生长期山羊囊内骨折复位术中保留髁突软骨的重要性及组织学研究

目的：通过组织学观察,探讨髁突囊内骨折内固定术中保留和切除髁突软骨对髁突生长发育的影响。方法：6个月龄山羊12只,随机分为实验组（n=8）和对照组（n=4）。实验组双侧髁突造成囊内骨折并同期行手术复位固定．一侧保留髁突软骨,另一侧切除髁突软骨。术后3个月、6个月处死动物,切取髁突标本行石蜡切片和硬组织切片观察骨折愈合和髁突生长情况。结果：实验组髁突骨折愈合良好,钛板被新生骨组织覆盖;HE染色显示．保留髁突软骨组,髁突软骨结构清晰,与正常对照髁突相同,软骨成骨活跃,髁突生长发育正常;切除髁突软骨组,髁突软骨层消失,表面为成熟的骨细胞覆盖,直接与关节盘的纤维组织相连,新生骨组织少见：硬组织切片显示,钛板与骨组织直接结合．未见组织渗出和排异反应。结论：手术复位髁突囊内骨折时保留髁突软骨,不会影响髁突的生长发育;损伤髁突软骨．会造成髁突与关节盘黏连．引起髁突生长发育障碍。     

Regeneration of the mandibular condyle after unilateral condylectomy and myotomy of the masseter in lambs

We investigated the degree of regeneration of the mandibular condyle after unilateral condylectomy and myotomy of the masseter in growing lambs. Four 10-week-old lambs had unilateral condylectomy and myotomy of the superficial layer of the masseter on the right side, and were killed 3 months later. The joints were examined radiologically and histologically. All joints showed poor regeneration of the condylar head. In the medial plane there was partial condylar and articular cartilage reformation, but in the lateral plane there was neither condylar nor cartilaginous reformation. The articular cartilage of the temporal bone was thicker in the medial plane and the disc was thicker in the central plane, than in unoperated joints. We conclude that unilateral condylectomy and myotomy of the masseter in the growing period results in poor regeneration of the condyle.     

颞下颌关节骨关节病髁突组织细胞凋亡的研究

目的研究颞下颌关节骨关节病骸突组织中软骨细胞凋亡发生的特点,探讨细胞凋亡在颞下颌关节骨关节病发病机制中的作用。方法通过手术切除部分关节盘的方法建立颞下颌关节骨关节病动物模型,15 d-6个月内采用TUNEL法标记裸突各相应时段的凋亡细胞,结合相应组织学变化,观察、分析颞下颌关节骨关节病裸突组织中细胞凋亡发生的特点。结果关节盘损伤后软骨产生明显应激性修复增殖反应时,凋亡细胞主要集中于关节表面的纤维层中;随着关节软骨和骨组织不断改建,软骨组织中逐渐出现大量的细胞凋亡现象,主要发生于表面纤维层与增殖层,尤其集中在软骨细胞簇中;在软骨组织消耗严重时,浅表区域内的细胞凋亡现象逐渐减少,肥大钙化层中出现了较多的凋亡细胞。结论颞下颌关节骨关节病骸突软骨组织中存在过量凋亡的现象,软骨细胞异常增殖与过度凋亡导致软骨基质自身调节机制的破坏可能是骨关节病发生的重要原因之一。     

The immunolocalisation of VEGF in the articular cartilage of sheep mandibular condyles.

