As a representative part of the oral system and masticatory robot system, the modeling method of the dental model is an important factor influencing the accuracy of the multi-body dynamic model. Taking the right first molars of the masticatory robot as the research object, an equivalent model, point-contact higher kinematic pair composed of v-shaped surface and sphere surface, was proposed. Firstly, the finite element method was used to analyze the occlusal dynamics of the original model in three static contact cases (intrusive contact, centric occlusion, and extrusive contact) and one dynamic chewing case, and the expected bite force was obtained. Secondly, the Hertz contact model was adopted to establish the analytical expression of the bite force of the equivalent model in three static contact cases. The normal vectors and contact stiffness in the expression were designed according to the expected bite force. Finally, the bite force performance of the equivalent model in three static contact cases and one dynamic chewing case was evaluated. The results showed that the equivalent model could achieve the equivalent bite force of 8 expected items in the static contact cases. Meanwhile, the bite force in the early and late stages of the dynamic chewing case coincides well with the original model. In the middle stage, a certain degree of impact is introduced, but it can be weakened by subsequent trajectory planning. The equivalent modeling scheme of the dental model proposed in this paper further improves the accuracy of the dynamic model of the multi-body system. It provides a new idea for the dynamic modeling of other complex human contacts.
Stress distribution of denture is an important criterion to evaluate the reasonableness of technological parameters, and the bite force derived from the antagonist is the critical load condition for the calculation of stress distribution. In order to improve the accuracy of stress distribution as much as possible, all-ceramic crown of the mandibular first molar with centric occlusion was taken as the research object, and a bite force loading method reflecting the actual occlusal situation was adopted. Firstly, raster scanning and three dimensional reconstruction of the occlusal surface of molars in the standard dental model were carried out. Meanwhile, the surface modeling of the bonding surface was carried out according to the preparation process. Secondly, the parametric occlusal analysis program was developed with the help of OFA function library, and the genetic algorithm was used to optimize the mandibular centric position. Finally, both the optimized case of the mesh model based on the results of occlusal optimization and the referenced case according to the cusp-fossa contact characteristics were designed. The stress distribution was analyzed and compared by using Abaqus software. The results showed that the genetic algorithm was suitable for solving the occlusal optimization problem. Compared with the reference case, the optimized case had smaller maximum stress and more uniform stress distribution characteristics. The proposed method further improves the stress accuracy of the prosthesis in the finite element model. Also, it provides a new idea for stress analysis of other joints in human body.
Objective To investigate the relationship between the red blood cell distribution width (RDW) and the severity of community-acquired pneumonia (CAP). Methods The clinical data of 285 adult patients with CAP admitted from November 2014 to August of 2017 were analyzed retrospectively. The severity of CAP was evaluated by pneumonia severity index (PSI) score. Meanwhile, 60 cases with qualified medical examination were collected as a healthy control group. The distributions of PSI score, RDW, procalcitonin (PCT), C-reactive protein (CRP) and neutrophil percentage (NEU%) were described in the patients with different risk degree. The correlation analysis of various indicators were analyzed by Spearman correlation. The threshold of RDW(%) was calculated through the construction of the general linear regression equation. The risk factors of PSI score were analyzed with multiple linear regression. Results The higher the risk stratification, the higher the distribution of PSI scores, RDW, PCT, CRP and NEU% were. RDW was positively correlated with PCT, CRP, and NEU% (r values were 0.417, 0.252, 0.318, respectively, P<0.05). PSI score was positively correlated with RDW, PCT, CRP, and NEU% (r values were 0.537,0.598, 0.557, 0.482, respectively, P<0.05). RDW was positively correlated with PSI score (r=0.537, P<0.05). The thresholds of RDW(%) were 14.514 and 19.041. Multiple linear regression showed that RDW, PCT, CRP and NEU% were all influential factors of PSI scores and explained 46.9% of the total mutation rate. Conclusion RDW is correlated with the severity of CAP, and can predict the severity of CAP.
