Masticatory robots have a broad application prospect in the field of denture material tests and mandible rehabilitation. Mechanism type of temporomandibular joint structure is an important factor influencing the performance of the masticatory robot. In view of the wide application of elastic components in the field of the biomimetic robot, an elastic component was adopted to simulate the buffering characteristics of the temporomandibular joint disc and formed the elastic temporomandibular joint structure on the basis of point-contact high pair. Secondly, the influences of the elastic temporomandibular joint structure (on mechanism degree, kinematics, dynamics, etc.) were discussed. The position and velocity of the temporomandibular joint were analyzed based on geometric constraints of the joint surface, and the dynamic analysis based on the Lagrange equation was carried out. Finally, the influence of the preload and stiffness of the elastic component was analyzed by the response surface method. The results showed that the elastic temporomandibular joint structure could effectively guarantee the flexible movement and stable force of the joint. The elastic joint structure proposed in this paper further improves the biomimetic behavior of masticatory robots. It provides new ideas for the biomimetic design of viscoelastic joint discs.
Objective To discuss the stabil ity and practical ity of temporomandibular joint replacement by establ ishing goats artificial temporomandibular joint replacement model. Methods Six healthy mature goats were selected, the male and female being half and weighing 35.3-37.0 kg. According to the parameters from X-ray films of goat’ s temporomandibular joint and the shape of the same kind goat’s skull, the total temporomandibular joint prosthesis was prepared. The one side temporomandibular joints of six goats were replaced by prosthesis randomly as the experimental group (n=6, fossa and condyle according to replacement location) and the other side by titanium plate as the control group (n=6). At 4,8, and 12 weeks, the histological observation, scanning electron microscope (SEM) observation were carried out for observing structural changes in the interface. The mechanical test and histochemistry test were used for observing the combination degree of interface and the alkal ine phosphatase (ALP) activity. Results All animals were al ive to the end of experiment with normal open mouth, good recovery of masticatory function, and normal eating. At 4, 8, and 12 weeks, implants were stable in 2 groups without loosening. The histological observation and SEM observation showed the amount of osteoblasts in interface increased over times. There were significant differences in the shearing force and the ALP activity between fossa in experimental group and control group at 4 weeks (P lt; 0.05), but there was no significant difference between other groups (P gt; 0.05). Conclusion The total temporomandibular prosthesis has good stabil ity in temporomandibular joint reconstruction of goat after replacement.
【Abstract】 Objective To assess the feasibility and clinical outcomes of artificial condylar process in reconstruction of the temporomandibular joint. Methods Between January 2005 and January 2010, the reconstructions of the temporomandibular joints with artificial condylar process were performed in 10 cases (11 sides, including 7 left sides and 4 right sides). There were 7 males and 3 females with an average age of 50 years (range, 40-68 years). Mandibular condyle defects were caused by mandible tumor in 7 patients with a mean disease duration of 15 months (range, 9-24 months) and by bilateral condylar fractures in 3 patients with the disease duration of 2, 3, and 2 days respectively. According to Neff classification, there were type M and A in 1 case, type M and B in 1 case, and type M in one side and subcondylar fracture in the other side in 1 case. Results Incisions in all patients healed by first intention, and no complication occurred. All cases were followed up 1 to 4 years, showed facial symmetry and good occluding relation, and the mouth opening was 22-38 mm (mean, 30 mm). No temporomandibular joint clicking or pain and no recurrence of tumor were observed. Most of the artificial condylar process were in good position except 1 deviated from the correct angle slightly. All the patients could have diet normally. Conclusion The results of temporomandibular joint reconstruction after tumor resection with artificial condylar process are good, but the clinical outcome for intracapsular condylar fracture is expected to be further verified.
