The temporomandibular joint(TMJ)is the critical functional unit in the human stomatognathic system.Damage of the TMJ causes orofacial dysfunction and secondary jaw deformities,leading to seriously decreased quality of life in patients.The TMJ prosthetic replacement is an important treatment method for severe joint destruction because of its remarkable advantages compared with other methods.In recent years,this technique has gradually attracted wide attention in China,but it has not been popularized on a large scale in our country because of several limitations.Thus,in this study,the clinical experience of patients with TMJ prosthetic replacement in clinical units was summarized,and the treatment principles,treatment processes,and technical advantages were systematically discussed,aiming to promote the popularization and application of TMJ prosthetic replace-ment in China.

Temporomandibular joint (TMJ) diseases are common clinical conditions. The number of patients with TMJ diseases is large, and the etiology, epidemiology, disease spectrum, and treatment of the disease remain controversial and unknown. To understand and master the current situation of the occurrence, development and prevention of TMJ diseases, as well as to identify the patterns in etiology, incidence, drug sensitivity, and prognosis is crucial for alleviating patients′suffering.This will facilitate in-depth medical research, effective disease prevention measures, and the formulation of corresponding health policies. Cohort construction and research has an irreplaceable role in precise disease prevention and significant improvement in diagnosis and treatment levels. Large-scale cohort studies are needed to explore the relationship between potential risk factors and outcomes of TMJ diseases, and to observe disease prognoses through long-term follw-ups. The consensus aims to establish a standard conceptual frame work for a cohort study on patients with TMJ disease while providing ideas for cohort data standards to this condition. TMJ disease cohort data consists of both common data standards applicable to all specific disease cohorts as well as disease-specific data standards. Common data were available for each specific disease cohort. By integrating different cohort research resources, standard problems or study variables can be unified. Long-term follow-up can be performed using consistent definitions and criteria across different projects for better core data collection. It is hoped that this consensus will be facilitate the development cohort studies of TMJ diseases.

Objective:To conduct a retrospective study on the treatment outcomes of patients who underwent artificial temporomandibular joint (TMJ) replacement surgery and to evaluate the effectiveness of artificial TMJ treatment.Methods:This study selected 62 patients who received standard Biomet artificial TMJ treatment at Department of Orthognathic and TMJ Surgery, West China Hospital of Stomatology, Sichuan University from May 2010 to September 2023 as the study subjects. Among them, there were 15 male patients and 47 female patients. The average age was 33.5 years old(ranging from 18 to 67 years). This study statistically analyzed postoperative indicators, including maximum mouth opening, forward jaw movement, lateral movement, postoperative pain scores, and patient satisfaction.Results:This study included a total of 62 patients with 99 TMJ joints. No infections occurred postoperatively. The average follow-up period was 33.7 months (ranging from 7 to 170 months). At 6 months postoperatively, the mean mouth opening was (36.1±6.2) mm, lateral movement was (2.1±0.9) mm, and forward jaw movement was (1.0±0.9) mm. The pain visual analog scale score at 6 months postoperatively was (2.8±0.6), and patient satisfaction with the surgery was (8.8±1.1). Spiral CT scans conducted after surgery showed no joint dislocation or migration, and the artificial joint remained stable during the follow-up period.Conclusions:Artificial TMJ replacement is a valuable method for effectively restoring TMJ structure and essential functions related to mouth opening and chewing. It is worthy of promotion as a reconstructive approach for the temporomandibular joint

The biological clock(also known as the circadian rhythm)is the fundamental reliance for all organisms on Earth to adapt and survive in the Earth's rotation environment.Circadian rhythm is the most basic regulatory mechanism of life activities,and plays a key role in maintaining normal physiological and biochemical homeostasis,disease occurrence and treatment.Recent studies have shown that the biologi-cal clock plays an important role in the development of oral tissues and in the occurrence and treatment of oral diseases.Since there is cur-rently no guiding literature on the research methods of biological clock in stomatology,researchers mainly conduct research based on pub-lished references,which has led to controversy about the research methods of biological clock in stomatology,and there are many confusions about how to rationally apply the research methods of circadia rhythms.In view of this,this expert consensus summarizes the characteristics of the biological clock and analyzes the shortcomings of the current biological clock research in stomatology,and organizes relevant experts to summarize and recommend 10 principles as a reference for the rational implementation of the biological clock in stomatology research.

