The SSA and GUSS scales deliver equally good reliability and validity in evaluating dysphagia among stroke survivors / 中华物理医学与康复杂志

Objective:To compare the reliability and validity of the Standard Swallowing Function Assessment Scale (SSA) with those of the GUSS Swallowing Function Assessment Screen (GUSS) in screening for and evaluating dysphagia among stroke survivors.Methods:Forty-seven stroke survivors had their swallowing function evaluated using the GUSS scale and the SSA scale. The results were compared with those of endoscopic swallowing function examinations.Results:Both scales delivered good reliability and validity. The SSA scale′s test-retest reliability had an ICC value=0.828 and an inter-evaluator reliability with an ICC value=0.909. Those were better than the GUSS scale′s values, but the latter had better intrinsic reliability (Cronbach′s α=0.939). Both scales showed good structural and calibration validity, with the sensitivity of the GUSS scale (72.73%) superior to that of the SSA scale, but the GUSS scales′ specificity, Jordan index and area under the operating characteristics curve were inferior to the SSA scale′s values. Combining the two scales in dysphagia screening could produce an area under the curve of 0.77.Conclusion:Both the SSA and GUSS scales have good reliability and validity in screening for swallowing disorders after a stroke. In clinical practice, the SSA alone or the two in series can improve diagnoses so as to prevent aspiration after a stroke.

Research on friction and wear behaviors of silicon-lithium spray coating on zirconia ceramics / 北京大学学报(医学版)

OBJECTIVE@#To study microstructure, friction and wear behaviors of silicon-lithium spray coating on the surface of zirconia ceramics and to preliminarily evaluate its esthetic so as to provide support and guidance for the clinical application.@*METHODS@#Zirconia ceramic specimens were randomly divided into three groups: coating group (two subgroups), polishing group (two subgroups), and glazing group (four subgroups), with 10 samples in each subgroup. The two subgroups of coating group were the zirconia ceramics with the untreated and preliminary polishing surfaces sprayed with silicon-lithium coating, respectively. The two subgroups of polishing group were preliminary polishing and fine polishing of zirconia ceramics, respectively. The four subgroups of glazing group were preliminarily polished zirconia ceramics glazed with Biomic and Stain/Glaze products, respectively; and untreated zirconia ceramics glazed with Biomic and Stain/Glaze products, respectively. The above 8 subgroups of zirconia ceramic specimens were used as friction pairs with 80 steatite ceramics for 50 000 chewing cycles under 50 N vertical load and artificial saliva lubrication using chewing simulation. Scanning electron microscope was used to observe the microstructure of the surface and section of the coating group, and the thickness of the coating and glazing were measured. The linear roughness of the coating and polishing groups was mea-sured using a laser confocal scanning microscope. Vickers hardness was measured using a microhardness tester and the esthetic of zirconia ceramic full crown sprayed with silicon-lithium coating was preliminarily evaluated. White light interferometer was used to measure the width, the maximum depth and the volume of the wear scars of each group, and the wear depth of steatite ceramics and wear rate of zirconia ceramic specimens were calculated. Kruskal-Wallis nonparametric test and Dunn's multiple comparisons test were used to analyze the wear depth of each group (α=0.05).@*RESULTS@#The microstructures of the silica-lithium spray coatings on the untreated and preliminarily polished zirconia ceramic surfaces showed the protruding defects, and the line roughness of coating group was larger than that of the polishing group. The median thickness of the silica-lithium spray coating on the preliminarily polished zirconia ceramic was 13.0 μm (interquartile range, IQR: 11.6, 17.9), while that of the silica-lithium spray coating on the untreated zirconia ceramic was 4.4 μm (IQR: 4.1, 4.7). The Vickers hardness and wear rate of the coating group were between the polishing group and the glazing group. The wear depths of the wear scars of steatite ceramics were the glazing group, coating group, and polishing group in descending order, and there was statistically significant difference between glazing and polishing groups (P < 0.05). With the increase of polishing procedure, the wear depth of steatite ceramics decreased in each subgroups. The orders of maximum depth and volume of wear scars of zirconia ceramic were the glazing group, coating group, and polishing group in descending order, and there was statistically significant difference in the maximum depth of wear scars between glazing and polishing groups (P < 0.05).@*CONCLUSION@#The silica-lithium spray coating on the zirconia ceramic, can be used as a new method for zirconia ceramic surface treatment, because it can increase the esthetic of zirconia ceramics compared with polishing and reduce the wear of steatite ceramics compared with glazing.

Application and research progress of digital virtual simulated design in dental esthetic rehabilitation / 中华口腔医学杂志

In dental esthetic rehabilitation, patients pay great attention to the rehabilitative esthetic effect before teeth preparation, and this is also an important content of doctor-patient communication. Along with the development and combined application of intraoral scan, three-dimensional (3D) face scan, digital design, numerical control machining and 3D printing technology, digital technology is gradually applied to the virtual simulated design before irreversible operation in dental esthetic rehabilitation. Digital technology can be used in dentistry to simulate the esthetic outcome in advance, to assist communication among the dentists, patients and dental technicians, and to realize satisfactory outcome in the final restorations precisely, which, as a result, increases the clinical satisfaction. This review focuses on the application of digital virtual simulated design technology in dental esthetic rehabilitation, analyzes the current research development, deficiency and future prospects, so as to provide guidance for clinical diagnosis and treatment.