Temporomandibular joint disorder (TMD) is a common oral and maxillofacial disease, which is difficult to detect due to its subtle early symptoms. In this study, a TMD intelligent diagnostic system implemented on edge computing devices was proposed, which can achieve rapid detection of TMD in clinical diagnosis and facilitate its early-stage clinical intervention. The proposed system first automatically segments the important components of the temporomandibular joint, followed by quantitative measurement of the joint gap area, and finally predicts the existence of TMD according to the measurements. In terms of segmentation, this study employs semi-supervised learning to achieve the accurate segmentation of temporomandibular joint, with an average Dice coefficient (DC) of 0.846. A 3D region extraction algorithm for the temporomandibular joint gap area is also developed, based on which an automatic TMD diagnosis model is proposed, with an accuracy of 83.87%. In summary, the intelligent TMD diagnosis system developed in this paper can be deployed at edge computing devices within a local area network, which is able to achieve rapid detecting and intelligent diagnosis of TMD with privacy guarantee.
Objective To assess the effectiveness of intraarticular injection of hyaluronate (HA) on temporomandibular disorders (TMD). Methods Searching various databases available, handsearching 15 Chinese dental journals to find articles, abstracts and unpublished literature with randomized or quasi-randomized design on the effects of intraarticular injection of HA on TMD.Data extraction, appraisal, and the methods for Meta-analysis were conducted based on the Cochrane guidelines. Results 12 RCTs and 2 CCT on TMD and 1 RCT on rheumatoid arthritis involving temporomandibular joints (TMJ) were located, 10 of them fulfilled inclusion criteria in which 561 patients were reported.Except 71 cases with only qualitative data, 490 cases could be calculated in Meta-analysis: 277 on HA, 113 on placebo or non-treatment (PL) and 100 on corticosteroids (CO). In comparison with PL, HA injection showed no statistically significant effect on short and long term improvement of symptoms, and short term improvement of VAS as well. But it presented significant better effects than PL in short and long term improvement of clinical signs, especially mouth opening. When sensitivity analysis was conducted for improvement of short term signs, the conclusion was not stable. Comparison of the effect between HA and CO showed the same efficacy levels. Adverse reactions of HA were mild and transient. Conclusions HA may improve short and long term clinical signs of TMD and have only mild and transient adverse reactions. However, more RCTs are needed to confirm its therapeutic effect.
Objective To investigate the effect of hydrostatic pressure and insulin-like growth factor 1 (IGF-1) on the expression of filamentous actin (F-actin) of temporomandibular joint disc cells in goats, and to analyze the F-actin changes of temporomandibular joint disc cells in vitro under hydrostatic pressure and IGF-1 stimulation. Methods The bilateral temporomandibular joint discs were harvested from 4 1-month-old goats, and temporomandibular joint disc cells were isolated with collagenase. Immunohistochemical staining for collagen type I and collagen type II was performed for identification. The cells at passages 2-3 were used; the experiment was divided into 4 groups according to different interventions: the cells were cultivated with complete medium in group A as control; the cells were intervened by hydrostatic pressure (0.2 MPa and 1 Hz for 3 hours) in group B, by complete medium containing IGF-1 (10 ng/mL) in group C, and by a combination of hydrostatic pressure (0.2 MPa and 1 Hz for 3 hours) and complete medium containing IGF-1 (10 ng/mL) in group D. The changes of F-actin at 24 and 72 hours after cultivation were observed by immunofluorescence staining. The cell fluorescence intensity was measured. Results The cultivated cells were identified to be temporomandibular joint disc cells by morphological observation and immunohistochemical staining. At 24 hours, fluorescence intensity of groups A and C was b and clear, with normal morphology of temporomandibular joint disc cells; F-actin arranged in disorder in group B, and F-actin was thinner with arrangement disorder in group D. At 72 hours, the F-actin arranged regularly in groups A and C; however, some F-actin became blurry with irregular arrangement, breakage, and pseudopodia in group B; and F-actin was thinner and ruptured formed in group D. With time passing, the fluorescence intensity of F-actin in groups A, B, and D had an increasing trend, showing significant differences between 24 hours and 72 hours (P lt; 0.05); but there was no significant difference between 24 and 72 hours in group C (t=0.284, P=0.781). At 24 hours, fluorescence intensity of F-actin was highest in group C and was lowest in group B, showing significant difference when compared with groups A and D (P lt; 0.05). At 72 hours, fluorescence intensity in groups B and D was significantly lower than that in groups A and C (P lt; 0.05), but there was no significant difference between groups B and D, and between groups A and C (P gt; 0.05). Conclusion Hydrostatic pressure may cause the F-actin breakage and rearrangement of temporomandibular joint disc cells, and IGF-1 can up-regulate the F-actin expression. Such effects may be correlated with the biological behavior of the temporomandibular joint disc cells.
