Objective: To investigate the role of growth arrest-specific protein 6 (Gas6) in the process of the migration and osteogenic differentiation of human periodontal ligament cells (hPDLCs).Methods: After different concentrations of recombinant human Gas6 (rhGas6) were added to hPDLCs, cell prolife-ration experiment (CCK-8) was taken to observe the effect of rhGas6 on hPDLCs cell proliferation. Scratch test and cell migration test (Transwell) were taken to analyze the migratory ability of hPDLCs in different concentrations of rhGas6 groups. After osteogenic induction, real-time quantitative polymerase chain reaction (real-time PCR) was taken to detect the expression of the Runt-related transcription factor 2 (Runx2) and alkaline phosphatase (ALP). ALP staining was used to detect the amount of mineralized nodules.Results: After adding different concentrations of rhGas6, there were no statistically significant differences in hPDLCs cell proliferation among the experimental groups and the control group at 24, 48 and 72 hours (P>0.05). After 24 h of scratch, the healing area in the 800 μg/L of the rhGas6 group was greater than that in the control group, but without statistically significant difference (31.06%±13.70% vs. 21.79%±9.51%, P>0.05). In the migration test, after 24 h, the number of hPDLCs cells which penetrated through the membrane in the 800 μg/L rhGas6 group was significantly higher than that in the control group (P<0.01). After rhGas6 was added and osteogenic induction, Runx2 and ALP gene expressions of hPDLCs in the 800 μg/L group were significantly higher than those in the control group (1.60±0.30 vs. 0.91±0.10, 2.81±0.61 vs. 0.86±0.12, P<0.01). After Gas6 was knocked down, the ALP expression of hPDLCs was significantly lower than that of the control group (0.39±0.07 vs. 0.92±0.14, P<0.01). There was no significant change in Runx2 expression (P>0.05). After 7 days of osteogenic induction, the mineralized nodules formed in the Gas6 knockdown group were significantly less than those in control group (0.25±0.04 vs. 1.00±0.11, P<0.001). After 14 days of induction, the staining degree of the Gas6 knockdown group was lower than that of the control group, but there was no significant difference (0.86±0.04 vs. 1.00±0.16, P>0.05).Conclusion: After downregulation of Gas6 gene, mineralized nodule formation was reduced and ALP gene expressions were decreased in the early stage of osteogenic induction (7 days). After addition of rhGas6, Runx2 and ALP gene expressions were increased and the number of cell migration was increased, suggesting that Gas6 might play a promoting role in the migration and osteogenic differentiation of human periodontal ligament cells.

Objective: To explore the association between the abnormal root morphology and bone metabolism or root development related gene polymorphism in patients with generalized aggressive periodontitis.Methods: In the study, 179 patients with generalized aggressive periodontitis were enrolled, with an average age of (27.23±5.19) years, male / female = 67/112. The average number of teeth remaining in the mouth was (26.80±1.84). Thirteen single nucleotide polymorphisms (SNPs) of nine genes which related to bone metabolism and root development were detected by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). Root abnormalities were identified using periapical radiographs. The abnormal root morphology included cone-rooted teeth,slender-root teeth,short-rooted teeth,curved-rooted teeth,syncretic-rooted molars,and molar root abnormalities. The number of teeth and incidence of abnormal root morphology in different genotypes of 13 SNPs were analyzed.Results: The constituent ratio of root with root abnormality in GAgP patients was 14.49%(695/4 798). The average number of teeth with abnormal root morphology in GAgP was (3.88±3.84). The average number of teeth with abnormal root morphology in CC, CT and TT genotypes in vitamin D receptor (VDR) rs2228570 was (4.66±4.10), (3.71±3.93) and (2.68±2.68). There was significant difference between TT genotype and CC genotype (t = 2.62, P =0.01). The average number of root morphological abnormalities in CC, CT and TT genotypes of Calcitotin Receptor (CTR) gene rs2283002 was (5.02±3.70),(3.43±3.95), and (3.05±3.12). The incidence of root morphological abnormalities in CC genotype was higher than that in the patients with CT and TT, and the difference was statistically significant(87.86% vs. 65.26% & 63.64%, P=0.006,adjusted OR =3.71,95%CI: 1.45-9.50). There was no significant difference in the incidence of abnormal root morphology between CT and TT genotypes.Conclusion: VDR rs2228570 and CTR rs2283002 may be associated with the occurrence of abnormal root morphology in patients with generalized aggressive periodontitis, which is worthy of further research.

Objective: To detect the ectodysplasin A (EDA) gene mutation in patients with hypohidro-tic ectodermal dysplasia (HED), and to analyze the distribution pattern of missing permanent teeth and the systemic manifestation of HED patients with EDA gene mutation.Methods: Twelve HED families were enrolled from clinic for genetic history collection, systemic physical examination and oral examination. Peripheral blood or saliva samples were collected from the probands and the family members to extract genomic DNA. PCR amplification and Sanger sequencing were utilized to detect the EDA gene variations, which were compared with the normal sequence (NM_001399.5). The functional impact of EDA gene variants was then evaluated by functional prediction of mutation, conservation analysis and protein structure prediction. The pathogenicity of each EDA gene variation was assessed according to the stan-dards and guidelines of the American College of Medical Genetics and Genomics (ACMG). The systemic phenotype and missing permanent tooth sites of HED patients with EDA gene mutations were summarized, and the missing rate of each tooth position was analyzed and compared.Results: Eight out of twelve HED families were identified to carry EDA gene mutations, including: c.164T>C(p.Leu55Pro); c.457C>T(p.Arg153Cys); c.466C>T(p.Arg156Cys); c. 584G>A(p.Gly195Glu); c.619delG(p.Gly207Profs*73); c.673C>T(p.Pro225Ser); c.676C>T(p.Gln226*) and c.905T>G(p.Phe302Cys). Among them, c.164T>C(p.Leu55Pro); c.619delG(p.Gly207Profs*73); c.673C>T(p.Pro225Ser); c.676C>T(p.Gln226*) and c.905T>G(p.Phe302Cys) were novel mutations. The HED patients with EDA gene mutations in this study were all male. Our results showed that the average number of missing permanent teeth was 13.86±4.49, the average number of missing permanent teeth in the upper jaw was 13.14±5.76, the missing rate was 73.02%. And in the lower jaw, the average number of missing permanent teeth was 14.57±3.05, the missing rate was 80.95%. There was no significant difference in the number of missing teeth between the left and right sides of the permanent dentition (P>0.05). Specifi-cally, the maxillary lateral incisors, the maxillary second premolars and the mandibular lateral incisors were more likely to be missing, while the maxillary central incisors, the maxillary and mandibular first molars had higher possibility of persistence.Conclusion: This study detected novel EDA gene pathogenic variants and summarized the distribution pattern of missing permanent teeth of HED patients, thus enriched the variation and phenotype spectrum of EDA gene, and provided new clinical evidence for genetic diagnosis and prenatal consultation.

Objective: To detect the expression of cartilage oligomeric matrix protein (COMP) in the synovial chondromatosis of the temporomandibular joint (TMJSC),and to discuss the possible interactions between COMP, transforming growth factor (TGF)-β3, TGF-β1 and bone morphogenetic protein-2 (BMP-2) in the development of this neoplastic disease.Methods: Patients in Peking University School and Hospital of Stomatology from January 2011 to February 2020 were selected, who had complete medical records, TMJSC was verified histologically after operation. The expressions of COMP, TGF-β3, TGF-β1 and BMP-2 in the TMJSC of the temporomandibular joint were detected by immunohistochemistry and quantitative real-time PCR (RT-PCR) at the protein level and mRNA level respectively, compared with the normal synovial tissue of temporomandibular joint. The histological morphology, protein expression and distribution of TMJSC tissues were observed microscopically, and the positive staining proteins were counted and scored. SPSS 22.0 statistical software was used to analyze the expression differences between the related proteins in TMJSC tissue and the normal synovial tissue of temporomandibular joint and to compare their differences. P<0.05 indicated that the difference was statistically significant.Results: Immunohistochemical results showed that the positive expression of COMP in TMJSC tissues was mostly found in synovial tissues and chondrocytes adjacent to synovial tissues, and the difference was statistically significant, compared with the normal temporomandibular joint synovial tissues. The positive expression of COMP was significantly different between recurrent TMJSC and non-recurrent ones. The positive expressions of TGF-β3, TGF-β1 and BMP-2 were higher than the normal synovial tissue, and were also mostly found in the synovial cells and adjacent chondrocytes, which was further confirmed by Western blot. According to the RT-PCR results, the expressions of COMP, TGF-β3, TGF-β1 and BMP-2 in TMJSC were higher than those in the normal synovial tissue.Conclusion: The expression of COMP in TMJSC of temporomandibular joint increased significantly, compared with the normal synovial tissue. There may be interactions between COMP and cytokines related to the proliferation and differentiation, like TGF-β3, TGF-β1 and BMP-2, which may play a potential role in the pathogenesis of TMJSC.