Accuracy analysis of full-arch implant digital impressions when using a geometric feature / 中华口腔医学杂志

Objective: To evaluate the effect of adding a geometric feature on the accuracy of digital impressions obtained by intraoral scanners for implant restoration of edentulous jaw quantitatively. Methods: A dentiform model of the maxilla of completely edentulous arch with 6 implant analogs+scan bodies (No. 1-6) was selected as the reference model. Without geometric feature, the dentiform model was scanned by dental model scanner and repeated for 5 times as true value group. Before and after adding the geometric feature, the same operator used intraoral scanner A (Trios 3) and B (Aoralscan 2) to scan the dentiform model with the same scanning path. Each type of intraoral scanner scanned 10 times and ".stl " datas were obtained. The results were imported into reverse engineering software (Geomagic Studio 2015). The linear distances of center point of upper plane between sacn body 1 to 6 was calculated, denoted as D12, D13, D14, D15 and D16. Trueness was the absolute value subtracted from the measured value of the intraoral scanner groups and true value; precision was the absolute value of pairwise subtraction of the measured values in the intraoral scanner groups.The smaller the value, the better the accuracy or precision.With or without the feature, all scan data were statistically analyzed, and the effect of adding geometric feature on the trueness and precision of the two intraoral scanners were evaluated. Results: As for intraoral scanner A, with the feature in place, significant differences were found in D14, D15, D16 for tureness(t=2.66, 2.75, 2.95, P<0.05); the trueness for D16 decreased from (101.9±47.1) μm to (49.6±30.3) μm. On the other hand, with features on the edentulous area, the precision was significantly increased in D15 and D16 (U=378.00, 672.00, P<0.05); the precision for D15 decreased from 40.8 (45.1) μm to 13.1 (17.0) μm. As for intraoral scanner B, the trueness of D12, D13 and D14 after adding geometric features was significantly better than before (t=3.02, 2.66, U=22.00, P<0.05). With feature on the edentulous area, the trueness for D13 decreased from (116.6±41.2) μm to (70.8±35.5) μm. There was no statistical significance in the trueness of D15 and D16 with or without geometric feature (P>0.05), however, the precision of D15 and D16 after adding geometric feature was significantly better than before (U=702.00, 489.00,P<0.05). The precision of D16 decreased from 112.5 (124.7) μm to 35.9 (85.8) μm. Conclusions: The use of geometric feature in edentulous space improves the trueness and precision of the different principle intraoral scanners tested.

Labelling, segmentation and application of neural network based on machine learning of three-dimensional intraoral anatomical features / 中华口腔医学杂志

With the advent of the era of big data, artificial intelligence based on machine learning, especially artificial neural network has rapidly developed and applicated in the field of stomatology, owning huge potential in segmentation and labelling of three-dimensional intraoral anatomical features. Automatic segmentation, labelling and diagnosis can assist dentists and technicians to complete heavy and repeat work, change stomatology from subjective perception to objective science, and help to make diagnosis and treatment plan efficiently and accurately. This review briefly summarized related knowledge and development of machine learning and artificial neural network, its application status and existing problems in the field of segmentation and labelling of three-dimensional intraoral anatomical features, and provided an outlook of its future development.

Independent innovation research, development and transformation of precise bionic repair technology for oral prosthesis / 北京大学学报(医学版)

According to the fourth national oral health epidemiological survey report (2018), billions of teeth are lost or missing in China, inducing chewing dysfunction, which is necessary to build physiological function using restorations. Digital technology improves the efficiency and accuracy of oral restoration, with the application of three-dimensional scans, computer-aided design (CAD), computer-aided manufacturing (CAM), bionic material design and so on. However, the basic research and product development of digital technology in China lack international competitiveness, with related products basically relying on imports, including denture 3D design software, 3D oral printers, and digitally processed materials. To overcome these difficulties, from 2001, Yuchun Sun's team, from Peking University School and Hospital of Stomatology, developed a series of studies in artificial intelligence design and precision bionics manufacturing of complex oral prostheses. The research included artificial intelligence design technology for complex oral prostheses, 3D printing systems for oral medicine, biomimetic laminated zirconia materials and innovative application of digital prosthetics in clinical practice. The research from 2001 to 2007 was completed under the guidance of Prof. Peijun Lv and Prof. Yong Wang. Under the support of the National Natural Science Foundation of China, the National Science and Technology Support Program, National High-Tech R & D Program (863 Program) and Beijing Training Project for the Leading Talents in S & T, Yuchun Sun's team published over 200 papers in the relevant field, authorized 49 national invention patents and 1 U.S. invention patent and issued 2 national standards. It also developed 8 kinds of core technology products in digital oral prostheses and 3 kinds of clinical diagnosis and treatment programs, which significantly improved the design efficiency of complex oral prostheses, the fabrication accuracy of metal prostheses and the bionic performance of ceramic materials. Compared with similar international technologies, the program doubled the efficiency of bionic design and manufacturing accuracy and reduced the difficulty of diagnosis and cost of treatment and application by 50%, with the key indicators of those products reaching the international leading level. This program not only helped to realize precision, intelligence and efficiency during prostheses but also provided functional and aesthetic matches for patients after prostheses. The program was rewarded with the First Technical Innovation Prize of the Beijing Science and Technology Awards (2020), Gold Medal of Medical Research Group in the First Medical Science and Technology Innovation Competition of National Health Commission of the People's Republic of China (2020) and Best Creative Award in the First Translational Medical Innovation Competition of Capital (2017). This paper is a review of the current situation of artificial intelligence design and precision bionics manufacturing of complex oral prosthesis.

