Divergent chondro/osteogenic transduction laws of fibrocartilage stem cell drive temporomandibular joint osteoarthritis in growing mice / 国际口腔科学杂志·英文版

The anterior disc displacement (ADD) leads to temporomandibular joint osteoarthritis (TMJOA) and mandibular growth retardation in adolescents. To investigate the potential functional role of fibrocartilage stem cells (FCSCs) during the process, a surgical ADD-TMJOA mouse model was established. From 1 week after model generation, ADD mice exhibited aggravated mandibular growth retardation with osteoarthritis (OA)-like joint cartilage degeneration, manifesting with impaired chondrogenic differentiation and loss of subchondral bone homeostasis. Lineage tracing using Gli1-CreER+; Tmfl/-mice and Sox9-CreER+;Tmfl/-mice showed that ADD interfered with the chondrogenic capacity of Gli1+ FCSCs as well as osteogenic differentiation of Sox9+ lineage, mainly in the middle zone of TMJ cartilage. Then, a surgically induced disc reposition (DR) mouse model was generated. The inhibited FCSCs capacity was significantly alleviated by DR treatment in ADD mice. And both the ADD mice and adolescent ADD patients had significantly relieved OA phenotype and improved condylar growth after DR treatment. In conclusion, ADD-TMJOA leads to impaired chondrogenic progenitor capacity and osteogenesis differentiation of FCSCs lineage, resulting in cartilage degeneration and loss of subchondral bone homeostasis, finally causing TMJ growth retardation. DR at an early stage could significantly alleviate cartilage degeneration and restore TMJ cartilage growth potential.

Application of digital three-dimensional surgical simulation system combined with 3D printing in specialist training of orthognathic surgery / 中华医学教育探索杂志

The teaching of orthognathic surgery is difficult because it is complex and emphasizes the combination of theory and practice. The traditional teaching method focuses on theoretical teaching, but due to the limitation of conditions, it is difficult for students to master the operation. In this paper, we apply the digital three-dimensional surgical simulation system combined with 3D printing in specialist training of orthognathic surgery. Digital software and 3D printing are applied in the theoretical teaching, surgical operation, summary and reflection to combine practical teaching with theoretical teaching, so as to stimulate the subjective initiative of the students. The results showed that the teaching evaluation of the experimental group [(3.89±0.84) points] was better than that of the control group [(2.91±1.21) points]. The application of digital three-dimensional surgical simulation system combined with 3D printing has achieved satisfactory results.

Common characteristics of temporomandibular joint surgery and orthognathic surgery / 中华口腔医学杂志

Orthognathic surgery and temporomandibular joint (TMJ) surgery are two relatively independent disciplines in oral and maxillofacial surgery. Dentofacial deformities and TMJ diseases commonly coexist. The diagnosis and treatment of the diseases with coexisting dentofacial deformities and TMJ disorders is complex. Thus it is very important to comprehensively understand the common characteristics of orthognathic and TMJ surgery, which places a greater demand on oral and maxillofacial surgeons. The present work focuses on our thinking on common characteristics of TMJ and orthognathic surgery based on the managements of these diseases.

Mesenchymal stem cells modified with Runt-related transcription factor 2 promote bone regeneration in rabbit mandibular distraction osteogenesis / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This work investigated mesenchymal stem cells (MSCs) modified with Runt-related transcription factor 2 (Runx2) therapy for bone regeneration in rabbit mandibular distraction osteogenesis.</p><p><b>METHODS</b>Forty-eight New Zealand mature white rabbits were randomly divided into three groups after the rabbit model of mandibular distraction osteogenesis was established: reconstruction plasmid modified with Runx2 (group A), plasmid without Runx2 (group B), and the same dose of saline as control (group C). At the fifth day of distraction phase, MSCs with reconstruction plasmid modified with adv-hRunx2-gfp were injected into the distraction gap of group A. MSCs with reconstruction plasmid modified with adv-gfp was injected into the distraction gap of group B, whereas group C was injected with the same dose of saline. At 8 weeks after injection, all animals were sacrificed, and the distracted mandibles were harvested. The general imaging histological observation and three-point bending test were used for evaluation.</p><p><b>RESULTS</b>CT plain scan and histological analysis confirmed that the amount of new bone forming in the distraction gap of group A was significantly higher than those in groups B and C. Dual-energy X ray and three-point bending test results also showed that the bone mineral density, bone mineral content, and maximum load of the distraction gap of group A were significantly higher than those of groups B and C (P<0.01).</p><p><b>CONCLUSION</b>Runx2-ex vivo gene therapy based on MSCs can effectively promote the bone regeneration in rabbit mandibular distraction osteogenesis and shorten the stationary phase. Therefore, reconstruction of craniofacial fracture would be a valuable strategy</p>