Objective: To analyze the clinicopathological characteristics of mucosa associated lymphoid tissue (MALT) lymphoma secondary to Sj?gren’s syndrome (SS) (SS-MALT lymphoma) in salivary gland and to explore the value of the combined application of histopathological morphology, protein expression and molecular phenotype in pathological diagnosis and prognostic evaluation of SS-MALT lymphoma.Methods: Sixteen patients with SS-MALT lymphoma were collected from 260 patients who were diagnosed with SS in Peking University School and Hospital of Stomatology from January 1997 to December 2016. Twelve patients with non-MALT lymphoma secondary to SS (non-SS-MALT lymphoma) in salivary gland were selected as controls. The clinical data of the patients were retrospectively reviewed and analyzed. All the patients were followed up until December 20, 2019. Hematoxylin-eosin staining, immunohistochemistry, polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH) techniques were used to observe the histologic characteristics and to detect the manifestations of light chain restrictive expression, immunoglobulin (Ig) gene clonal rearrangement, chromosome translocation and gene abnormality, so as to evaluate their values in pathological diagnosis and prognostic evaluation.Results: The malignant transformation rate of SS to MALT lymphoma was about 6.15%, ranged from 3 to 240 months, during which 2 patients died due to high-level deterioration. Microscopically, the acini of the glandular tissue were atrophied and destroyed. The tumor cells dominated by central cell-like lymphocytes grew diffusely, destroying the epithelial islands. All SS-MALT lymphoma cases were positive in CD20 and Pax5. Half of them had the Ki-67 proliferation index of 10% or less, and half greater than 10%. 93.75% cases expressed AE1/AE3 protein, which showed the residual glandular epithelium. All the tumor cells were negative in CD3ε, and the plasma cells were detected by CD138 antigen. The light chain restrictive expression of κ and λ was 37.5% in SS-MALT lymphoma group. The positive detection rates of immunoglobulin heavy chain (IgH)-FR1, IgH-FR2, IgH-FR3, immunoglobulin kappa chain (IgK)-A, and IgK-B in SS-MALT lymphoma group were 33.3%, 53.3%, 33.3%, 20.0%, and 26.7%, respectively, and 93.3% when together used with IgH and IgK. The positive rates of the MALT1, IGH and BCL6 genes with dual color break-apart probes were 36.4%, 27.3% and 27.3%, and the detection rate of chromosome translocation and gene abnormality by applying the three probes was 72.7%.Conclusion: There are no specific histological characteristics and protein phenotypes in the histologic diagnosis of SS-MALT lymphoma in salivary gland. The combined application of histopathological manifestations, immunohistochemistry, PCR and FISH techniques helps the accurate pathologic diagnosis of the disease. Although SS-MALT lymphoma is considered as an indolent lymphoma with a relatively favorable prognosis, the regular return visit and long-term follow-up should be conducted to detect the clues of recurrence and advanced deterioration.

Objective: To compare the bonding durability of three different self-etch adhesives to primary enamel and dentin, and to investigate the effect of mild salivary contamination followed by air drying on the bonding durability.Methods: Two hundred and forty enamel specimens were divided randomly into 16 groups (n=15/group)according to the adhesive system [self-etch adhesives: Clearfil SE Bond(SE), AdperTM Easy One (EO), Scotchbond Universal (SBU); total-etch adhesive: AdperTM Single Bond Plus(SL)], contamination status (non-contaminated vs. salivary-contaminated ) and storage condition (stored in distilled water for 24 h vs. aging mode 5 000 thermal cycles in 5 ℃ and 55 ℃). Two hundred and forty dentin specimens were assigned in the same way. Shear bond strength for 12 specimens in each group were measured. The adhesive interface for the residual specimens in each group was observed by scanning electron microscopy(SEM). Data were analyzed by three-way analysis of variance and Tukey test(P<0.05).Results: For primary enamel, total-etch adhesive showed higher initial shear bond strength values (28.92±1.83) MPa and shear bond strength values (27.27±3.03) MPa after thermal cycles compared with the other groups, and the difference between the groups was statistically significant (P<0.01). Shear bond strength values of EO decreased significantly in salivary-treated groups, regardless of storage conditions, and the difference was statistically significant (P<0.01). For primary dentin, shear bond strength values of EO decreased significantly in salivary-treated groups after 24 h (P<0.01). After 5 000 thermal cycles, total-etch adhesive showed significantly lower shear bond strength values (14.31±1.97) MPa compared with the other groups, and the difference between the groups was statistically significant (P<0.01), and shear bond strength values of EO were significantly lower than those in SE and SBU groups (P<0.01), regardless of contamination status.Conclusion: Total-etch adhesive SL has better bonding durability to primary enamel. SE and SBU have better bonding durability to primary dentin and have a certain resistance to salivary contamination, while the bonding performance of EO is compromised greatly by mild salivary contamination followed by air drying.

Objective: To establish a method for the production of digital individual tooth tray based on three-dimensional (3D) scan, computer-aided design (CAD) and 3D printing, and to evaluate the effect of impression taking of full-arch crown abutments by digital individual tooth tray technique and conventional method through in vitro study.Methods: The full crown preparation was performed on all the fourteen resin teeth in a standard model of mandibular dentition. The surface data of prepared abutments was collected by 3D scanning. A new project was created in a dental CAD software including all the fourteen teeth in the mandibular dentition. The design modules of anatomy crown and coping were selected for each tooth. The dentition was divided for three sections: right posterior teeth, anterior teeth, and left posterior teeth areas. The connector design was added between the abutments within the same section. The scanned data of the abutments were imported. The occlusal plane and insertion path were determined. The position of margin line, as well as the shape of anatomy crown and connector as the main body of the individual tooth tray were designed for each abutment. The shape of coping was generated as the space for holding the impression material. The finalized data of the main body was imported into Geomagic software. The retentive attachment was added at the external surface and the tissue stop was formed at the internal surface. The completed individual tooth tray was manufactured by 3D printing with resin material. The data of full-arch crown abutments were modified and printed. The conventional dentition trays A and B, as well as digital individual tooth tray were designed and printed for four copies each. The polyether impressions of the full-arch abutments were made by conventional one-step method using dentition tray A, and by sectional-impression technique using digital individual tooth tray and dentition tray B for four times each. The time spent for each impression taking and the numbers of defects at the shoulder and axial/occlusal surface in each impression were recorded. The impression quality of each abutment was evaluated. The overall quality distribution and the pass rate of abutments between the two methods were analyzed.Results: The impressions made by conventional method had more defects at shoulder than those made by digital individual tooth tray technique. No difference of the number of defects at axial/occlusal surface between the two methods was observed. The digital individual tooth tray technique for the full-arch abutment impression exhibited higher pass rate of abutments and better quality of impression, compared with conventional methods.Conclusion: A new method for the production of digital individual tooth tray based on digital scanning, CAD and 3D printing was established. Compared with conventional method, using digital individual tooth tray technique for impression taking of full-arch abutments can achieve better effect.

Objective: To explore the preliminary application of “biocopy function” in digital technology of temporary crown in severe tooth attrition, so as to reduce the difficulty of final restoration adjustment in severe tooth wear cases, and save clinical time.Methods: Twelve patients aged between 40 and 65 years with severe tooth attrition were recruited in this study. The experimental group (6 cases, 3 females and 3 males) used the method of digital copy of temporary restoration shape when making the final restoration, and the control group (6 cases, 3 females and 3 males) used the traditional method to make the final restoration. The mean time of central occlusal adjustment and protrusive and lateral occlusal adjustment of each crown, the number of follow-up visits of the patients were recorded and statistically analyzed. The occlusal comfort of the first and the third months after wearing the prosthesis was evaluated by the patients, and the difference of the occlusal comfort of the final prosthesis made by the two methods was compared (the full score was 10 points). The occlusal adjustment time and occlusal comfort score were used as measurement data. Single sample t test was used. The number of follow-up visits was count data. Rank sum test was used for non-normal continuous variables.Results: The mean occlusal time of each crown adjustment in the experimental group was significantly lower than that in the control group (P<0.01), and the median number of follow-up visits in the experimental group was lower than that in the control group (P<0.01). The average occlusal comfort score of the experimental group was higher than that of the control group at the first time (P<0.01). After three months of crown wearing, the median occlusal comfort score of the experimental group was higher than that of the control group (P<0.05).Conclusion: In the case of severe tooth attrition, it is feasible to use the “biocopy function” in the design software to design the final prosthesis, which is conducive to reduce the difficulty of adjustment and achieve predictable functional and aesthetic effects, which is of great significance to save clinical time and improve the accuracy of restoration.

