BACKGROUND:Lingual movable wing is a new type of lingual orthodontic technique and the different stretching lengths of the wring affect the torque control effect of anterior teeth.However,there is yet no related biomechanical research. OBJECTIVE:To investigate the displacement trend of dentition during adduction of mandibular anterior teeth and the effect of different wing stretching lengths on the biomechanical effect of mandibular anterior teeth. METHODS:The data of the mandible and lower dentition were collected by cone-beam CT and reconstructed using Mimics software to establish a three-dimensional finite element model of mandibular anterior teeth adducted by the lingual movable wing.The ANSYS software was used to analyze the initial displacement of the mandibular anterior teeth under the following conditions:A,2 mm stretching length;B,2.5 mm stretching length;C,3 mm stretching length;and D,3.5 mm stretching length. RESULTS AND CONCLUSION:The trend of initial displacement of lower dentition:The central incisors moved lingually with depression,the lateral incisors and canines moved mildly lingually with mesial lingual torsion,the second premolar was tilted distally with a marked lingual inclination and the first molar showed an overall mesial inclination with mesial crown eversion.Therefore,in the adduction cases of mandibular tooth extraction,attention should be paid to the lingual movement of the second premolar,which could be offset by corresponding techniques in clinic.The trend of anterior tooth displacement in all directions:from condition A to condition D,in the sagittal direction,the difference value in crown-root displacement of central incisors changed from-11.891 μm to-5.757 4 μm,indicating that the central incisor changes from oblique movement to overall movement.The difference value in crown-root displacement of lateral incisors changed from-11.828 1 μm to-6.711 45 μm,and that of canines changed from-7.572 3 μm to-4.695 5 μm,indicating that the oblique movement of the lateral incisors and canines is also changing to an overall movement.In the vertical direction,from condition A to condition D,the reduction of incisors was gradually increased,while that of canines was gradually decreased.These findings indicate that the stretching length of the wing can affect the oblique movement trend of the anterior teeth.As the wing continues to stretch,the torque control of the lower anterior teeth will become better.

This study aims to explore the association between different genotypes of WT1 gene variations and the phenotypes of Denys-Drash syndrome (DDS) and Frasier syndrome (FS).

Objective:To compare the clinical efficacy of arthroscopy-assisted and open reduction and internal fixation in the treatment of Schatzker type I-III tibial plateau fractures.Methods:The data of patients with Schatzker type I-III tibial plateau fractures who were treated from August 2017 to July 2019 were retrospectively analyzed. According to the treatment, the patients were divided into the arthroscopic-assisted minimally invasive reduction and internal fixation group (arthroscopy group) and the conventional open reduction and internal fixation group (incision group). In the arthroscopy group, there were 30 patients, 19 males and 11 females were included; the age was 45.13±7.12 years old (range, 29-60 years). Among them, 13 cases were Schatzker type I fractures, 14 cases were Schatzker type II fractures, and 3 cases were Schatzker type III fractures. In the incision group, there were 30 patients, 17 males and 13 females were included; the age was 43.53±7.79 years old (range, 31-58 years). Among them, 11 cases were Schatzker type I fractures, 15 cases were Schatzker type II fractures, and 4 cases were Schatzker type III fractures. The operation time, intraoperative blood loss, postoperative ambulation time, postoperative complete weight-bearing time and postoperative complications were recorded. The degree of knee joint swelling, knee flexion and extension range of motion and the American knee society knee score (AKS score) were compared between the arthroscopy group and the incision group.Results:Both groups were followed up. The follow-up time of the arthroscopy group were 10-18 months, with an average of 14 months; the follow-up time in the incision group were 12-18 months, with an average of 15 months. In the arthroscopy group, the operation time (87.60±9.20 min vs. 94.33±10.65 min), intraoperative blood loss (57.16±9.63 ml vs. 71.93±11.15 ml), postoperative ambulation time (5.13±1.28 d vs. 6.17±1.53 d) and postoperative complete weight-bearing time (12.83±1.68 weeks vs. 14.23±1.77 weeks) were superior to the incision group, and the differences were statistically significant ( t=2.62, 5.49, 2.83, 3.94; all P<0.05). The healing time was 13.33±1.37 weeks in the arthroscopy group and 14.86±1.63 weeks in the incision group, and the difference was statistically significant ( t=3.94, P<0.001). At 1 year after surgery, the range of flexion and extension of knee joint in the arthroscopy group was 116.77°±12.46°, which was better than that in the incision group, which was 109.13°±9.89°, and the difference was statistically significant ( t=2.63, P=0.011). The AKS score in the arthroscopy group was 164.57±11.16 points, and the score in the incision group was 149.53±14.77 points, and the difference was statistically significant ( t=4.45, P<0.001). There were no malunion or compartment syndrome in the arthroscopy group and the incision group. The total incidence of complications in the arthroscopy group was 13% (4/30), including 2 cases of poor wound healing, 2 of poor knee range of motion after operation. The total incidence of complications in the incision group was 23% (7/30), including 4 cases of poor wound healing, 1 of wound infection, 2 of poor knee range of motion after operation. And the difference between the two groups in complication incidence was not statistically significant (χ 2=1.00, P=0.317). Conclusion:Arthroscopic-assisted reduction and internal fixation in the treatment of Schatzker I-III tibial plateau fractures has the advantages of less trauma, less bleeding, early mobility, fewer complications, and better knee joint function, and there are no obvious arthroscopic-related complications, which is a safe and reliable treatment method.