INTRODUCTION: Vascular endothelial growth factor (VEGF) has recently been found to be essential for hypertrophic chondrocyte apoptosis and angiogenesis at the growth plate of long bones, indicating a central role in endochondral ossification. VEGF has more recently, also been shown to be expressed in articular cartilage chondrocytes in human osteoarthritic and rheumatoarthritic joints but not healthy adult joints. To investigate the role of VEGF in the fibrocartilage of the temporomandibular joint, this study aimed to document the presence and distribution of VEGF in the condylar articular cartilage of sheep temporomandibular joints. METHODS: Mandibular condyles of the temporomandibular joints of five 18-month old Wether sheep were fixed, decalcified, paraffin embedded and sectioned. The sections were analyzed using immunohistochemistry for VEGF. RESULTS: VEGF was found to be localised predominantly to the proliferative and maturing layers of chondrocytes in the condylar fibrocartilage of the temporomandibular joints. Articular cartilage is an avascular and alymphatic tissue. As such, the localisation of VEGF to the articular cartilage of normal temporomandibular joint condyles suggests a role for VEGF other than angiogenesis. CONCLUSION: VEGF is shown here for the first time to be present in mandibular condylar cartilage, leading us to propose a possible role in non-angiogenic extracellular matrix remodeling.     

纤维软骨和透明软骨不同染色方法的对比研究

目的 研究不同软骨染色方法在髁突软骨、股骨软骨和生长板软骨中的染色差异。方法 取健康雌性新西兰大白兔颞下颌关节髁突、膝关节股骨,分别进行苏木精-伊红（HE）染色、甲苯胺蓝染色、阿利新蓝染色、番红O 阿利新蓝染色、番红O染色、番红O 快绿染色,光学显微镜下观察分析各软骨组织结构。结果 HE染色髁突纤维软骨各层结构清晰,关节软骨基质呈嗜碱性蓝染,骨组织呈嗜酸性红染;甲苯胺蓝染色关节软骨基质呈蓝紫色,骨组织不着色;阿利新蓝染色软骨基质呈淡蓝色,骨组织不着色;番红O 阿利新蓝染色关节软骨呈浅蓝色,骨组织呈淡红色,但是髁突软骨纤维层和增殖层红染;番红O染色中髁突软骨基质呈红色,股骨软骨和生长板软骨呈橘黄色,骨组织呈淡红色;番红O 快绿染色关节软骨基质呈红色,骨组织呈绿色,在髁突纤维软骨中纤维层呈明显绿染。结论 不同的染色方法可以特异性展现软骨组织结构。在今后透明软骨和纤维软骨的研究中,因根据研究对象、研究目的等选用适合的染色方法,以期最佳的反映研究部位的形态结构。     

山羊髁突刨削术后髁突软骨面修复的初步观察

目的:观察山羊髁突刨削术后髁突的愈合过程。方法:实验动物7只山羊,将6只山羊两侧髁突软骨面磨除,另1只未做手术为正常对照。分别于术后4、8、12周;每个时间点取材2只实验动物进行HE染色加以评价。结果:术后4周山羊髁突软骨缺失区粗糙,为骨样及一些纤维样组织修复,或可见少许纤维样软骨;术后8周及12周髁突表面较术后4周时光滑,修复组织逐渐变为以骨性组织为主,软骨样成分逐渐消失。结论:经过关节髁突的刨削术,术后3个月时,实验动物髁突软骨缺失区不能形成正常的软骨组织。     

Regeneration of mandibular condyle following unilateral condylectomy in canines.

PURPOSE: The purpose of this experimental study was to investigate regeneration of the mandibular condyle after unilateral condylectomy in canines. MATERIAL AND METHODS: Five 2-year-old beagle dogs underwent unilateral mandibular condylectomy and were sacrificed either immediately postoperatively (n=1) or 3 months later (n=4). Temporomandibular joints were examined radiologically and histologically, and sides were compared. RESULTS: All joints showed postoperative regeneration of the condylar head. Maximum regeneration of the condyle occurred medially, where most bone of the glenoid fossa was present, rather than laterally. From an anteroposterior perspective, regeneration of the condylar head was more favourable anteriorly, facing the inferior slope of the glenoid fossa. Regenerated articular cartilage was irregular. Articular discs displayed central thickening compared with unoperated joints. The bone of the glenoid fossa was normal. CONCLUSION: Unilateral mandibular condylectomy in canines resulted in a certain degree of condylar regeneration during a 3-month postoperative period, with some irregular articular cartilage formation.     

