兔关节盘前移位后髁突软骨PRG4 mRNA表达改变的研究

目的 分析兔颞颌关节盘前移位后髁突软骨PRG4 mRNA表达的动态改变及其意义。方法 62只日本大耳白兔,48只建立关节盘前移位的动物模型,分期处死。6只为手术对照组,8只为空白对照。合成兔PRG mRNA探针,原位杂交检测关节盘前移位后髁突软骨PRG4 mRNA表达的动态改变。结果 PRG4 mRNA表达于髁突全层软骨。关节盘前移位后,PRG4 mRNA表达一过性升高,8周后回落至正常。4只样本术区骨关节病样表现,软骨崩解区域PRG4 mRNA的表达水平显著下降。结论 关节盘前移位后,髁突软骨细胞PRG4 mRNA一过性升高以保护髁突软骨表层的完整性,促进滑液润滑,有利于实现关节的适应性改建。?     

Histological changes in the rabbit condyle following posterolateral disk perforation

PURPOSE: To examine changes in condylar cartilage following perforation in the posterolateral region of the articular disk of the craniomandibular joint of a rabbit. MATERIAL AND METHODS: The circular perforation in the left joint of 25 female Japanese white rabbits measured precisely one-sixteenth of a disk. Histological examination, including the immunohistochemical proliferating cell nuclear antigen (PCNA) procedure, was performed on separate sets of five rabbits each 2, 4, 8, 12, and 24 weeks postoperatively. RESULTS: Microscopic examination revealed hypertrophy of the condylar cartilage with osteophyte formation up to 8 weeks after perforation. Proliferative activity then decreased near the condylar surface as the perforation flattened. Twenty-four weeks postoperatively, the condylar surface was found to be fibrous and flattened. Positive PCNA results in cartilage cells indicated proliferation following disk perforation which peaked in the 4th week and then decreased. CONCLUSION: Disk perforation was followed initially by hypertrophy of condylar cartilage, and later by degeneration of the condylar surface. Although osteoarthritic cartilage was found 24 weeks after perforation, degeneration decreased over time. This suggests that remodelling took place after the perforation.     

Immunohistochemical localization of cytokeratin 19, involucrin and proliferating cell nuclear antigen (PCNA) in cultured human gingival epithelial sheets

It has been suggested that human cultured gingival epithelial sheets may serve as a possible grafting material. The purpose of this study was to examine the biological characteristics of human cultured gingival epithelial sheets by epithelial differentiation and proliferation markers. Immunohistochemical localization of cytokeratin 19, involucrin and proliferating cell nuclear antigen (PCNA) were examined in human cultured gingival epithelial sheets samples from twenty patients. Cytokeratin 19-immunopositive cells were scattered mainly in the suprabasal layer. Immunoreactivity for involucrin was observed in all layers except for the basal layer. The majority of proliferating cell nuclear antigen-immunopositive cells was found in the basal layer. These results suggested that the cultured human gingival epithelial sheets were biologically active and in proliferative condition, which implies that this biological product may be a potential grafting material.     

Immunohistochemical localization of cytokeratin 19, involucrin and proliferating cell nuclear antigen (PCNA) in cultured human gingival epithelial sheets

It has been suggested that human cultured gingival epithelial sheets may serve as a possible grafting material. The purpose of this study was to examine the biological characteristics of human cultured gingival epithelial sheets by epithelial differentiation and proliferation markers. Immunohistochemical localization of cytokeratin 19, involucrin and proliferating cell nuclear antigen (PCNA) were examined in human cultured gingival epithelial sheets samples from twenty patients. Cytokeratin 19-immunopositive cells were scattered mainly in the suprabasal layer. Immunoreactivity for involucrin was observed in all layers except for the basal layer. The majority of proliferating cell nuclear antigen-immunopositive cells was found in the basal layer. These results suggested that the cultured human gingival epithelial sheets were biologically active and in proliferative condition, which implies that this biological product may be a potential grafting material.     

A histomorphometric study of adaptive responses of cancellous bone in different regions in the sheep mandibular condyle following experimental forward mandibular displacement

Forward mandibular displacement in animal models is associated with faster and/or redirected condylar growth. Here the effect of forward displacement induced with an intraoral appliance on modelling/remodelling of the mandibular condyle was investigated in eight, 4-month-old, castrated male Merino sheep, randomly allocated to experimental and control groups (n=4 in each group). The study period was 15 weeks, during that time, (1). calcein, (2). tetracycline, and (3). alizarin red S fluorochromes were given to all animals from day 1. Midsagittal sections of the temporomandibular joints were selected for analysis. Dynamic variables of bone formation, static indices of bone-forming and -resorbing activity, and structural indices of trabecular bone were estimated histomorphometrically. The sampling site was divided into two regions for analysis: (a). a 'subchondral region' (2 and 3 labels only), believed to be the bone newly formed during the experimental period; (b). a 'central region' (labelled by all three fluorochromes), believed to be the bone that existed before the experiment. Regional differences in adaptive response were found. In the experimental group, the bone-volume fraction (BV/TV) of the subchondral regions had decreased, although the specific bone-surface and bone-formation rates had increased. This low BV/TV was associated with decreased trabecular thickness and increased trabecular separation. In the central condylar region of the experimental group, BV/TV was unchanged, but an increased osteoid surface was apparent when the eroded surface was taken into consideration. These adaptive condylar responses to forward mandibular displacement appeared to be the result of increased osteoblastic activity. Further studies are recommended to examine why the subchondral and central regions responded differently.     

