Objective To compare the accuracy of the original-mirror alignment algorithm and a landmark-indepen-dent method in constructing the midsagittal plane(MSP)of the cone beam computed tomography in patients with facial deformities,so as to provide a theoretical basis for symmetric analysis.Methods The study was approved by the hospi-tal ethics committee.Cone beam computed tomography data of 30 patients with facial deformities were obtained,and the output was saved in DICOM format.The scan data were imported into Mimics 21.0;after segmentation,three-dimension-al(3D)skull models were reconstructed.Furthermore,the 3D scan data of skulls were transformed into mirror skull models using Geomagic Studio 2014 reverse engineering software.The MSP of each skull was generated using both the original-mirror alignment algorithm and the landmark-independent method.Original-mirror alignment algorithm:the original skull model and its mirror model were combined,and the new data to calculate the MSP(S1)of the original data in Geomagic Studio 2014 were obtained.Landmark-independent method:the following anatomical landmarks were deter-mined using Mimics 21.0:nasion(N),crista galli(CG),sella(S),basion(Ba),vomer(V),posterior nasal spine(PNS),in-cisive foramen(IF),and anterior nasal spine(ANS).The MSP(S2)of best fit was then found by minimizing the mean square distance of these eight anatomical landmarks to a plane in Geomagic Studio 2014.The results of the S1 and S2 models constructed using the original-mirror alignment algorithm and the landmark-independent method,respectively,were scored subjectively by five senior maxillofacial surgeons,and a paired t-test was performed for the two groups.The internal consistency analysis was performed based on secondary experiments to verify the repeatability of the expert evaluation method.Results The average scores of the S1 and S2 models were 65.73 and 75.90,respectively.The aver-age score of the model constructed using the landmark-independent method was significantly higher than that of the model constructed using the original-mirror alignment algorithm(P＜0.01).Furthermore,the results of the internal con-sistency analysis showed that the expert evaluation method had good reliability and validity.Conclusion In patients with facial deformities,the MSP constructed using the landmark-independent method is superior to that constructed us-ing the original-mirror alignment algorithm.This study provides a theoretical basis for maxillofacial symmetry analysis in clinical settings and is clinically feasible.