Objective: To compare the residual cement between computer aided design/computer aided manufacturing customized abutments (CCA) and stock abutments (SA), and to evaluate the feasibility of digital measurement for residual cement volume by three-dimensional scanning.Methods: Twenty master models needed in this study were all taken from one 47-year-old patient with arrested periodontitis, who had already had an implant placed at his right upper central incisor site in the Department of Periodonto-logy, Peking University School and Hospital of Stomatology. After 4 weeks of soft tissue conditioning by means of customized healing abutment, the height of peri-implant soft tissue was measured, from the implant platform to mucosal margin, as 5 mm. Using customized impression coping, the impression was taken and twenty models were fabricated and allocated to 4 groups according to the type of abutments: CCA1 (5 mm transmucosal height CCA, with margin at tissue level), CCA2 (4 mm transmucosal height CCA, with 1 mm submucosal margin), SA1 (3 mm transmucosal height SA, with 2 mm submucosal margin) and SA2 (1 mm transmucosal height SA, with 4 mm submucosal margin). Crowns were cemented to the abutments, which were seated on the working models. Excess cement was removed by a prosthodontic specialist. Thereafter, the volume of residual cement was evaluated by using three-dimensional scanning technique. The area proportion of residual cement was calculated on photographs taken by a single lens reflex camera. The weight of residual cement was weighed by an analytical balance. And the correlation of residual cement volume data with residual cement area proportion or weight of residual cement acquired by traditional methods was analyzed.Results: Residual cement was observed on all the experiment samples. The residual cement volume of CCA was significantly less than that of SA [(0.635 3±0.535 4) mm³ vs. (2.293 8±0.943 8) mm ³, P<0.001]. Consistently, CCA had less residual cement area proportion and weight than those of SA [area proportion: 7.57%±2.99% vs. 22.68%±10.06%,P<0.001; weight: (0.001 5±0.001 0) g vs. (0.003 7±0.001 4) g, P<0.001]. The residual cement volume was strongly correlated with the residual cement area proportion and residual cement weight (r>0.75, P<0.001).Conclusion: These in vitro results suggest that CCA minimized the residual cement more effectively than SA. The method to digitally evaluate the residual cement volume is feasible, but its validity and reliability need to be further studied.

Objective: To establish the workflow of determining the jaw position of repositioning splint with the aid of digital technique, and to evaluate the accuracy of this workflow and compare the accuracy of raising different vertical dimensions in vitro.Methods: A volunteer was recruited. The data of full-arch scans, cone beam computed tomography (CBCT) image and ultrasonic jaw motion tracking of the volunteer were acquired. The full-arch scans were merged with the CBCT image, which were then matched to the jaw motion tracking reference system. The jaw position of repositioning splint was determined when the anterior teeth opening was 3 mm and the condyle was in centric relation of the fossa in the sagittal plane. A digital repositioning splint was designed in the software based on virtual articulator and fabricated with additive manufacturing technique. After the splint was tried in, another CBCT image was taken and a qualitative analysis was conducted to compare the position of condyle between these two CBCT images. In the in vitro study, standard dental plaster casts with resin ball markers attached to the base were mounted onto a fully adjustable articulator in the intercuspal position. The dental casts were scanned by an extraoral scanner to establish digital models. The ultrasonic jaw motion tracking device was used to obtain simulated jaw movements on the articulator, which was repeated for three times. The digital models and data of jaw movements were merged in one coordination with the aid of bite forks. The jaw position of repositioning splint was determined by adjusting data of jaw movements, each of which was used to determine three vertical jaw positions 4 mm, 5 mm, and 6 mm with the horizontal jaw position of protrusion 2 mm. The virtual articulators with differently adjusted jaw movements were applied in designing repositioning splints, and the final repositioning splints and virtual jaw relationships were exported in STL format. Then the repositioning splints were fabricated with additive manufacturing technique and tried in plaster casts on the mechanical articulator, which were scanned and the jaw relationships on the mechanical articulator were exported later. The virtual jaw relationships and scanned jaw relationships were registered according to lower models and displacement of upper models was calculated. Ball markers were fit to acquire the coordinates of centers and absolute difference values of centers along three coordinating axes X, Y, and Z were calculated. One-way analysis of variance was conducted using SPSS 18.0 software to compare deviations of the three different vertical jaw relationships in two-side test and the significance level was 0.05.Results: With the aid of multi-source data fusion and individualized jaw motion, the clinical workflow of determining jaw position of repositioning splint was preliminarily established. The designed jaw position was realized on the right and the condyle was more inferior than the designed position on the left. Both displacement of the upper models and absolute difference values of centers showed no significant differences (P>0.05) in different vertical jaw dimensions. The displacement of the upper models was (0.25±0.04) mm. The absolute difference values of centers along the three coordinating axes X, Y, and Z were respectively (0.08±0.01) mm, (0.30±0.02) mm, and (0.21±0.04) mm.Conclusion: A novel method of determining the jaw position of repositioning splint with the aid of digital technique is established. It is proved to be feasible by try-in after multi-data fusion, computer-aided design and computer-aided manufacturing. As is shown in vitro, it is accurate to apply this method in adjusting jaw position. Further clinical trial will be designed to evaluate its clinical effect.

Objective: To compare the registration accuracy of three-dimensional (3D) facial scans for the design of full-arch implant supported restoration by five methods and to explore the suitable registration method.Methods: According to the criteria, ten patients with maxillary edentulous jaw or end-stage dentition requiring implant supported restorations were enrolled in this study. A special rim with individual feature marks reflected appropriate occlusal relationship and esthetic characteristics was made for each patient. Both 3D facial scan data of natural laughter and with opener traction to expose the teeth or occlusal rim of each patient were acquired by facial scan and input to the digital analysis software Geomagic Qualify 2012. The dataset was superimposed by five different methods: seven facial anatomical landmark points alignment, facial immobile area alignment (forehead and nasal area), facial anatomical landmark points and immobile area combining alignment, facial feature points alignment, facial and intraoral feature points alignment with the same local coordinate system. The three-dimensional deviation of the same selected area was calculated, the smaller the deviation, the higher the registration accuracy. The 3D deviation was compared among the three registration methods of facial anatomical landmark points, facial immobile area alignment and the combination of the above two methods. Friedman test was performed to analyze the difference among the three methods (α=0.05). The effect of the aid of the facial and intraoral feature points were evaluated. Paired t test were performed to analyze the difference (P<0.05).Results: The average three-dimensional deviation of the selected area after alignment with the facial anatomical landmarks was (1.501 2±0.406 1) mm, significantly larger than that of the facial immobile area best-fit alignment [(0.629 1±0.150 6) mm] and the combination of the two methods[(0.629 1±0.150 6) mm] (P<0.001). The aid of the facial feature points could significantly reduce the deviation (t=1.001 3, P<0.001). There was no significant statistical difference in the remaining groups.Conclusion: The forehead area of the 3D facial scan can be exposed as much as possible. The establishment of facial characteristic landmark points and the use of the invariant area alignment can improve the accuracy of registration. It should be clinically feasible to apply three-dimensional facial scan to the design of full-arch implant supported restoration with the registration of the immobile area on the face especially the forehead area.

Objective: To provide the basis for the clinical development of ultrasonic shoulder preparation by comparing the roughness and three-dimensional topography of shoulder surface between ultrasonic instruments and conventional rotary instruments, to make preliminary suggestions for clinical use of ultrasonic instruments.Methods: (1) Four areas of buccal and palatal surfaces of six extracted human premolars were prepared with different grit size of rotary instruments. Polyether was used to take impression of the shoulder area, 3-D topography measurement laser microscope (3-D TMLM) was used to scan the impressions and compare the shoulder surface roughness of the four areas. (2) Six extracted human premolars were prepared, mesial half of the shoulder was finished with traditional rotary instruments and distal half with ultrasonic instruments. Polyether was used to take impression of the shoulder area, 3-D TMLM was used to scan the impressions and compare the shoulder surface roughness and 3-D topography, and the shoulder surface morphology was observed by surgical microscope (×25 magnification). (3) Twenty extracted human maxillary symmetrical homonymous anterior teeth were poured into die stone using artificial gingiva, ultrasonic instruments group and rotary instruments group were divided randomly. After preparing the teeth and taking the shoulder impression with polyether in dental simulate on the training system, the surface roughness of the shoulder impression in mesial, middle and distal areas was scanned and compared. The data were analyzed using SPSS 25.0 software package.Results: (1) There was no significant difference in Ra and Rz values between the abutment shoulder and impression shoulder in different areas. (2) The surface roughness of the shoulder impression prepared by ultrasonic instruments [Ra:(6.59±2.33) μm, Rz:(34.69±7.29) μm] was significantly smaller than that of the rotary instruments [Ra:(21.79±4.89) μm, Rz:(91.69±14.82) μm] (P<0.05). The morphology of the shoulder prepared by ultrasonic instruments was clear and continuous under microscope observation. (3) The surface roughness of each area of the shoulder prepared by ultrasonic instruments was significantly lower than that of the rotary instruments (P<0.001); there was no significant difference of the surface roughness (Ra) in each area of the shoulder impression after ultrasonic instrument preparation, while the shoulder impression roughness in the mesial and distal areas was significantly higher than that in the middle area (P<0.001) after rotary instrument preparation.Conclusion: Compared with the rotary instruments, the ultrasonic instruments can obtain a smoother shoulder surface, especially can significantly improve the shoulder preparation effect near the proximal surface.

