouth opening. The authors have applied the method of total and partial sliding vertical osteotomy on the posterior border of the mandibular ramus for reconstruction of the mandible condyle as a pedicled graft for the correction of temporomandibular joint (TMJ) ankylosis. From 2004 to 2008, 18 patients who were diagnosed with TMJ ankylosis underwent operations for resection of the ankylosed condyle. Two methods were performed depending on the level of osteotomy on the posterior part of the mandibular ramus. All patients were followed-up for an average of 36 months (range 24-48 months). All patients showed apparent improved joint function with no cases of re-ankylosis. The results showed that sliding vertical osteotomy on the posterior border of the mandibular ramus seems to be an alternative and promising method for condylar reconstruction in patients with TMJ bony ankylosis.     

Aberrant mandibular growth: theoretical implications.

There is a multiplicity and variety of studies investigating mandibular growth. The exact role of the mandibular condyle in influencing mandibular growth is still a point of conflict. This study was conducted with six subjects who had different condylar defects. The cranium and the skeletal profile, as well as the position of the maxilla and the mandible, were investigated. In all cases, the mandible showed a tendency toward posterior rotation. The total mandibular length was reduced with deficient corpus length and ramus height. The influence of the integrity of the condylar head and its normal articulation in the temporal fossa on mandibular growth were emphasized.     

成人下颌骨髁突骨折的手术治疗

对成人髁突骨折采用手术与非手术治疗,学术界一直存在着不同程度的分歧。随着各种小型接骨板、坚强内固定技术的成熟应用,许多学者主张对成人双侧髁突颈部以下脱位性骨折,双侧髁突矢状外脱位性骨折,单侧髁突颈部以下脱位性、移位性骨折行积极外科手术治疗。对髁突骨折患者行外科手术、坚强内固定治疗,可以保证骨折固定具备坚固性和稳定性,并尽早行使功能。本文对髁突骨折外科手术治疗的固定方式、手术入路(耳前入路、下颌下入路、颌后入路、除皱手术入路和近年来报道增多的内窥镜辅助下口内入路)的选择进行了阐述。     

Osteochondroma of the mandibular condyle: literature review and report of a case

AIM: The intent of this report is to present a brief review of the literature on osteochondroma and to present a case involving the surgical removal and replacement of a major portion of the condyle and angle of the mandible using free autogenous mandibular bone. BACKGROUND: While osteochondroma is the most common tumor of skeletal bones, it is relatively uncommon in the jaws occurring at the condyle or the tip of the coronoid process. This benign cartilage-capped growth is usually discovered incidentally on radiographic examination or on palpation of a protruding mass in the affected area. Malocclusion and progressive facial asymmetry are common findings in most cases of condylar osteochondroma. REPORT: A case of a 29-year-old woman with an osteochondroma of the mandibular condyle is presented. Surgical treatment was tumor resection, grafting, and reshaping of the mandibular angle and ramus. As this lesion is usually asymptomatic and discovered incidentally on radiographic examination, the general practitioner usually is the first professional to make the diagnosis. SUMMARY: Condylectomy cannot be recommended as routine in all cases.37 Common surgical treatments include condylectomy and reconstruction.24 If the tumor involves only a limited area of the condylar surface, then preservation of the remaining portion of the condyle and reshaping should be done. Reasons for not taking such a conservative approach are the possibilities of malignancy and the risk of recurrence. In this case report the extraoral vertical ramus osteotomy, associated with free autogenous mandibular bone, presented several advantages.     

双侧下颌升支垂直截骨术对髁状突影响的小型猪动物模型建立

目的建立髁状突移动对颞下颌关节产生影响的大型实验动物模型。方法本研究对4只小型猪分组施行双侧下颌升支垂直截骨术,将双侧髁状突向前移动3mm、6mm及向后移动3mm,应用螺旋CT扫描及组织学,初步观察髁状突向前或向后方向移动不同的距离后对颞下颌关节产生的影响。结果4只小型猪所建的模型在观察期内生长良好,观察指标能较好地反映此术式对髁状突的影响。结论本研究在小型猪上建立了双侧下颌升支垂直截骨术对颞下颌关节产生影响的大型实验动物模型,为进一步研究此术式对髁状突的影响打下基础。     

The effect of dietary consistency on bone mass and turnover in the growing rat mandible.

Hard and soft diets were fed to weanling rats for up to 8 weeks. Some animals were switched after 4 weeks to the opposite diet. A histomorphometric study of bone formation activity at the mandibular ramus, body, and condyle was made after in vivo fluorochrome labelling. Mineral apposition rates at the lateral and inferior periosteal surfaces of the ramus were lower in the soft diet than in the hard diet animals. The rate of bone formation at the lateral periosteal surface of the ramus was significantly lower in soft than in hard diet animals. The medial periosteal surface of the ramus sometimes changed to bone formation in the soft diet groups. Condylar cartilage zones were somewhat thinner in soft diet groups. In the mandibular body, differences due to dietary consistency were less marked than near the gonial angle. Adaptation of periosteal bone and condylar cartilage to a new dietary consistency occurred within 4 weeks of switching. These results suggest that lateral and inferior periosteal bone growth of the ramus and condylar elongation were slowed in rats consuming soft diets. Decreased functional force during rapid mandibular bone growth causes changes in shape. The changes are due to regional decreases in osteoblast function, realignment of bone formation surfaces in the ramus area, and slowed growth in the condylar cartilage.     

Control of the condylar-proximal mandibular segments after sagittal split osteotomies to advance the mandible

Maintenance of the normal or presurgical anatomic position of the mandibular condyles and contiguous proximal mandibular ramus segments after sagittal split ramus osteotomies is important, not only to enhance the stability of results but also to avoid iatrogenic temporomandibular joint complications. Accordingly, during the past few years, we have attempted to improve the surgical control of condyle and proximal segment position while using the sagittal split ramus osteotomy to advance the mandible. After several modifications, the device reported herein was used and the results evaluated in ten consecutive patients who underwent bilateral sagittal split ramus osteotomies with symmetric advancement of the mandible. This device enables the surgeon to obtain very precise reproduction of the "normal" proximal segment and condyle position at the time of surgery. The use of the device and documentation of its efficiency are presented.     

Activator矫治对颞下颌关节的影响及其与颞下颌关节紊乱病的关系

Activator矫治器是较早用于临床的功能矫治器,由Andresen于1908年设计,对安氏Ⅱ类1分类错(牙合)畸形患者有良好的治疗效果,通过前移下颌刺激下颌骨的生长且抑制上颌矢状向生长,从而调节上下颌骨矢状向的关系.目前,关于Activator矫治器的矫治原理还存在较多的分歧,其中之一就有Activator是否能刺...