Objective:To fabricate the composite scaffolds for bone regeneration with silk fibroin (SF), bacterial cellulose nanofibers (BCNR) and hydroxyapatite (HAp) and evaluate their osteogenic activity.Methods:HAp particles, BCNR and bone morphogenetic protein-2 (BMP2) were added into SF aqueous solution in turn, poured into molds of different sizes after being mixed evenly and processed at -25 ℃ for 24 hours to obtain frozen molds, and the composite scaffolds were frozen-dried by freezing-drying machine. The composite scaffolds with different mass ratios of SF and BCNR were divided into groups A (2∶1), B (4∶1) and C (6∶1), and the inactive composite scaffolds without BMP2 fell into group D. The surface morphology and pore structure of the scaffolds were detected by scanning electron microscopy. The porosity of the scaffolds was measured by mercury intrusion porosimeter. The stress-strain curve was obtained by using the universal material testing machine to compress the scaffolds, with which their compressive strength and Young′s modulus were analyzed. Immortalized mouse embryonic fibroblasts (iMEF) were inoculated on the composite scaffolds of group A, B, C and D. At 4 and 8 days after cell inoculation, the proportion of alive and dead cells in each group was detected by cell survival/death staining; the cell counting kit-8 (CCK-8) was used to detect cell proliferation activity in each group; the positive staining cells were detected in each group by alkaline phosphatase (ALP) staining; the ALP activity was observed in each group with ALP activity detection. A total of 15 female SD rats were selected to establish osteogenesis models with ectopic muscle bag. The composite scaffolds implanted with different SF/BCNR mass ratios and the inactive composite scaffolds without BMP2 fell into group A′ (2∶1), B′ (4∶1), C′ (6∶1) and D′ respectively, and a sham operation group was set at the same time, with 3 rats in each groups. In the sham operation group, the muscle bag and skin were sutured without scaffold implantation after the incision of skin, the blunt separation of the quadriceps muscle, and the formation of muscle bag in the muscle. In the other four groups, the corresponding scaffolds were implanted in the muscle bag and the muscle bag and skin were sutured. X-ray examination was performed at 2 and 4 weeks after operation to observe the osteogenesis in each group. At 4 weeks after operation, the implanted scaffolds and tissue complexes were collected by pathological tissue sectioning, HE staining and Masson staining, and for observing the osteogenesis by in each group. Immunohistochemical staining was also performed on the tissue sections to observe the expression of osteogenic markers type I collagen (COL1) and osteopontin (OPN) in each group.Results:Scanning electron microscopy showed that the lamellar and micropore structures of group B were more regular and uniform than those of groups A and C. The porosity rate analysis showed that the porosity rates of groups B and C were (89.752±1.866)% and (84.257±1.013)% respectively, higher than that of group A [(81.171±1.268)%] ( P<0.05 or 0.01), with the porosity rate of group C lower than that of group B ( P<0.01). The mechanical property test showed that the compressive strengths of groups B and C were (0.373±0.009)MPa and (0.403±0.017)MPa respectively, higher than that of group A [(0.044±0.003)MPa] ( P<0.01), and the Young′s moduli of groups B and C were (7.413±0.094)MPa and (9.515±0.615)MPa respectively, higher than that of group A [(1.881±0.036)MPa] ( P<0.01), with the compressive strength and Young′s modulus of group C higher than those of group B ( P<0.05 or 0.01). The cell survival/death staining showed that the number of dead cells of group B was significantly smaller than that of groups A, C and D at 4 days after cell inoculation, and that group B had the most living cells and the fewest dead cells at 8 days after cell inoculation. The results of CCK-8 experiment showed that at 4 days after cell inoculation, the cell proliferation activity of groups A and B was 0.474±0.009 and 0.545±0.018 respectively, higher than 0.394±0.016 of group D ( P<0.01); the cell proliferation activity of group C was 0.419±0.005, with no significant difference from that of group D ( P>0.05), while the cell proliferation activity of groups A and C were both lower than that of group B ( P<0.01). At 8 days after cell inoculation, the cell proliferation activity of group B was 1.290±0.021, higher than 1.047±0.011 of group D ( P<0.01); the cell proliferation activity of group C was 0.794±0.032, lower than that of group D ( P<0.01); the cell proliferation activity of group A was 1.086±0.020, with no significant difference from that of group D ( P>0.05); the cell proliferation activity of groups A and C was lower than that of group B ( P<0.01). At 4 and 8 days after cell inoculation, ALP staining showed that more positive cells were found in groups A, B and C when compared with group D, and more positive cells were found in group B than in groups A and C. At 4 days after cell inoculation, the ALP activity detection showed that the ALP activity of groups A, B and C was 1.399±0.071, 1.934±0.011 and 1.565±0.034 respectively, higher than 0.082±0.003 of group D ( P<0.01), while the ALP activity of groups A and C was lower than that of group B ( P<0.01). At 8 days after cell inoculation, the cell activity of groups A, B and C was 2.602±0.055, 3.216±0.092 and 2.145±0.170 respectively, higher than 0.101±0.001 of group D ( P<0.01), while the ALP activity of groups A and C was lower than that of group B ( P<0.01). X-ray examination results showed that at 2 weeks after operation, no obvious osteogenesis was observed in the sham operation group, group D′, A′ and C′, while it was observed in group B′. At 4 weeks after operation, obvious osteogenesis was observed in group A′, B′ and C′, with significantly more osteogenesis in group B′ than in the other two groups, while there was no obvious osteogenesis in the sham operation group and group D′. At 4 weeks after operation, the HE staining and Masson staining showed that a large number of uniformly distributed new bone tissue was formed in group B′, while only a small amount of new bone tissue was found locally in groups A′ and C′, and only part of new tissue was found to grow in group D′ with no obvious new bone tissue observed. The maturity of new bone tissue formed in group B′ was higher than that in group A′ and C′. Immunohistochemical staining showed more COL1 and OPN positive staining in group B′ when compared with groups A′ and C′. The expression intensity analysis of COL1 and OPN showed that in groups A′, B′ and C′, the expression intensity of COL1 was 2.822±0.384, 22.810±2.435 and 12.480±0.912 respectively and the expression intensity of OPN was 1.545±0.081, 5.374±0.121 and 2.246±0.116 respectively, with higher expression intensity of COL1 and OPN in groups B′ and C′ than that in group A′ ( P<0.01) and lower expression intensity of COL1 and OPN in group C′ than that in B′ group ( P<0.01). Conclusions:The composite scaffold for bone regeneration is successfully fabricated with SF, BCNR and HAp. The composite scaffold with a mass ratio of SF to BCNR of 4∶1 has uniform pore structure, high porosity, good mechanical properties and biocompatibility, excellent pro-osteogenic properties in vitro, as well as excellent osteo-inductivity and osteo-conductivity.

