Transcriptomic and proteomic studies of condylar ossification of the temporomandibular joint in porcine embryos

Background:The ossification mechanism of the temporomandibular joint(TMJ)condyle remains unclear in human embryo.The size and structure of TMJ,shape of articular disc and the characteristics of omnivorous chewing in the pig are similar to those of humans.The pig is an ideal animal for studying the mechanism of ossification of the TMJ condyle during the embryonic period.Method:In a previous study by our group,it was found that there was no condylar ossification on embryonic day(E)45,but the ossification of condyle occurred between E75 and E90.In this study,a total of 12 miniature pig embryos on E45 and E85 were used.Six embryos were used for tissue sections(3 in each group).The remaining six embryos were used for transcriptomic and proteomic studies to find differential genes and proteins.The differentially expressed genes in transcriptome and proteomic analysis were verified by QPCR.Results:In total,1592 differential genes comprising 1086 up-regulated genes and 506 down-regulated genes were screened for fold changes of≥2 to≤0.5 between E45 and E85.In the total of 4613 proteins detected by proteomic analysis,there were 419 differential proteins including 313 up-regulated proteins and 106 down-regulated proteins screened for fold changes of≥2 to≤0.5 between E45 and E85.A total of 36 differential genes differing in both transcriptome and proteome analysis were found.QPCR analysis showed that 14 of 15 selected genes were consistent with transcriptome analysis.Conclusion:Condylar transcriptome and proteomic analysis during the development of TMJ in miniature pigs revealed the regulatory genes/proteins of condylar ossification.

Hybrid treatment of varied orthodontic appliances for a patient with skeletal class II and temporomandibular joint disorders:A case report and review of literature

BACKGROUND The relation between orthodontic treatment and temporomandibular disorders(TMDs)is under debate;the management of TMD during orthodontic treatment has always been a challenge.If TMD symptoms occur during orthodontic treatment,an immediate pause of orthodontic adjustments is recommended;the treatment can resume when the symptoms are managed and stabilized.CASE SUMMARY This case report presents a patient(26-year-old,female)with angle class I,skeletal class II and TMDs.The treatment was a hybrid of clear aligners,fixed appliances and temporary anchorage devices(TADs).After 3 mo resting and treatment on her TMD,the patient’s TMD symptom alleviated,but her anterior occlusion displayed deep overbite.Therefore,the fixed appliances with TAD were used to correct the anterior deep-bite and level maxillary and mandibular deep curves.After the levelling,the patient showed dual bite with centric relation and maximum intercuspation discrepancy on her occlusion.After careful examination of temporomandibular joints(TMJ)position,the stable bite splint and Invisible Mandibular Advancement appliance were used to reconstruct her occlusion.Eventually,the improved facial appearance and relatively stable occlusion were achieved.The 1-year follow-up records showed there was no obvious change in TMJ morphology,and her occlusion was stable.CONCLUSION TMD screening and monitoring is of great clinical importance in the TMD susceptible patients.Hybrid treatment with clear aligners and fixed appliances and TADs is an effective treatment modality for the complex cases.

Loss of Masticatory Function Affects Growth and Development of the Mandibular Condyle in Rats

The effects of childhood masticatory function loss and soft foods on the mandibular condyle have been the subject of much research. However, the corresponding bone turnover is not fully understood. The purpose of the present study was to clarify the effects of a lack of teeth and a soft food diet during the growth period on bone turnover in the mandibular condyle. We divided 3-week-old Wistar rats into the following three groups: 1) Extraction group: The maxillary molars were extracted at the age of 4 weeks, and animals were fed powdered standard feed. 2) Powder group: Animals were fed powdered standard feed without tooth extraction. 3) Control group: Animals were fed solid standard feed without tooth extraction. Non-decalcified thin-slice specimens of sagittal sections of the mandibular condyle were obtained at the age of 20 weeks for histological analysis. We used micro-CT analysis and bone histomorphometry to measure bone volume (BV), bone mineral content (BMC), bone mineral density (BMD), bone microstructure, bone resorption, and osteogenesis in the mandibular condyle, and we compared the results among groups. In the extraction and the powder groups, we found deformation and disruption of the arrangement of chondrocytes, coagulation of chondrocytes, and duplication of the tidemark in the cartilage. We also found an increase in multinuclear osteoclasts in the cancellous bone. We found a reduction in BV, BMC, and BMD in the extraction and powder groups compared to the control group, as well as a reduction of bone volume, a lowering of osteogenesis parameters, and an increase in bone resorption parameters in the secondary cancellous bone. These results suggest that a lack of teeth and a soft food diet during the growth period cause a decline in bone microstructure, a decrease in osteogenesis, and an increase in bone resorption.