Histopathologic comparison of normal and hyperplastic condyles

OBJECTIVE: The aim of this study was to compare normal and hyperplastic mandibular condyles using two different histopathologic staining techniques. STUDY DESIGN: Nine cases of condylar hyperplasia and 13 normal cases were studied after hematoxylin and eosin and silver staining. RESULTS: There was a significant difference between the two groups in the thickness of the hyperplastic cartilage layer of condylar soft tissue (P = 0.017). Also, the number of argyrophilic nucleolar organizer regions was significantly higher in the condylar hyperplasia case group (P = 0.0001). No significant differences could be demonstrated in cartilage island frequency, penetration depth, and distribution in the cancellous bone of condyles. CONCLUSION: The thickness of the hyperplastic cartilage layer appears significantly increased in condylar hyperplasia. In addition, argyrophilic nucleolar organizer region count may be useful in histopathological identification of condylar hyperplasia.     

Relationship of TMJ articular soft tissue to underlying bone in young adult condyles

This investigation used a histological model to study the relationship of articular soft-tissue thickness and contour to the underlying bone in the TMJ condyle of young adults. The usefulness of selected dental and demographic factors in the prediction of the articular soft-tissue thickness and contour was also tested. One sagittal histological section was studied from the lateral, central, and medial thirds of 53 left mandibular condyles. Outline tracings of the articular and compact bone surface were divided into anterior, superior, and posterior sectors for the study of curvature measured by the overlaying of a template of a harmonic series of arcs. The thickness and composition of the articular tissues were measured in each sector by light microscopy. The fibrous connective tissue layer always maintained the articular surface, even in the absence of a cartilage layer. The histological character, including the presence or absence of cartilage, rather than the overall tissue thickness, was considered to be a more useful marker of functionally thickness was not related to surface deviation in form and was not correlated with age in this young adult sample. Reduced soft-tissue thickness in the anterior part of the condyle was more common in cases with lack of molar support. Dental attrition was not a useful predictor of soft-tissue thickness. Compact bone contour correlated with soft-tissue contour in the superior (r = 0.816) and posterior (r = 0.808) sectors, explaining only 64% of the variance, but not in the anterior sector (r = 0.265). Thicker or thinner articular soft tissue was not predictable by the underlying compact bone contour or thickness. Therefore, the clinician should not automatically assume that the radiographic osseous image represents the actual articular surface.     

Histological evaluation of condylar hyperplasia model of rabbit following distraction osteogenesis of the condylar neck

Summary Condylar hyperplasia is the excessive unilateral growth of mandibular leading to facial asymmetry, occlusal disturbance, joint pain and dysfunction. The aim of this study is to evaluate the histological presence of temporomandibular joint in model of condylar hyperplasia by lengthening unilateral condylar neck of distraction osteogenesis. An extra oral distractor was employed to achieve unilateral condylar neck distraction (1·0 mm daily for 7 days). The experimental condylar necks were elongated by 7 mm compared to the contralateral. Eleven adult white rabbits were used. Eight rabbits were, respectively, sacrificed after the post‐distraction period (4 or 8 weeks). All animals were evaluated clinically and histomorphometrically. The condyles radiologically showed remodelling, flattening and sclerosis. In 4‐week group, thinning of the cartilage was evident, and the trabeculae were long, not multiply connected. A thin, dense fibrous layer covered all over the surface of cartilage. In 8‐week group, the cartilaginous layer was similar to thickness of the normal cartilage, but still thinner than control. However, the fibrous layers covering condyle manifested slight degenerative changes, and even depressions and erosions were seen in the cartilage and subchondral bone. The trabeculae showed denser and multiply connected. In 8‐week group, the cartilaginous thickness of surgical condyles was significantly thinner than the contralateral. This study indicates that unilateral distraction of condylar neck loads the condyles asymmetrically. Asymmetrical loads affect more on the surgical condyles than the contralateral, and after 8 weeks of the post‐distraction, condyle could recover from asymmetrical loads in some degree.     