ObjectiveTo investigate the clinical characteristics of uniportal and three-port subxiphoid video-assisted thoracoscopic surgery (XVATS) extended thymectomy.MethodsThe clinical data of 60 consecutive patients of XVATS thymectomy in Xuzhou Central Hospital from January 2017 to May 2019 were retrospectively analyzed. There were 29 males and 31 females, with an average age of 53.1 (27.0-76.0) years. The patients were divided into an uniportal XVATS group (30 patients) and a three-port XVATS group (30 patients). The clinical effectiveness was compared between the two groups.ResultsThere was no significant difference in age, sex, body mass index, tumor size, intraoperative blood loss, postoperative time of thoracic tube indwelling and thoracic drainage, or postoperative hospitalization time between the two groups (P>0.05). There was no perioperative mortality, conversion to thoracotomy, thrombosis or mediastinal infection. The operation time of the uniportal XVATS group was significantly longer than that of the three-port group (87.5±19.0 min vs. 75.8±15.7 min, P=0.012). Besides, patients in the uniportal group had significantly lower pain score during 3-14 postoperative days than that of the three-port group (P=0.001).ConclusionUniportal XVATS extended thymectomy is feasible with less pain as compared with the patients using three-port XVATS, but it needs longer operation time at initial stage.
ObjectiveTo explore the feasibility and short-term efficacy of uniportal and three-port single-direction video-assisted thoracoscopic surgery (S-VATS) anatomical lobectomy for lung cancer.MethodsClinical data of 60 lung cancer patients, including 40 males and 20 females with an average age of 62.2±9.0 years, who received S-VATS anatomic lobectomy and systematic lymph nodes dissection by the same surgeon in our hospital between July 2016 and January 2019 were retrospectively analyzed. These patients were divided into a uniportal S-VATS group and a three-port S-VATS group according to surgical procedures, with 30 patients in each group. The clinical data of the two groups were compared.ResultsThere was no conversion to thoracotomy, surgical port addition, or mortality in this cohort, with tumor-negative surgical margin. There was no statistical difference in the operation time between the two groups (70.8±16.4 min vs. 73.7±14.3 min, P>0.05). Meanwhile, both groups showed similar intraoperative blood loss, stations and numbers of dissected lymph nodes, incidence of operation-related complications, duration and volume of chest tube drainage, as well as postoperative hospital stay (P>0.05). Besides, pain score of the patients in the uniportal S-VATS group was significantly lower than that of the three-port S-VATS group on postoperative 3-14 d (P<0.05). The mean duration of follow-up was 10 months, and all the patients were survived without tumor recurrence or metastasis.ConclusionThe transition from three-port S-VATS to uniportal S-VATS anatomical lobectomy for treatment of lung cancer is feasible. However, further studies are needed to elucidate the optimal resection sequence of pulmonary vessels.
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 study the expression of NLRP3 inflammasome and its downstream inflammatory factors in patients with chronic obstructive pulmonary disease (COPD) and healthy controls, and to reveal the effect and significance of NLRP3 inflammasome in the pathogenesis of COPD. Methods Forty patients with acute exacerbation COPD (AECOPD) who were hospitalized from November 2016 to May 2017 were recruited in the AECOPD group, and recruited in the stable COPD group when they entered the stable stage. Forty healthy individuals were recruited in the control group. General information and peripheral blood were collected from each subject. The levels of NLRP3 mRNA and caspase-1 mRNA in peripheral blood mononuclear cells were measured by real-time PCR. The levels of IL-18 and IL-1β were measured by enzyme-linked immunosorbent assay. Results The levels of NLRP3 mRNA, IL-18 and IL-1β in the AECOPD patients were significantly higher than those in the stable COPD group [2.11±0.77, 12.79 (7.10, 43.13) pg/ml, 17.02 (8.36, 52.21) pg/ml vs. 1.60±0.44, 10.66 (6.32, 18.59) pg/ml, 13.34 (7.07, 16.89) pg/ml, all P<0.05] . The levels of NLRP3 mRNA, IL-18 and IL-1β in the AECOPD patients were significantly higher than those in the control group [2.11±0.77, 12.79 (7.10, 43.13) pg/ml, 17.02 (8.36, 52.21) pg/mlvs. 1.00±0.49, 6.29 (4.73, 7.93) pg/ml, 5.93 (4.81, 9.67) pg/ml, all P<0.05]. The levels of NLRP3 mRNA, IL-18 and IL-1β were significantly higher in the stable COPD group than the control group [1.60±0.44, 10.66 (6.32, 18.59) pg/ml, 13.34 (7.07, 16.89) pg/mlvs. (1.00±0.49, 6.29 (4.73, 7.93) pg/ml, 5.93 (4.81, 9.67) pg/ml, all P<0.05]. Correlation analysis showed that the plasma IL-18 level was positive correlated with leukocyte count and neutrophil percentage in the AECOPD group (r=0.372, P<0.05;r=0.386, P<0.05). The expression of NLRP3 mRNA in the AECOPD group and stable COPD group were positively correlated with the CAT score (r=0.387, P<0.05;r=0.399, P<0.05) . Conclusion NLRP3 inflammasome is involved in the inflammatory response in COPD patients.