Objective: To investigate the change of endo-sinus bone height and bone volume in osteotome sinus floor elevation (OSFE) without bone graft but placing implants simultaneously by using cone beam computed tomography (CBCT) and three dimensional analysis, and to find the impacting factors on endo-sinus bone augmentation.Methods: OSFE was performed in 38 edentulous patients with missing teeth at posterior maxillary region, and 44 implants were placed and referred for OSFE using no graft materials. CBCT was performed pre-surgery and 9-68 months post-surgery when the patients encountered another implant surgery. The gained bone height at mesial, distal, buccal and palatal sites around the implant in sinus were measured, volumetric measurements of the endo-sinus gained bone volume (ESGBV) in the elevated region were calculated by Mimics software. Univariate analysis and multiple linear regression were performed to investigate the impacting factors on the gained bone height and ESGBV. Marginal bone loss was recorded according to the periapical radiography after implant restoration.Results: The mean residual bone height (RBH) pre-surgery was (3.41±1.23) mm, the mean protruded length (PL) into sinus of implant post-surgery was (3.41±1.28) mm, the mean endo-sinus gained bone height was (2.44±1.23) mm at distal sites, (2.88±1.20) mm at mesial sites, (2.83±1.22) mm at buccal sites and (2.96±1.16) mm at palatal sites, the mean endo-sinus gained bone height at distal sites was significantly lower than the other three sites (P<0.05). The average endo-sinus gained bone height was (2.78±1.13) mm. The mean ESGBV was (122.15± 73.27) mm³. Univariate analysis showed the more RBH, the less bone height gained in sinus, which existed at buccal, lingual, mesial and distal sites (P<0.001), and the more RBH, the smaller ESGBV gained (P=0.012). The ESGBV was significantly higher in the subjects whose bone generation period was more than 24 months than those whose bone generation period less than 24 months (P=0.034). The more PL, the more bone height and ESGBV gained (P=0.008). Multivariate analysis showed after adjusting factors of gender, age, smoking, width of sinus floor, thickness of sinus membrane pre-surgery, diameter and length of the implant, PL and bone generation period was positively correlated with mean endo-sinus gained bone height and ESGBV, while RBH negatively correlated with mean endo-sinus gained bone height. During the follow-up, the mean marginal bone loss was 0 (0-1.41) mm and all the implants loaded successfully.Conclusion: OSFE without bone graft but with placed implant simultaneously can increase endo-sinus gained bone height and ESGBV. RBH, PL and bone generation period are the significant factors impacting endo-sinus bone augmentation.

Objective: To investigate the factors affecting the trueness of finish lines of full crown preparations in digital impressions.Methods: A full crown preparation of the right maxillary molar was prepared on the standard resin dentition model, the trueness of the finish lines, the full crown preparation in the whole dentition and the isolated full crown preparation were measured respectively. Detection of scanning trueness of the finish lines of the full crown preparation in the whole dentition: (1) Using Imetric scanner to scan the full crown preparation, obtaining STL (Stereo lithographic) format data as the reference true value; (2) Using CEREC Omnicam oral scanner and 3Shape TRIOS oral scanner to scan the full crown preparation, obtaining all the STL format data, import Geomagic Studio 2013 software, extraction of images and data of the complete finish lines or local finish lines (mesial, distal, buccal, lingual) of the full crown preparation, then using the data to 3D Compare Analysis with the reference true value, outputting RMS (root mean square) values which could evaluate the scanning trueness, the lower RMS value was, the lower the trueness was. The detection of scanning trueness of the finish lines of the isolated full crown preparation: (1) the anterior and posterior adjacent teeth of the preparation were removed to establish the model of the isolated full crown preparation; (2) CEREC Omnicam oral scanner and 3Shape TRIOS oral scanner were used to scan the isolated preparations, and each group was repeated 6 times. Data collection and analysis were the same as the first part, that is, detection of scanning trueness of finish lines of the full crown preparation in the whole dentition.Results: In the whole dentition, (1) the RMS value [(44±7) μm] of CEREC Omnicam oral scanner scanning complete finish lines was greater than that of 3Shape TRIOS oral scanner [(35±6) μm](P<0.05). (2) the RMS values of the mesial [(45±9) μm], buccal [(38±3) μm] and lingual [(40±3) μm] finish lines in CEREC Omnicam oral scanner scanning were all lower than that in distal [(63±7) μm](P<0.05), and the RMS values in mesial were higher than that in buccal and lingual (P>0.05). The RMS values of 3Shape TRIOS oral scanner scanning mesial and distal finish lines were significantly higher than those of the buccal and lingual side (P>0.05), in which:(45±8) μm in mesial, (50±10) μm in the distal, (33±8) μm in the buccal and (33±6) μm in the lingual side. The RMS value of CEREC Omnicam oral scanner scanning distal finish line was greater than that of 3Shape TRIOS oral scanner (P<0.05). Without adjacent teeth, (1) the RMS values of the complete finish lines of CEREC Omnicam oral scanner and 3 Shape TRIOS oral scanner were significantly reduced (P<0.05), including CEREC Omnicam oral scanner (34±3) μm and 3 Shape TRIOS oral scanner (26±4) μm; (2) the RMS values of the buccal and lingual finish lines of CEREC Omnicam oral scanner and 3Shape TRIOS oral scanner showed no significant changes (P>0.05), among which, CEREC Omnicam oral scanner buccal (44±7) μm, lingual (43±3) μm, 3Shape TRIOS oral scanner buccal (29±5) μm, lingual (40±7) μm. The RMS values of CEREC Omnicam oral scanner and 3Shape TRIOS oral scanner were significantly reduced and there was no significant difference between them (P>0.05). CEREC Omnicam oral scanner (32±8) μm and 3Shape TRIOS oral scanner (32±6) μm. The RMS values of the distal finish lines of CEREC Omnicam oral scanner and 3 Shape TRIOS oral scanner also decreased significantly (P<0.05), and CEREC Omnicam oral scanner (38±3) μm decreased more significantly, similar to 3Shape TRIOS oral scanner (36±1) μm, P>0.05.Conclusion: When adjacent teeth exist in the full crown preparation, the mesial and distal parts of the finish line will be blocked by adjacent teeth, which will affect the trueness of the local finish line, and ultimately reduce the trueness of the complete finish line.

Objective: To compare temporomandibular joint (TMJ) morphology and position among skeletal class Ⅱ female adolescents with different vertical patterns using cone-beam CT (CBCT). Methods: Diagnostic CBCT images of 80 female patients aged 11 to 14 years were assessed retrospectively. According to subspinale-nasion-supramental angle (ANB) and Frankfort horizontal plane-gonion-gnathion angle (FH-GoGn), the participants were categorized into four groups (20 subjects each), i.e. class Ⅰ normal angle (group 1, 0°≤ANB<4°, 22°≤FH-GoGn≤32°), class Ⅱ low (group 2, ANB≥4°, FH-GoGn<22°), normal (group 3, ANB≥4°, 22°≤FH-GoGn≤32°) and high angle (group 4, ANB≥4°, FH-GoGn>32°). Cephalometrics, morphology and position of TMJ were measured in Dolphin software. Using paired-samples t test to analyze TMJ symmetry, One-way analysis of variance (One-way ANOVA) and Chi-square tests to detect differences among the groups. The correlations between cephalometrics and TMJ measurements were also analysed within the skeletal class Ⅱ patients.Results: (1) Analysing TMJ morphologic symmetry, some measurements differed statistically although the mean diffe-rences were negligibly relative to their values. No statistically significant difference was found among the groups though group 4 showed the highest probability of condylar position asymmetry (65%). (2) Comparing group 1 with group 3, statistical difference was found in condylar position (χ²=6.936, P<0.05) instead of morphologic measurements. Anterior and concentric condylar position were more frequently observed in group 1, yet posterior position was more prevalent in group 3. (3) In groups 2, 3, and 4, statistically, group 2 had the deepest glenoid fossa depth (H_2&4=10.517,P=0.002), biggest superior (LSD-t_2&3=3.408, LSD-t_2&4=5.369, P<0.001) and lateral (LSD-t_2&3=2.767, LSD-t_2&4=3.350, P=0.001) joint spaces, whereas group 4 showed the shortest condylar long axis diameter (H_2&4=13.374, P<0.001), largest glenoid fossa vertical distance (LSD-t_2&4=4.561, P<0.001, LSD-t_3&4=2.713, P=0.007), smallest medial (LSD-t_2&4=-4.083, P<0.001) and middle (LSD-t_2&4=-4.201, P<0.001) joint spaces. The posterior condylar position proportion gradually increased from groups 2 to 3 to 4. Correlation analysis revealed ANB correlated with anterior joint space positively (r=0.270, P=0.037) and condylar long axis angle negatively (r=-0.296, P=0.022). FH-GoGn correlated with superior (r=-0.488, P<0.001), posterior (r= -0.272, P=0.035), mesial (r=-0.390, P=0.002), middle (r=-0.425, P=0.001), and lateral (r=-0.331, P=0.010) joint spaces, articular eminence inclination (r=-0.259, P=0.046), as well as condylar long axis diameter (r=-0.327, P=0.011) negatively, and glenoid fossa depth (r=0.370, P=0.004) positively. Conclusion: TMJ characteristics of skeletal class Ⅱ sagittal pattern mainly reflected in condylar position rather than morphology. TMJs of different vertical patterns differed more in joint spaces, position of condyle and glenoid fossa than in morphologic measurements. Vertical position of glenoid fossa and proportion of posterior condyle increased gradually from hypodivergent to hyperdivergent. Highest glenoid fossa position, maximum ratio of posterior positioned condyle, smallest joint spaces, shallowest glenoid fossa depth, and narrowest condylar long axis diameter were found in skeletal class Ⅱ high angle group, which means that patients with this facial type have considerable joint instable factors, and we should especially pay attention when orthodontic treatment is carried out on them.

