[ANCA-negative granulomatosis with polyangiitis: a case report]

We reported a case of 73-year-old male with multiple pulmonary nodules and cavities. The patient was admitted with a chief complaint of "dry cough with shortness of breath for 3 months". Chest CT showed multiple irregular masses, nodules, and patchy lesions in both lungs, accompanied by the formation of cavities. He also had anemia and renal dysfunction. Despite given empirical anti-infective and anti-tuberculosis treatments, the pulmonary nodules progressed, and the cavities enlarged. Anti-neutrophil cytoplasmic antibodies (ANCA) were negative twice. Bronchoscopic biopsy was performed. The mucosal pathology of the right middle lobe lesion showed little necrosis, focal granulomatous structure formation, and relevant vasculitis and remaining vessel wall structure in the necrosis lesions by elastic fiber staining. A clinical diagnosis of ANCA-negative necrotizing granulomatous polyangiitis was made and the patient was treated with glucocorticoids and cyclophosphamide. The nodules and cavities shrank, and some lesions were absorbed.

[Preliminary measurement and analysis of the condylar movement envelope surface parameters in healthy adults]

Objective: To measure and analyze parameters of the three-dimensional (3D) model of the condylar movement envelope surface (ES) and provide a reference for the design of the temporomandibular prosthesis. Methods: Thirty-four healthy adults aged (25.4±2.8) years were recruited from the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology as subjects. There were 9 males and 25 females, most of them were university students and others outside the university have received undergraduate education or above. Condylar movement ES were obtained using the previous method on the 3D trajectory of condyle. The simulations of condylar movement were projected according to opening movements, protrusion movements, and lateral movements respectively. The total area of the ES and the area proportions of models formed by above different mandibular movements were measured and calculated. The adults' head and maxillofacial 3D models reconstructed by cone beam CT were registered with ES in Geomagic Studio. The inner and outer poles of the condyle, the corrective sagittal axis of the ES, and the median sagittal plane (MSP) were calibrated in registration models using Geomagic Studio, and the parameters were measured as follows: the anteroposterior and medialateral diameters of the condyle, the anteroposterior diameters and the transverse diameters (anterior, middle and posterior parts) of the ES, the angles between the corrective sagittal axis of the ES and MSP (ES-MSP). Pearson correlation analysis was performed by SPSS 24.0. Results: The total area of the ES was (760±133) mm², the opening movement part accounted for (63.3±15.2)%, the protrusion movement part accounted for (14.9±9.6)%, the lateral movement part accounted for (21.8±13.3)%. Parameter measurements were as follows: mediolateral diameters of condyle was (19.8±2.3) mm; anteroposterior diameter of the ES was (21.2±3.1) mm, the transverse diameters (anterior, middle and posterior parts) of the ES were (20.6±2.4), (20.4±2.4), (22.0±2.6) mm, respectively; the transverse diameters of the ES were about 2 mm larger than that of the condyle. The angle between the corrective sagittal axis of ES and the MSP was 6.8°±6.2°. The coefficient of variation (CV) in these parameters showed: CV of the transverse diameters (anterior, middle and posterior parts) of the ES and mediolateral diameter of the condyle were 0.98, 0.99, 0.93, respectively (P<0.001). CV of aera of ES and mediolateral diameter of the condyle was 0.64 (P=0.002). CV of aera of ES and anteroposterior diameter of ES was 0.62 (P=0.004). Conclusions: The 3D envelope surface model formed by mandibular opening movements accounted for the largest proportion of the ES. The corrective sagittal axis of the ES was at an angle to the MSP, the transverse diameters (anterior, middle and posterior parts) of the ES were approximately 2 mm larger than the mediolateral diameter of the condyle, the transverse diameters (anterior, middle and posterior parts) of the ES were highly positively correlated with the mediolateral diameter of the condyle.

[Nutrition management of patients with acute exacerbation of chronic obstructive pulmonary disease hospitalized in Respiratory Intensive Care Unit]

Acute exacerbation of chronic obstructive pulmonary disease (COPD) is an important part of the course of COPD. Patients with life-threatening acute exacerbation need to be admitted to the respiratory intensive care unit (RICU) for treatment in time. Malnutrition is common in COPD patients, and nutritional risk also has a high prevalence in patients with COPD exacerbation, which is closely associated with the clinical outcome and mortality of these patients. Identifying patients with high nutritional risk and providing appropriate nutritional treatment will help to improve survival rate, shorten length of hospital stay and reduce complications. This review describes the potential mechanisms of malnutrition in patients with COPD, the nutritional risk assessment of patients with COPD exacerbation hospitalized in RICU, the selection of nutritional treatment methods and formulas, and the relevant problems of nutritional management of patients required noninvasive ventilation, hoping to provide information for the optimization of nutritional treatment strategy for acute exacerbation of COPD and the exploration of clinical research in the future.

[Significance of aspergillus fumigatus-specific IgG in the diagnosis of allergic bronchopulmonary aspergillosis]

The data of 18 patients with allergic bronchopulmonary aspergillosis (ABPA) who received aspergillus fumigatus-specific IgG detection from 2015 to 2021 in Peking University Third Hospital were retrospectively analyzed. Among them, 11 were male and 7 were female, aged 18-79 years. All patients had a history of asthma or symptoms of cough and asthma, and aspergillus fumigatus-specific IgE was positive; 16 patients had total serum IgE>500 U/ml, of which 13 patients had total serum IgE>1 000 U/ml. Among other diagnostic indicators, peripheral blood eosinophils were >0.5×10⁹/L in 16 cases; lung CT showed bronchiectasis in 15 cases; serum aspergillus fumigatus-specific IgG was positive (>120 AU/ml) in 10 cases. There was no significant difference in serum total IgE level, peripheral blood eosinophil count, and bronchiectasis ratio between positive and negative cases of aspergillus fumigatus-specific IgG (all P>0.05). In this study, the positive rate of aspergillus fumigatus-specific IgG in patients with ABPA was more than 50%, which has auxiliary value in the diagnosis of ABPA.

[Labelling, segmentation and application of neural network based on machine learning of three-dimensional intraoral anatomical features]

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.

[A survey on the application of diagnostic and evaluation tools for chronic obstructive pulmonary disease among respiratory physicians]

Objective: To investigate the current status of the application of diagnostic and assessment tools for chronic obstructive pulmonary disease(COPD) by respiratory physicians in China. Method: An on-line questionnaire was designed to address the common questions in COPD diagnosis and evaluation, and this survey was conducted through Wechat. Result: A total of 3 204 valid questionnaires were collected. 71.7% of the physicians were from tertiary hospitals. 75.4% of the physicians diagnosed COPD strictly on the basis of lung function results after inhaled bronchodilators, and this percentage was higher in tertiary hospitals than in secondary hospitals(78.71% vs. 66.92%, P<0.01). 99.3% of the physicians evaluated symptoms of dyspnea, but 26.8% of physicians did not use a scoring system(CAT or mMRC) for quantitative assessment. Although 83.8% of physicians would use the guideline-recommended comprehensive assessment(ABCD classification), only 45.1% of them chose initial therapy exactly according to the classification. In addition, 28.3% of physicians did not routinely order blood eosinophil counts and 20.1% did not inquire the history of tuberculosis. Conclusions: Although most respiratory physicians followed the guidelines in the diagnosis and evaluation of COPD, the use of assessment tools was inadequate, which should be addressed in educational programs for COPD management.

[Focus on influenza vaccination in patients with chronic obstructive pulmonary disease]

Influenza vaccination has been shown to reduce lower airway infections requiring hospitalization, and reduce mortality and exacerbation frequency in patients with chronic obstructive pulmonary disease(COPD), and therefore is recommended for all COPD patients by guidelines. However, the coverage of influenza vaccination in Chinese COPD patients is far from satisfactory. The large-scale COVID-19 vaccination may have a positive impact on the attitude towards influenza vaccines, and healthcare professionals should take active measures to improve the rate of influenza vaccination in patients with COPD.

[Effect of porous zirconia ceramics on proliferation and differentiation of osteoblasts]

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.

[Accuracy analysis of full-arch implant digital impressions when using a geometric feature]

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.

[Application and research progress of digital virtual simulated design in dental esthetic rehabilitation]

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.