Immunohistochemical localization and distribution of proliferating cell nuclear antigen in the rabbit mandibular condyle following experimental induction of anterior disk displacement

The purpose of the present study was to identify proliferating cells in control versus experimental condyles two weeks following experimental induction of anterior disk displacement (ADD) in the rabbit craniomandibular joint (CMJ). The right joint of 15 rabbits was exposed surgically and all diskal attachments were severed except for the posterior attachment. The disk was then repositioned anteriorly and sutured to the zygomatic arch. The left joint served as a sham-operated control. Ten additional joints were used as nonoperated controls. Mandibular condyles were excised two weeks following surgery and processed for proliferating cell nuclear antigen (PCNA) immunostaining. In control and sham operated condyles, PCNA was localized in the nuclei of chondroblasts of the reserve cell layer, chondrocytes of the upper hypertrophic layer and bone marrow cells of the subchondral bone. In contrast to control joints, the PCNA positive cells of the experimental joints were located throughout the osteoarthritic condylar cartilage. In addition, the percentage of PCNA positive cells of the osteoarthritic condylar cartilage was statistically significantly higher when compared to the control group, p < 0.05. It was concluded that surgical induction of ADD in the rabbit CMJ leads to an increase in mitosis of chondrocytes, which lead to cell proliferation and subsequent hyperplasia of the condylar cartilage.     

Temporomandibular joint: surgically created disk displacement causes arthrosis in the rabbit.

To document a causal relationship between temporomandibular joint disk displacement and arthrosis, the disk was surgically displaced in one temporomandibular joint in each of three rabbits. The rabbits were sacrificed after 4 weeks and the mandibular condyles were studied radiographically and histologically. All three joints that underwent disk displacement had radiographic and histologic evidence of arthrosis, which included erosion of the bone, irregularity and fissure formation of the articular soft tissue cover, disruption of the subchondral layer of cartilage cells, and chondrocyte proliferation. No radiographic or histologic changes occurred in the joints that were untouched. The results suggest that surgically created disk displacement can cause arthrosis in the temporomandibular joint of the rabbit.     

Histological and immunohistochemical studies on the articular cartilage after experimental discectomy of the temporomandibular joint in rabbits

Total discectomy was performed experimentally in the rabbit temporomandibular joint (TMJ). In order to evaluate the injury and repair of the articular cartilage of the mandibular condyle after discectomy, both histologic and immunohistochemical observations were made. Immunohistochemical observation by using bromodeoxyuridine (BrdU) and its monoclonal antibody in vivo labelling method was used.
The present study demonstrated that the cartilage on the articular surface of the condyle disappeared at 1 week post-operatively. This defect in the injured articular cartilage was not repaired by the cartilage, but was covered by a fibrous connective tissue at 6 weeks post-operatively, where the condylar recontouring by the adjacent articular cartilage, and flattening and hyperplasia of the condyle were observed. Thus, the cartilaginous repair following discectomy was characterized by the proliferation of the adjacent cartilage to the injured site and osteoblastic formation in the bone marrow at the exposed subchondral bone.     

Growth hormone and insulin-like growth factor I receptors in the temporomandibular joint of the rat.

While there are numerous investigations on hormonal control of long bone epiphyseal growth, corresponding knowledge is sparse concerning the condylar cartilage. We investigated the distribution of growth hormone (GH) and insulin-like growth factor I (IGF-I) receptors in the temporomandibular joint (TMJ), especially the condyle, and compared the findings with information of long bone epiphyseal plates. The localization of the receptors was examined in vivo by immunohistochemical methods in one- to 21-day-old rats. GH receptors were detected in various components of the TMJ, but not in the fibrous articular surface or in the cartilage layers of the condyle. IGF-I receptors were found in the fibrous articular surface of the condyle and particularly in the superior and posterosuperior regions of the condylar cartilage, the depth of the labeled cell layer increasing significantly with age. It is evident that the expression of GH and IGF-I receptors is area-specific in the TMJ. Early post-natal growth and development of the mandibular condylar cartilage seem to be IGF-I-dependent but not directly dependent on GH.     