Transforming Adolescent Smiles:Correcting Skeletal Mandibular Retrusion and Bimaxillary Protrusion with Clear Aligners

Maxillary protrusion combined with mandibular retraction is a highly prevalent but extremely complex maxillofacial deformity that can have a serious negative impact on patients’facial aesthetics and mental health.The traditional orthodontic treatment strategy often involves extracting 4 first premolars and conventional fixed techniques,combined with mini-implant screws,to retract the anterior teeth and improve facial protrusion.In recent years,an invisible orthodontic technique,without brackets,has become increasingly popular.However,while an invisible aligner has been used in some cases with reasonable results,there remain significant challenges in achieving a perfect outcome.This case report presents an adolescent patient with bimaxillary protrusion and mandibular retrognathia.Based on the characteristics of the invisible aligners and the growth characteristics of the adolescent’s teeth and jawbone,we designed precise three-dimensional tooth movement and corresponding resistance/over-correction for each tooth,while utilizing the patient’s jawbone growth potential to promote rapid development of the mandible,accurately and efficiently correcting bimaxillary protrusion and skeletal mandibular retrognathia.The patient’s facial aesthetics,especially the lateral morphology,have been greatly improved,and various aesthetic indicators have also shown significant changes,and to the patient’s great benefit,invasive mini-implant screws were not used during the treatment.This case highlights the advantages of using invisible aligners in adolescent maxillary protrusion combined with mandibular retraction patients.Furthermore,comprehensive and accurate design combined with good application of growth potential can also enable invisible orthodontic technology to achieve perfect treatment effects in tooth extractions,providing clinical guidance for orthodontists.

Classification and Management of Mandibular Condyle Fractures in a Tertiary Health Center

Background: Condyle fractures are not common but could lead to detrimental effects of growth disturbance of the mandible, ankylosis of temporomandibular joint and facial asymmetry especially in children, if not promptly and adequately managed, the aim of this study was to document our experience in the management of mandibular condyle fractures. Method: The fractures were classified based on the age of the patient, unilateral/bilateral, location on the condyle, presence of displacement and dislocation, for those displaced, whether there was medial or lateral overlap, and features presented. Treatment done for each patient was documented. Both clinical and radiological assessments were done to ascertain the outcome of treatment. Result: 11 patients presented with 14 condyle fractures, 3 patients with bilateral and 8 with unilateral condyle fractures out of which 5 cases were on the right side. Age range of patients was between 13 and 44 years with a mean (SD) of 25.3 (10.7) years. Nine (81.8%) of the patients were males and 2 (18.2%) were females. Eight (72.7%) of the patients with condyle fracture had associated fractures affecting other sites of the mandible while 3 (27.3%) patients had isolated condyle fractures. Intracapusular fractures recorded were 2 (14.2%), while extracapsular accounted for 12 (85.8%) cases. Conservative treatment was not applied in any patient, 9 (81.8%) patients had IMF and 2 (18.2%) patients had ORIF. Conclusion: Most fractures of the condyle were extracapsular and, closed surgical treatment (IMF) was very useful to manage most of the cases.

Two-stage extraction by partial grinding of impacted mandibular third molar in close proximity to the inferior alveolar nerve

BACKGROUND Extraction of impacted third molars often leads to severe complications caused by damage to the inferior alveolar nerve(IAN).AIM To proposes a method for the partial grinding of an impacted mandibular third molar(IMM3)near the IAN to prevent IAN injury during IMM3 extraction.METHODS Between January 1996 and March 2022,25 patients with IMM3 roots near the IAN were enrolled.The first stage of the operation consisted of grinding a major part of the IMM3 crown with a high-speed turbine dental drill to achieve sufficient space between the mandibular second molar and IMM3.After 6 months,when the root tips were observed to be away from the IAN on X-ray examination,the remaining part of the IMM3 was completely removed.RESULTS All IMM3s were extracted easily without symptoms of IAN injury after extraction.CONCLUSION Partial IMM3 grinding may be a good alternative treatment option to avoid IAN injury in high-risk cases.