An immunohistochemical study of collagen types III, VI and IX in rabbit craniomandibular joint tissues following surgical induction of anterior disk displacement

The purpose of this study was to determine the effect of surgical induction of anterior disk displacement (ADD) on type-Ill. VI and IX collagens of the rabbit craniomandibular joint (CMJ) tissues using an immunohistochemical technique. The right joint was exposed surgically, all discal attachments were severed except for the posterior discal attachment (bilaminar zone). 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 non-operated controls. Deeply anesthetized rabbits were perfused with 2% buffered formalin 2 weeks (10 rabbits) or 6 weeks (10 rabbits) following surgery. The articular disk, bilaminar zone, mandibular condyle and articular eminence were excised. The last two were decalcified in EDTA. All tissues were then sectioned at 10 um in a cryostat. Sections were incubated with monoclonal antibodies directed against type-Ill. VI or IX collagens. Following incubation in the appropriate FITC-fabelled secondary antibodies, all sections were studied under the fluorescence microscope. The results showed a reduction in immunostaining for type-VI and IX collagens in the condylar cartilage, disk and articular eminence at 2 weeks, followed by an increase in their immunostaining at 6 weeks and the appearance of a de novo type-Ill collagen in the condylar cartilage and the articular eminence. It is concluded that surgical induction of ADD in the rabbit CMJ leads to alterations in its type-III. VI and IX collagens.     

Relations between anterior disc displacement and maxillomandibular morphology in skeletal anterior open bite with changes to the mandibular condyle

In this study we investigated the relation between anterior disc displacement (ADD) and maxillomandibular morphology in skeletal anterior open bite with changes to the mandibular condyle. Thirty female patients (60 joints) with both conditions were evaluated. Magnetic resonance imaging of the temporomandibular joint (TMJ) was used to diagnose both ADD and changes to the mandibular condyle (erosion, osteophyte, and deformity). The relations among ADD, changes to the mandibular condyle, and maxillomandibular morphology were examined statistically. Changes to the mandibular condyle had a higher score than sym anterior open bite, the deviated side in asymmetric anterior open bite, and the non-deviated side. The score for disc displacement on the non-deviated side was lower than both the sym side and the deviated side. Unilateral changes to the mandibular condyle and unilateral disc displacement were not apparent in sym anterior open bite, but a unilateral non-displaced disc was seen only on the asymmetric side. Mandibular condylar changes were significantly more common on the deviated, than on the non-deviated, side. The SNB angle was significantly smaller, and the ANB, GZN, and SN-mandibular plane angles were significantly larger in sym anterior open bite. Overjet, ANB angle, GZN angle, and SN-MP angle were significantly larger, and the SNB angle was significantly smaller, in the presence of ADD without reduction and mandibular condylar deformity. We conclude that the prevalence of ADD without reduction and changes to the mandibular condyle were related to mandibular asymmetry and mandibular morphology in anterior open bite. This retrospective study suggests that ADD without reduction and mandibular condylar bone changes may be related to the progression of skeletal class II open bite and mandibular asymmetry in cases of skeletal open bite.     

Biochemical and autoradiographical evidence that anterior mandibular displacement in the young growing rat does not stimulate cell proliferation or matrix formation at the mandibular condyle

A removable bite plate was used to induce forward mandibular displacement in four-week-old rats for 10 h/day for 1, 3, 7, 11 and 14 days. The animals were killed and the condylar explants pulsed in vitro for 6 h with either [3H]-thymidine or [3H]-proline or 35SO(2-)4. The specific activity of radio-isotope incorporation was expressed as dis/min per microgram DNA, dis/min per mg protein and dis/min per microgram sulphated glycosaminoglycans (GAG). [3H]-thymidine autoradiography was also used in a 14-day experiment to establish a radioactive index (labelled cells per 1000 cells counted) for the anterior, middle and posterior regions of the condyle. There was no significant alteration in either cell proliferation (dis/min per microgram DNA and radioactive index) or matrix formation (dis/min per mg protein and dis/min per microgram GAG) at any point in the time scale.     