Denervation effects on bone regeneration and expression of Runx2 during distraction osteogenesis / 中国组织工程研究

BACKGROUND:During the healing of fractures, removal of sciatic nerve can result in insufficient mechanical rigidity of newborn woven bone. However, there are less reports concerning the denervation effects during distraction osteogenesis. OBJECTIVE:To observe the effect of removal of the sciatic nerve on bone regeneration and the expression of Runt-related transcription factor 2 (Runx2) protein during distraction osteogenesis in a rabbit model. METHODS:Twenty-four adult male New Zealand rabbits were selected and underwent left tibial osteodistraction to construct animal models of distraction osteogenesis. Before distraction, the animals were randomly divided into group R (resecting the left sciatic nerve) and group I (intact left sciatic nerve). Six weeks after completion of distraction, the animals were kil ed and the lengthened tibias were harvested for radiography, three-dimensional CT reconstruction, histological evaluation, connectivity density (Conn.D) evaluation. RESULTS AND CONCLUSION:New regenerated bone was present and Runx2 protein was expressed in the distraction gaps of al animals at the end of the study, as revealed by radiography, three-dimensional CT reconstruction, and histological observation. However, less new bone formation and a lower degree of mineralization and expression of Runx2 protein were observed in group R compared with group I. The results suggest that the denervation appears to have an inhibitory effect on bone formation and the expression of Runx2 protein during distraction osteogenesis.

Two-stage treatment protocol for the management of temporomandibular joint ankylosis with secondary deformities in adults / 实用口腔医学杂志

Objective:To introduce a 2-stage treatment protocol for the management of temporomandibular joint ankylosis with sec-ondary deformities in adults.Methods:24 adult patients (9 males and 15 female)(30 joints)at the average age of 26.1 years un-derwent TMJ reconstruction as the initial surgery,followed by orthodontic treatment and correction of secondary deformities as the sec-ond surgery.Clinical outcome was assessed based on maximal incisal opening,radiography and medical photography.Results:Skele-tal deformities were significantly improved in all patients,satisfactory occlusion was achieved with the orthodontic treatment,average maximal incisal opening increased from 3.4 mm to 32.5 mm(P <0.05).Conclusion:The 2-stage treatment protocol is an effective approach for management of TMJ ankylosis with secondary deformities in adult patients.

Notch signaling pathway,articular cartilage development and osteoarthritis / 中国组织工程研究

BACKGROUND:Osteoarthritis,often accompanied by cartilage abnormal signal transduction,suggesting that intracellular signal transduction may play an important role in osteoarthritis genesis and development.OBJECTIVE:To review recent advances in the research of Notch signaling pathway,and explore the mechanisms of chondrogenic differentiation of bone marrow mesenchymal stem cells and its role in cartilage development and chondrogenesis.To analysis the role of dysregulated Notch signaling in the development of osteoarthritis.METHODS:Pubmed was undertaken to identify the relevant articles published from March 1919 to February 2009 with the key words of"Notch signaling pathway,osteoarthritis,chondrocytes,chondrogenesis,bone marrow stem cells"in English.Simultaneously,CNKI Database was searched for relevant articles published from February 2004 to September 2008 with the key words of"Notch signaling pathway,osteoarthritis,chondrocytes,chondrogenesis,bone marrow stem cells"in Chinese Articles with the Notch signaling pathway-related research,Notch signaling pathway of bone marrow-derived mesenchymal stem cells,differentiation of cartilage relative to the mechanism studies,and the Notch signaling pathway disorders and osteoarthritis research were included,Reproducibility articles were excluded Development regulation of articular cartilage and cartilage cell proliferation were considered as evaluation indexes.RESULTS AND CONCLUSION:Of 632 articles retrieved,30 were included in our study according to the inclusive and exclusive criteria.The Notch pathway is a highly consewed signaling mechanism involved in many processes determining cell fate during development and maintenance of homeostasis of mature tissues in the adult organism.Activation of Notch occurs following Notch receptor/ligand engagement upon cell-cell contact,which initiates translocation of the Notch intracellular domain to the nucleus and activation of target genes.It has been demonstrated that the Notch signaling plays an important role in regulating articular cartilage development and chondrocyte proliferation and differentiation In recent studies abnormality of notch signaling was also found in disease,which suggests that notch signaling is involved in osteoarthritis initiation and development.Further study of the specific mechanism of notch signaling in the initiation and development of osteoarthritis will enable us to develop targeted approaches in the treatment of osteoarthritis,thus bring more strategies in the future treatment of osteoarthritis.