Condylar and Occlusal Changes after High Condylectomy and Orthodontic Treatment for Condylar Hyperplasia

Condylar hyperplasia（CH） of human temporomandibular joint（TMJ） often occurs unilaterally, and causes occlusal disturbance and facial asymmetry. The purpose of this study was to compare the effects of high condylectomy with and without postsurgical orthodontic treatment. Forty patients were diagnosed as having active CH and treated with high condylectomy. Patients in group A（n=24） took the postsurgical orthodontic therapy immediately after surgery, and those in group B（n=16） did not take orthodontic therapy. For both groups, the mandibular ramus height on the affected side was decreased significantly after surgery. Orthodontic treatment promoted maxillary alveolar remodeling significantly by depressing alveolar bone of the affected side and increasing alveolar bone of the nonaffected side. Better improvement for facial midline deviations was observed in group A than in group B. In both groups, the condylar remodeling was observed and manifested by the smoothening of condylar surface and returning of condyle to normal position in glenoid fossa. It was concluded that high condylectomy in the treatment of active CH of TMJ improved the functional occlusion and facial aesthetic. Postsurgical orthodontic therapy could more effectively enhance maxillary alveolar and condylar remodeling, and more rapidly and meticulously establish the stable occlusal and normal position of condyle than the spontaneous remodeling.

Comparison of computed tomography and magnetic resonance imaging for the detection of mandibular condylar osteochondroma

Objective The purpose of this study was to compare computed tomography(CT) and magnetic resonance imaging(MRI) for the detection of mandibular condylar osteochondroma.Methods Preoperative CT and MRI of 33 patients with unilateral condylar osteochondroma were reviewed. The morphology, location, continuity with the parent bone, cartilage cap, perichondrium of tumors, and changes in soft and hard tissues adjacent to the lesions were investigated by two reviewers. Data were analyzed using Mc Nemar test. A P value < 0.05 was considered significant.Results Among the 33 condylar osteochondromas, 11 were of the diffuse type, 10 were of the sessile type, and 12 were of the pedunculated type. Continuity with the cortex and marrow of the host condyle was observed on both CT and MRI. Both modalities had identical detection rates of surface reconstruction of the temporal bone joint, condylar dislocation, and pseudarthrosis formation. However, MRI showed significantly higher detection rates of the cartilage cap and perichondrium than CT(P < 0.05). Furthermore, MRI showed ipsilateral and contralateral temporo-mandibular joint(TMJ) disc displacement in 4 cases and 6 cases, respectively, and ipsilateral and contralateral TMJ effusion in 20 cases and 14 cases, respectively.Conclusion CT can intuitively display the morphology and spatial location of condylar osteochondromas through three-dimensional reconstruction. MRI may be superior to CT in the detection of cartilage cap, perichondrium of the condylar osteochondroma, and changes in the TMJ and adjacent soft tissues.

Genetic expression of Col-2A and Col-10A as a function of administration of IGF-1 &TGF-<i>β</i>with and without anterior mandibular repositioning appliance on the growth of mandibular condylar cartilage in young rabbit

New Zealand (NZ) young rabbits with the administration of insulin-like growth factor (IGF-1) and transforming growth factor-β (TGF-β) with and without mandibular anterior repositioning appliances are explored for the growth of the mandibular condylar cartilage (MCC). 32 growing NZ and rabbits were divided into 4 groups: the group with saline injection in TMJ, the group which received growth factor injection in TMJ, the group which received anterior positioning appliance and the group which received growth factors injection as well as mandibular repositioning appliance. Gene expression was studied by real-time RT-PCR and cartilage growth by histomorphometry. Administration of growth factors along with mandibular repositioning appliances has induced 1) 1.70-fold expression of Col-2Agene (p value < 0.0005) and 2) 1.47-fold expression of Col-10Agene (p value < 0.0005). In contrast, administration of only mandibular repositioning appliances induced 1) 1.28-fold expression of Col-2Agene (p value < 0.0005) and 2) merely 0.62-fold expression of Col-10Agene (p value < 0.0005), while administration of growth factors only induced 1) mere 0.56-fold expression of Col-2Agene (p value 10A gene (p value growth factors along with mandibular repositioning appliances causes an increase in genetic expressions which have been corroborated by histomorphometry and validated by statistical analysis, during an accelerated growth of mandibular condylar cartilage. Administration of growth factors in the TMJ could provide a synergistic role along with mandibular repositioning appliances for treatment of mandibular retrognathism as well as disorders on the MCC.