ObjectiveTo analyze the biomechanical properties of the rod-screw prosthesis based on a pelvic three-dimensional finite element model including muscle and ligament, and evaluate the effectiveness of zoneⅠ+Ⅱ+Ⅲ reconstruction of hemipelvis with rod-screw prosthesis in combination with clinical applications. Methods A total of 21 patients who underwent hemipelvic tumor resection (zoneⅠ+Ⅱ+Ⅲ) and rod-screw prosthesis reconstruction between January 2015 and December 2020 were selected as the research subjects. Among them, there were 11 males and 10 females; the age ranged from 16 to 64 years, with an average age of 39.2 years. There were 9 cases of chondrosarcoma, 7 cases of osteosarcoma, 3 cases of Ewing sarcoma, and 2 cases of undifferentiated pleomorphic sarcoma. According to the Musculoskeletal Tumor Society Score (MSTS) staging, there were 19 cases of stage ⅡB and 2 cases of stage Ⅲ. Preoperative Harris Hip Score (HHS) and MSTS score were 54.4±3.1 and 14.1±2.0, respectively. Intraoperative 15 cases underwent extensive resection, 5 cases underwent marginal resection, and 1 case underwent intralesional resection. The CT image of 1 patient after reconstruction was used to establish a three-dimensional solid model of the pelvis via Mimics23Suite and 3-matic softwares. At the same time, a mirror operation was used to obtain a normal pelvis model, then the two solid models were imported into the finite element analysis software Workbench 2020R1 to establish three-dimensional finite element models, and the biomechanical properties of the standing position were analyzed. The operation time, intraoperative blood loss, and operation-related complications were recorded, and the postoperative evaluation was carried out with HHS and MSTS scores. Finally, the local recurrence and metastasis were reviewed. ResultsFinite element analysis showed that the peak stress of the reconstructed pelvis appeared at the fixed S1, 2 rod-screw connections; the peak stress without muscles was higher than that after muscle construction, but much smaller than the yield strength of titanium alloy. The operation time was 250-370 minutes, with an average of 297 minutes; the amount of intraoperative blood loss was 3 200-5 500 mL, with an average of 4 009 mL. All patients were followed up 8-72 months, with an average of 42 months. There were 7 cases of pulmonary metastasis, of which 2 cases were preoperative metastasis; 5 cases died, 16 cases survived, and the 5-year survival rate was 72.1%. There were 3 cases of local recurrence, all of whom did not achieve extensive resection during operation. The function of the affected limbs significantly improved, and the walking function was restored. The HHS and MSTS scores were 75.2±3.0 and 20.4±2.0 at last follow-up, respectively, and the differences were significant when compared with those before operation (t=22.205, P<0.001; t=11.915, P<0.001). During follow-up, 2 cases of delayed incision healing, 2 cases of deep infection, 1 case of screw loosening, and 1 case of prosthesis dislocation occurred, and no other complication such as prosthesis or screw fracture occurred. Conclusion The stress and deformation distribution of the reconstructed pelvis are basically the same as normal pelvis. The rod-screw prosthesis is an effective reconstruction method for pelvic malignant tumors.