Effect of porous zirconia ceramics on proliferation and differentiation of osteoblasts / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effect of porous surface morphology of zirconia on the proliferation and differentiation of osteoblasts.@*METHODS@#According to different manufacturing and pore-forming methods, the zirconia specimens were divided into 4 groups, including milled sintering group (M-Ctrl), milled porous group (M-Porous), 3D printed sintering group (3D-Ctrl) and 3D printed porous group (3D-Porous). The surface micromorphology, surface roughness, contact angle and surface elements of specimens in each group were detected by scanning electron microscope (SEM), 3D laser microscope, contact angle measuring device and energy-dispersion X-ray analysis, respectively. MC3T3-E1 cells were cultured on 4 groups of zirconia discs. The cell morphology of MC3T3-E1 cells on zirconia discs was eva-luated on 1 and 7 days by SEM. The cell proliferation was detected on 1, 3 and 5 days by cell counting kit-8 (CCK-8). After osteogenic induction for 14 days, the relative mRNA expression of alkaline phosphatase (ALP), type Ⅰ collagen (Colla1), Runt-related transcription factor-2 (Runx2) and osteocalcin (OCN) in MC3T3-E1 cells were detected by real-time quantitative polymerase chain reaction.@*RESULTS@#The pore size [(419.72±6.99) μm] and pore depth [(560.38±8.55) μm] of 3D-Porous group were significantly larger than the pore size [(300.55±155.65) μm] and pore depth [(69.97±31.38) μm] of M-Porous group (P < 0.05). The surface of 3D-Porous group appeared with more regular round pores than that of M-Porous group. The contact angles of all the groups were less than 90°. The contact angles of 3D-Ctrl (73.83°±5.34°) and M-Porous group (72.7°±2.72°) were the largest, with no significant difference between them (P>0.05). Cells adhered inside the pores in M-Porous and 3D-Porous groups, and the proliferation activities of them were significantly higher than those of M-Ctrl and 3D-Ctrl groups after 3 and 5 days' culture (P < 0.05). After 14 days' incubation, ALP, Colla1, Runx2 and OCN mRNA expression in 3D-Porous groups were significantly lower than those of M-Ctrl and 3D-Ctrl groups (P < 0.05). Colla1, Runx2 and OCN mRNA expressions in M-Porous group were higher than those of 3D-Porous group (P < 0.05).@*CONCLUSION@#The porous surface morphology of zirconia can promote the proliferation and adhesion but inhibit the differentiation of MC3T3-E1 cells.

Finite element analyses of retention of removable partial denture circumferential clasps manufactured by selective laser melting / 北京大学学报(医学版)