[Identification of serum peptide biomarker for ovarian cancer diagnosis by Clin-TOF-II-MS combined with magnetic beads technology]

Objective: To explore the serum cyclic polypeptide biomarkers for ovarian cancer diagnosis. Methods: A total of 54 patients with epithelial ovarian cancer confirmed by pathology in Cancer Hospital, Chinese Academy of Medical Sciences from March 2018 to September 2018 were selected as the study subjects, and 40 healthy women with normal examination results in the cancer screening center were selected as the control. All of the samples were randomly divided into training set and validation set at the ratio of 1∶1 with a random number. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) combined with magnetic bead technology was used for detecting peptide profiling in serum samples to screen significantly differently expressed peptides between ovarian cancer group and control group of the training set (score>5). Receiver operating characteristic (ROC) curve analysis was used to screen differential peptide peaks with area under curve (AUC) ≥0.8, sensitivity and specificity>90% in the training set and validation set. Liquid chromatography-mass spectrometry (LC-MS/MS) was further used to determine the composition of differentially expressed peptides. Results: By comparing the peptide profiles of the two groups, 102 differential peptide peaks were initially detected in the mass-to-charge ratio range of 1 000 to 10 000. ROC curve analysis showed that there were 42 differential peptide peaks with AUC ≥0.8 in both training set and validation set, 19 of which were highly expressed in ovarian cancer group, and 23 were lowly expressed. There were 15 different peptide peaks in highly expressed ovarian cancer group with sensitivity and specificity over 90%. The mass-to-charge ratios were 7 744.27, 5 913.41, 5 329.87, 4 634.21, 4 202.02, 3 879.26, 3 273.35, 3 253.79, 3 234.34, 2 950.33, 2 664.51, 2 018.38, 1 893.37, 1 498.69 and 1 287.55. There were 15 different peptide peaks in lowly expressed ovarian cancer group with sensitivity and specificity over 90%, the mass-to-charge ratios were 9 288.46, 7 759.77, 5 925.24, 4 652.77, 4 210.42, 3 887.02, 3 279.90, 3 240.82, 2 962.15, 2 932.70, 2 022.42, 1 897.16, 1 501.69, 1 337.38 and 1 290.13. No protein composition was identified in 15 different peptide peaks in lowly expressed ovarian cancer group. The two protein compositions identified in 15 different peptide peaks in highly expressed ovarian cancer group were recombinant serglycin (SRGN) and fibinogen alpha chain (FGA), the mass-to-charge ratios of which were 1 498.696 and 5 913.417, respectively. The sensitivity and specificity of the two proteins for ovarian cancer diagnosis were 100%, 100% and 90.9%, 100%, respectively. Conclusion: SRGN and FGA are highly expressed in the serum of ovarian cancer patients, which may be potential diagnostic markers for ovarian cancer.

[Quantitative study of intraoral scanners' accuracy]

Objective: To establish a standard method to evaluate the scanning accuracy of intraoral scanner (IOS) and to investigate six IOS's scanning accuracy and the relationship between different scan span. Methods: Five simplified six abutments full arch model were fabricated by high accuracy (5 μm) milling machine with 7075 aluminum alloy. The machining accuracy, which was verified by a coordinate measuring machine with higher accuracy (0.7 μm), was considered as the reference accuracy. The model with the highest machining accuracy was considered as the test model in IOS's scanning accuracy test, and computer-aided design (CAD) data of the model was used as the reference data. Six IOS scanned the test model 10 times with the same scanning path, obtained 60 test data. CAD data and test data were input into Geomagic Studio 2014. The preparation part above the margin of the abutments of the data was isolated and divided into 4 segments of interest: single crown, three-unit bridge, five-unit bridge, and full arch. The test data were then best-fit aligned to CAD data or each other followed by deviation analysis. Scanning trueness and precision were then calculated. Results: The mid-value of scanning trueness and precision of six IOS in single crown, three-unit bridge, five-unit bridge and full arch were 13.3-29.6 μm and 7.6-20.7 μm, 15.4-30.9 μm and 8.7-26.5 μm, 17.0-66.1 μm and 11.3-44.2 μm, 24.0-107.9 μm and 24.6-150.1 μm respectively. Conclusions: Long-span scanning can affect the accuracy of IOS to a varying extent.

[Application and outlook of robotics in prosthetic dentistry]

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

[Research and application progress of mechanical measures for oral plaque control]

Effective removal of dental plaque is a key measure to prevent and control common oral diseases and to maintain the long-term effect of dental prostheses. The methods of oral plaque control are mainly depending on mechanical measures, including regular toothbrushing, interdental cleaning and oral irrigation. Toothbrushing is the most common and effective method for mechanical removal of dental plaque.How ever the effect of toothbrushing alone to remove dental plaque is limited. It is necessary to control the interdental plaque using tools such as dental floss and interdental brushes. Oral irrigation is an assistant method to improve oral hygiene. Toothbrushing combined with the use of oral irrigator can significantly improve the removal rate of dental plaque. The present article reviews the research progress of the mechanical plaque control methods and their application results.

[Quantitative evaluation of printing accuracy of multi-color and multi-hardness three-dimensional printing dental model with photopolymer jetting]

Objective: To quantitatively evaluate the accuracy of multi-color and multi-hardness dental models printed by using the photopolymer jetting (PJ) technology, and to provide protocol for the clinical application. Methods: A maxillary partially edentulous (Kennedy class Ⅱ subclass 1) standard digital model obtained through scanning and processing was selected as reference data. Five monochromatic DLP (digital light processing) models with single hardness were printed by printer DLP-800d based on DLP technology (DLP group), and five multi-color and multi-hardness PJ models were printed by printer J300Plus based on PJ technology (PJ group). Scan the printed model and register the scanning data to the reference data in Geomagic Studio 2013 software. The three-dimensional (3D) deviations of the whole and each area, including residual dentition, abutments adjacent to the edentulous area, gingiva, gingiva in the distal-extended edentulous area, gingiva in other edentulous areas, gingiva supporting the removable partial denture (RPD), were calculated and represented by the root mean square error (RMS) value. The smaller the RMS value was, the higher the trueness of printing was. The scanning data of the five models in the same group were registered in pairs to calculate the 3D deviation. The smaller the RMS value was, the higher the precision of printing was. The threshold of clinical acceptability was 200 μm. Statistical analysis was performed to compare the difference of trueness and precision between the two groups. Results: The overall trueness of the DLP group [57.70 (2.10) μm] was significantly better than that of the PJ group [71.00 (7.70) μm]. The overall precision of the DLP group [15.20 (5.05) μm] was significantly better than that of the PJ group [37.55 (15.55) μm]. The overall trueness and precision of both groups were within the clinically acceptable range. Conclusions: The domestic PJ printer used in this study can print multi-color and multi-hardness dental models with good trueness and precision, which can provide integrated 3D printing technology support for realizing the simulation of regional hardness differentiation between soft and hard tissues of dental models.

[Analysis of PARP inhibitors induced anemia in advanced and relapsed epithelial ovarian cancer]

Objective: To explore the clinical features of poly ADP-ribose polymerase (PARP) inhibitor-related anemia in advanced and relapsed epithelial ovarian cancer (EOC). Methods: Patients diagnosed with advanced or relapsed EOC and treated with PARP inhibitor at National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College between January 2015 to October 2020 were accrued. The data included PARP inhibitors, treatment details, and lab tests before treatment and during treatment were collected and the clinical characteristics of PARP inhibitor-related anemia were analyzed. Results: (1) A total of 98 patients with a median age of 56.5 years old (30-82 years old) were enrolled in this study. All patients were treated with PARP inhibitor (65 cases of olaparib, 17 cases of niraparib, and 16 cases of fluzoparib). The median treatment duration was 37.5 weeks (4-119 weeks). (2) The anemia rate was 40% (39/98), including 5% (5/98) of grade Ⅰ, 14% (14/98) of grade Ⅱ, 11% (11/98) of grade Ⅲ, and 9% (9/98) of grade Ⅳ. Fourteen patients with pre-treatment grade Ⅰ anemia had a higher rate of anemia events than the 80 patients without pre-treatment anemia, 7/14 vs 35% (28/80; χ²=4.281, P=0.039). (3) The median anemia occurrence time was 7.0 weeks (1-52 weeks), including 41% (16/39) of anemia cases occurred in 1-4 weeks, 26% (10/39) occurred in 5-8 weeks, 13% (5/39) occurred in 9-12 weeks, 3% (1/39) occurred in 13-16 weeks, 10% (4/39) occurred in 17-20 weeks, 8% (3/39) occurred ≥21 weeks. At the time of the lowest hemoglobulin tested, the median value of mean corpuscular volume (MCV) was 106 fl,which was higher than the up limit of normal range (100 fl), 74% (29/39) of anemia patients had an elevated MCV level; the median value of mean corpuscular hemoglobin (MCH) was 36 pg, 54% (21/39) of anemia patients had an elevated MCH level; the median value of mean corpuscular hemoglobin concentration (MCHC) was 320 g/L, 69% (27/39) of anemia patients had a higher MCHC level; 92% (36/39) of anemia patients had a normal level of serum iron; 79% (31/39) of anemia patients had a normal level of transferrin. 74% (29/39) of the anemia patients were macrocytic orthochromatic anemia. (4) Among the 39 patients with anemia, 20 patients (51%, 20/39) withhold the treatment of PARP inhibitor due to grade Ⅲ or Ⅳ anemia, including 10 patients (50%, 10/20) who resumed the PARP inhibitor treatment by suppling iron, folate, and vitamin B₁₂. The median stopping time of PARP inhibitor was 5.5 weeks (2-10 weeks), while the other 10 patients terminated the PARP inhibitor treatment for not recovering from severe anemia. Conclusions: One of the common adverse effects of PARP inhibitors is anemia, which mostly happened in the first 3 months of treatment. In the treatment of EOC, PARP inhibitor-related anemia mainly manifest as macrocytic orthochromatic anemia, and most patients with normal serum iron and transferrin.