Objective:To compare the changes of biliary microbiota after enteral extended biliary stents (EEBS) implantation with that of conventional plastic stents in animal experiment, and to preliminarily investigate its possible mechanism in preventing stents occlusion.Methods:A total of 12 healthy Bama minipigs were randomly assigned to the conventional plastic stent group ( n=6) and the EEBS group ( n=6) using simple random method. The bile samples of all pigs were collected before stents implantation and 4 weeks after stents placement. The biliary microbiota composition and diversity before and after different stents implantation were analyzed by 16S rRNA gene sequencing and compared. Results:No complications including acute cholangitis, perforation, bleeding, or death occurred in 12 pigs. Eight days after stents implantation, stents were out of bile duct in all pigs under endoscopy, while the bile samples were collected again for analysis. The main composition of biliary microbiota at the phylum level were Proteobacteria, Firmicutes and Bacteroidota. Alpha-diversities revealed the Shannon ( P=0.004) and Simpson index ( P=0.008) significantly decreased in the conventional stent group after stents placement, and Bata diversity analysis also showed a significant difference in microbial composition (Anosim: R=0.514 8, P=0.011). There was no significant difference in Observed species index ( P=0.095), Chao1 index ( P=0.136), Shannon index ( P=0.353), Simpson index ( P=0.227) or Bata diversity (Anosim: R=0.059 3, P=0.187) in the EEBS group before and after stents placement. LEfSe algorithm indicated Bacteroides_ fragilis and Proteobacteria- Gammaproteobacteria- Enterobacterales- Enterobacteriaceae- scherichia_ Shigella- Escherichia_ coli significantly increased in the conventional stent group, and Desulfobacterota- Desulfovibrionia- Desulfovibrionales- Desulfovibrionaceae- Bilophila significantly increased in the EEBS group after stents placement. Conclusion:The biliary microbiota change slightly after EEBS implantation in the short-term, and EEBS may prevent duodenobiliary reflux by prolonging the reflux path.

Objective:To explore the clinical characteristics of pancreaticobiliary maljunction (PBM) and its disease spectrum, and to evaluate therapeutic endoscopic retrograde cholangiopancreatography (ERCP).Methods:Data of 52 PBM patients who received therapeutic ERCP procedures for abdominal pain, jaundice and fever in Department of Gastroenterology of Peking University Third Hospital from June 2006 to March 2021 were collected. The clinical characteristics, typing, the change of disease spectrum and ERCP procedures were analyzed.Results:Among 52 PBM patients, female was more common. Abdominal pain and jaundice were the most common clinical manifestations, among which 20 were type Ⅰ, 25 type Ⅱ and 7 type Ⅲ. Half patients had the choledochal cyst. The mean timespan from the first onset to the final diagnosis was 12.2 years. Twenty-four cases (46.2%) had changes in PBM disease spectrum. Among 69 ERCP procedures, 5 (7.2%) failed. Difficult cannulation rate was 34.6% (18/52), and 11 patients underwent advanced cannulation techniques, while it was 15.4% (657/4 275) in the conterpart non-PBM patients in the same period, with significant difference between them ( χ2=14.455, P<0.05). Multiple therapeutic ERCP techniques including endoscopic sphincterotomy, pancreatic stent placement, removal of stones from the duct were applied with the successful rate of 92.8% (64/69). The incidence of post-ERCP pancreatitis was 15.4% (8/52). Conclusion:The chief clinical problem may be changed over time in PBM patients. Although ERCP plays an important role in PBM and its disease spectrum, there may be a higher rate of difficult cannulation and postoperative complications.

At present, robotic system has been applied in many aspects of the field of prosthetic dentistry, such as tooth preparation, oral implant surgery, full denture arrangement, prosthodontic material testing and robotic education of prosthodontics. The advantages of prosthodontic robotics lie in their ability to perform quantitative and precise operations whilerepeating the work flow indefinitely, which assist dentists to complete heavy and complicated daily treatment. In the research and development of prosthodontic robotics, the limitation of oral operation space should be fully considered, and robotics should have high safety and flexibility. The review briefly summarizes the application and existing problems of robotics in prosthodontics, and provides references for further development and design.