Objective: To investigate the inhibitory effect of polydopamine (PDA) on enamel demineralization in isolated teeth and the induction of hydroxyapatite (HA) production on the surface of demineralized enamel to provide a novel protocol for the prevention and treatment of enamel demineralization. Methods: Twenty isolated bovine teeth were cut into 20 enamel slices and randomly divided into an experimental group and a control group, with 10 slices in each group. The enamel slices in the experimental group were immersed in 2 mg/mL freshly prepared dopamine solution and incubated for 24 hours at room temperature in the dark to prepare the PDA coating, while the control group was left untreated. Then, the isolated bovine teeth, with and without PDA coating, were immersed in artificial demineralization solution at 37 °C for 3 days, followed by 7 days in simulated body fluid (SBF), and the immersion solution was changed daily. The surface morphology of enamel was observed by scanning electron microscopy (SEM), the calcium/phosphorus ratio of the enamel surface was analyzed by energy dispersive spectroscopy (EDS), and the characteristic functional groups in enamel deposits were analyzed by Fourier transform infrared spectroscopy (FTIR). Results: Compared with the control group, the number of demineralized pores produced after 3 d of enamel demineralization with polydopamine coating was less, and the diameter was smaller. EDS elemental analysis showed that the Ca/P ratio after enamel demineralization was 2.37 in the experimental group, which was smaller than the 2.53 ratio in the control group. In the remineralization experiment, after 7 days of remineralization of PDA coated enamel in the experimental group, lamellar grains were produced on the enamel surface, and the growth showed obvious directionality, growth regularity and uniform arrangement. In the control group, the surface of enamel was flocculent mineral deposit, and the crystallinity was poor. The FTIR results proved that the enamel surface deposit of PDA-coated enamel was HA after 7 d of remineralization. Conclusion PDA can affect the nucleation process of HA and promote the production of HA on the surface of demineralized enamel.