Objective: To observe the wear performance of Giomer and universal composite for posterior restorations by 3D laser scan method, in order to guide the material selection in clinic.Methods: In this study,48 patients (108 teeth) were selected according to the inclusion and exclusion criteria. All the patients in need of a minimum of 2 Class Ⅰ and/or Class Ⅱ restorations were invited to join the study. The teeth were restored with Giomer (Beautifil Ⅱ, BF) and universal composite (Filtek Z350, Z350) randomly. The restorations were evaluated at baseline and after 6-, 18-, 48-month using the modified United States Public Health Service (USPHS) criteria for clinical performance. The in vivo images and gypsum replicas were taken at each recall. A 3D-laser scanner and Geomagic Studio 12 were used to analyze the wear depth quantitatively. Statistical analysis was performed with SPSS 20.0.Results: After 4 years, 89.6% patients were recalled. The survival rate of both materials was 95.8% (Kaplan-Meier survival analysis). Seven restorations of the two materials failed due to loss of restoration, bulk fracture, secondary caries and pulp necrosis. The wear patterns of restorations were divided into 2 classes. Pattern Ⅰ: occlusal contact areas showed the deepest and fastest wear depth; pattern Ⅱ: the wear depth was slow and uniform. Both materials showed a rapid wear in the first 6 months. Then the wear rate was decreased. The occlusal wear depth after 4 years were (58±22) μm and (54±16) μm for BF group and Z350 group respectively, which were in accordance with the American Dental Association (ADA) guidelines (wear depth for 3 years <100 μm). No significant differences (P>0.05) were observed between the two groups. Regarding the restorations with wear pattern Ⅰ, the wear depth of BF group was higher than Z350 group at 6- and 48-month (P<0.05), while there was no significant difference between restorations with wear pattern Ⅱ (P>0.05).Conclusion: Within the limitation of the study, after 4 years, the survival rate and wear resistance of Giomer met ADA guidelines for tooth-colored restorative materials for posterior teeth. When the two materials were applied in occlusal contact areas, wear resistance of Giomer was slightly lower than universal composite resin. No significant difference was found when they were applied in none of the occlusal contact areas.

Objective: To measure the weight and volume of normal submandibular gland by in vitro detection of glandular body, to compare with the measurement values of CT volume rendering to evaluate the consistency of the two methods, and to explore the related factors affecting the weight and volume of the submandibular gland.Methods: The patients who underwent neck dissection due to oral cancer and were confirmed with normal submandibular gland by postoperative histopathology in Peking University School and Hospital of Stomatology from May 2019 to January 2020 were collected in this study and divi-ded into 4 groups according to the age standards raised by the Society of Geriatrics Chinese Medical Association and WHO (2000) age standards. The submandibular gland was carefully dissected along with the capsule immediately after neck dissection. The weight and volume of submandibular gland were accurately measured by an integrated aseptic measuring device. The volume of submandibular gland was measured by CT volume rendering before operation and the consistency of the two methods was evaluated. The 95% confidence interval of the weight and volume of submandibular gland in the different groups of Chinese people, which were divided by gender and age, were calculated, and the correlation with age, gender, height, weight, body mass index (BMI) and other factors was analyzed.Results: The weight and vo-lume of submandibular gland were measured in 220 subjects. The average weight and volume of submandibular gland were (11.69±2.45) g and (11.55±2.41) cm³ respectively. The volume of submandibular gland measured by CT volume rendering ranged from 70% to 82% of that measured by in vitro detection of glandular body, and the correlation coefficient between the two methods was 0.976 (P<0.05). The gender difference of weight and volume of submandibular gland existed in the groups of youth, middle-aged, young elderly and elderly groups, the values of males were obviously higher than those of females (P<0.05). There was no gender difference of weight and volume of submandibular gland in the adolescent group (P>0.05). The weight and volume of submandibular gland had a strong positive correlation with body height (P<0.05), a weak positive correlation with body weight (P<0.05), and no correlation with BMI (P>0.05). The female’s weight and volume of submandibular gland in the young elderly and elderly groups were significantly lower than those in the other three groups (P<0.05). Conclusion: The normal reference range of the weight and volume of submandibular gland in vitro were established in different age and gender groups of Chinese people. The volume of submandibular gland mea-sured by CT volume rendering was 70%-82% of that measured by in vitro detection of glandular body. The results of the two methods had a high degree of consistency. The weight and volume of submandibular gland were related to age, gender, body height and body weight.

Objective: To investigate the correlation between morphological stages of midpalatal suture (MPS) and Demirjian dental age.Methods: In this retrospective study, 1 076 cone-beam CT (CBCT) images (female: 675, male: 401; age range: 6.0 to 21.0 years) were included. Horizontal view of each sample’s CBCT images was observed, each sample’s MPS stage was recorded, and dental age. MPS stage and dental age were ordered with categorical variables. Therefore, their correlation was investigated through Spearman correlation coefficient analysis and diagnostic test analysis.Results: (1) For left lower second premolar: 95.2% of those in dental age stage B-D were in MPS 1-2, accounting for the largest proportion. 85.3% of those in dental age stage E were in MPS 1-2, still accounting for the largest proportion. Another 14.7% were in MPS 3. 45.1% of those in dental age stage F were in MPS 3, 46.1% in MPS 1-2, and another 8.8% in MPS 4s1. 49.8% of those in dental age stage G were in MPS 3. 24.9% in MPS 4s1, and 18.9% in MPS 1-2. 80.1% of those in dental age stage H were in MPS 4-5. Another 16.3% were in MPS 3. (2) For left lower second molar: 89.7% of those in dental age stage B-D were in MPS 1-2, accounting for the largest proportion. 67.4% of those in dental age stage E were in MPS 1-2, still accounting for the largest proportion. Another 26.1% were in MPS 3. 55.3% of those in dental age stage F were in MPS 3, 34.2% in MPS 1-2, and another 10.5% in MPS 4s1. 50.7% of those in dental age stage G were in MPS 3, 24.3% in MPS 4s1, and 16.8% in MPS 1-2. 83.8% of those in dental age stage H were in MPS 4-5, another 14.2% were in MPS 3. (3) To diagnose MPS stage with dental age, diagnostic pairs with good performance included: Dental age of left lower second molar-MPS: H-4s2, H-5, D-1; Dental age of left lower second premolar-MPS: H-4s2, H-5, G-3. Other diagnostic pairs were of ordinary diagnostic efficiency. (4) For dental age-MPS Spearman correlation analysis, dental age of left lower second molar-MPS had the highest Spearman coefficient (0.68), dental age of left lower second premolar-MPS was the second high (0.64). (5) Dental age stage H of left lower second molar or left lower second premolar indicated that the individual was later than MPS 4s2.Conclusion: Dental age’s diagnostic efficiency for MPS stage is ordinary on the whole, except for some pairs with good performance. Therefore, pre-treatment CBCT examination should be considered as assistance for evaluating maturation and fusion status of midpalatal suture.

Objective: To develop a software based on “UniDental” system which is a virtual reality dental simulation system and applied to undergraduate majoring in stomatology to improve the ability of identifying caries.Methods: A software was developed applying to identify virtual dental caries based on UniDental system. In the software, a virtual dental caries model was designed and carious tissue was separated to 3 layers by the depth. The stiffness was the same within each layer which was increasing gradually layer by layer. The roughness was also the same within each layer which was decreasing gradually layer by layer. Sixty-four participants in pre-clinical stage of the class of 2014 majoring in stomatology from Peking University School of Stomatology were trained with the software. During the training, the students should probe on the virtual dental carious tissue layer by layer and feel the difference of vertical stiffness and horizontal roughness of each layer by using a handpiece with realistic force feedback. After training, a questionnaire survey was conducted to evaluate the software including a score of 1-5 for haptic fidelity of stiffness and roughness and their relevant gradient and benefit of improving the ability of identifying caries, choosing the preferred training method. The data were statistically analyzed using Kruskal-Wallis test.Results: The median of subjective evaluation scores of the proposed metrics were all “4”, demonstrating that the software operated above medium fidelity. The stiffness scores of all 3 layers were statistically significant (P<0.05) on the stiffness gradient score. The roughness scores of the 1st and 2nd layers were statistically significant (P<0.05) on the roughness gradient score. The training was helpful to improve the ability of identifying caries (median was 4). The scores of all 3 layers stiffness and relevant gradient were statistically significant (P<0.05) on the score of benefit of improving the ability of identifying caries. 90.4% of the participants preferred the traditional extracted teeth training method.Conclusion: The virtual reality dental simulation system was helpful to improve students’ ability of identifying caries. It couldn’t replace the traditional extracted teeth training method by now, it should be used as a supplement to the traditional training method.