Efficacy of invisible advancement correction for mandibular retraction in adolescents based on Pancherz analysis

BACKGROUND Mandibular retraction is the main etiological mechanism of class II malocclusion in China and the subsequent distal molar relationship can cause functional discomfort in mastication,breathing and the temporomandibular joint.The use of mandibular advancement(MA)devices has recently emerged as an adolescent mandibular retraction treatment;however,current studies regarding the effect thereof are relatively few,and there is lack of sufficient clinical support.AIM To investigate the clinical effect of invisalign MA on the treatment of mandibular retraction in adolescents.METHODS This study included 30 adolescent patients who underwent treatment with the MA appliances from December 2017 to June 2021.The lateral cephalometric data before and after treatment were collected and imported into Dolphin Imaging software.The changes were measured by linear measurement superimposed with lateral cephalometric trajectory based on the Pancherz technology.RESULTS There was no significant difference in the length and position of maxilla before and after the treatment.The position of the mandible moved 3.13 mm,the length increased 4.14 mm,the mandibular ramus length increased 4.09 mm,the body length increased 4.25 mm,and the position of the condyle moved 1.03 mm forward after treatment.Additionally,changes in the incisor sagittal position and labial inclination were observed.The position of the upper incisor point moved back 1.33 mm,without statistical difference,the inclination and tooth angle decreased by 3.44°and 4.06°,respectively;the position of the lower incisor point was moved 2.98 mm,and the inclination and tooth angle increased by 2.62°and 1.23°,respectively.Furthermore,changes in the incisor overjet and molar relationship were seen.Overjet decreased by 4.31 mm,of which 1.78 mm was due to dental factors,accounting for 41.3%of the effect as opposed to 58.7%due to skeletal factors.Molar relationship improved 3.87 mm,with 1.34 mm due to dental factors,and dental and skeletal factors were accounted for 34.6%and 65.4%of the effect,respectively.CONCLUSION For adolescent patients with mandible retraction,invisalign MA can effectively promote the mandible growth,and it was proven to be mainly due to skeletal effects.

Added Value of SPECT-CT Imaging in the Diagnosis of Unilateral Active Mandibular Hypercondylia in Adult: A Case Report and Review

Planar bone Scintigraphy has been frequently used to assess the active or inactive nature of mandibular hypercondylia. We report here the case of a patient whose diagnosis of active mandibular hypercondylia was retained after a complement with SPECT/CT imaging, the planar bone scan being negative. This case confirms the use of SPECT/ CT as the examination of choice for full assessment of mandibular hypercondylia in adults. Using bone Scintigraphy SPECT/CT improves both sensitivity and specificity of diagnosing this condition.

Planar scintigraphy in assessment of mandibular asymmetry: Unilateral condylar hyperplasia vs asymmetric mandibular hyperplasia

Objectives: To 1) explore the planar scintigraphic findings in asymmetry patients caused by unilateral condylar hyperplasia (UCH) or asymmetric mandibular hyperplasia (AMH);2) develop a local agecondylar activity reference norm;and 3) check the accuracy of the new norm and compare with other analytical methods. Material and Method: Chinese patients with mandibular asymmetry and scintigraphic findings available were recruited. Clinical, radiographic records and scintigraphic condylar activity ratio (CAR) were studied. Regression analysis was performed to quantify the relationship between age and CAR to develop a new norm. The sensitivity of condylar activity assessment using a) traditional norm;b) new norm;and c) percentile difference was compared. In patients with serial data available, longitudinal analysis of the scintigraphic changes were checked. Result: 109 patients were eligible for the study. Significant difference in CAR was noted between UCH and AMH patients. Linear relationship was observed between age and CAR. A new norm of the age-CAR was established, which showed improved sensitivity in condylar activity prediction in UCH and AMH when compared with traditional norm. Relative to percentile difference, the sensitivity of new norm was lower in AMH but not in UCH patients. Serial analysis revealed gradual decline in CAR with minimal change in percentile difference. Conclusion and Clinical Relevance: There is difference in scintigraphic condylar activity between UCH and AMH patients. A norm of age-CAR relationship was established, which showed improved sensitivity in condylar activity prediction in UCH patients. Further study is required to confirm the role of scintigraphy in AMH.