OBJECTIVE@#To compare the retentions of different designs of cobalt-chromium (Co-Cr), pure titanium (CP Ti), and titanium alloy (Ti-6Al-4V) removable partial denture (RPD) circumferential clasps manufactured by selective laser melting (SLM) and to analyze the stress distribution of these clasps during the removal from abutment teeth.@*METHODS@#Clasps with clasp arm size A (1.9 mm width/1.1 mm thickness at the body and 0.8-taper) or B (1.2 times A) and 0.25 mm or 0.50 mm undercut engagement were modeled on a prepared first premolar die, named as designs A1, A2, A3, and A4, respectively. The density and elastic modulus of SLM-built Co-Cr, CP Ti, and Ti-6Al-4V were measured and given to different groups of clasps. The density, elastic modulus, and Poisson ' s ratio of enamel were given to the die. The control group was the cast Co-Cr clasp with design A1, to which the density and elastic modulus of cast Co-Cr alloy were given. The Poisson's ratio of all metals was 0.33. The initial 5 N dislodging force was applied, and the maximum displacement of the clasp along the insertion path was computed. The load was reapplied with an increment of 5 N than in the last simulation until the clasp was completely dislodged. The retentive force range of different groups of clasps was obtained. The retentive forces of the SLM-built Co-Cr, CP Ti, and Ti-6Al-4V clasps with equivalent computed retentive force range to the control group were validated through the insertion/removal experiment. The von Mises stress distributions of these three groups of SLM-built clasps under 15 N loads were analyzed.@*RESULTS@#SLM-built Co-Cr, CP Ti, and Ti-6Al-4V clasps with designs B1 or B2, and Co-Cr clasps with design A2 had higher retentive forces than those of the control group. SLM-built CP Ti and Ti-6Al-4V clasps with design A1 had lower retentive forces than those of the control group. SLM-built Co-Cr clasp with design A1 and SLM-built CP Ti and Ti-6Al-4V clasps with design A2 had equivalent retentive forces to those of the control group. The insertion/removal experiment showed that the measured retentive forces of these three groups of SLM-built clasps were (21.57±5.41) N, (19.75±4.47) N, and (19.32±2.04) N, respectively. No statistically significant measured retentive force difference was found among these three groups of SLM-built clasps (P>0.05). The maximum von Mises stress of these three groups of SLM-built clasps exceeded their responding yield strength except for the Ti-6Al-4V one.@*CONCLUSION@#SLM-built Co-Cr circumferential clasps had higher retention than CP Ti and Ti-6Al-4V ones with the same clasp arm size and undercut engagement. The retention of SLM-built circumferential clasps could be adjusted by changing the undercut engagement and clasp arm size. If SLM-built circumferential clasps are used in clinical practice, the Ti-6Al-4V clasp with clasp arm size A and 0.50 mm undercut engagement is recommended considering the long-term use of RPD in the patient's mouth.

Preliminary experience of surgical treatment for torus tubarius hypertrophy in children / 中华耳鼻咽喉头颈外科杂志

Objective: To assess the incidence of symptomatic torus tubarius hypertrophy (TTH) in recurred OSA in children, and to explore the preliminary experience of partial resection of TTH assisted with radiofrequency ablation. Methods: From January 2004 to February 2020, 4 922 children, who diagnosed as OSA and received adenotonsillectomy at the Department of Otolaryngology, The 4th Medical Center of the PLA General Hospital, were retrospectively reviewed. There were 3 266 males and 1 656 females, the age ranged from 1 to 14 years old(median age of 5.0 years). Twenty-two cases were identified with recurrence of OSA syndrome, and the clinical data, including sex, age of primary operation, age of recurrence and presentation, and opertation methods were analyzed. Follow-up was carried out by outpatient visit or telephone. Graphpad prism 5.0 software was used for statistical analysis. Results: Twenty-two cases were identified as recurred OSA and received revised surgery in 4 922 cases. Among these 22 cases, 11 cases were diagnosed as TTH resulting in an incidence of 2.23‰(11/4 922), 1 case was cicatricial adhesion on tubal torus (0.20‰, 1/4 922), 10 cases were residual adenoid combined with tubal tonsil hypertrophy (2.03‰, 10/4 922). Median age of primary operation was 3.0 years (range:2.4 to 6.0 years) in 11 TTH cases. Recurrent interval varied from 2 months to 5.5 years (2.4±1.9 years) after first operation. Age of revised partial resection of TTH was 7.0±2.7 years (range: 4.0 to 12.0 years). Average time interval between primary operation and revised operation was 3.5±2.1 years (range: 0.5 to 6.0 years). Individualized treatments were carried out based on partial resection of TTH assisted with radiofrequency ablation. All of 11 cases received satisfied therapeutic results without nasopharyngeal stenosis occured. Twenty-two cases were followed up for 1.6 to 13 years (median follow-up time was 6.2 years). Conclusions: TTH contributed to recurred OSA in child. TTH might be misdiagnosed as tubal tonsil hypertrophy. Partial resection of TTH assisted with radiofrequency ablation was a safty and effective treatment.

A scoping review on strategies, influencing factors and evaluation of foreign stroke service system integration / 中华医院管理杂志

Objective:To summarize the strategies, influencing factors and evaluation methods of foreign stroke service system integration, so as to provide reference for the construction of integrated stroke service system in China.Methods:The scoping review method was used to search, screen and analyze the literature. Using search terms such as stroke and integration, a total of 7 527 articles from PubMed and other databases from 2000 to 2021 were obtained. The strategies, influencing factors, evaluation methods and results of stroke service system integration were extracted from the literature. The rainbow model of health integration was used to establish the literature analysis framework.Results:A total of 103 articles involved system integration strategies were included in the analysis, 49 articles involved integration influencing factors, and 32 articles involved integration evaluation. Stroke service system integration strategies included 3 categories and 13 forms, including service coverage, normative shaping and information technology integration. The influencing factors of integration included local stroke service resources, implementation ability, social development level and institutional environment. System integration evaluation included systematic evaluation and case evaluation.Conclusions:The goal of stroke service system integration is to improve the coverage, quality and efficiency of stroke services. The internal drive comes from market and technology. The three types of integration strategies have their own emphasis and are integrated with each other. They are deeply embedded in the regional resource, institutional and cultural environment. Their evaluation is facing the challenge of high situational and low universality.