Objective: To evaluate frequency and patterns, risk factors of MSU (monosodium urate) crystal deposition at lower extremity tendon by ultrasonography in gout patients, and to explore diagnostic value by ultrasonography.Methods: Patients diagnosed with gout and age matched healthy controls had ultrasound scanning of both feet and knees including joints and tendons (achilles, quadriceps, and patellar tendon). Readers who scored the ultrasound scans for MSU crystal deposition were blinded to the patients’ clinical diagnoses. Clinical characteristics were compared between positive and negative crystal deposition groups by US, and risk factors of MSU deposition in tendons were analyzed. Diagnostic values of MSU deposition were evaluated by ultrasonography according with positive MSU crystal in synovial fluid or tophi by polarized microscopy.Results: Eighty patients and eighty healthy controls were included. Thity-three patients (47.5%) had tophi by physical examination. The achilles tendon was the most commonly involved tendon site 41(51.2%), followed by the quadriceps tendons 22(27.5%), and patella tendon 10(12.5%). There were no MSU deposition in healthy control group at tendon by ultrasonography. Compared with negative MSU deposition at tendon site by ultrasonography, tendon MSU positive patients had longer mean gout duration [(87.3±40.9) months vs. (7.7±2.6) months, P=0.001];higher frequency of gout flare [2(1, 2) /year vs. 1(1,1) /year, P=0.001]; higher BMI [(26.3±2.5) kg/m²vs. (23.3±2.1) kg/m², P=0.05]. Also, the mean serum uric acid and creatinine levels were higher in tendon MSU positive group [(584.6±87.6) μmol/L vs. (460.4±96.7) μmol/L, P=0.001] and [(90.9±33.3) μmol/L vs. (70.6±40.2) μmol/L, P=0.02] separately. Logistic regression analysis showed gout duration and flare frequency were independent risk factors for MSU deposition at tendon by ultrasonography (P<0.01). Joint or tophi aspirations were performed in all the eighty gout patients, and positive MSU crystals in synovial fluid analysis by polarized microscopy were defined as the golden standard of gout diagnosis. When compared with the golden standard, the sensitivity and specificity were 94.0% and 78.0% separately for MSU deposition at tendon by ultrasonography. Conclusion: Tendon involvement at the lower extremity tendons in gout is very common. Long gout disease duration and high frequency of gout flare are both independent risk factors of tendon MSU deposition by ultrasonography. Ultrasonography had good sensitivity and specificity for detecting tendinous tophi and aggregates.

Objective: To explore the natural mutations in Spike protein (S protein) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the changes of affinity between virus and associated receptors or drug molecules before and after the mutation based on whole length sequencing results.Methods: In the study, the bioinformatics analysis of all the published sequences of SARS-CoV-2 was conducted and thus the high frequency mutation sites were affirmed. Taking advantages of PolyPhen-2, the functional influence of each mutation in S protein was prospected. The 3D homologous modelling was performed by SWISS-MODEL to establish mutated S protein structural model, in which the protein-docking was then implemented with angiotensin-converting enzyme 2 (ACE2), dipeptidyl peptidase-4 (DPP4) and aminopeptidase N (APN) by ZDOCK, and the combining capacity of each mutated S protein evaluated by FiPD. Finally, the binding ability between mutated S proteins and anti-virus drugs were prospected and evaluated through AutoDock-Chimera 1.14.Results: The mutations in specific region of S protein had greater tendency to destroy the S protein function by analysis of mutated S protein structure. Protein-receptor docking analysis between naturally mutated S protein and host receptors showed that, in the case of spontaneous mutation, the binding ability of S protein to ACE2 tended to be weakened, while the binding ability of DPP4 tended to be enhanced, and there was no significant change in the binding ability of APN. According to the computational simulation results of affinity binding between small molecular drugs and S protein, the affinity of aplaviroc with S protein was significantly higher than that of other small molecule drug candidates.Conclusion: The region from 400-1 100 amino acid in S protein of SARS-CoV-2 is the mutation sensitive part during natural state, which was more potential to mutate than other part in S protein during natural state. The mutated SARS-CoV-2 might tend to target human cells with DPP4 as a new receptor rather than keep ACE2 as its unique receptor for human infection. At the same time, aplaviroc, which was used for the treatment of human immunodeficiency virus (HIV) infection, may become a new promising treatment for SARS-CoV-2 and could be a potential choice for the development of SARS-CoV-2 drugs.

Objective: To investigate the risk factors for acute myocardial injury in coronavirus disease 2019 (COVID-19) patients.Methods: This is a retrospective analysis of a COVID-19 cohort, in which 149 confirmed COVID-19 patients enrolled were divided into the group of myocardial injury (19 cases) and the group of non-myocardial injury (130 cases). Myocardial injury was defined according to Fourth universal definition of myocardial infarction released by European Society of Cardiology (ESC) in 2018, that cardiac troponin (cTn) was above 99th percentile of the reference level. Clinical information and results of laboratory tests of the eligible patients were collected. Factors associated with myocardial injury in COVID-19 patients were evaluated.Results: Compared with the group of non-injury, the patients in the group of injury were older and had a larger proportion of severe or critical cases (P<0.05), higher respiratory rate and lower percutaneous oxygen saturation (SpO₂) without oxygen therapy on admission (P<0.05). All inflammatory indexes except for tumor necrosis factor α (TNF-α) showed significant elevation in the patients of the group of injury (P<0.05). Analyzed by Spearman correlation test, we showed that the levels of circulatory cTnI were in positive correlation with the levels of high-sensitivity C-reactive protein (hs-CRP), ferritin, receptor of interleukin-2 (IL-2R), interleukin-6 (IL-6) and interleukin-8 (IL-8) (ρ>0, P<0.05). Lower SpO₂ without oxygen therapy on admission (OR: 0.860, 95%CI: 0.779-0.949, P=0.003) and higher plasma IL-6 levels (OR: 1.068, 95%CI: 1.019-1.120, P=0.006) were independent risk factors for acute myocardial injury in the patients with COVID-19 by multivariate Logistic regression analyses.Conclusion: Hypoxic state and inflammation may play a key role in the pathogenesis of acute myocardial injury in COVID-19 patients.

Objective: To analyze the risk factors of recurrent kyphosis after removal of short segmental pedicle screw fixation in patients with thoracolumbar burst fractures.Methods: Retrospective analysis was conducted of 144 cases of thoracolumbar burst fractures without neurological impairment treated in Peking University Third Hospital from January 2010 to December 2017. There were 74 males and 70 females, with an average age of (39.1±13.2) years. The distribution of the injured vertebrae was T12: 42, L1: 72 and L2: 30, with fracture types of A3: 90, B1: 25 and B2: 29. The patients were divided into two groups: Recurrent kyphosis group (n=92) and non-recurrent kyphosis group (n=52). SPSS 26.0 software was used for univariate analysis and Logistic regression analysis.Results: The average follow-up time was 28 (20-113) months. The imaging indexes of pre-operation, 3 days post-operation, 12 months post-operation and the last follow-up were measured and compared. Anterior vertebral body height, segmental kyphosis, vertebral wadge angle and Gardner deformity were significantly improved after operation (P<0.05), and there were some degrees of loss in the 1-year follow-up; anterior vertebral body height and vertebral wadge angle were no longer changed after the removal of the screws; however, segmental kyphosis and Gardner deformity were still aggravated after the removal of the screws (P<0.05). There were some degrees of collapse of the height of the upper and lower discs during the follow-up. Univariate analysis showed that there were statistically significant differences (P<0.05) between the two groups in gender, age (36.9 years vs. 43.0 years), upper disc injury, CT value (174 vs. 160), segmental kyphosis (16.6° vs. 13.3°), vertebral wadge angle (16.7° vs. 13.6°), Gardner deformity (19.1° vs. 15.2°) and ratio of anterior vertebral body height (0.65 vs. 0.71). Logistic regression analysis showed that male (OR: 2.88, 95%CI: 1.196-6.933), upper disc injury (OR: 2.962, 95%CI: 1.062-8.258) and injured vertebral wedge angle were risk factors of recurrent kyphosis after removal of internal fixation for thoracolumbar burst fracture (P<0.05).Conclusion: The patients with thoracolumbar burst fracture can obtain satisfactory effect immediately after posterior short segmental pedicle screw fixation, however, there may be some degree of loss during the follow-up. Male, upper disc injury and injured vertebral wedge angle are the risk factors of recurrent kyphosis after removal of internal fixation for thoracolumbar burst fracture.

Objective: Severe hip osteoarthritis, caused by bone or joint maldevelopment, biomechanical transformation and previous surgical intervention, is inclusively existed in spondyloepiphyseal dysplasia (SED). To investigate and discuss the short-term efficacy and possible effects of total hip arthroplasty in the treatment of Tönnis grade 3 hip osteoarthritis in patients with SED.Methods: From January 2017 to June 2019, 374 patients with hip osteoarthritis were involved for total hip arthroplasty conducted by senior professional surgeons, of whom 9 patients (6 males and 3 females) with 12 hip osteoarthritis secondary to the SED met the inclusive and exclusive criteria and received the above-mentioned hip operation. The short-term outcomes were observed.Results: All the patients were implanted with Johnson & Johnson ceramic on ceramic cementless hip prostheses within the arthroplasty. They were followed up for an average period of 20 months. Except for one muscular calf vein thrombosis case, no complications, such as aseptic loosening, joint dislocation, fracture, neurovascular injury, deep vein thrombosis and infection were observed in all the 9 patients. Before the surgery, the average Harris hip score was 35.55, while the average of the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) was 56.56. The level of quality of life indicated by SF-12 score was 41.56 on average. The mean pre-operation visual analogue scale (VAS) was 7.44. At the last follow-up, the average Harris hip score increased to 89.56, whereas the average WOMAC declined to 41.11. Compared with the baseline point, the average SF-12 score went up to 56.33. Dramatic drop of the mean VAS value to 2.67 was also observed at the last follow-up. In addition, post-operative increase of several pelvic-related parameters including pelvic incidence, pelvic tilt and sacral slope could be observed in the SED patients. The average measured pelvic incidence, pelvic tilt and sacral slope were 68.95°±4.60°, 52.75°±1.06° and 17.45°±1.77° before operation, respectively; whilst the mean value of these specific parameters increased to 76.98°±5.12°, 60.51°±4.35° and 18.10°±2.02°, respectively. The even leg lengths of the lower extremities were obtained after total hip arthroplasty.Conclusion: Total hip arthroplasty is satisfactory in the short-term pain relieve and function recovery for the management of Tönnis grade 3 hip osteoarthritis secondary to the SED.