Microscopic changes in the condyle and disc in response to distraction osteogenesis of the minipig mandible.

PURPOSE: Unilateral mandibular distraction osteogenesis (DO) has been shown to cause gross changes in the mandibular condyle and articular disc. The purpose of this study was to correlate histologic findings with these gross changes in a minipig distraction model. MATERIALS AND METHODS: Semiburied distractors were placed via submandibular incisions in 15 minipigs. Two unoperated animals served as controls. The protocol consisted of 0-day latency and rates of 1, 2, or 4 mm/day for a 12-mm gap. After the minipigs were killed (at 0, 24, or 90 days), ipsilateral and contralateral condyles and discs were harvested, decalcified, prepared for standard paraffin embedding, and evaluated to determine changes in 1) morphology and thickness of the articular cartilage and subchondral bone and 2) morphology of the disc. RESULTS: In control animals, there were no degenerative changes in the articular cartilage and underlying condylar bone; there were no significant differences in the mean articular cartilage thickness. The temporomandibular joint discs were normal. In experimental animals, distracted condyles showed increasing degenerative changes and mean articular cartilage thickness as the DO rate increased. The discs were thinner. These changes were present, but to a lesser degree, in the contralateral condyles. After 90 days, degenerative changes in the condyles and discs were reduced, after remodeling, except in the 4 mm/day DO group. CONCLUSIONS: Histologic changes in the condyles and temporomandibular joint discs in response to mandibular DO correlated with previously reported gross changes. These changes were greater at higher distraction rates and remodeling back to normal occurred in mandibular condyles distracted at 1 mm/day.     

Osteoplasty of the mandibular condyle with preservation of the articular soft tissue cover: comparison of fibrin sealant and sutures for fixation of the articular soft tissue cover in rabbits

Fibrin sealant and sutures were compared for fixation of the articular soft tissue cover after it had been raised in association with osteoplasty of the mandibular condyle. Nine adult rabbits were operated on bilaterally with the use of fibrin sealant on one joint and sutures on the other joint. The rabbits were killed after 3 months. Macroscopic and histologic evaluations of the condyles did not reveal any appreciable differences between the two techniques. Fibrin sealant was, however, technically easier to apply than the sutures. It was concluded that fibrin sealant might be an alternative to sutures for fixation of the articular soft tissue cover after it has been raised in association with osteoplasty of the mandibular condyle.     

Immunohistochemical Localization and Distribution of Proliferating Cell Nuclear Antigen in the Rabbit Mandibular Condyle Following Experimental Induction of Anterior Disk Displacement

The purpose of the present study was to identify proliferating cells in control versus experimental condyles two weeks following experimental Induction of anterior disk displacement (ADD) in the rabbit craniomandibular joint (CMJ). The right joint of 15 rabbits was exposed surgically and all diskal attachments were severed except for the posterior attachment. The disk was then repositioned anteriorly and sutured to the zygomatic arch. The left joint served as a sham-operated control. Ten additional joints were used as nonoperated controls. Mandibular condyles were excised two weeks following surgery and processed for proliferating cell nuclear antigen (PCNA) immunostaining. In control and sham operated condyles, PCNA was localized in the nuclei of chondroblasts of the reserve cell layer, chondrocytes of the upper hypertrophic layer and bone marrow cells of the subchondral bone. In contrast to control joints, the PCNA positive cells of the experimental joints were located throughout the osteoarthritic condylar cartilage. In addition, the percentage of PCNA positive cells of the osteoarthritic condylar cartilage was statistically significantly higher when compared to the control group, p < 0.05. It was concluded that surgical induction of ADD in the rabbit CMJ leads to an increase in mitosis of chondrocytes, which lead to cell proliferation and subsequent hyperplasia of the condylar cartilage.     