[Advances in computer aided design and computer aided manufacturing of removable partial denture]

Computer aided design, numerically controlled milling, additive manufacturing and other digital technologies have been widely used in clinical practice of prosthodontics. The application of these technologies not only changed the design and manufacturing workflow of removable partial denture (RPD), but also improved the production efficiency of dentures, and changed the design and manufacturing concept of dentures. A large number of researches on computer aided design and computer aided manufacturing (CAD/CAM) of RPD have emerged in recent years, including researches on the properties of selective laser melting metal powder and other new dental materials, the innovative design of retainers, connectors, artificial teeth and other denture components, high precision manufacturing of the RPD framework, denture base and artificial teeth, quantitative laboratory evaluations of the accuracy, adaption and mechanical properties of RPD with new structures and made of new materials, clinical evaluations of RPD and others. This paper introduces these recent developments in CAD/CAM of RPD.

[Investigation of posterior teeth displacement under normal bite force by an intraoral scanner]

Objective: To quantitatively evaluate the change of the long axis angle and the relative displacement of the crown feature points of the posterior teeth under normal bite force utilizing an intraoral scanner, and to provide clinical reference. Methods: From May to December 2019, fifteen graduate volunteers (5 males and 10 females, aged from 22 to 30, with an average age of 25.7 years) from Peking University School and Hospital of Stomatology were recruited to participate in the study. The surface data (U1, L1) of the maxillary and mandibular posterior teeth were scanned by an intraoral scanner i500, and saved as original data. The volunteers were guided to bite in the intercuspal position with normal bite force. The buccal bite data of the posterior teeth were scanned as the basis for registration. The digital casts were imported into Geomagic studio 2013 software and the boundary lines along the gingival margin and mesial and distal contact area of posterior teeth of data (U1, L1) were determined. Long axis of the crown, crown centroid and mesial functional cusp vertex were establishd. The data (U1, L1) were segmented into single tooth. Single tooth was aligned to buccal bite data separately using best-fit alignment command based on the buccal common area of the crown and new casts data (U2, L2) were obtained as the data under bite force. The long axis angle and centroid distance between adjacent teeth (second premolar and first molar, second molar and first molar) were measured and the deviation between data obtained at mouth-open state and that at biting state was calculated. Negative value meant centroid distance became shorter under bite force. The first molar was set as the common area and registrate the U1, L1 to U2, L2. The angle of long axes, and displacement of centroid and of functional cusp vertex between second premolar of two casts were calculated, as well as between second molar of two casts. Wilcoxon signed rank test was used to analyze the differences of teeth displacement between second premolar and second molar, and between maxillary and mandibular jaws with SPSS 26.0 statistical software. Results: The result of second premolar and second molar in the same jaw had no statistical difference (P>0.05). The centroid distance deviation of mandibular second premolar-first molar [-0.022(0.046) mm] was larger than that of maxilla [-0.006 (0.040) mm] (P<0.05). The long axis angle of second premolar itself [0.913°(0.647°)] and centroid distance of second molar itself [0.102 (0.106) mm] on the mandibular jaw were different from that on the maxillary jaw, which were 0.590°(0.550°) and 0.074(0.060) mm respectively (P<0.05). Conclusions: Under bite force, displacement of the second premolar and second molar was present, including the displacement of centroids and deflection of long axes. The mandibular posterior teeth have larger displacement than the maxillary teeth.

Exosomes overexpressing miR-34c inhibit malignant behavior and reverse the radioresistance of nasopharyngeal carcinoma

BACKGROUND

Malignant behavior and radioresistance, which severely limits the efficacy of radiation therapy (RT) in nasopharyngeal carcinoma (NPC), are associated with tumor progression and poor prognosis. Mesenchymal stem cells (MSCs) are used as a therapeutic tool in a variety of tumors. The aim of this study was to reveal the effect of tumor suppressor microRNA-34c-5p (miR-34c) on NPC development and radioresistance, as well as to confirm that exosomes derived from MSCs overexpressing miR-34c restore the sensitivity to radiotherapy in NPCs.

METHODS

Potentially active microRNAs were screened by cell sequencing, Gene Expression Omnibus (GEO) database analysis, and analysis of clinical serum samples from 70 patients. The expression of genes and proteins was detected by Western blotting, quantitative reverse transcription PCR (qRT-PCR), and immunohistochemistry (IHC). Proliferation, apoptosis, invasion, migration and radioresistance of NPC were detected. Luciferase reporter assays were used to verify the interactions of microRNAs with their downstream targets. MSCs exosomes were isolated by ultrafiltration and verified by electron microscopy and nanoparticle tracking technology.

RESULTS

The expression of miR-34c was associated with the occurrence and radiation resistance of NPC. In vitro and in vivo experiments indicated that overexpression of miR-34c inhibit malignant behavior such as invasion, migration, proliferation and epithelial-mesenchymal transition (EMT) in NPCs by targeting β-Catenin. In addition, we found alleviated radioresistance upon miR-34c overexpression or β-catenin knockdown in NPCs. Exosomes derived from miR-34c-transfected MSCs attenuated NPC invasion, migration, proliferation and EMT. Moreover, miR-34c-overexpressing exosomes drastically increased radiation-induced apoptosis in NPC cells.

CONCLUSION

miR-34c is a tumor suppressor miR in NPC, which inhibits malignant behavior as well as radioresistance of tumor. Therefore, exogenous delivery of miR-34c to NPCs via MSC exosomes inhibits tumor progression and increases the efficiency of RT. Combination IR with miR-34c-overexpressing exosomes may be effective treatment for radioresistant NPCs.

[Prediction of syncope with nonlinear dynamic analysis during head-up tilt in vasovagal syncope patients]

OBJECTIVE

To quantify the relationship between cerebral blood flow velocity and peripheral blood pressure during hypotension period, aiming to predict the brain hypotension before symptomatic occurrence.

METHODS

Twenty vasovagal syncope (VVS) patients who had a previous clinical history were selected in groups and 20 pair-matched control subjects underwent 70° tilt-up test. The subjects remained supine for 30 minutes before recordings when Doppler probes, electrodes and Finapres device were prepared. After continuous baseline recordings for 10 min, the subjects underwent head up tilt (HUT) test (70°), and were standing upright for 30 minutes or until syncope was imminent. For ethical reasons, the subjects were turned back to supine position immediately after SBP dropped to ≥20 mmHg, when their consciousness persisted. The point of syncope was synchronized for all the subjects by the point SBP reached the minima. Their beat-to-beat blood pressures (BP) were recorded continuously and bilateral middle cerebral artery (MCA) flow velocities were obtained with two 2 MHz Doppler probes from a transcranial Doppler ultrasonography (TCD) system. A nonlinear dynamic method--multimodal pressure flow (MMPF) analysis was introduced to access cerebral autoregulation during different time intervals. We introduced a new indicator--syncope index (SI), which was extracted from blood flow velocity (BFV) signal to evaluate the variation of cerebral vascular tension, and could reflect the deepness of dicrotic notch in BFV signal.

RESULTS

Compared with the syncope index of the baseline value at the beginning of the tilt test, SI in VVS group showed significantly lower when the VVS occurred (0.16±0.10 vs.0.27±0.10,P<0.01),while there was no significant difference in syncope index between the control group at the end of the tilt test and the baseline value at the beginning of the tilt test. For those VVS patients, pulse index and resistance index had no significant change. Syncope index decreased significantly 3 minutes before the point of syncope (0.23±0.07 vs.0.29±0.07,P<0.01).

CONCLUSION

Dynamic regulation is exhausted when vasovagal syncope occurred. Tension decrease of small vessels could have some relationship with loss of the cerebral autoregulation capability. The proposed syncope index could be a useful parameter in predicting syncope of VVS patients since it decreased significantly up to 3 minutes earlier from the point of syncope.