ObjectiveTo discuss the fixed restoration for severe dental attrition with partial dentition defect. MethodsWe selected 15 patients who had received treatments in Hebei Ophthalmology Hospital due to dental allergy, chewing weakness and temporomandibular joint dysfuction caused by severe attrition from February 2007 to October 2012. Among them, there were 9 males and 6 females, aged from 22 to 58 years old averaging 33. We performed occlusal reconstruction by fixed restoration for these patients, recovered their vertical dimension, and then carried out the follow-up. ResultsIn the two-year follow-up, two patients had porcelain cracking, one patient's metal-ceramic crown dropped; no gingiva swelling occurred, periodontal tissues were healthy, occlusal functions recovered well, temporomandibular joint dysfunction and masticatory muscles were not discomfortable, subfacial 1/3 was normal, and patients were satisfied with their appearance and facial contour. ConclusionUsing the fixed restoration to reconstruct occlusions can effectively recover patients' masticatory functions, add height for subfacial 1/3, and improve the symptoms of temporomandibular joint.
The aim of this study was to design a simple, economic, with high Common Mode Rejection Ratio (CMRR), preamplifier and multi-channel masticatory muscle surface electromyography (sEMG) signal acquisition system assisting to diagnose temporomandibular disorders (TMD). We used the USB interface technology in the EMG data with the aid of the windows to operate system and graphical interface. Eight patients with TMD and eight controls were analyzed separately using this system. In this system, we analyzed sEMG by an optional combination of time domain, frequency domain, time-frequency, several spectral analysis, wavelets and other special algorithms under multi-parameter. Multi-channel sEMG System of Masticatory Muscles is a simple, economic system. It has high sensitivity and specificity. The sEMG signals were changed in patients with TMD. The system would pave the way for diagnosis TMD and help us to assess the treatment effect. A novel and objective method is provided for diagnosis and treatment of oral-maxillofacial disease and functional reconstruction.
Objective To compare effects of intra-articular injection of corticosteroid or viscoelastic agent alone or a combination of the two drugs for treatment of temporomandibular joint disorders. Methods A prospective quasirandomized controlled trial was conducted to compare 3 treatment protocols of intra-articular injections in the upper compartment of the joint immediately following arthrocentesis repeatedly every 10 days: ① triamcinolone 8 mg alone for 3 times, ② 1% hyaluronate 1 ml alone for 4 times, and ③ triamcinolone 8 mg for 2 times then 1% hyaluronate 1 ml for 2 times. Clinical examinations were done at baseline, 1, 12, and 24 months after end of the treatments. According to improvement of the symptoms and clinical signs, the effectiveness was graded in 3 classes: excellent, better, no change, or worse. The first two were classified as effective. Effective rates of the treatments and subgroups were compared statistically. Results Five hundred and sixty four patients with temporomandibular disorders were included and randomly allocated to 3 groups with 188 patients in each group. The rate of lost follow up at 24 months was 6.9% to 10.1%. At one month after treatment, the triamcinolone group had a better effective rate at 92.0%. At 12 and 24 months of follow up, effective rates of the hyaluronate group were better than those in the triamcinolone alone group (84.6% vs. 54.1% and 83.4% vs. 40.4%). Effective rates of combining triamcinolone and hyaluronate group at 12 and 24 months were 90.4% and 66.3% respectively. Conclusion Intra-articular injection of corticosteroid has better results in a short term and hyaluronate has better results in a long term in the treatment of temporomandibular joint disorders.