Objective:To describe the treatment of the first carpometacarpal arthritis in Eaton Ⅱ, Ⅲ combining the hemi excision of trapezium with tendon ball and evaluate its clinical efficacy.Methods:Data of patients with the first carpometacarpal arthritis who were treated by hemi excision of trapezium and tamponade of the tendon ball from March 2013 to October 2018 were retrospectively analyzed. Twelve patients were all females with an average age of 55±2.8 years (range, 48-61 years). There were 3 cases of left thumbs and 9 cases of right. The study was only researched with primary osteoarthritis patients, preoperative imaging Eaton stages, including 8 cases inⅡstage, 4 cases in Ⅲ stage. Postoperative X-ray examination was performed, and the subsidence rate of the first metacarpal bone was evaluated according to height of arthroplasty. Preoperative and postoperative pain was evaluated according to visual analogue scales (VAS) score and DASH score. Preoperative and postoperative finger movement was evaluated according to the changes in preoperative and postoperative grip and pinch force.Results:The average follow-up period was 12±4.8 months (range, 6-17 months). The mean score of VAS after operation was 1.2±1.0 which was lower than 6.3±1.5 before operation ( t=13.4, P=0.0001); DASH score after operation was 26.2±9.6 which was lower than 48.9±13.0 before operation ( t=5.7, P=0.0001); Grip force after operation was 25.5±6.8 kg which was higher than 15.0±2.9 kg before operation ( t=7.3, P=0.0001); Pinch force after operation was 3.2±0.8 kg which was higher than 2.1±0.4 kg before operation ( t=3.6, P=0.0045), and all of these four above data has statistic difference. At the latest postoperative follow-up, the height index of arthroplasty was 0.299±0.022, and there was no significant change ( F=1.337, P=0.276) when compared with 0.306±0.021 before surgery and 0.313±0.024 after surgery. After the operation, 2 patients presented with incision redness and swelling and exudation. It was considered that local hematoma in the intra-articular operation could not be completely absorbed. After several dressing changes, the redness and swelling subsided and the exudation was controlled. Conclusion:Preserving the proximal joint surface of trapezium and tamponading tendon ball, could reduce the subsidence rate of the first metacarpal bone and alleviate the pain of the first carpometacarpal joint, thus may effectively improve the joint function. It has a significant effect on the treatment of Eaton Ⅱ,Ⅲ stage of the first carpometacarpal arthritis.

Objective:To introduce ulnar shortening oblique osteotomy combined with arthroscopy technique for ulnar impaction syndrome and to evaluate the outcomes.Methods:From August 2012 to January 2015, data of 25 cases with ulnar impaction syndrome who were treated in our hospital with oblique osteotomy of the ulna and internal fixation were retrospectively analyzed. There were 14 males and 11 females with an average age of 32.5±4.9 years old (range, 18-62 years). All 25 cases had wrist triangular fibrocartilage complex (TFCC) injuries. Intraoperative arthroscopy was conducted to investigate the pathologic changes of the articular disk of the triangular fibrocartilage complex (TFCC), chondromalacia of the lunate and triquetrum, and tears of the lunotriquetral interosseous ligament (LTIL), debridement of the synovial membrane and the free edge of the central perforation of TFCC, to remove the cartilage from the lunate and triangular bone, and to perform oblique osteotomy of the ulna and internal fixation after repairing of TFCC ulnar tear. We evaluated the outcomes by means of comparing the postoperative values of modified Mayo and visual analogue scale (VAS).Results:There were 5 cases of IB, 5 of IIA, 7 of IIB, 4 of IIC, 4 of IID according to Palmer's classification. All 25 cases were followed-up for 24.6±1.9 months (range, 12-46 months). All patients achieved bone healing with an average of 14.0±1.9 weeks (range, 12-20 weeks). The mean value of preoperative ulnar variation was 3.8 ±1.5 mm which decreased to -1.5±0.5 mm after operation. The preoperative VAS was 7.8±0.7 which decreased to 1.3±1.5 at the latest follow-up. The modified Mayo value increased from 52.8±15.8 to 83.0±11.2. There were 19 cases with excellent wrist function, 5 good and 1 fair. The excellent-good rate was 96% (24/25). Grip strength value increased from 6.3±1.5 kg preoperative to 12.3±1.9 kg postoperative. There was no postoperative infection, delayed or nonunion of bone, but irritation of steel plate appeared in 10 patients, which disappeared after the removal of the steel plate.Conclusion:Arthroscopy combined with ulnar shortening oblique osteotomy technique for ulnar impaction syndrome can reduce wrist pain, increase hand grip strength, improve the activity of the wrist joint, and the clinical effect is positive.