[Prevalence and attribution of high-risk HPV in different histological types of cervical cancer]

Objective: To investigate the prevalence of high-risk HPV subtypes in different pathological types of cervical cancer, and analyze the attribution of carcinogenic HPV subtypes in different pathological types. Methods: A total of 1 541 patients with cervical cancer were treated between February 2009 and October 2016 in Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College. The median age at diagnosis was 49 years (ranged 20-82 years old). The numbers of patients with cervical cancer from North China, Northeast China, East China, Central China and other regions (including Northwest, Southwest and South China) were 961, 244, 175, 87 and 74 cases, respectively. Pathological types: 1 337 cases of squamous cell carcinoma (SCC), 87 usual adenocarcinoma (ADC), 23 adenosquamous carcinoma (ASC), 20 mucinous carcinoma (MC), 19 clear cell carcinoma (CCC), 12 endometrioid carcinoma (EC), 25 neuroendocrine carcinoma (NEC), 9 serous carcinoma (SC), 5 villous adenocarcinoma (VADC) and 4 minimal deviation adenocarcinoma (MDAC). The prevalence of high-risk HPV in different regions, age groups at diagnosis and pathological types in cervical cancer were analyzed. The attribution of 13 high-risk HPV subtypes in different pathological types of cervical cancer based on proportional attribution method, and the attribution of high-risk HPV subtypes prevented by 9-valent HPV vaccine in SCC and ADC were calculated. Results: (1) The prevalence of high-risk HPV in 1 541 patients with cervical cancer was 86.6% (1 335/1 541). The multiple high-risk HPV infection rate in patients with SCC ≥60 years old (23.0%, 37/161) was significantly higher than those in patients aged 45-59 years old and ≤44 years old [11.4% (85/747) vs 11.7% (50/429), P<0.01], and the high-risk HPV infection rates of patients with cervical cancer in North China, Northeast China, East China, Central China and other regions were respectively 86.8% (834/961), 87.7% (214/244), 83.4% (146/175), 83.9% (73/87) and 91.9% (68/74). SCC (86.8%, 1 337/1 541) and ADC (5.6%, 87/1 541) were the most common pathological types in cervical cancer. The high-risk HPV prevalence of SCC, ADC, ASC, MC, NEC and VADC were 90.1% (1 205/1 337), 74.7% (65/87), 87.0% (20/23), 65.0% (13/20), 72.0% (18/25) and 5/5 respectively. The high-risk HPV infection rates of SC, EC, CCC and MDAC were 4/9, 3/12, 2/19 and 0/4 respectively. (2) According to proportional attribution, HPV 16 (69.5%), HPV 18 (5.6%), HPV 58 (2.2%), HPV 31 (1.9%), HPV 52 (1.4%) and HPV 33 (1.3%) were the six common high-risk HPV subtypes in SCC. While, HPV 18 (44.1%), HPV 16 (20.5%), HPV 52 (2.3%), HPV 58 (1.2%) and HPV 51 (1.2%) were the main carcinogenic subtypes in ADC. The main carcinogenic high-risk HPV subtypes of ASC, NEC and MC were HPV 18 and HPV 16. The total attribution of HPV 16, 18, 31, 33, 45, 52 and 58 prevented by 9-valent HPV vaccine in SCC and ADC were 82.6% and 68.1% respectively; the attribution of HPV 45 in SCC and ADC were only 0.8% and 0. Conclusions: SCC and ADC are the main pathological types in cervical cancer. SCC, ADC, ASC, MC, NEC and VADC are closely related to high-risk HPV infection. HPV 16 is the main carcinogenic genotypes of SCC. HPV 18 maybe play an important role in the pathogenesis of ADC.

[Etiology and clinical technology of the food impaction with tight proximal contacts]

Food impaction with tight proximal contacts, also known as kinetic food impaction and food impaction without anatomical structure destruction, is mainly caused by a transient separation in contacts area during mastication. It's an intractable food impaction with high morbidity and low cure rate. There are two kinds of pathogenesis accepted: the shifting of anterior teeth incongruous with adjacent teeth or lack of anterior shifting; lack of food escape grooves. The preferred treatment is occlusal adjustment, but it's difficult to determine the area and extent of selective grinding, to quantify the occlusal adjustment, or to predict the prognosis. This review summarized the pathogenesis and treatment modality for kinetic food impaction in order to provide evidence for future researches and clinical application.

[Establishment of a 3D printing system for bone tissue engineering scaffold fabrication and the evaluation of its controllability over macro and micro structure precision]

OBJECTIVE

To establish a 3D printing system for bone tissue engineering scaffold fabrication based on the principle of fused deposition modeling, and to evaluate the controllability over macro and micro structure precision of polylactide (PLA) and polycaprolactone (PCL) scaffolds.

METHODS

The system was composed of the elements mixture-I bioprinter and its supporting slicing software which generated printing control code in the G code file format. With a diameter of 0.3 mm, the nozzle of the bioprinter was controlled by a triaxial stepper motor and extruded melting material. In this study, a 10 mm×10 mm×2 mm cuboid CAD model was designed in the image ware software and saved as STL file. The file was imported into the slicing software and the internal structure was designed in a pattern of cuboid pore uniform distribution, with a layer thickness of 0.2 mm. Then the data were exported as Gcode file and ready for printing. Both polylactic acid (PLA) and polycaprolactone (PCL) filaments were used to print the cuboid parts and each material was printed 10 times repeatedly. After natural cooling, the PLA and PCL scaffolds were removed from the platform and the macro dimensions of each one were measured using a vernier caliper. Three scaffolds of each material were randomly selected and scanned by a 3D measurement laser microscope. Measurements of thediameter of struts and the size of pores both in the interlayer overlapping area and non-interlayer overlapping area were taken.

RESULTS

The pores in the printed PLA and PCL scaffolds were regular and interconnected. The printed PLA scaffolds were 9.950 (0.020) mm long, 9.950 (0.003) mm wide and 1.970 (0.023) mm high, while the PCL scaffolds were 9.845 (0.025) mm long, 9.845 (0.045) mm wide and 1.950 (0.043) mm high. The struts of both the PLA and PCL parts became wider inthe interlayer overlapping area, and the former was more obvious. The difference between the designed size and the printed size was greatest in the pore size of the PLA scaffolds in interlayer overlapping area [(274.09 ± 8.35) μm)], which was 26.91 μm. However, it satisfied the requirements for research application.

CONCLUSION

The self-established 3D printing system for bone tissue engineering scaffold can be used to print PLA and PCL porous scaffolds. The controllability of this system over macro and micro structure can meet the precision requirements for research application.

[Computer aided design and three-dimensional printing for apicoectomy guide template]

OBJECTIVE

To establish an apicoectomy guide template design and manufacturing method, based on multi-source data fusion, computer aided design (CAD) and fused deposition modeling (FDM). The feasibility of the guide template was preliminary evaluated by the in vitro model experiment.

METHODS

An extracted upper anterior tooth, after root canal treatment, was optical scanned, after which the extracted upper anterior tooth was poured in an apicoectomy plaster model. Cone-beam computed tomography (CBCT) scanning of the apicoectomy plaster model was performed, after which optical scanning of the plaster model for apical resection surgery was carried out. All of the relevant CBCT and optical scanning data of the extracted upper anterior tooth and the apicoectomy plaster model were introduced into the Geomagic Studio 2012 software. The multi-source data fusion technology was used to virtually simulate the three-dimensional positional relationship of the extracted tooth, the dentition, the alveolar bone and the gingival, based on which, the three-dimensional design of the apicoectomy guide template was completed in the Geomagic Studio 2012 software. With the technology of fused deposition modeling, the apical resection surgical guide template was three-dimensionally printed with the material of polylactic acid (PLA). Under the guidance of the surgical guide template, the root apical resection was performed on the plaster model. After the apicoectomy, the extracted upper anterior tooth was taken off from the apicoectomy plaster model and then was given the optical scanning. The apical resection length and angle were calculated by the function of distance measurement and angle measurement, and the results were compared with the preset values.

RESULTS

The length of the apical resection was 2.88 mm along the direction of the long axis of the tooth, which was 0.12 mm lower than the preset 3 mm. The included angle between the apical resection plane and the long axis of the tooth was 77.9°, 12.1° lower than the preset 90°.

CONCLUSION

This study successfully established a digital design and production method of apicoectomy guide template by combing the multi-source data fusion, CAD and FDM technology. The design route and the production method are feasible. The study will provide a technology and methodology reference for the development of domestic special software for the digital design of apicoectomy guide template.

[A preliminary study on the three-dimensional trajectory of condyle]

Objective: To calculate the three-dimensional trajectory and motion morphology of condyle by combining the trajectory of the mandible movement and the three-dimensional model of the mandible. Methods: Cone beam CT (CBCT) scanning was performed on the volunteer. The mandible three-dimensional model was built with image data transferred to the graphical user interface of the computer workstation. The novel virtual articulator PN300 recorded the three-dimensional trajectory of mandible. All these data were transferred to software system of computer workstation calculating the three-dimensional trajectory of condyle. The motion morphology of condyle was simulated by merging function surface at each point. Results: When the mandible moved in an opening process, the recorded data was calculated and it was shown that: the condylar functional surface moved moved forward and downward inward in advance, and in the process of continuously increasing the opening degree, the function faced the front upper inner side. The straight-line distance between the position and the final position was 8.34 mm. During the forward movement of the mandible, the coracoid process slided forward downward and inward with a sliding distance of 8.64 mm. During lateral movement, the range of the working side condyle function surface motion was small, only slight rotation, the maximum range of motion was 1.97 mm; in the process of row side movement, the non-working condyle function surface had a larger movement range than the working side, the movement direction was the front lower inner side, and the movement distance was 7.65 mm. Conclusions: The novel virtual articulator PN300 and digital technology can achieve the accurate measurement of three-dimensional trajectory of the condyle, and furthermore simulate the motion morphology of the condyle.