The Correlation between Femoral Anteversion and Femoral Condyle Rotation in Patients with Osteoarthritis of the Hip Joint: Investigation about the Asian Female Patients

An abnormality of femoral anteversion (FA) is often recognized in patients with osteoarthritis of the hip joint (hip OA). And it is considered that rotation abnormality in the knee and the lower leg occurs as compensation, in cases of FA abnormality. The purpose of this study was to assess the magnitude and variability of FA and femoral condyle rotation (FCR) in order to identify the association between FA and FCR in female patients with hip OA who require total hip arthroplasty. A total of 174 hips from 174 hip OA patients undergoing THA were included in this study. All patients were Asian women (average age: 71.1 years). An equilateral correlation was accepted in FA and FCR. It was thought that FA abnormality might be accompanied by morphological rotation abnormalities of the knee joint. Caution is needed in considering femoral anteversion using the posterior condylar line. We must consider FA in patients undergoing THA after having considered the whole leg rotation.

An optimized medial parapatellar approach to the goat medial femoral condyle

Goats or sheep are the preferred animal model for the preclinical evaluation of cartilage repair techniques due to the similarity of the goat stifle joint to the human knee.The medial femoral condyle of the stifle joint is the preferred site for the assessment of articular cartilage repair,as this is the primary location for this type of lesion in the human knee.Proper surgical exposure of the medial femoral condyle is paramount to obtain reproducible results without surgical error.When applying the standard human medial arthrotomy technique on the goat stifle joint,there are some key aspects to consider in order to prevent destabilization of the extensor apparatus and subsequent postoperative patellar dislocations with associated animal discomfort.This paper describes a modified surgical technique to approach the medial femoral condyle of the caprine stifle joint.The modified technique led to satisfactory exposure without postoperative incidence of patellar luxations and no long-term adverse effects on the joint.

Root Canal System Variation in Mandibular Second Molar: Middle-Mesial Canal

Middle-mesial canals in mandibular molars are present in the population depending on age, sex and ethnicity. However, limited literature alludes to its prevalence. Troughing procedures may enhance identification, cleaning and shaping. This case report expresses the recognition and management of middle-mesial canal in a mandibular second molar of 24 years old Hispanic-Latino male.

Diagnostic accuracy of the tongue blade test combined with clinical signs to detect maxillary and mandibular fractures in the emergency department

BACKGROUND: To evaluate the diagnostic accuracy of clinical signs combined with the tongue blade test(TBT) to detect maxillary and mandibular fractures.METHODS: A cross-sectional study enrolled patients with maxillary and mandibular injuries in the emergency department. Physical examination and the TBT were performed, followed by radiological imaging(facial X-ray or computed tomography [CT]). The diagnostic accuracy was calculated for individuals and a combination of clinical findings at predicting maxillary and mandibular fractures.RESULTS: A total of 98 patients were identified, of whom 31.6% had maxillary fractures and9.2% had mandibular fractures. The combination of malocclusion, tenderness on palpation and swelling with positive TBT had 100% specificity to detect maxillary and mandibular fractures. In the absence of malocclusion, the combination of tenderness on palpation and swelling with positive TBT produced a specificity of 97.8% for maxillary fracture and a specificity of 96.2% for mandibular fracture. A clinical decision tool consisting of malocclusion, tenderness on palpation, swelling and TBT revealed a specificity of 100% and a positive predictive value of 100%.CONCLUSION: The clinical decision tool is potentially useful to rule out mandibular fractures,thus preventing unnecessary radiation exposure.