Traditional Chinese medicine for prevention and treatment of hepatocellular carcinoma: A focus on epithelial-mesenchymal transition / 中西医结合学报

Hepatocellular carcinoma (HCC) is one of the most prevalent malignant cancers worldwide. Epithelial-mesenchymal transition (EMT), which endows epithelial cells with mesenchymal properties, plays an important role in the early stages of metastasis. Conventional cancer therapies have promising effects, but issues remain, such as high rates of metastasis and drug resistance. Thus, exploring and evaluating new therapies is an urgent need. Traditional Chinese medicines (TCMs) have been acknowledged for their multi-target and coordinated intervention effects against HCC. Accumulating evidence indicates that TCM can inhibit the malignancy of cells and the progression of EMT in HCC. However, studies on the effects of TCM on EMT in HCC are scarce. In this review, we summarized recent developments in anti-EMT TCMs and formulae, focusing on their underlying pharmacological mechanisms, to provide a foundation for further research on the exact mechanisms through which TCM affects EMT in HCC.

Evaluation of fracture strength of two kinds of zirconia all-ceramic crowns with different edge compensation angles / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the effects of different edge compensation angles on the fracture strength of multilayer zirconia all-ceramic crowns and traditional uniform zirconia all-ceramic crowns.@*METHODS@#The resin tooth preparation specimen of the mandibular first molar with a knife-edge was fabricated. A 3D digital model of the specimen was obtained by scanning it with a 3D dental model scanner. The 3D digital model was imported into computer aided design (CAD) software, and three 3D digital models of the full crown with the same surface shape are designed with the edge compensation angles of 30°, 45° and 60°, respectively. Then, the designed 3D digital model is imported into computer aided manufacturing (CAM) software. Three kinds of multilayer and homogeneous zirconia all-porcelain crowns with different edge compensation angles were fabricated, 10 each for a total of 60. The fracture load of each crown was measured under the electronic universal testing machine.@*RESULTS@#Fracture load of multilayer and uniform zirconia all-ceramic crowns, (4 322.86±610.07) N and (5 914.12±596.80) N in the 30° group, (5 264.82±883.76) N and (5 220.83±563.38) N in the 45° group and (4 900.42±345.41) N and (5 050.22±560.24) N in the 60° group, respectively. The fracture load of multi-layer zirconia all-ceramic crowns in the 30° group was significantly lower than that of homogeneous zirconia all-ceramic crowns(P < 0.05); there was no statistical significance in 45° group and 60° group(P>0.05). In the multi-layer zirconia all-ceramic crowns: the fracture load of the 30° group was significantly lower than that of the 45° group (P < 0.05); there was no significant difference between the 30° group and the 60° group, the 45° group and the 60° group (P>0.05).In uniform zirconia full crown group: the 30° group was higher than the 45° group, the 30° group was higher than the 60° group (P < 0.05), and there was no significant difference between the 45° group and the 60° group (P>0.05).@*CONCLUSION@#The fracture loads of three kinds of uniform and multilayer zirconia all ceramic crowns with different edge compensation angles can meet the clinical requirements. A smaller edge compensation angle is recommended when using traditional zirconia all-ceramic crowns, while 45° is recommended when using multi-layer zirconia all-ceramic crowns.

Evaluation of methods for fitness of removable partial denture / 北京大学学报(医学版)

OBJECTIVE@#To compare the differences and indications of three evaluation methods for fitness evaluation of removable partial denture (RPD).@*METHODS@#A RPD was fabricated and seated on the stone cast of a partially edentulous mandible, and the spaces between RPD and stone cast were recorded with polyvinyl siloxane (PVS) impression material forming PVS replicas. Using cross sectional measurement, the average thicknesses of PVS replicas were measured under stereomicroscope with different numbers of selected measuring points in the denture base, major connector, occlusal rest of the RPD, and the average thicknesses of the PVS replicas measured with different numbers of measuring points were compared using one-way analysis of variance (ANOVA) and independent sample t test. Three kinds of method, including cross sectional measurement, three-dimensional analysis on the stone cast, and three-dimensional analysis on the polyether cast, were applied to measure the average thicknesses of the PVS replicas, and the average thicknesses of the PVS replicas measured by these three evaluation methods were compared with ANOVA.@*RESULTS@#For cross sectional measurement, statistically significant differences were found in the average thicknesses of the PVS replicas in the denture base and the major connector among the different numbers of measuring points (P < 0.05), but no differences were found in the average thicknesses of the PVS replicas in the occlusal rest (P>0.05). There were significant differences among the average thicknesses of the PVS replicas measured by these three evaluation methods in each component of the RPD (P < 0.01). The average thickness measured by three-dimensional analysis on the stone cast and three-dimensional analysis on polyether cast were smaller than that measured by cross sectional measurement (P < 0.05). And there were no differences between the average thicknesses of PVS replicas measured by three-dimensional analysis on stone cast and three-dimensional analysis on polyether cast (P>0.05).@*CONCLUSION@#For cross sectional measurement, the average thickness of the PVS replicas was influenced by the number of measuring points, and the measurement accuracy of cross sectional measurement was not reliable enough. Three-dimensional analysis on stone cast which is suitable for evaluation in vitro and three-dimensional analysis on polyether cast which is suitable for evaluation in vivo can evaluate the fitness of RPD more comprehensively and effectively than that of cross sectional measurement.