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⁺; Tm^fl/-mice and Sox9-CreER⁺;Tm^fl/-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.
Animals ; Mice ; Osteogenesis ; Zinc Finger Protein GLI1 ; Fibrocartilage ; Temporomandibular Joint ; Disease Models, Animal ; Osteoarthritis ; Stem Cells ; Growth Disorders

Orthognathic surgery changes the jaw position and occlusion, and also affects the original structure and function of the temporomandibular joint (TMJ). With the widespread development of orthognathic surgery, the impact of orthognathic surgery on the structure and function of the TMJ is increasingly valued, and the importance of the TMJ in orthognathic surgery is gradually recognized. Proper understanding the relationship between orthognathic surgery and TMJ not only helps to elucidate how the orthognathic surgery affects the condyle and causes temporomandibular disorders (TMD), but also has significant clinical significance in preventing and treating TMD in patients underwent orthognathic surgery.

Objective: To generate a new classification for adult temporomandibular joint ankylosis (TMJA), which could effectively guide treatment strategies for adult TMJA patients with various clinical features. Methods: We developed a new "CD" classification system according to the preservation of the condyle (C) and the severity of dentofacial bone deformity (D). From January 2016 to April 2020, 56 TMJ patients (with 73 ankylosed joints) in our department were classified into 4 subgroups by ‘CD’ classification: condylar head preservation but no dentofacial deformities (C+D-), no condylar head preservation and no dentofacial deformities (C-D-), condylar head preservation and dentofacial deformities (C+ D+), and no condylar head preservation but dentofacial deformities (C-D+). Different strategies were used according to the clinical features of each subgroup. The clinical outcomes of these patients were analyzed. Different treatment strategies of temporomandibular joint reconstruction were adopted for different subclasses of patients and were followed. "C +": lateral arthroplasty (LAP) was used to remove the rigidity and preserve the medial residual condyle. "C-": if the ankylosing bone ball is small and the loss of ascending branch height is not obvious, arthroplasty should be performed to relieve ankylosis; however, if the ankylosing bone ball is large and the ascending branch height decreases significantly, joint reconstruction should be carried out after the ankylosis is relieved. "D +": surgical treatment of secondary dental and maxillofacial malformations at the same time or over stages. "D-": orthodontic treatment after operation to improve occlusal relationship and symptomatic treatment of oral diseases. Results: After treatment, all 73 ankylosed joints were completely released, and the average maximal interincisal opening increased from (3.6±3.2 )to (32.8 ± 5.4) mm (P<0.001), with no recurrence of ankylosis found during the 12-48 month follow-up period. Conclusion The generation and elaboration of a ‘CD’ classification system is intended to help as a TMJA reconstruction guide for adult TMJA treatment and be widely used in more hospitals.