Transfer learning-based super-resolution in panoramic models for predicting mandibular third molar extraction difficulty: a multi-center study

Background:This study aims to predict the extraction difficulty of mandibular third molars based on panoramic images using transfer learning while employing super-resolution(SR)technology to enhance the feasibility and validity of the prediction.Methods:We reviewed a total of 608 preoperative mandibular third molar panoramic radiographs from two medical facilities:the First Affiliated Hospital of Zhengzhou University(n=509;456 in the training set and 53 in the test set)and the Henan Provincial Dental Hospital(n=99 in the validation set).We conducted a deep-transfer learning network on high-resolution(HR)panoramic radiographs to improve the longitudinal resolution of the images and obtained the SR images.Subsequently,we constructed models named Model-HR and Model-SR using high-dimensional quantitative features extracted through the Least Absolute Shrinkage and Selection Operator method.The models’performances were evaluated using the receiver operating characteristic curve(ROC).To assess the reliability of the model,we compared the results from the test set with those of three dentists.Results:Model-SR outperformed Model-HR(area under the curve(AUC):0.779,sensitivity:85.5%,specificity:60.9%,and accuracy:79.8%vs.AUC:0.753,sensitivity:73.7%,specificity:73.9%,and accuracy:73.7%)in predicting the difficulty of extracting mandibular third molars.Both Model-HR(AUC=0.821,95%CI 0.687–0.956)and Model-SR(AUC=0.963,95%CI 0.921–0.999)demonstrated superior performance compared to expert dentists(highest AUC=0.799,95%CI 0.671–0.927).Conclusions:Model-SR yielded superior predictive performance in determining the difficulty of extracting mandibular third molars when compared with Model-HR and expert dentists’visual assessments.

171例颌面部骨软骨瘤及恶变病例临床病理分析

目的:探讨颌面部骨软骨瘤(osteochondroma)的临床及病理特征,总结罕见的骨软骨瘤恶变患者的临床病理特点,为临床诊治提供指导。方法:回顾性收集2018年1月—2023年8月上海交通大学医学院附属第九人民医院手术治疗的171例骨软骨瘤患者,总结分析临床、影像及病理学特点。结果:171例骨软骨瘤患者中,66%(113/171)为女性,34%(58/171)为男性,发病年龄11~76岁,平均44岁。95.3%(163/171)发生于髁突,4%(7/171)发生于冠突,0.5%(1/171)发生于颧弓。98%(159/161)的髁突骨软骨帽厚度小于1 cm。171例骨软骨瘤中,2例(2/171,1.1%)发生恶变,1例恶变为软骨肉瘤(Ⅰ级),1例恶变为高分化骨肉瘤。结论:颌面部骨软骨瘤多发生于女性,以髁突最常见,恶变率为1.1%,与全身其他部位骨软骨恶变率相当。影像学表现对骨软骨瘤恶变的诊断具有重要意义。

舌侧活动翼不同翼拉伸长度内收下前牙的生物力学特征

背景:舌侧活动翼矫治技术是一种新型舌侧矫治技术,不同翼的拉伸长度影响前牙转矩控制效果,目前尚无相关的生物力学研究。目的:探讨舌侧活动翼矫治技术内收下前牙时牙列的位移趋势以及不同翼拉伸长度对下颌前牙生物力学效应的影响。方法:利用锥形束CT采集患者下颌骨以及下牙列数据信息,通过Mimics软件进行三维重建,建立舌侧活动翼内收下前牙的三维有限元模型。在ANSYS软件中分别分析工况A(2 mm拉伸长度)、工况B(2.5 mm拉伸长度)、工况C(3 mm拉伸长度)和工况D(3.5 mm拉伸长度)时下颌前牙的初始位移。结果与结论:①下牙列初始位移趋势:中切牙舌向倾斜移动伴有压低,侧切牙、尖牙轻度舌侧移动伴近中舌向扭转,第二前磨牙远中倾斜并伴有明显舌倾,第一磨牙整体表现为近中倾斜并伴有近中牙冠外翻。因此在下颌拔牙内收病例中,对第二前磨牙的舌向移动应给予重视,临床中可以通过相应的技术予以抵消。②前牙各方向位移趋势:从工况A到工况D,矢状方向:中切牙冠根位移差值由-11.891μm变为-5.7574μm,表示中切牙由倾斜移动向整体移动转变;侧切牙冠根位移差值由-11.8281μm变为-6.71145μm,尖牙冠根位移差值由-7.5723μm变为-4.6955μm,表示侧切牙及尖牙的倾斜移动也在向整体移动转变。垂直方向:从工况A到工况D,切牙的压低量逐渐增大,尖牙的压低量逐渐减小。结果表明,翼的拉伸长度会影响前牙的倾斜移动趋势;随着翼的不断拉伸,下前牙的转矩控制效果越好。