Objective:To explore the morphological characteristics, treatment strategies and clinical results of complex hyperextension tibial plateau fractures.Methods:From October 2017 to January 2019, data of 27 patients with complex hyperextension tibial plateau fractures were retrospectively analyzed. There were 19 males and 8 females with an average age of 43.4 years (range, 23-68 years). According to Schatzker classification of tibial plateau fractures: there are 8 cases of type IV, 5 of type V, and 14 of type VI; according to the three-column theory classification: there are 8 cases of two-column fracture and 19 cases of three-column fracture. Bicondylar fractures were treated with medial Tomofix locking plate and anterolateral L-shaped locking plate through medial and anterolateral approach; tibialmedial condylar fractures was treated with T-shaped plate and posteromedial locking plate through extended medial approach. Patients with anterior tibial fractures were treated with horizontal strip plate through modified anterior median approach. Combined soft tissue or bone injury was repaired. The fracture healing and reduction were evaluated by X-ray and CT scan. The reduction of tibial plateau fracture was evaluated by Rasmussen radiology standard, and the knee joint function was evaluated 12 months after the operation by the score of American hospital for special surgery (HSS).Results:All the 27 surgeries were performedsuccessfully. The operation time was 130-350 minutes, with an average time of 165 minutes. Twenty-seven cases were followed up for 12-24 months, with an average period of 15.8 months. All fractures were healed. The average clinical healing time was 13.5 weeks (range, 10-18 weeks). Twelve months after operation, Rasmussen's radiology score was 13-18, with an average of 16.7 points, among them there were 19 excellent and 8 good. Twelve months after the operation, the score of HSS knee joint was 82-98, with an average score of 93.2 points, and there were 22 cases excellent, 4 cases good and 1 case fair. The excellent and good rate was 96.2% (26/27).Conclusion:Complex hyperextension tibial plateau fractures often combined with tibial bicondylar, medial tibial condyle or anterior tibial fractures. According to the morphological characteristics of complex hyperextension tibial plateau fractures, using appropriate surgical approach and internal fixation, repairing ligament soft tissue structure and reconstructing knee joint stability can achieve satisfactory results.

OBJECTIVE: To investigate the effect of orthodontic traction on the microstructure of dental enamel. METHODS: Forty-eight isolated premolars were randomly divided into 6 groups (=8), including Group A (blank control group), in which the teeth were bonded with the orthodontic brackets without any loading force; Groups B1, B2, and B3 where the teeth were bonded with the orthodontic brackets using clinical adhesives and loaded with 50 g force for 6 months, 200 g force for 6 months, and 200 g force for 1 month, respectively; and Groups C1 and C2, where the teeth were bonded with straight wire brackets using light curing bonding and chemical curing bonding techniques, respectively. All the teeth were embedded with non-decalcified epoxy resin. Scanning electron microscope (SEM), atomic force microscope (AFM), and energy spectrometer (EDS) were used to analyze interface morphology and elemental composition of the teeth sliced with a hard tissue microtome. RESULTS: Compared with those in Group A, the teeth in the other 5 groups showed increased adhesive residue index with microcracks and void structures on the enamel surface under SEM; AFM revealed microcracks on the enamel surface with angles to the grinding direction. A larger loading force on the bracket resulted in more microcracks on the enamel interface. The interface roughness differed significantly between Groups A and C2, and the peak-to-valley distance differed significantly between Groups A, C, and C2. CONCLUSIONS Orthodontic traction can cause changes in the microstructure of normal dental enamel.
Dental Enamel ; Materials Testing ; Orthodontic Brackets ; Resin Cements ; Surface Properties ; Traction

Objective:To discuss how to make the surgical strategy for tibial tubercle fracture associated with bicondylar tibial plateau fracture.Methods:Data of thirty-five patients of tibial tubercle fractures associated with bicondylar tibial plateau fractures who were treated from October 2014 to May 2018 were retrospectively analyzed. There were 26 males and 9 females with an average age of 37.6 years (range, 21-68 years). According to Schatzker classification in tibial plateau fracture, 16 cases were type V and 19 cases were type VI. According to the integrity of tibial tubercle fracture and cortical bone of the proximal tibia in bicondylar tibial plateau fracture, they were divided into four types: type A, tibial tubercle fracture fragment and cortical bone of the proximal tibia are both complete; type B, tibial tubercle fracture fragment is complete but cortical bone of the proximal tibia is comminuted; type C, tibial tubercle fracture fragment is comminuted but cortical bone of the proximal tibia is complete; type D, both of them are comminuted. The surgical approaches and fixation methods of all the tibial tubercle fractures were according to the four different types. There were 22 cases with type A and B that were treated via an anterolateral and a medial incision, 13 cases with type C and D were treated via an anterior midline and a medial incision. There were 4 cases belonging to type A fixed with lag screws singly, 18 cases with type B fixed with 1/4 tubular plates, 7 cases with type C and 6 cases with type D fixed by 1/4 tubular plates combined with lag screws.Results:Thirty-five patients were followed up for 16.8 months (range, 12-24 months). All fractures healed with an average time of 4.7 months (range, 3-6 months). Loss of reduction didn’t occur in 34 cases except one. According to Rasmussen radiographic evaluation, the average score was 14.1 (range, 10-18) and clinical outcomes were rated with excellent in 11 cases, good in 19, fair in 5. The excellent and good rate was 85.7% (30/35) . The mean Hospital for Special Surgery (HSS) scores of all cases were 86.8 (range, 64-98) and the functional scores were excellent in 22 cases, good in 10 cases and fair in 3 cases with the excellent and good rate of 91.4% (32/35) . Surgical complications included fat liquefaction in 2 cases, superficial wound infection in 1, loosening of implant in 1and traumatic arthritis in 1.Conclusion:This kind of tibial tubercle fracture associated with bicondylar tibial plateau fracture is rare and special. Therefore, the preoperative plan should be made by considering the morphological features of the tibial tubercle fragments and the cortical bone of the proximal tibia. The middle longitude approach is the best way to expose tibial tubercle fragments which should be fixed with 1/4 tubularplate and/or lag screws.