Application of 3D-CT simulation image in the description of gastric artery variation to guide laparoscopic total gastrectomy / 中华胃肠外科杂志

Objective: Anatomic variations in the perigastric vessels during laparoscopic radical gastrectomy often affect the operator's judgment and prolong the operation time, and even cause accidental injury and surgical complications, and hence the safety and quality of the operation cannot be ensured. In this study, multiple slice CT was reconstructed by 3-dimensional CT simulation software (3D-CT), and 3D-CT images were used to describe the variation of celiac trunk and splenic artery before surgery. The guiding role of the different variation of vessels was analyzed for laparoscopic total gastrectomy+D2 lymph node dissection (LTG+D2LD). Methods: A retrospective cohort study was conducted. Case inclusion criteria: (1) Gastric cancer was at an advanced stage. All the patients were preoperatively examined by digestive endoscopy and 64-row enhanced CT scan, and were histopathologically diagnosed with gastric adenocarcinoma. (2) 3D-CT simulation images were reconstructed to guide the operation. (3) LTG+D2LD surgery was performed by the same surgical team. (4) Clinical data were complete, and all the patients had signed the informed consent. From 2014 to 2018, 98 patients with gastric cancer at the Gastrointestinal Surgery Department of Henan Provincial People's Hospital were enrolled. According to the Adachi classification, celiac trunk variation was divided into common type (Adachi type I) and rare type (Adachi type II-VI). According to the Natsume classification, splenic artery was classified into "flat type" and "curved type". Based on 3D-CT simulation images, variation of celiac trunk and splenic artery was described, and the differences in operation time, intraoperative blood loss and the number of postoperative retrieved lymph nodes were compared between groups with different types of arterial variation. Results: For celiac trunk, common type was found in 84 cases (86%) and rare type was found in 14 cases, including 6 cases (6%) of type II, 2 cases (2%) of type III, 2 cases (2%) of type IV, 3 cases (3%) of type V, 1 case (1%) of type VI. No other types were found. There were no statistically significant differences in clinical characteristics and number of retrieved lymph nodes between patients of the common type group and rare type group (all P>0.05). Compared with common type patients, those of rare type had longer operative time [(321.1±29.0) minutes vs. (295.1±46.5) minutes, t=2.081, P=0.040] and more intraoperative blood loss (median: 66.0 ml vs. 32.0 ml, Z=-4.974, P=0.001). For splenic artery, 41 patients (42%) were flat type and 57 patients (58%) were curved type. There were no statistically significant differences between the two groups in terms of clinical characteristics, intraoperative blood loss, operative time and number of retrieved lymph nodes (all P>0.05). Conclusions: The method of describing the variation in the perigastric vessels by 3D-CT simulation has certain clinical value in laparoscopic radical gastrectomy. The duration of LTG+D2LD is prolonged and the intraoperative blood loss is increased with the variation of celiac trunk, while the variation of splenic artery has no effect on LTG+D2LD.

Pneumonia, Multiple Pulmonary Infarction and Abscess Caused by a Bamboo Stick Accidentally Piercing into Chest: a Case Misdiagnosed as Pulmonary Tuberculosis / 中国医学科学杂志(英文版)

Computed tomography (CT) examination is the major measure for detecting and diagnosis of foreign bodies in human body. Although CT has high sensitivity in diagnosis of foreign body, some interference factors may still lead to missed diagnosis or misdiagnosis. Here we report a rare case that a bamboo stick accidentally pierced into the left chest of a young man who was drunk and unware of this hurt. The patient experienced cough, chest pain, fever, hemoptysis, and was misdiagnosed as primary and secondary tuberculosis based on chest CT examinations at a local hospital, although no tubercular bacillus detected by sputum smear. He subsequently received anti-tuberculous treatments in the following three years, but no improvement of his symptoms was observed. Until one month before his death, the bamboo stick was detected by spiral CT examination as well as three-dimensional image reconstruction at another hospital. Postmortem examination revealed pneumonia, pulmonary infarction, and abscess as the causes of his death. We analyze the potential reasons of misdiagnosis in this case, aiming to provide reference for the diagnosis and treatment of pulmonary inflammation associated with foreign body in the future.

Clinical application and research progress of digital complete denture / 华西口腔医学杂志

Digital technologies use high-precision three-dimensional scanning, intelligence-aided design software, and multi-axis numerical control milling or 3D printing, which can produce restorations with reliable precision and suitable function. However, the development of digital technologies in the field of complete denture restoration has been slow due to the complexity of prosthesis. This review article introduces the current research status and clinical applications of digital complete dentures in prosthodontic clinics and dental laboratories to provide beneficial references to prosthodontists and dental technicians.