Xuebijing enhances neuroprotective effects of ulinastatin on transient cerebral ischemia via Nrf2-are signal pathways in the hippocampus

Prior studies have demonstrated that ulinastatin (UTI) plays a beneficial role in regulating cerebral ischemic injury evoked by cardiac arrest (CA). It is noteworthy to find interventions that can enhance effects of this drug and thereby increase its clinical application. Xuebijing (XBJ) is comprised of extracts from Chinese herbs and has been widely used in China as an anti-endotoxicity drug for the treatment of sepsis and ischemic disorders associated with multiple organ dysfunction syndrome. Thus, in this study we examined the effects of a combination of UTI and XBJ to improve neural injury in the process of neurological functions after transient cerebral ischemia. Our results show that CA impaired Nrf2- antioxidant response element (Nrf2-ARE) and superoxide dismutase (SOD) in the hippocampus CA1 region. This process further amplified products of oxidative stress, namely 8-isoprostaglandin F2α (8-iso PGF2α) and 8-hydroxy-2'-deoxyguanosine (8-OHdG). A lower dose of UTI failed to restore Nrf2-ARE and attenuate 8-iso PGF2α and 8-OHdG SOD following CA; however, systemic administration of XBJ amplified the effects of this dose of UTI on antioxidative signal pathway of the hippocampus. Overall, the results of this study have implications for the enhanced neuroprotective role played by a combination of XBJ and UTI in improving neural injury observed in transient cerebral ischemia; and Nrf2-ARE signal is a part of key mechanisms that are involved in neuroprotective effects of XBJ and UTI.

[Airway inflammation and small airway wall remodeling in neutrophilic asthma]

OBJECTIVE

To investigate the distribution of airway inflammation phenotype in patients with bronchial asthma (asthma), and to analyze clinical characteristics, inflammatory cytokines, pulmonary small vessels remodeling and small airway wall remodeling in patients with neutrophilic asthma.

METHODS

Sixty-three patients with asthma were enrolled from January 2015 to December 2015 in Peking University Third Hospital. Clinical data including gender, age, body mass index (BMI), pulmonary function tests (PFTs), asthma control test (ACT) were recorded. All the patients underwent sputum induction. The cellular composition of the sputum was evaluatedand the concentration of active MMP-9 in the sputum tested. Blood routine tests were done and the concentration of IgE, periostin, and TGF-beta1 levels were measured in serum by enzyme-linked immunosorbent assay (ELISA). Small airway wall remodeling was measured in computed tomography (CT) scans, as the luminal diameter, luminal area, wall thickness and wall area % adjusted by body surface area (BSA) at the end of the 6th generation airway, in which the inner diameter was less than 2 mm. Small vascular alterations were measured by cross-sectional area (CSA), and the total vessel CSA < 5 mm² was calculated using imaging software.

RESULTS

The distributions of airway inflammatory phenotypes of the asthmatic patients were as follows: neutrophilic asthma (34.9%, 22/63), eosinophilic asthma (34.9%, 22/63), mixed granulocytic asthma (23.8%, 15/63), and paucigranulocytic asthma (6.3%, 4/63). The neutrophilic subtype patients had a significantly higher active MMP-9 level in sputum compared with the eosinophilic phenotypepatuents, as 179.1 (74.3, 395.5) vs. 50.5 (9.7, 225.8), P<0.05. Sputum neutrophil count was negatively correlated with FEV1%pred (r=-0.304,P<0.05), and positively correlated with active MMP-9 level in sputum (r=-0.304, P<0.05), and positive correlation trend with airway wall thickness (r=0.533, P=0.06). There was a significantly negative correlation of active MMP-9 level in sputum with FEV1%pred (r=-0.281, P<0.05), in positive correlation with small airway wall area (%)(r=0.612, P<0.05), and inpositive correlation trend with airway wall thickness (r=0.612, P=0.06). Neutrophils count in peripheral blood was positively correlated with neutrophil counts in sputum.

CONCLUSION

Neutrophil count in airway is related to lung function in asthmatic patients. Neutrophils may accelerate small airway wall remodeling through the release of active MMP-9. Neutrophil count in peripheral blood is related to neutrophils count in sputum, which may be used as a substitute for evaluating inflammatory phenotype.

Cancer stem cell-like characteristics and telomerase activity of the nasopharyngeal carcinoma radioresistant cell line CNE-2R

The radioresistance of nasopharyngeal carcinoma (NPC) may be related to cancer stem cells (CSCs), and the characteristics of CSCs may be maintained by telomerase activity. In this study, we explored the CSC‐like characteristics and telomerase activity of the NPC radioresistant cell line CNE‐2R. This work provides a foundation for future studies on stem cell‐targeted therapies by targeting the radioresistance of NPC. The expression of stem cell‐related genes/proteins and the hTERT gene/protein in CNE‐2R and its parent radiosensitive cell line CNE‐2 were detected using qPCR/Western Blot. Label‐retaining cells (LRCs) were detected through immunocytochemistry, and telomerase activity was detected using a PCR‐ELISA kit. CD133 expression was detected with flow cytometry. CNE‐2R‐CD133+ and CNE‐2R‐CD133− cells were separated with magnetic‐activated cell sorting. The proliferation and tumorigenesis capacities of CNE‐2R‐CD133+, CNE‐2R‐CD133−, and CNE‐2R cells were compared with a CCK‐8 assay, sphere formation assay, and an in vivo experiment. Our results showed that the expression of stem cell‐related genes and the hTERT gene in CNE‐2R cells was higher than those in CNE‐2 cells. Similarly, the expression of stem cell‐related proteins and the hTERT protein in CNE‐2R cells was markedly higher than those in CNE‐2 cells. The proportion of LRCs in CNE‐2R and CNE‐2 cells was (3.10 ± 0.63%) vs (0.40 ± 0.35%; P < 0.001), respectively. Telomerase activity in CNE‐2R cells was remarkably higher than that in CNE‐2 cells. Flow cytometry suggested that the CD133 positive rates in CNE‐2R and CNE‐2 cells were (2.49 ± 0.56%) vs (0.76 ± 0.25%; P = 0.008), respectively. Meanwhile, the proliferation capacity, tumorigenesis capacity, and telomerase activity of CNE‐2R‐CD133+ cells were notably higher than those of CNE‐2R‐CD133− and CNE‐2R cells. Collectively, CNE‐2R displayed CSC‐like characteristics; our results also showed that CNE‐2R cells, especially the sorted CSCs, had high telomerase activity levels.

[Preliminary study on the automatic preparation of dental implant socket controlled by micro-robot]

Objective: To analyze the quantitative relationship between the number of layers of laser pulses and the amount of step in ultra-short pulse laser cutting of cortical bone, optimize the robot's vertical single stepping parameters, and to explore the feasibility of automatic preparation of dental implant cavity using robot controlling ultra-short pulse laser, in order to lay the foundation for automated dental implant surgery. Methods: Eight pig ribs were segmented into to make 16 specimens. Using the robotic surgical system and path planning software independently developed by our group, circular holes with a diameter of 4 mm were cut two-dimensionally in the rib segments to obtain the quantification relationship of the number of laser pulse layers (n) and the depth of two-dimensional (2D) cutting (d). When conducting the three-dimensional (3D) cutting procedure, the number of pulse layers were set to 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 layers, the vertical single step amount was an integer value corresponding to the results of 2D cutting depth, and the number of pulses (n') corresponding to the minimum difference between the theoretical depth of cut and the actual depth of cut was obtained. The n' was taken as the most suitable single step pulse layer, the rib segment was cut, and the depth of single cut was measured while the integer value was taken as the most appropriate vertical single step amount (d'). The vertical parameters of laser single stepping were set as n' layer pulse and d' μm step size. The 3D cutting produces a cylindrical cavity with a diameter of 4 mm and a height of 2 mm to evaluate the 3D cutting accuracy (the difference between the measured value and the theoretical value of cutting diameter or depth). Ten 4 mm×3 mm implant holes were automatically prepared on the bilateral femurs of 5 Japanese big white rabbits, and ten 4 mm×3 mm implants made by 3D printer were artificially implanted, and the preparation effect of the implant cavities was evaluated. Results: The quantitative relationship curve between the number of laser pulses (n) and 2D depth of cut (d) showed a linear upward trend. The linear fitting obtained the quantitative relation function formula d=9.278 4 n±26.763 0, R(2)=0.988 9. The optimum number of single step pulse layers was 5 layers, and the vertical single step amount was 50 μm, so as to set the vertical parameters of a single step of a 3D cutting, and the 3D cutting diameter accuracy was (3.98±2.87) μm, with a depth accuracy of (15.42±5.44) μm. Automated preparation of 10 implant cavities on the femur of the rabbit were completed. When the implants were placed into the implant cavities, there was resistance, but they were fully seated and primary stability has been achieved after seating implant placement. Conclusions: The method of non-contact automatic preparation of dental implant cavities using robot controlling ultra-short pulse laser is feasible. By optimizing the single cutting process parameters, precise control of laser cutting cortical bone can be realized.