Objective: To evaluate the value of CT spectral curve in differentiating spinal tumor metastasis (STM) from spinal infections (SI).Methods: In the study, 29 STM and 18 SI patients proved pathologically and clinically were examined by dual energy spectral CT (DESCT). The monochromatic images and CT spectral curves were generated automatically by GSI Viewer software. The attenuation values at different energy levels (40-140 keV, every 10 keV), the attenuation values of the lesions on the conventional polychromatic CT images and the gradients of the curve were calculated and compared between STM and SI.Results: The median age of STM and SI (58 years vs. 64 years) were not significantly different (U=171, P=0.4). The attenuation values of STM at 40-100 keV were 281.79 (143.67, 446.19) HU, 199.68 (100.04, 321.49) HU, 151.54 (81.47, 243.49) HU, (122.64±27.72) HU, (99.90±23.88) HU, (85.82±21.61) HU, and (75.94±20.27) HU, respectively, which were significantly higher than SI: 185.29 (164.19, 277.03) HU, 138.44 (124.98, 238.56) HU, 105.46 (92.94, 169.53) HU, (93.77±15.55) HU, (79.15±12.84) HU, (68.99±11.75) HU, and (62.22±11.71) HU (all P<0.05). The attenuation values at 110-140 keV and the attenuation value on the conventional CT images were not significantly different between STM and SI. The gradient of CT spectral curve of STM was 2.43±0.58, which was higher than the value of 1.50±0.40 for SI (P<0.001). Using 1.72 and 248.80 HU as the threshold value for CT spectral curve slope and the attenuation value at 40 keV, could obtain the area under receiver operating characteristic (ROC) curve of 0.905 and 0.892, sensitivity of 88.0% and 80.0%, and specificity of 76.9% and 92.3%.Conclusion: CT spectral curve provides valuable semi-quantitative information for the differential diagnosis of STM and SI, which can be used as a supplement to traditional CT imaging.

Objective: To explore the influence of intraoperative urine volume on postoperative acute kidney injury (AKI) and the independent risk factors of AKI.Methods: This was a retrospective cohort study recruiting patients who received selective pulmonary resection under general anesthesia in Peking University First Hospital from July, 2017 to June, 2019. The patients were divided into the AKI group and the control group according to whether they developed postoperative AKI or not. Firstly, univariate analysis was used to analyze the relationship between perioperative variables and postoperative AKI. Secondly, receiver operating characteristic (ROC) curve was used to explore the predictive value of intraoperative urine output for postoperative AKI. The nearest four cutoff values [with the interval of 0.1 mL/(kg·h)] at maximum Youden index were used as cutoff values of oliguria. Then univariate analysis was used to explore the relationship between oliguria defined by these four cutoff values and the risk of AKI. And the cutoff value with maximum OR was chosen as the threshold of oliguria in this study. Lastly, the variables with P<0.10 in the univariate analysis were selected for inclusion in a multivariate Logistic model to analyze the independent predictors of postoperative AKI.Results: A total of 1 393 patients were enrolled in the study. The incidence of postoperative AKI was 2.2%. ROC curve analysis showed that the area under curve (AUC) of intraoperative urine volume used for predicting postoperative AKI was 0.636 (P=0.009), and the cutoff value of oliguria was 0.785 mL/(kg·h) when Youden index was maximum (Youden index =0.234, sensitivity =48.4%, specificity =75.0%). Furthermore, 0.7, 0.8, 0.9, 1.0 mL/(kg·h) and the traditional cutoff value of 0.5 mL/(kg·h) were used to analyze the influence of oliguria on postoperative AKI. Univariate analysis showed that, when 0.8 mL/(kg·h) was selected as the threshold of oliguria, the patients with oliguria had the most significantly increased risk of AKI (AKI group 48.4% vs. control group 25.3%, OR=2.774, 95%CI 1.357-5.671, P=0.004). Multivariate regression analysis showed that intraoperative urine output <0.8 mL/(kg·h) was one of the independent risk factors of postoperative AKI (OR=2.698,95%CI 1.260-5.778, P=0.011). The other two were preoperative hemoglobin ≤120.0 g/L (OR=3.605, 95%CI 1.545-8.412, P=0.003) and preoperative estimated glomerular filtration rate <30 mL/(min·1.73 m²) (OR=11.009, 95%CI 1.813-66.843, P=0.009). Conclusion: Oliguria is an independent risk fact or of postoperative AKI after pulmonary resection, and urine volume <0.8 mL/(kg·h) is a possible screening criterium.

Objective: To evaluate the effect of different anesthesia management on clinical outcomes in former prematurely born infants undergoing surgeries for retinopathy of prematurity (ROP).Methods: In this retrospective study, electronic medical record database was searched for all former prematurely born infants (gestational age<37 weeks and post conceptual age<60 weeks) who received ROP surgery under inhalational general anesthesia between November 2016 and October 2018. The patients were divided into two groups based on anesthesia management: laryngeal mask airway (LMA) insertion without intravenous muscle relaxant injection and with pressure support ventilation (LMA group) or airway secured with endotracheal tube (ETT) with intravenous muscle relaxant injection and pressure controlled ventilation (ETT group). Primary outcomes included perioperative adverse events and complications. Extubation time and length of stay after surgery were also recorded.Results: Sixty eight preterm infants in the LMA group and 100 preterm infants in the ETT group were included. The incidence of adverse events during surgery (including airway management change and desaturation) was similar in LMA group and ETT group (4.4% vs. 1.0%, P =0.364). During the early recovery period after surgery, the incidence of difficult extubation (extubation time >30 min) was significantly lower in LMA group compared with ETT group (4.4% vs.15.0%, RR=0.262, 95%CI:0.073-0.942, P=0.029). The incidence of respiratory events was similar between the two groups (20.6% vs. 27.0%, P =0.342). However, the incidence of apnea was significantly lower in the LMA group than in the ETT group (5.9% vs.19.0%, RR=0.266, 95%CI: 0.086-0.822, P =0.015). No significant difference was observed between the LMA group and ETT group in incidences of cardiovascular events (0% vs. 1.0%, P =1.000) and unplanned admission to neonatal intensive care unit (5.9% vs. 7.0%, P=0.774). No airway spasm, re-intubation, aspiration or regurgitation was observed during early recovery. During late recovery after returning to ward, the incidence of adverse events was also similar between the two groups (0% vs. 2.0%, P =0.241). The median (IQR) extubation time was 6 (5,10) min in LMA group and 10 (6, 19) min in ETT group (P <0.001). The median length of stay after surgery was significantly shortened in LMA group compared with ETT group [20 (17,22) hours vs. 22 (17,68) hours, P =0.002].Conclusion: Compared with endotracheal intubation with intravenous muscle relaxant injection, laryngeal mask airway insertion without muscle relaxant could achieve an early extubation, and reduce the incidence of apnea during early recovery period in former prematurely born infants undergoing ROP surgery.

Objective: To summarize and analyze the treatment process, long-term efficacy and clinical economics of children’s hepatoblastoma (HB) in multi-disciplinary team (MDT) mode, so as to provide basis for the rational choice of diagnosis and treatment.Methods: From January 2014 to February 2019, 13 cases of hepatoblastoma in children who completed the whole treatment course in the Pediatric Hematology Tumor Ward of Peking University First Hospital were collected and analyzed, and were followed up until June 30, 2020. There were 9 males and 4 females who were diagnosed and treated according to the MDT process in the hospital. The median age was 16 months (2-54 months), 69.23% (9/13) were under 2 years old. The characteristics, diagnosis and treatment process and treatment effect of the cases were summarized, and the cost of clinical treatment was analyzed.Results: According to the pretreatment extent of disease(PRETEXT), there were 1, 9 and 3 children with stages Ⅱ, Ⅲ and Ⅳ. 76.92% (10/13) of the patients had the largest tumor diameter > 10 cm. All the patients received preoperative neoadjuvant chemotherapy (8 patients received 4 cycles of chemotherapy, and 6 patients changed the chemotherapy plan), surgical treatment and postoperative chemotherapy, the tumor volume decreased by more than 50% (64%-95%) in 12 cases, except 1 case with no significant increase of alpha fetal protein and multiple lesions .The median length of stay was 87 days (68-214 days), the median cost of stay was 200 000 yuan (115 000-500 000 yuan), the median length of stay was 7 days (5-17 days), the median cost of stay was 20 000 yuan (15 000-60 000 yuan), and the incidence of postoperative complications was 7.69% (1/13). All the patients were followed up for 16-69 months. All the patients survived.Conclusion: Under the MDT mode, the treatment is seamless connection, the long-term prognosis of children with HB is good, and the total hospitalization cost and time are within the acceptable range. Standard preoperative neoadjuvant chemotherapy can significantly reduce the tumor, improve the resection rate, reduce postoperative complications, reduce the total individual expenditure, shorten the total hospital stay, and further improve the long-term disease-free survival rate.