下颌前伸后大鼠髁突软骨增殖细胞核抗原表达昼夜节律

目的 比较昼夜不同时段戴用功能矫治器后,髁突软骨增殖细胞核抗原（ＰＣＮＡ）表达的昼夜变化,为探讨功能矫治昼夜最佳介入时段,提供直接实验依据。方法 采用免疫组织化学法,检测不同时段前伸大鼠下颌后,髁突软内ＰＣＮＡ表在的昼液变化。结果 戴用功能矫治器后,ＰＣＮＡ表达强度增加;白天戴用组明显高于夜晚组。结论 功能矫治器可以刺激髁突软骨增生;在髁突软骨昼夜自发性生长最旺盛时段戴用矫治器,效果最佳。     

Type II collagen and aggrecan mRNA expressions in rabbit condyle following disc displacement

The aim of this investigation was to study the remodelling of cartilage in the mandibular condyle following disc displacement (DD) of the temporomandibular joint (TMJ). Forty adult Japanese white rabbits were used in this study. The right joints of 28 of the 40 rabbits had their discs surgically displaced. Four of the 28 were killed at 4 days or 1, 2, 4, 6, 8 and 12 weeks after surgery. The messenger RNA (mRNA) expression levels of aggrecan and type II collagen in cartilages were measured using in situ hybridization techniques. Results showed that aggrecan mRNA expression reduced in the first week after DD. The expression began to recover after 4 weeks and reached a normal level after 6 weeks. Type II collagen mRNA expression reduced from 4 weeks and the expression recovered after 8 weeks. This suggests that the chondrocyte reacting to the displacement of the TMJ disc, alters its matrix gene expression patterns and it is may be the cause of the shape changes of TMJ after DD.     

Effect of experimental lipoarthrosis on the articular fibrocartilage of the rabbit mandibular condyle.

Articular fibrocartilage was examined microscopically 4 days after unilateral injection of glyceryl trioleate into the lower joint cavity. In injected joints, cells had an increase in lipid content compared with tissue from the opposite control joints, although the amount varied between specimens. When the intracellular lipid content showed a considerable increase, a 25–30 per cent reduction in cell density and thickness occurred in the fibrocartilage. The bulk of the loss of cells and of tissue thickness occurred in the deep cartilaginous layer of the articular fibrocartilage. There was little or no change in the cell density and thickness when there was only a small increase in intracellular fat. It is suggested that matrix degradation partially accounts for the loss of tissue thickness and that lipoarthrosis might also affect the growth and remodelling potential of the rabbit condyle.     

兔关节盘前移位后髁突软骨细胞中OPG和OPGL的表达及意义

目的:探讨关节盘前移位后髁突软骨中护骨素(osteoprotegerin,OPG)及其配体(osteoprotegerinligand,OPGL)表达的变化及意义。方法:20只日本大耳白兔,16只用弹力丝牵引关节盘前伸部,建立颞下颌关节盘前移位的动物模型,分别于术后1、2、4、8周处死。2只行模拟手术作为手术对照组,术后2周处死;另2只不行手术,作为空白对照。取颞下颌关节标本,HE染色,观察其镜下结构,SP免疫组化法检测髁突软骨中OPG和OPGL的表达与分布,并对各标本OPG和OPGL的表达进行灰度测定。用单因素方差分析法对所得数据进行统计学分析。结果:各实验组动物术后体重无明显减轻,伤口愈合良好,大体及显微镜下观察,关节盘明显前移位。OPG和OPGL在各组髁突软骨的增殖层及肥大层浅层均有表达,其中关节盘移位组OPG、OPGL染色较强,染色灰度值与对照组均有显著性差异(P<0.05),但OPG/OPGL比率基本稳定。结论:关节盘移位后OPG和OPGL的表达均有升高,可能参与关节盘移位后髁突软骨病变的发展及转归。     

下颌稳定型(牙合)垫治疗可复性盘前移位的临床评价

目的 探讨下颌稳定型(牙合)垫治疗颞下颌关节可复性盘前移位的疗效.方法 对32例(34侧)关节盘可复性前移位患者,采用下颌稳定型(牙合)垫治疗,疗程为3个月,采用Fricton指数及疼痛量化表来评价治疗效果.结果 统计学分析表明治疗前后的差异有统计学意义(P＜0.05),Fricton颞下颌关节指数(CMI)从治疗前的...     