Objective To evaluate the efficacy of distal radioulnar joint (DRUJ) dorsal ligament reconstruction using extensor retinaculum transposition with triagular fibrocartilage complex (TFCC) repair and dorsal capsuloplasty for chronic DRUJ dorsal instability.Methods From October 2007 to July 2016,data of 18 patients (11 men and 7 women with a mean age of 37.4 years) were retrospectively analyzed who underwent DRUJ dorsal ligament reconstruction with extensor retinaculum transposition,DRUJ dorsal capsuloplasty,and TFCC repair for DRUJ dorsal instability.The tissue flap of extensor retinaculum was fixed at the ulnar edge of distal radius by two micro anchors after TFCC repair and dorsal capsuloplasty of the DRUJ capsule.X-ray examination of wrist was performed for all the patients after operation to identify the reduction of DRUJ.The wrist range of flexion and extension,the forearm range of rotation,and the grip strength of hand were measured.Modified Mayo wrist scores,DASH scores and visual analogue scale (VAS) were used to evaluate the function and pain of wrist and upper extremity.Results 18 patients were followed up for 12-70 months with an average period of 34 months.The stability of the DRUJ was restored in 16 patients.The other 2 cases wore long arm splint for 6 weeks after operation due to the residual instability of the DRUJ,after that the instability of DURJ were improved to grade I.The flexion and extension of wrist,the rotation of forearm were improved,but there were no significant difference comparing to those of pre-operation.The VAS,modified Mayo and DASH scores,grip strength of hand were significantly improved from preoperative 4.2±1.1,67.4±11.2,51.3±14.2,16.3±3.7 kg to postoperative 0.2±0.5,83.9±11.6,15.9±3.2,24.9±6.4 kg at the latest follow-up.Conclusion Extensor retinaculum transposition with TFCC repair and DRUJ dorsal capsuloplasty can effectively relieve pain and recovery stability of DRUJ,which was an effective method for chronic DRUJ dorsal instability.

Objective To evaluate the efficacy of the suspended overlength biliary stents modified from nasobiliary tube for prevention of duodenobiliary reflux. Methods Suspended overlength biliary stents were placed in the intrahepatic bile duct of 18 patients with extrahepatic bile duct stricture who underwent biliary stents implantation once or more via ERCP from February 2014 to May 2016.Data of these patients were followed up to June 30, 2017 with self-control method. The patency time of suspended overlength biliary stents was compared with the ordinary biliary stents which were implanted in the last ERCP. Incidence of complications was recorded.Results Eighteen patients were enrolled in the study, but one patient lost follow-up. Finally 17 patients were enrolled in the analysis. Nine patients were malignant and 8 benign biliary stricture. The median patency time of suspended overlength biliary stents was 210 days, which was much longer than that of ordinary stents with median patency time of 139 days(P＝0. 015). The median patency time of overlength biliary stents and metal stents in 3 patients with malignant stricture were 278 days and 205 days (P＝1. 000). The median patency time of overlength biliary stents and traditional plastic stents in 6 patients with malignant stricture were 156 days and 65 days, respectively(P＝0. 049). The median patency time of this innovative stents was prolonged in benign biliary stricture patients (254 days VS 143 days, P＝0. 025). Only one patient developed mild pancreatitis after ERCP. Conclusion Suspended overlength biliary stents can prolong the patency time without increasing postoperative complications, which is worth popularization.

Objective To reduce the occurrence of recurrent choledocholithiasis caused by biliary sphincter dysfunction after extensive endoscopic sphincterotomy ( EST ) for large stone extraction, and to investigate the sphincter-preserving effects of duodenal papilla occlusion by SureClip from MicroTech. Methods Three patients with large biliary stones ( 1. 0-2. 5 cm in stone size, 1. 2-3. 0 cm in common bile duct diameter) and without ERCP history underwent EST ( larger than 1. 0 cm) in Peking University Third Hospital from March 2018 to May 2018. Biliary and pancreatic stents were placed after stone extraction, followed by duodenal papilla occlusion with SureClip from MicroTech. Pressures of biliary duct and Oddi sphincter were measured at pre-EST, immediately after EST, and when stents were removed 3 weeks after EST, respectively. Healing conditions of papilla and complications were documented. Five pigs underwent similar experiments without stone extraction. Results The pressure of Oddi sphincter was significantly reduced after EST, and recovered after papilla occlusion 3 weeks after operation both in pigs and human. All stones were completely removed in the 3 patients without any post-ERCP complications. The papilla was healed under endoscopic observation when stents were removed 3 weeks after papilla occlusion. In animal experiments, histology revealed completely muscularis propria disruption of post-EST papilla without occlusion. In contrast, the muscle layer of post-EST papilla with occlusion by SureClip from MicroTech appeared scar healing. Conclusion The duodenal papilla occlusion by SureClip from MicroTech after EST works as "papilla remolding", which accelerates healing of papilla, and retains the sphincter pressure and anti-reflux barrier function.