Objective: To distinguish the endoscopic and clinical features of ampullary polyps,to investigate the endoscopic cancer risk factors of ampullary polyps based on the compared differences of benign lesions and adenocarcinoma, and to assess the accuracy of forceps biopsy.Methods: Authors retrospectively analyzed the data extracted from patients treated with endoscopic papillectomy (EP) from January 2009 to May 2019 in the Department of Gastroenterology, Peking University Third Hospital. Endoscopic pictures and pathology reports were reevaluated and analyzed. Differences between benign and cancer groups were conducted.Results: In the study,42 cases were involved, 35 to 83 years old, containing 83.3% older than 50 years old patients. The histological types were as follows, 2 for inflammatory polyps (4.8%), 1 for neuroendocrine tumor (2.4%), 1 for hyperplastic polyp (2.4%), 5 for grade Ⅰ adenoma (11.9%), 10 for grade Ⅱ adenoma (23.8%), 4 for grade Ⅲ adenoma (9.5%) and 19 for adenocarcinoma (45.2%),and 90.5% were adenoma or adenocarcinoma. The average age of benign group (inflammatory polyps and adenomas) was (56.7±9.2), which was significantly younger than that of adenocarcinoma group [(66.0±9.8), P=0.004]. Tumor diameter in adenocarcinoma group[(2.3±0.8) cm] was significantly larger than that in benign group[(1.6±0.6) cm, P=0.002]. Benign lesions only showed Yamada type Ⅰ(57.1%)and type Ⅱ(42.9%). The percentage of Yamada type Ⅰ (36.8%)and type Ⅱ(31.6%) in adenocarcinoma group was lower than that in benign group. Moreover, Yamada type Ⅲ (31.5%) was only found in the adenocarcinoma group. Significant differences were observed between the two groups in Yamada types (P=0.046). Most of the benign lesions had clear boundary(18/21,85.7%). The percentage of clear boundary in adenocarcinoma group (2/19,10.5%) was significantly lower than that in the benign group (P<0.001). No significant differences were investigated in color (P=0.353) and surface (P=0.324) between benign and adenocarcinoma lesions. Pooling age, lesion diameter, Yamada type and clear boundary into Logistic regression analysis, only age (OR=1.186, 95%CI 1.025-1.373, P=0.022) and clear boundary (OR=66.218, 95%CI 3.421-1 281.840, P=0.006) were the independent cancer risk factors. Only 2 (10.5%) in the 19 cancer patients had positive biopsy results before EP. As compared with post-EP, 55.3% (21/38) biopsies were under-estimated, including 17 (17/19, 89.5%) adenocarcinomas and 4 (4/10, 40%) grade Ⅱ adenomas.Conclusion: adenoma and adenocarcinoma were the major histological type of ampullary po-lyps. Age and unclear boundary were the independent risk factors of ampullary adenocarcinoma. Forceps biopsy was not enough for ampullary polyp differentiation.

Objective: To analyze and summarize the clinical features, diagnosis, treatment and prognosis of 61 patients with thrombotic thrombocytopenic purpura (TTP),so as to improve the ability of diagnosis and treatment.Methods: The clinical data of 61 TTP patients admitted to Peking University People’s Hospital from January 2004 to March 2019 were retrospectively analyzed, and the clinical manifestations, blood routine, hemolysis indicators, and von Willebrand factor lyase (von Willebrand factor-cleaving protease, vWF-CP, also known as ADAMTS13) of these patients were observed. According to the outcome at the time of discharge, they were divided into survival group and death group, and the differences in clinical characteristics, neutrophil to lymphocyte ratio (NLR) and plasma exchange between the two groups were compared. The PLASMIC scores were calculated and compared with ADAMTS13 to determine the accuracy of the PLASMIC score in predicting ADAMTS13.Results: Among the 61 TTP patients, 22 were males and 39 were females, with an average age of (48±17) years. In the study, 48 cases had pentalogy, only 9 had triad, and the remaining 4 had no neuropsychiatric symptoms. Twenty-seven cases (44.3%) died and 34 cases (55.7%) survived. Among the 61 TTP patients, the platelet count was (12.9±9.5)×10⁹/L, the hemoglobin (66.5±20.7) g/L, the percentage of erythrocyte fragments 3% (2%, 7%), and the plasma free hemoglobin increased to 360 (200, 457) mg /L, and the lactate dehydrogenase 1 508 (811, 2 133.8) U/L. The blood clotting was basically normal. The ADAMTS13 value of 30 patients was 49.0 (40.8, 61.3) μg/L, the ADAMTS activity of 10 patients was<5%, and the remaining 21 patients were not checked. The PLASMIC score was 6-7 in 58 cases, 5 in 2 cases, and 4 in 1 case. The PLASMIC score predicted the decreased activity or the reduction of ADAMTS with a sensitivity as high as 97.5%. The NLR in the death group was higher than that in the survival group, but the difference was not statistically significant (P>0.05). The total amount and frequency of plasma exchange (PEX) in the death group were significantly less than those in the survival group, and the difference was statistically significant (P<0.05). There was no significant difference in the treatment of glucocorticoids and human immunoglobulin between the two groups (P>0.05). Conclusion: PEX can significantly improve the survival rate of TTP patients. PLASMIC score can easily and quickly predict the possibility of ADAMTS13 activity reduction, which is beneficial to the early diagnosis of TTP and PEX treatment. NLR can reflect the systemic inflammatory process, but its significance in TTP needs further study.

Objective: To investigate trends in hospitalization expenditures in adults with kidney disease, to analyze the time pattern of outpatient and inpatient medical expenditures for patients with kidney diseases, and to support the health care reform by exploring the causes.Methods: Medical expenditure data for kidney disease patients aged ≥18 years from the outpatient and in-patient data of the information center in the Grade?A tertiary hospital in Beijing, China from January 1, 2012, to December 31, 2017, were retrospectively analyzed. It provided descriptive evidence on the time patterns of expenditures per visit and capita, and potential influencing factors of the time changes were further explored.Results: It was found that medical expenditures had increased rapidly from 2012 to 2017. The result showed that the average outpatient expenditure per capita for kidney disease patients was 4 598 yuan in 2012, with an increasing tendency to 11 536 yuan in 2017. There was an obvious increase in the average number of visits (per year) from 3.94 in 2012 to 9.11 in 2017. Meanwhile, the mean inpatient expenditures per capita had an increasing tendency from 323 753 yuan in 2012 to 45 904 yuan in 2017. There was also an increase of mean inpatient expenditures per admission from 27 184 yuan in 2012 to 34 933 yuan in 2017, with a similar number of admissions over the 6 years. The increases in outpatient and inpatient expenditures per capita were driven by different reasons. The increase in outpatient expenditures per capita was driven by the increase of patient visits, while the increase in inpatient expenditures per capita was driven by the increase of the expenditures per admission. Also, drug and medical materials were the two categories that had the largest contribution to the inpatient expenditures. Drug expenses were the highest one, with an average of 12 524 yuan per visit in 2017, accounting for 32.4% of the average total expenditure in that year, while the average cost of consumables was 9 215 yuan, accounting for 23.9%.Conclusion: The increase of outpatient expenditures per capita was related to the increase of patient visits. Meanwhile, the growth of drug and consumable costs contributed to the total increase in the total inpatient healthcare costs. It is necessary to increase the proportion of treatment costs and medical service fees in the total expenditure.

Objective: To establish a novel method based on three-dimensional (3D) shape analysis and weighted Procrustes analysis (WPA) algorithm to construct a 3D facial symmetry reference plane (SRP), automatically assigning weight to facial anatomical landmarks. The WPA algorithm suitability for commonly observed clinical cases of mandibular deviation were analysed and evaluated.Methods: Thirty patients with mandibular deviation were recruited for this study. The 3D facial SRPs were extracted independently based on original-mirror alignment method. Thirty-two anatomical landmarks were selected from the overall region by three times to obtain the mean coordinate. The SRP of experimental groups 1 and 2 were using the standard Procrustes analysis (PA) algorithm and WPA algorithm, respectively. A reference plane defined by experts based on regional iterative closest point (ICP) algorithm, served as the ground truth. Three experts manually selecting facial regions with good symmetry for original model, and common region was included in the study. The angle error values between the SRP of WPA algorithm in the experimental group 1 and the truth plane were evaluated in this study, and the SRP of PA algorithm of experimental group 2 was calculated in the same way. Statistics and measurement analysis were used to comprehensively evaluate the clinical suitability of the WPA algorithm to calculate the SRP. A paired t-test analysis (two-tailed) was conducted to compare the angles.Results: The average angle error between the SRP of WPA algorithm and the ground truth was 1.53°±0.84°, which was smaller than that between the SRP of PA and the ground truth (2.06°±0.86°). There were significant differences in the angle errors among the groups (P<0.05). For the patients with severe mandibular deviation that the distance between pogonion and facial midline greater than 12 mm, the average angle error of the WPA algorithm was 0.86° smaller than that of the PA algorithm.Conclusion: The WPA algorithm, based on weighted shape analysis, can provide a more adaptable SRP than the standard PA algorithm when applied to mandibular deviation patients and preliminarily simulate the diagnosis strategies of clinical experts.