Cofilin-2 Acts as a Marker for Predicting Radiotherapy Response and Is a Potential Therapeutic Target in Nasopharyngeal Carcinoma

Background

The purpose of this study was to determine whether cofilin-2 could serve as a protein marker for predicting radiotherapy response and as a potential therapeutic target in nasopharyngeal carcinoma (NPC).

Material/Methods

Cofilin-2 protein levels in serum and tissue samples from patients with NPC were assessed by sandwich ELISA and IHC. In vitro, cofilin-2 levels in CNE-2R cells were significantly higher than those of CNE-2 cells. Meanwhile, CNE-2R cells were silenced for cofilin-2 to obtain a stable cofilin-2-RNAi-LV3 cell line. Then, cell proliferation, radiosensitivity, invasion and migration abilities, cell cycle, and apoptosis were evaluated by Cell Counting Kit 8 assay (CCK-8), flow cytometry (FCM), clone formation assay, and in vitro.

Results

The secreted levels of the cofilin-2 protein in radioresistant NPC patients were significantly higher than those of radiosensitive cases. After cofilin-2 knockdown in nasopharyngeal carcinoma CNE-2R cells, proliferation was decreased, while apoptosis and radiosensitivity were enhanced; cell cycle distribution was altered, and the transplanted tumors in nude mice grew significantly less.

Conclusions

Overall, our findings suggest that cofilin-2 acts as a marker for predicting radiotherapy response and is a potential therapeutic target in nasopharyngeal carcinoma.

[Analysis of correlative factors of serum leptin levels in asthmatic patients]

Objective: To analysis the correlative factors that probably affect serum leptin levels in asthmatic patients. Methods: Seventy-eight patients with asthma and 29 health controls who were admitted into outpatient clinic of Peking University Third Hospital from April 2014 to December 2015 were consecutively enrolled in our study prospectively. Serum leptin level was measured by enzyme-linked immunosorbent assay (ELISA). The sex, body mass index (BMI), onset age of asthma, allergen detection test, induced sputum cell count and classification, lung function test and asthma control level were recorded. Asthmatic patients were further divided into groups according to these factors and serum leptin levels were compared among groups. Results: Serum leptin levels were not different between asthmatic patients and health controls [(15.0±10.4) vs (15.2±11.7) μg/L, P=0.939]. Female asthmatic patients had significantly higher serum leptin levels than male [(18.2±10.7) vs (7.9±4.8) μg/L, P<0.001]. Asthmatic patients with obesity had significantly higher serum leptin levels than asthmatic patients with overweight, with normal BMI, with underweight and health controls [(29.7±10.8) vs (17.1±11.1), (11.8±7.7), (9.1±0.96), (15.2±11.7) μg/L, all P<0.01]. Serum leptin level was positively related to percentage of induced sputum eosinophil in female asthmatic patients (r=0.331, P=0.032). Onset age of asthma, positive allergen detection, airflow limitation or asthma control level did not affect serum leptin level. Conclusion: Sex and BMI are important factors affecting serum leptin levels in patients with asthma.

[Influence of intraoral scan and dental cast scan on occlusal quantitative analysis of virtual dental model]

OBJECTIVE

To make more accurate occlusal quantitative analysis of three-dimensional (3D) virtual dental models and to compare the occlusal contact obtained by intraoral and dental cast scan.

METHODS

In this study, 5 subjects were intraoral scanned using laser scanner (3 shapes, Germany) to obtain the 3D virtual models of one tooth (the first molar), two teeth (the second premolar and the first molar), three teeth (the premolars and the first molar) and their opposite teeth, respectively. The silicone impressions were made and dental stone models were poured for each of them. The dental casts were scanned and then they were fixed to the maximum intercuspal position with a special locating jig for a rescanning of occlusal position. The virtual models taken intraorally and obtained with dental cast scan were introduced to a 3D quantitative analysis system, and some criteria regarding to occlusal contact were calculated and analyzed. The occlusal criteria were mean values of occlusal clearance space between the upper and lower occlusal surface (clearance), occlusal contact area (area), and cusp inclination (angle) of the mandibular first molar. Paired t tests were used to evaluate differences of occlusal criteria between the virtual models obtained with the intraoral scan and dental cast scan (α=0.05).

RESULTS

The mean values of occlusal clearance of one to three teeth obtained by way of intraoral scan were smaller than those obtained by way of cast scan by 0.134 mm, 0.177 mm, and 0.207 mm, respectively. While the occlusal contact areas were greater than the cast scan by 8.65 mm², 10.28 mm², and 11.46 mm². No statistically significant differences were found between the cusps inclinations obtained with the two scanning methods, and the interclass correlations were high.

CONCLUSION

Occlusal clearance obtained by intraoral scan was less than that by cast scan while the occlusal contact area was greater than the latter, indicating that intraoral occlusal contact was closer. The difference of the standard deviations of occlusal clearance measured by the two methods were small and that of occlusal contact area was influenced by the number of teeth scanned intraorally. There was no statistical difference in cusp inclination between the two methods.

[Research status of tooth preparation quantitative guide technique]

Tooth preparation is a basic operation in prosthodontics treatment and the quality of preparation influences the effect of treatment directly. How to achieve a precise and quantitative tooth preparation is always one of the main aims of dental prosthodontics. The known types of tooth preparation guide technique can be divided into visual guidance, passive constraint guidance and active constraint guidance (automated tooth preparation), respectively represented by silicon rubber index, tooth preparation guide plate and computerized numerical control cutting system (CNC cutting system). Studies in advanced manufacturing technologies such as robot systems and numerical control ultra-short pulse laser (USPL) have also been reported recently. This review comprehensively introduced tooth preparation quantitative guide techniques and partially summarized the application effects and limitations to provide reference for relative researches and clinical application.

[Research and development of digital design and fabrication of complete denture]

Removable complete denture are still the primary prosthetic solution for edentulous patients. Functional pressure impression obtaining, jaw relation recording, personalized balance occlusion and highly precise fabrication of denture are difficult. The digital restoration technique represented by intraoral three-dimensional scanning and three-dimensional (3D) printing compensates for the shortages of the manual techniques, but there are still many limitations in the application of complete dentures. At present, a few computer aided design and computer aided manufacture (CAD/CAM) complete denture systems have been developed both domestically and abroad, and these system are mainly focused on the digital design and manufacture of denture, and are seldom used for the recording of impression and jaw relation. This review is based on the main clinical procedures of the traditional complete denture restoration, elaborating the research and application status of digital technique in each steps, in order to provide reference for clinical application.

[Quantitative evaluation of printing accuracy and tissue surface adaptation of mandibular complete denture polylactic acid pattern fabricated by fused deposition modeling technology]

Objective: To quantitatively evaluate the adaptation of polylactic acid (PLA) pattern of mandibular complete denture fabricated by fused deposition modeling (FDM) technology. Methods: A mandibular complete denture digital model was designed through a complete denture design software based on a pair of standard maxillomandibular edentulous plaster model and their occlusion bases. Ten PLA mandibular complete dentures were printed with a FDM machine. The dentures were scanned with and without the plaster model using a three-dimensional (3D) scanner. In Geomagic software, the scanning data of printed dentures were registered to its computer aided design (CAD) data, and the printing error was analyzed using the multipoint registration command. For quantitatively evaluating the adaptation of the denture, the data of plaster model and PLA denture were registered to the whole data of denture located in the plaster model using the best-fit alignment command, the 3D deviation of the plaster model and tissue surface of the denture represent the space between them. The overall area was separated into three parts: primary stress-bearing area, secondary stress-bearing area and border seal area, and the average deviations of these three parts were measured. The values were analyzed using analysis of variance. Results: Compared with the CAD data, the printing error was (0.013±0.004) mm. The overall 3D deviation between PLA denture and plaster model was (0.164±0.033) mm, in which the primary stress-bearing area was (0.165± 0.045) mm, the secondary stress-bearing area was (0.153 ± 0.027) mm, the border seal area was (0.186 ± 0.043) mm. These showed a good fit in the majority parts of the FDM denture to the plaster model. No statistically significant difference was observed between the three areas (F=1.857, P=0.175>0.05). Conclusions: Combined with the 3D scanning, CAD and FDM technology, a FDM 3D printing process of complete denture for injection moulding can be established. As a result, high efficiency and low cost can be used to print out the complete denture, to lay the basis for further clinical applications.