Objective:To evaluate the 2-dimension and 3-dimension changes of upper airway of patients who were diagnosed with idiopathic condylar resorption (ICR) and anterior open bite as well as received bilateral temporomandibular joint (TMJ) prostheses replacement or bimaxillary orthognathic surgery.Methods:This study is a retrospective study. Seventeen patients diagnosed as ICR and anterior open bite in Department of Orthognathic and TMJ surgery, West China Hospital of Sichuan University were selected (January 2018 to December 2021) and divided into bilateral TMJ protheses replacement group (group R, n=8) and orthognathic group (group O, n=9), according to which surgery they have performed. In order to compare variation of upper airway before and after surgery in different dimensions and sections within the same group or between groups, Spiral computed tomography data were obtained before (1 month) and after operation (10 to 12 months) to measure the total volume of airway (VT), the maximum sagittal area (MSA), the maximum cross-sectional area (MACA), the minimum cross-sectional area (MICA), the area of the most posterior plane(PPA), the area of soft-palate plane (SPA), the area of the most posterior point of tongue base plane (PTA), the area of the root of epiglottis plane (EA), the oropharyngeal airway volume (VO), the glossopharyngeal airway volume (VG) and the laryngeal airway volume (VL). Wilcoxon signed-rank test were used to complete statistical analyses for VO (T2),SPA (T2),ΔMSA,ΔMACA in group R as well as PTA (T1),EA (T2) in group O. Statistical analyses of other items were performed with student′s t test. Results:VT, VO, VG, VL, MSA, MACA, MIC, PPA, PTA and EA of group R (T2) were significantly increased after TMJ prosthesis with Lefort Ⅰ osteotomy ( P<0.05). Meanwhile the VT, VO, VG, MSA, MACA, MICA, PPA and SPA of group O (T2) were significantly increased ( P<0.05). There were significant difference in ΔVT and ΔVL between group R [(6 854.80±3 197.82) mm 3, (2 252.85±1 527.96) mm 3] and group O [(3 367.91±3 124.62) mm 3, (413.21±1 244.44) mm 3]( t=2.27, P=0.038; t=2.74, P=0.015). Conclusions:Bilateral temporomandibular joint (TMJ) prostheses replacement and bimaxillary orthognathic surgery can both enlarge the areas and volumes of upper airway in patients who suffer from ICR and anterior open bite. Compared with bimaxillary orthognathic surgery, bilateral temporomandibular joint prostheses replacement plays a more pronounced role in enlargement and reconstruction of middle-inferior section of upper airway.

Objective : To design a novel biomimetic micro/nano hierarchical interface on endosseous titanium implants and investigate its effect on the biological activity of bone marrow mesenchymal cells. Methods: Electrochemical anodization and spark plasma sintering were used to modify smooth titanium (untreated Ti group) with a microporous trabecular bone-like architecture (micro-Ti group) and TiO2 nanotube architecture (nano-TiO2 group). Additionally, electrochemical anodization was employed to prepare TiO2 nanotubes on microporous trabecular bone-like architectures, which formed a novel biomimetic hierarchical interface (micro/nano-TiO2 group). Four groups of titanium samples were characterized by field emission scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle (CA). Bone marrow mesenchymal cells (BMMCs) were seeded on four groups of titanium samples. Scanning electron microscopy (SEM) was employed to observe cell morphology. Cell proliferation was determined by MTT assay. The expression of focal adhesion proteins (F-actin; vinculin; osteocalcin, OCN; osteopontin, OPN) were observed under a confocal laser scanning microscope (CLSM). The mRNA expression levels of osteogenic factors (runt-related transcription factor 2, RUNX2; osteocalcin, OCN; osteopontin, OPN; collagen I, COL I) were assessed by qRT-PCR. Results: The micro/nano- TiO2 group featured a hydrophilic surface (CA=9° ± 2.1°). The results of the MTT assay indicated that the relative cell proliferation rates for the nano- TiO2 and micro/nano-TiO2 samples were significantly increased compared with those for the untreated-Ti and micro-Ti samples (P＜0.001) after 5-9 days. The ALP results indicated that the micro/nano-TiO2 sample gained the highest value at 14 days. After 72 h of incubation, the expression of osteocalcin (OCN) and osteopontin (OPN) on micro/nano-TiO2 was the strongest. After 24 h incubation, the expression of F-actin on micro/nano-TiO2 was the strongest. In comparison with untreated-Ti and micro-Ti samples,the mRNA expression levels of all the osteogenic factors (runt-related transcription factor 2, RUNX2; osteocalcin, OCN; osteopontin, OPN; Collagen I, COL I) were markedly increased on the nano-TiO2 and micro/nano-TiO2 samples, the mRNA expression levels of collagen I (COL I) were significantly different between the nano-TiO2 and micro/nano-TiO2 samples versus the untreated-Ti and micro-Ti samples (P＜0.001). Conclusion The novel biomimetic micro/nano hierarchical interface has a positive effect on cell attachment, viability and osteogenic differentiation of bone marrow mesenchymal cells.

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.