Objective: To explore the clinical features and treatment strategies of tibial plateau fractures sustained with hyperextension varus. Methods: Data of 11 patients of tibial plateau fractures with hyperextension varus treated from January 2008 to November 2017 were retrospectively analyzed. There were 7 males and 4 females with an average age of 41.2 years old (range, 25-67 years). Injuries were caused by falling down in 7 cases, traffic accident in 3 cases, and falling from height in 1 case, respectively. On the basis of Luo's three columns classification in tibial plateau, there were 9 cases of medial column fracture and 2 cases of medial combined with posterior column fracture. Six cases were concomitant with fibular head fracture and 2 cases with the injury of common peroneal nerve. Preoperative magnetic resonance imaging showed that there were anterior cruciate ligament injury in 3 cases, posterior cruciate ligament injury in 4 cases, medial meniscus injury in 5 cases, lateral meniscus injury in 3 cases, medial collateral ligament injury in 6 cases, iliotibial band injury in 2 cases and posterolateral complex injury of the knee joint in 9 cases, respectively. All tibial plateau fractures were treated firstly by open reduction and internal fixation via medial approach of the knee. The medial meniscuses and collateral ligaments were explored, in which of them there were 2 medial meniscuses with the marginal tear been sutured simultaneously. Then the knee joints which were still unstable after the examination of stable tests in 6 cases with posterolateral complex injuries were repaired surgically via lateral approach. Fibular head fractures were fixed with anchor nails or cannulated screws in 6 cases. The ruptured posterior cruciate ligaments in 2 cases were reconstructed with autologous tendon transplantation under endoscopy. Results: All the patients were followed up for an average period of 16.2 months (range, 12-22 months). All fractures were healed in 10-20 weeks with an average time of 16.5 weeks. The range of extension of the affected knee joint in all patients was 0° and the average flexion was 135° (range, 120°-145°) one year after surgery. The average flexion of affected knee in 4 cases which were only treated with the tibial plateau fracture without the mild ligament injuries was 137° (range, 132°-145°) and the average flexion of affected knee in 7 cases who were treated with tibial plateau fracture and severe posterolateral complex included posterior cruciate ligaments completely broken with reconstruction was 132° (range, 120°-140°). According to Rasmussen radiographic evaluation, the average score of all patients was 16.3 (range, 14 to 18) and clinical outcomes were rated with excellent in 10 cases and good in 1. The excellent and good rate was 100% (11/11). The mean of the hospital for special surgery (HSS) score was 86.7 (range, 79-96) and the functional scores were excellent in 9 cases, good in 2 cases thus the excellent and good rate was 100% (11/11). Both varus stress test 30° and dial test were positive in one case considered for the ligament laxity postoperatively who didn’t accept further treatment and the stabilization tests were negative in the other 10 cases. There were no intraoperative complications in all patients such as neurovascular injury. No incision infection, failure of the implants and fracture nonunion occurred postoperatively. Traumatic arthritis of the affected knee occurred one year after surgery in 1 case who had no obvious pain after treated with oral medicine. Conclusion The hyperextension varus injuries of the knee are rare clinically. The posterolateral complex should be evaluated thoroughly for this injury pattern. If it's necessary, the posterolateral structures must be repaired surgically after the tibial plateau fractures are fixed.