[Study on the appropriate parameters of automatic full crown tooth preparation for dental tooth preparation robot]

Objective: To further study the most suitable parameters for automatic full crown preparation using oral clinical micro robot. Its purpose is to improve the quality of automated tooth preparing for the system and to lay the foundation for clinical application. Methods: Twenty selected artificial resin teeth were used as sample teeth. The micro robot automatic tooth preparation system was used in dental clinic to control the picosecond laser beam to complete two dimensional cutting on the resin tooth sample according to the motion planning path. Using the laser scanning measuring microscope, each layer of cutting depth values was obtained and the average value was calculated. The monolayer cutting depth was determined. The three-dimensional (3D) data of the target resin teeth was obtained using internal scanner, and the CAD data of full-crown tooth preparation was designed by CAD self-develged software. According to the depth of the single layer, 11 complete resin teeth in phantom head were automatically prepared by the robot controlling the laser focused spot in accordance with the layer-cutting way. And the accuracy of resin tooth preparation was evaluated with the software. Using the same method, monolayer cutting depth parameter for cutting dental hard tissue was obtained. Then 15 extracted mandibular and maxillary first molars went through automatic full crown tooth preparation. And the 3D data of tooth preparations were obtained with intra oral scanner. The software was used to evaluate the accuracy of tooth preparation. Results: The results indicated that the single cutting depth of cutting resin teeth and in vitro teeth by picosecond laser were (60.0±2.6) and (45.0±3.6) μm, respectively. Using the tooth preparation robot, 11 artificial resin teeth and 15 complete natural teeth were automatically prepared, and the average time were (13.0±0.7), (17.0±1.8) min respectively. Through software evaluation, the average preparation depth of the occlusal surface of 11 resin teeth was approximately (2.089±0.026) mm, the error was about (0.089±0.026) mm; the average convergence angle was about 6.56°±0.30°, the error was about 0.56°±0.30°. Compared with the target preparation shape, the average shape error of the 11 resin tooth preparations was about 0.02-0.11 mm. And the average preparation depth of the occlusal surface of 15 natural teeth was approximately (2.097±0.022) mm, the error was about (0.097±0.022) mm; the average convergence angle was about 6.98°±0.35°, the error was about 0.98°±0.35°. Compared with the target preparation shape, the average shape error of the 15 natural tooth preparations was about 0.05-0.17 mm. Conclusions: The experimental results indicate that the automatic tooth preparation for resin teeth and the teeth were completed according to the specific parameters of the single cutting depth by the micro robot controlling picosecond laser respectively, its preparation accuracy met the clinical needs. And the suitability of the parameter was confirmed.

[Three-dimensional data fusion method for tooth crown and root based on curvature continuity algorithm]

OBJECTIVE

To explore a three-dimensional (3D) data fusion and integration method of optical scanning tooth crowns and cone beam CT (CBCT) reconstructing tooth roots for their natural transition in the 3D profile.

METHODS

One mild dental crowding case was chosen from orthodontics clinics with full denture. The CBCT data were acquired to reconstruct the dental model with tooth roots by Mimics 17.0 medical imaging software, and the optical impression was taken to obtain the dentition model with high precision physiological contour of crowns by Smart Optics dental scanner. The two models were doing 3D registration based on their common part of the crowns' shape in Geomagic Studio 2012 reverse engineering software. The model coordinate system was established by defining the occlusal plane. crown-gingiva boundary was extracted from optical scanning model manually, then crown-root boundary was generated by offsetting and projecting crown-gingiva boundary to the root model. After trimming the crown and root models, the 3D fusion model with physiological contour crown and nature root was formed by curvature continuity filling algorithm finally. In the study, 10 patients with dentition mild crowded from the oral clinics were followed up with this method to obtain 3D crown and root fusion models, and 10 high qualification doctors were invited to do subjective evaluation of these fusion models.

RESULTS

This study based on commercial software platform, preliminarily realized the 3D data fusion and integration method of optical scanning tooth crowns and CBCT tooth roots with a curvature continuous shape transition. The 10 patients' 3D crown and root fusion models were constructed successfully by the method, and the average score of the doctors' subjective evaluation for these 10 models was 8.6 points (0-10 points). which meant that all the fusion models could basically meet the need of the oral clinics, and also showed the method in our study was feasible and efficient in orthodontics study and clinics.

CONCLUSION

The method of this study for 3D crown and root data fusion could obtain an integrate tooth or dental model more close to the nature shape. CBCT model calibration may probably improve the precision of the fusion model. The adaptation of this method for severe dentition crowding and micromaxillary deformity needs further research.

In vivo metacarpophalanageal joint collateral ligament length changes during flexion

We investigated the in vivo length changes of the collateral ligaments of metacarpophalangeal joint during flexion. We obtained computed tomography scans of index, middle, ring and little fingers at 0°, 30°, 60° and 90° of joint flexion from six hands of six healthy adult volunteers. Three of them had their dominant right hand studied, and the other three had their non-dominant left hand studied. We measured and analysed the radial and ulnar collateral ligaments of each metacarpophalangeal joint from the reconstructed images. We found that the dorsal and middle portions of the both radial and ulnar collateral ligament lengthened progressively during digital flexion and reached the maximum at 90° flexion. The length of the volar portion increased from 0° to 30° flexion and then decreased from 30° to 60° flexion, reaching the minimum at 90°. In conclusion, three portions of collateral ligaments on both sides of the metacarpophalangeal joint have variable length changes during flexion, which act to stabilize the joint through its flexion arc.

Size reduction-induced chain breaking in Haldane-chain compounds SrNi2-x Mg x V2O8 (x = 0 and 0.1)

We report size reduction-induced chain breaking in the spin-1 Haldane-chain SrNi_2-x Mg _x V₂O₈ (x  =  0 and 0.1) by magnetization and electron spin resonance measurements. For x  =  0.0, the magnetic susceptibility of all samples can be well described by a temperature-independent term, a Curie-Weiss term and a Haldane-gap term. This implies that a reduced sample grain size breaks the long chain and creates a considerable number of S  =  1/2 edge spins, resulting in the enhancement of magnetization and the decrease of Haldane gap in the samples. These edge spins as well as the other paramagnetic ions at grain boundary and surface might be weakly coupled with each other. For the Mg-doped sample with x  =  0.1, there are more S  =  1/2 spins creased in relative to x  =  0.0 because of a combined effect of lattice defects, Mg-doping and reduced size. In addition, the antiferromagnetic resonance of x  =  0.1 is also presented.

[Application and outlook of three-dimensional printing in prosthetic dentistry]

At present, three-dimensional (3D) printing has been applied in many aspects in the field of prosthodontics, such as dental models, wax patterns, guide plates, dental restoration and customized implants. The common forming principles include light curing, sintering and melting-condensation, the materials include pure wax, resin, metal and ceramics. However, the printing precision and the strength of multi-material integrated forming, remains to be improved. In addition, as a technology by which the internal structure of a material can be customized manufacturing, further advantage of 3D printing used in the manufacture of dental restoration lies in the customization functional bionic micro-structures, but the related research is still in its infancy. The review briefly summarizes the commonly used 3D printing crafts in prosthetic dentistry, and details clinical applications and evaluations, provides references for clinical decision and further research.

[Clinical Analysis of Surgery for Recurrent Cervical Cancer: A Review of 45 Cases]

Objective: To study the efficacy of surgery for recurrent cervical cancer and the influencing factors on prognosis. Methods: To retrospectively analyze the clinical data of 45 patients with recurrent cervical cancer undergoing surgical treatment in our hospital from January 1980 to October 2015, and study their clinical features and prognosis. Results: The Recurrence Free Interval (RFI) of these 45 patients was 3~120 months, and their median RFI was 15 months. Of the 45 cases, 21 recurred inside the radiotherapy field, including 18 with central recurrence and 3 with non-central recurrence; and 24 recurred outside the radiotherapy field, including 16 with pelvic recurrence who did not receive radiotherapy and 8 with distant recurrence. The overall survival time after recurrence of these 45 cases was (39.1±1.0) months, and their 2-year and 5-year survival rates were 55.6% and 22.2%, respectively. The univariate analysis showed that clinical stage, RFI, recurrent site, and initial treatment method affected the survival rate of the patients with recurrent cervical cancer (P<0.05), while the multivariate analysis revealed that recurrent site was an independent prognostic factor for recurrent cervical cancer (P=0.047). Conclusions: Appropriate surgery should be chosen for recurrent cervical cancer according to initial treatment and recurrent site. For patients with central recurrence inside their radiotherapy field, surgery is an effective treatment. Surgery is also suitable for patients without previous radiotherapy and with isolated recurrence, and adjuvant radiotherapy and chemotherapy can improve their survival.

[Effect of low-level laser irradiation on proliferation and osteogenic differentiation of human adipose-derived stromal cells]

OBJECTIVE

To examine the in vitro effects of low-level laser irradiation (LLLI) on proliferation and differentiation of human adipose-derived stromal cells (hASCs).