Visual sensitivity threshold of lateral view of nasolabial Angle changes in edentulous jaw patients / 北京大学学报(医学版)

OBJECTIVE@#To study the visual sensitivity threshold of physician's naked eye to the difference of nasolabial angle in edentulous jaw patients, and to provide a reference value for the study of aesthetic evaluation of soft tissue profile for the difference of nasolabial angle that can be recognized by human eyes.@*METHODS@#Three-dimensional facial images of three edentulous patients with different diagnostic dentures introoral were obtained. Lateral screenshots of each patient's three-dimensional facial image with the same scale were obtained by using reverse engineering software (Geomagic studio 2014).The screenshot of the patient's three-dimensional facial image with suitable lip support (The suitable lip support was confirmed by both patients and prosthodontists who had clinical experience for more than 20 years) was taken as the reference picture, and the remaining pictures were grouped with it respectively. All the pictures were observed in random order by the subjects. Fifteen dentists were asked to judge the difference of nasolabial angle between the two pictures of each group on the computer screen. The difference of nasolabial angle between the two pictures in each group was measured and calculated. The ROC curve was drawn, and the best cut-off value was calculated as the visual sensitivity threshold.@*RESULTS@#The data of the 15 subjects were used to draw ROC curves separately. The maximum and minimum best cut-off values were 5.55 degrees and 3.12 degrees respectively. The ROC curve of the whole 15 subjects was drawn after data aggregation, and the best cut-off value was 5.36 degrees (AUC=0.84>0.5, P=0.000<0.05). When the difference of nasolabial angle was above 5.36 degrees, the subjects could recognize it effectively.@*CONCLUSION@#There is a visual limit in the observation of the nasolabial angle with the naked eye. In this study, a visual sensitivity threshold of 5.36 degrees for the difference of the nasolabial angle was obtained. The difference of nasolabial angle below this value can be regarded as no clinical significance. This result provides a reference value for human eyes to recognize the difference of nasolabial angle in soft tissue profile aesthetic evaluation. It can be applied to the aesthetic evaluation of soft tissue profile and can be used as the error level of related research with nasolabial angle as an index for accuracy evaluation.

Accuracy of three intraoral scans for primary impressions of edentulous jaws / 北京大学学报(医学版)

OBJECTIVE@#To provide a reference for using intraoral scanners for making clinical diagnostic dentures of edentulous jaws by comparing the accuracy of three intraoral scanners for primary impression and jaw relation record of edentulous jaws.@*METHODS@#This study contained 6 primary impressions of the edentulous patients. Each of the impressions consisted of the maxillary primary impression, the mandibular primary impression and the jaw relation record. For each of them, a dental cast scanner (Dentscan Y500) was used to obtain stereolithography (STL) data as reference scan, and then three intraoral scanners including i500, Trios 3 and CEREC Primescan were used for three times to obtain STL data as experiment groups. In Geomagic Studio 2013 software, trueness was obtained by comparing experiment groups with the reference scan, and the precision was obtained from intragroup comparisons. Registered maxillary data of the intraoral scan with reference scan, the morphological error of jaw relation record was obtained by comparing jaw relation record of the intraoral scan with the reference scan. Registered mandibular data with jaw relation record of intraoral scan and the displacement of the jaw position were evaluated. Independent samples t test and Mann-Whitney U test in the SPSS 20.0 statistical software were used to statistically analyze the trueness, precision and morphological error of jaw relation record of three intraoral scanners. The Bland-Altman diagram was used to evaluate the consistency of the jaw relationship measured by the three intraoral scanners.@*RESULTS@#The trueness of i500, Trios 3 and CEREC Primescan scanners was (182.34±101.21) μm, (145.21±71.73) μm, and (78.34±34.79) μm for maxilla; (106.42±21.63) μm, and 95.08 (63.08) μm, (78.45±42.77) μm for mandible. There was no significant difference in trueness of the three scanners when scanning the maxilla and mandible(P>0.05). The precision of the three scanners was 147.65 (156.30) μm, (147.54±83.33) μm, and 40.30 (32.80) μm for maxilla; (90.96±30.77) μm, (53.73±23.56) μm, and 37.60 (93.93) μm for mandible. The precision of CEREC Primescan scanner was significantly better than that of the other two scanners for maxilla (P<0.05). Trios 3 and CEREC Primescan scanners were significantly better than i500 scanner for mandible (P<0.05). The precision of the i500 and Trios 3 scanners for mandible was superior to maxilla (P<0.05). The upper limit of 95% confidence intervals of trueness and precision of three scanners for both maxilla and mandible were within ±300 μm which was clinically accepted. The morphological error of jaw relation record of the three scanners was (337.68±128.54) μm, (342.89±195.41) μm, and (168.62±88.35) μm. The 95% confidence intervals of i500 and Trios 3 scanners were over 300 μm. CEREC Primescan scanner was significantly superior to i500 scanner(P<0.05).The displacement of the jaw position of the three scanners was (0.83±0.56) mm, (0.80±0.45) mm, and (0.91±0.75) mm for vertical dimension; (0.79±0.58) mm, (0.62±0.18) mm, and (0.53±0.53) mm for anterior and posterior directions; (0.95±0.59) mm, (0.69±0.45) mm, and (0.60±0.22) mm for left and right directions. The displacement of the jaw position of the three scanners in vertical dimension, anterior and posterior directions and the left and right directions were within the 95% consistency limit.@*CONCLUSION@#Three intraoral scanners showed good trueness and precision. The i500 and Trios 3 scanners had more errors in jaw relation record, but they were used as primary jaw relation record. It is suggested that three intraoral scanners can be used for obtaining digital data to make diagnostic dentures and individual trays, reducing possible deforming or crack when sending impressions from clinic to laboratory.