Objective To explore the guiding significance of posterior tibial plateau partition for the selection of surgical approach in treatment for posterior column fracture.Methods From June 2008 to May 2015,46 patients with posterior column fractures of tibial plateaus treated were retrospectively analyzed.There were 31 males and 15 females with an average age of 35.1±12.8 years old (range,19-62 years).Nineteen patients were left side and twenty-seven patients were right side.Injury was caused by traffic accident in 27 cases,falling from bicycle in 12 cases and falling from height in 7 cases.On the basis of the posterior condyle with anatomical structure in tibia1 plateau,the posterior column was divided into four parts.All fractures were treated via the optimal approach based on the location of them.The posteromedial approach was used with fractures in zone 1 and 2,posterolateral approach used in zone 3,lateral approach via the fibular head osteotomy was used in zone 4 and combined approaches were used in multiple zones.All the fractures involved the posterior column were treated by anatomical reduction and fixation with plates and screws under direct vision.Results All the patients were followed up with an average of 15.5±3.7 months (range from 12 to 24 months).The healing time of all patients was 11-18 weeks,with an average time of 14.6±2.3 weeks.According to Rasmussen radiographic evaluation,the average score was 15.1 (range from 11 to 18) and clinical outcomes were rated with "excellent" in 17 cases,"good" in 24 cases,"fair" in 5 cases.The excellent and good rate was 89.1％ (41/46).The mean HSS (the Hospital for Special Surgery) score of all patients at 12 months operatively were 86.7±8.6 (range from 67 to 98) and the functional scores were excellent in 25 cases,good in 17 cases and fair in 4 cases with the excellent and good rate was 91.3％ (42/46).The average range of motion in affected knee was 118°±13.7° (range from 0° to 135°) in 17 cases via posterolateral approach,123°±15.6° (range from 0° to 135°) in 18 cases via posteromedial approach,115°±16.7° (range from 0° to 130°) in 18 cases via combined posteromedial and posterolateral approaches and 124°±7.4° (range from 0° to 130°) in 4 cases via the fibular head osteotomy lateral approach.Complications included fat liquefaction in 1 case,anterior tibial artery spasm in 1 case and traumatic arthritis in 1 case.Conclusion The partition of posterior tibial plateau can be used to guide the surgical approach to the posterior column simply and accurately.For the fractures of isolated posterior column and posterior column mainly involved,the partition has a certain guiding significance.

Objective To discuss the clinical application of percutaneous radiologic gastrostomy (PRG) in treating dysphagia associated with amyotrophic lateral sclerosis (ALS),and to evaluate its safety and improvement effect on patient's nutritional status in ALS patients with pulmonary insufficiency.Methods The clinical data of 51 ALS patients who received PRG were retrospectively analyzed.The success rate of surgery and postoperative complications were recorded.All patients were regularly followed up,and the longterm complications as well as the one-,3-and 6-month mortality rates after the surgery were documented.The improvement of patient's nutritional status was evaluated.Results PRG was successfully accomplished in all 51 patients,the technical success rate was 100％.Mild postoperative complications occurred in 7 patients (13.73％) and severe massive hemorrhage in one patient (2.0％).After PRG,no signs or symptoms of impaired respiratory function were observed.No death occurred in one month and in 3 months after PRG.Six months after PRG,three patients died(6.8 ％,3/44).One month after PRG,31 patients had an increase in body weight of more than 1 kg,and the mean BMI was increased from preoperative t8.60±2.14 to postoperative 19.27±1.81 (one month after PRG),19.17±1.93 (3 month after PRG) and 18.89±2.33 (6 month after PRG).Conclusion For the performance of PRG no gastroscopy or anesthesia is needed,thus,the risk of aspiration asphyxia can be reduced in ALS patients complicated by pulmonary insufficiency and the success rate as well as the safety can be improved.Therefore,this technique is an effective means to ensure that the ALS patients with pulmonary insufficiency can get adequate energy intake to improve their nutritional status.