Differential expression of apoptosis-associated proteins in chondrocytes of the mandibular condyles of rabbits with anterior disk displacement

Apoptosis is a potential contributor to anterior disk displacement (ADD) in temporomandibular joint disorders (TMD). The aim of this study was to investigate the expression of key protein regulators involved in apoptosis in the chondrocytes of mandibular condyles with induced ADD in experimental animals. ADD was surgically induced in the left temporomandibular joint (TMJ) of 15 rabbits without opening their bursas. A sham operation was performed on the right TMJ without displacing the disk forward. At the end of one, two, and four weeks after surgery, mandibular condyle samples were collected for protein extraction. The production of apoptosis-associated proteins Fas, capase-8, Bcl-2, and Bax was determined using Western blotting. The results indicate that the production of Fas and caspase-8 increased continuously after ADD. Meanwhile, the level of Bcl-2 decreased, and the production of Bax gradually increased following ADD. These results indicate that alterations in protein production of Fas, caspase-8, and the ratio of Bcl-2 to Bax are consistent with an increase of apoptotic activity in the chondrocytes, which may eventually lead to TMD.     

Outcomes of anterior disc displacement and condylar remodelling for sagittal fracture of the mandibular condyle in children after closed treatment

The aim of this study was to evaluate the outcomes of temporomandibular joint (TMJ) anterior disc displacement and condylar remodelling for sagittal fracture of the mandibular condyle (SFMC) in children. Disc displacement was observed in 20 patients with 24 SFMCs (age 4–12 years) via magnetic resonance imaging. After 6 months of closed treatment (T1), the joints were categorized based on the displaced disc status as complete reduction (DCR) or incomplete reduction (DICR). Moreover, condylar remodelling was compared between the groups using cone beam computed tomography images of the TMJ obtained at T1 and at the 1-year follow-up (T2; 15 patients with 18 displaced SFMCs). At T1, 17 of 24 joints with SFMC were assigned to the DCR group and six to the DICR group; one unilateral SFMC case developed ankylosis. Condylar depth and height differed significantly between the groups at T1, but not at T2. Intra-group comparison exhibited significant changes in the condylar depth and height over time in the DICR group. Thus, most of the anteriorly displaced discs (17/24, 70.8%) achieved reduction following closed treatment. Although sustained anterior disc displacement was associated with an increased depth and reduced height of the condyle, no clinical impairment was noted unless ankylosis developed.     

颞下颌关节盘前移位关节盘及盘后区超微结构变化的实验研究

目的通过建立关节盘前移位实验动物模型的方法,研究颞下颌关节盘前移位后关节盘及盘后区早期超微结构的变化。方法10只兔左侧关节经手术诱导为关节盘前移位模型,右侧为手术对照组;2只为正常对照组。术后24小时、1周、2周、3周、4周,麻醉下活体各切取2只手术组实验动物同一部位的关节盘和关节盘后区组织,制成透射电镜标本观察。结果关节盘组织中软骨样细胞逐渐增多,细胞周围的淡区逐渐变小并消失,胞浆中微丝增加,胶原纤维间排列紊乱数量减少,并见新生毛细血管及神经纤维,最后软骨样细胞转化为纤维母细胞和肌纤维母细胞。盘后区早期出现幼稚的软骨样细胞,有排列相对致密的胶原纤维,最后转化成类似于关节盘样组织。结论颞下颌关节盘前移位后,关节盘失去纤维软骨盘的特性转化为纤维结缔组织;盘后区则由疏松的结缔组织变成纤维软骨盘样组织。     

Experimental induction of anterior disk displacement of the rabbit craniomandibular joint: an immuno-electron microscopic study of collagen and proteoglycan occurrence in the condylar cartilage

BACKGROUND: Results from our previous studies suggest that surgical induction of anterior disk displacement (ADD) in the rabbit craniomandibular joint (CMJ) leads to histopathological alterations consistent with osteoarthritis. In addition, molecular changes in collagens and glycosaminoglycans (GAGs) were observed using immunohistochemistry. The purpose of the present study was to further characterize those molecular changes in collagens and GAGs using immuno-electron microscopy. METHODS: The right joint of 15 rabbits was exposed surgically and all discal attachments were cut except for the posterior attachment (the bilaminar zone). The disc was then repositioned anteriorly and sutured to the zygomatic arch. The left joint was used as a sham-operated control. Ten additional joints were used as non-operated controls. Mandibular condyles were removed 2 weeks following surgery and processed for light and immuno-electron microscopy using colloidal gold-labeled antibodies against collagen type I, II, VI and IX and against keratan sulfate, chondroitin-4 and -6-sulfate, and link protein. RESULTS: Light microscopic results showed osteoarthritic changes. Immuno-electron microscopy of osteoarthritic cartilage demonstrated a decline in type II collagen, the abnormal presence of type I collagen and loss of type VI and IX collagens. Quantitative colloidal gold immuno-electron microscopy confirmed the depletion of keratan sulfate, chondroitin-4 and -6-sulfate, and link protein in osteoarthritic cartilage. CONCLUSION: Anterior disk displacement leads to molecular alterations in both the collagen and the proteoglycans of rabbit condylar cartilage characteristic of osteoarthritis in other synovial joints. These alterations are consistent with loss of the shock absorber function of the cartilage and injury of the underlying bone.