Histologic comparison of the costochondral, sternoclavicular, and temporomandibular joints during growth in Macaca mulatta

The costochondral joint (CCJ) is commonly used to replace defective mandibular condyles in children for the restoration of normal temporomandibular (TMJ) growth and function. However, continued and harmonious growth following rib grafting is the exception rather than the rule. This may be due to the differences in the growth characteristics of the costal cartilage and the condyle. A joint that is similar both developmentally and structurally to the TMJ is the sternoclavicular joint (SCJ). The purpose f this study was to describe histologically the SCJ and CCJ during growth in Macaca mulatta and to compare the histomorphologic features with those of the TMJ. Costochondral and sternoclavicular joints were obtained from infant, juvenile, adolescent, and adult Macaca mulatta. The histologic sections were compared with mandibular condyles of the same ages available in our laboratory. The results indicate that the TMJ and SCJ are very similar morphologically throughout the growth period. The clavicular head contained layers of cartilage typical of the mandibular condyle, i.e., articular, prechondroblastic, chondroblastic, hypertrophic, and endochondral ossification layers, at each age during growth. Like those in the condyle, the hypertrophic cartilage cells were arranged in an apparently random, noncolumnar fashion. The CCJ, however, did not resemble the condyle but appeared to be more similar to the growth plate in a long bone epiphysis during growth. The results of this investigation indicate that the SCJ may be more suitable for mandibular condylar replacement than the CCJ.     

Unilateral mandibular condylectomy in lambs.

The purpose of this experimental study was to investigate the degree of regeneration of the mandibular condyle after unilateral condylectomy in 10-week-old lambs. The lambs were killed three months after the operation, and the joints examined radiologically and histologically. Scoring systems were used to assess the radiological changes and histological regeneration of the condyle. All joints showed regeneration of the condylar head postoperatively. The maximum degree of regeneration occurred on the medial side rather than the central or lateral areas. There was a significant correlation among the medial, central, and lateral planes (P<0.05). The reformed articular cartilage was irregular and thin (P<0.01), and the disc was thick in the central plane (P<0.01) compared with the control joints. The temporal bone was normal. This study shows that unilateral condylectomy in the growing period results in some condylar regeneration particularly on the medial side and reformation of some irregular and thin articular cartilage.     

Effects of estrogen on the condylar cartilage of the rat mandible in organ culture.

PURPOSE: The effects of estrogen on bone have been well documented. However, very little is known about the regulatory role of estrogen on cartilage and, in particular, the secondary cartilage of the mandibular condyle. The aims of this study were to determine whether estrogen receptors are present in the condylar cartilage of the rat mandible and to assess the effect of varying 17beta-estradiol (E2) concentrations on the proteoglycan content of this tissue. MATERIALS AND METHODS: Mandibular condyles of 16 female Sprague-Dawley rats were resected. Eighteen of these condyles were divided into three groups and the condylar cartilage was removed and placed in organ culture for 4 days with media containing different concentrations of estrogen: 10(-11) mol/L, 10(-8) mol/L, and 10(-6) mol/L. The cartilage then was analyzed for proteoglycan content along with six specimens not passed through the organ culture. Six intact mandibular condyles also were resected and placed in organ culture with the same varying E2 concentrations, and the condylar cartilage was analyzed for estrogen receptors along with two condyles not passed through the culture system. RESULTS: Estrogen receptors were evenly distributed within the chondroblastic and hypertrophic zones in the control group and the group with 10(-11) mol/L E2. With E2 concentrations of 10(-8) mol/L and 10(-6) mol/L, there was a qualitative decrease in hypertrophic chondroblasts, thickness of the condylar cartilage, and a significant decrease in proteoglycan content. CONCLUSIONS: This study shows the presence of estrogen receptors in the secondary cartilage of the rat mandibular condyle. Estrogen has the potential to cause a decrease in extracellular matrix and thickness of this cartilage.