METHODS

Cultured cells were exposed to different doses of LLLI with a semiconductor diode laser (980 nm; 100 mW-12 W power output). The effects of laser on proliferation were assessed daily up to seven days of culture in cells irradiated for four consecutive days with laser doses of 2, 4, 6 or 8 J/cm², the cells without irradiation were used as controls. Half of the cells were changed to osteogenic medium (OM) when they had grown to 70% confluence. The hASCs both with and without osteogenic supplements were divided into three groups, and each group was irradiated at doses of 0, 2 and 4 J/cm². In order to examine the in vitro effects of LLLI on osteogenic differentiation of hASCs, the alkaline phosphatase activity was assessed on day 7, and alizarin red staining (AR-S) and quantitative detection were assessed on days 14 and 21. The expression of osteoblast master genes (ALP and Runx2) were tested on days 7 and 14.

RESULTS

The proliferation medium(PM)+LLLI4 J/cm² group had the highest multiplication rate. In the groups with osteogenic supplements, LLLI increased alkaline phosphatase activity and mineralized nodule formation, and stimulated the expression of ALP and Runx2. Furthermore, the effect became more obvious at high dose.

CONCLUSION

Our data demonstrated that hASCs proliferation and osteogenic differentiation were enhanced by LLLI. With the increase of laser dose, the effect of LLLI would be enhanced at first, and then be decreased after reaching a peak.

Accurate wavelength calibration method for compact CCD spectrometer

Wavelength calibration is an important step in charge-coupled device (CCD) spectrometers. In this paper, an accurate calibration method is proposed. A model of a line profile spectrum is built at the beginning, followed by noise reduction, bandwidth correction, and automatic peak-seeking treatment. Experimental tests are conducted on the USB4000 spectrometer with a mercury-argon calibration light source. Compared with the traditional method, the results show that this wavelength calibration procedure obtains higher accuracy and the deviations are within 0.1 nm.

[Evaluation of production and clinical working time of computer-aided design/computer-aided manufacturing (CAD/CAM) custom trays for complete denture]

OBJECTIVE

To compare the technician fabrication time and clinical working time of custom trays fabricated using two different methods, the three-dimensional printing custom trays and the conventional custom trays, and to prove the feasibility of the computer-aided design/computer-aided manufacturing (CAD/CAM) custom trays in clinical use from the perspective of clinical time cost.

METHODS

Twenty edentulous patients were recruited into this study, which was prospective, single blind, randomized self-control clinical trials. Two custom trays were fabricated for each participant. One of the custom trays was fabricated using functional suitable denture (FSD) system through CAD/CAM process, and the other was manually fabricated using conventional methods. Then the final impressions were taken using both the custom trays, followed by utilizing the final impression to fabricate complete dentures respectively. The technician production time of the custom trays and the clinical working time of taking the final impression was recorded.

RESULTS

The average time spent on fabricating the three-dimensional printing custom trays using FSD system and fabricating the conventional custom trays manually were (28.6±2.9) min and (31.1±5.7) min, respectively. The average time spent on making the final impression with the three-dimensional printing custom trays using FSD system and the conventional custom trays fabricated manually were (23.4±11.5) min and (25.4±13.0) min, respectively. There was significant difference in the technician fabrication time and the clinical working time between the three-dimensional printing custom trays using FSD system and the conventional custom trays fabricated manually (P<0.05).

CONCLUSION

The average time spent on fabricating three-dimensional printing custom trays using FSD system and making the final impression with the trays are less than those of the conventional custom trays fabricated manually, which reveals that the FSD three-dimensional printing custom trays is less time-consuming both in the clinical and laboratory process than the conventional custom trays. In addition, when we manufacture custom trays by three-dimensional printing method, there is no need to pour preliminary cast after taking the primary impression, therefore, it can save the impression material and model material. As to completing denture restoration, manufacturing custom trays using FSD system is worth being popularized.

[Progress in research and application of the edentulous custom trays]

Well designed and fabricated custom tray is the precondition to acquire qualified edentulous impression and key to successful complete denture. It has shown that primary impression without custom trays is hard to meet clinical requirements for successful restoration of complete denture. According to the fabrication techniques, edentulous custom tray can be classified into several types such as: compound trimming technique, handcrafted technique with polymerizing acrylic resin based on the study cast, and computer aided design and three dimensional printing(CAD & 3DP) technique based on the primary impression or study cast, etc. With regard to some special edentulous jaws, the custom tray and impression techniques such as open-window, frame cut, closed-mouth custom trays, and so on can be applied to acquire accurate impressions. All above technologies have their own characteristics and emphases. In clinic, appropriate custom trays should be selected according to residual ridge condition, oral status, and other clinical requirements of each edentulous patient.

[Computer aided design and 3-dimensional printing for the production of custom trays of maxillary edentulous jaws based on 3-dimensional scan of primary impression]

OBJECTIVE

To establish a digital method for production of custom trays for edentulous jaws using fused deposition modeling (FDM) based on three-dimensional (3D) scans of primary jaw impressions, and to quantitatively evaluate the accuracy.

METHODS

A red modeling compound was used to make a primary impression of a standard maxillary edentulous plaster model. The plaster model data and the primary impression tissue surface data were obtained using a 3D scanner. In the Gemomagic 2012 software, several commands were used, such as interactive drawing curves, partial filling holes, local offset, bodily offset, bodily shell, to imitate clinical procedures of drawing tray boundary, filling undercut, buffer, and generating the tray body. A standard shape of tray handle was designed and attached to the tray body and the data saved as stereolithography (STL) format. The data were imported into a computer system connected to a 3D FDM printing device, and the custom tray for the edentulous jaw model was printed layer upon layer at 0.2 mm/layer, using polylactic acid (PLA) filament, the tissue surface of the tray was then scanned with a 3D scanner. The registration functions of Geomagic 2012 was used to register the 3-dimentional surface data, and the point-cloud deviation analysis function of the Imageware 13.0 system was used to analyze the error. The CAD data of the custom tray was registered to the scan data, and the error between them was analyzed. The scanned plaster model surface was registered to the scanned impression surface and the scanned tray data to the CAD data, then the distance between the surface of plaster model and the scanned tissue surface of the custom tray was measured in Imageware 13.0.

RESULTS

The deviation between the computer aided design data and the scanned data of the custom tray was (0.17±0.20) mm, with (0.19±0.18) mm in the primary stress-bearing area, (0.17±0.22) mm in the secondary stress-bearing area, (0.30±0.29) mm in the border seal area, (0.08±0.06) mm in the buffer area; the space between the tissue faces of the plaster model and the scanned tissue surface of custom tray was (1.98±0.40) mm, with (1.85±0.24) mm in the primary stress-bearing area, (1.86±0.26) mm in the secondary stress-bearing area, (1.77±0.36) mm in the border seal area, (2.90±0.26) mm in the buffer area.

CONCLUSION

With 3D scanning, computer aided design and FDM technology, an efficient means of custom tray production was established.

[Quantitative evaluation of fabricating complete denture by computer numerical control in manufacturing dentition and baseplate separately plus adhesive molding]

OBJECTIVE

To quantitatively evaluate the assembly precision of fabricating complete denture by computer numerical control (CNC) in manufacturing dentition and baseplate separately plus adhesive molding.

METHODS

The 3D surface data of a standard edentulous maxilla plaster cast model and the temporary base-plate were obtained using an Activity 880 3D scanner. The data (data1) of a complete denture were designed using a set of computer aided design (CAD) software developed by the research group of this study. The pins without undercut were designed as 3D shape of the joining area of the dentition and the baseplate by using the software of Imageware 13.2 and Geomagic Studio 2013. Zero in the top and 0.05 mm in the rest surfaces of the retention pins were set for adhesive clearance. Zenotec T1 (5-axis milling machine) was employed to manufacture polymethyl methacrylate (PMMA) dentition and baseplate. Double sides posterior and one anterior "union teeth" were got. The teeth were inserted into the retention pins in the baseplate and cemented with self-curing resin (Huge Dental Material Co., Ltd). The denture was scanned with the 3D scanner to obtain dataset Data4. Data2 and Data3 registration was set in Data4, Data2 and Data3 were united to gain Data 5. The adhesive clearance on the top of the retentional pins was measured, which was originally designed into 0 mm, and the assembly precision of dentition and baseplate obtained.

RESULTS

The average clearance measurements between the dentition and the baseplate: left molar teeth (0.44±0.04) mm, max 0.52 mm, min 0.29 mm; right molar teeth (0.52±0.07) mm, max 0.64 mm, min 0.28 mm; anterior teeth (0.60±0.10) mm, max 0.81 mm, min 0.40 mm; total average clearance (0.52±0.10) mm.

CONCLUSION

The adhesive clearance can be controlled to the level of 0.5 mm when the joining part of the artificial teeth and the base was designed into the shape of retentional pins and the artificial dentition divided into 3 parts. We succeeded in using the CAD/ computer aided manufacturing (CAM) technology to fabricate the complete denture. Although the assembly precision of the dentition and the baseplate is not perfect, the results have proved that the technical routes are workable.