Accuracy of intercuspal occlusion in 3D reconstruction with the dental articulator position method / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the three-dimensional (3D) reconstruction accuracy of the intercuspal occlusion (ICO) of the dental casts, by the dental articulator position method, and provide a reference for clinical application.@*METHODS@#The standard dental casts in ICO were mounted on average values articulator, and five pairs of milling resin cylinders were respectively attached to the base of both the casts. 100 μm articulating paper and occlusal record silicone rubber were used to detect the occlusal contact number between the posterior teeth of casts mounted on articulator in ICO. The occlusal contact numbers NA detected by the two methods were calculated simultaneously, as the reference. After the upper and lower casts were scanned separately, and the buccal data of casts in ICO were scanned with the aid of the dental articulator position, registration was carried out utilizing the registration software. Then the digital casts mounted in ICO as well as the buccal occlusal data were saved in standard tessellation language (STL) format. Geomagic Studio 2013 software was used to analyze the contact number NS between digital upper and lower casts by the "deviation analysis" function. The differences were compared between NS and NA, to evaluate the sensitivity and positive predict value (PPV) of the model scanner to reproduce the occlusal contact with the aid of dental articulator position. The distance DR between the centers of the circles at the top surface of the upper and lower corresponding cylinders was obtained by the three-coordinate measuring system Faro Edge, as the reference value. The Geomagic Studio 2013 software was used to construct the cylinders of digital casts and the distance DM between the centers of the circles at the top surface of the corresponding cylinders were measured, as the test value. The one-sample T test was used to analyze the variable differences between DM and DR.@*RESULTS@#The PPV of reproducing the occlusal contact point was 0.76 and sensitivity was 0.81. The distance error of the opposite cylinder was (0.232±0.089) mm. There was no statistical difference between the feature points 5-5', while there were statistical differences between the other feature points.@*CONCLUSION@#By the dental articulator position method, the model scanner reproduces the occlusal contact point with high sensitivity and PPV, and that meets clinical needs. Meanwhile, the distance between the feature points is greater than the reference value, which will lead to occlusal disturbance, and require clinical grinding.

Preliminary study on three digital analysis methods for analyzing the distribution and area of occlusal contacts / 北京大学学报(医学版)

OBJECTIVE@#To analyze the distribution and area of occlusal contacts of clinical dental model using three kinds of digital analysis methods, to compare the results of these methods and traditional occlusal analysis method, and to further analyze the characteristics of each digital analysis method.@*METHODS@#A set of plaster models of normal subjects was selected. The models were scanned by lab scanner 3shape E4 and the files were exported in a stereolithography file format. In 3D analysis software Geomagic Studio 2013 and Geomagic Qualify 2013, the corresponding results of 3D occlusal contact distribution and occlusal contact area were obtained through three digital analysis methods: "3D color difference map method", "point cloud analysis method", and "virtual articulating paper method". The occlusal contact distribution and occlusal contact area were also obtained by two traditional occlusal analysis methods: "silicone interocclusal recording material method" and "scanned articulating paper mark method". A threshold of 100 μm was used to analyze the occlusal contacts and 100 μm was also the thickness of articulating paper used in this study. The results of these five different occlusal analysis methods were evaluated qualitatively and quantitatively.@*RESULTS@#The results of 3D occlusal contact distribution obtained by the above five methods were basically consistent. The total occlusal contact area obtained by 3D color difference map method, point cloud analysis method, virtual articulating paper method, silicone interocclusal recording material method and scanned articulating paper mark method were 133.10 mm², 142.08 mm², 128.95 mm², 163.31 mm², and 100.55 mm² respectively. There was little difference between the results of three digital analysis methods. The results of occlusal contact area obtained by the digital methods and the traditional methods were different.@*CONCLUSION@#The three digital analysis methods can provide reliable and accurate analysis results of occlusal contact distribution and occlusal contact area of dental model. The results obtained by these methods can serve as references for the digital occlusal surface design of dental prosthesis and clinical occlusal analysis.