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Comparative study on the accuracy of implant-borne single restoration by two production processes with Ti-base CAO Wei-yu, CAO Jie, LIU Bin-yi, XU Zhou, LU Wei-qing Shanghai Journal of Stomatology    2022, 31 (4): 414-417.   DOI: 10.19439/j.sjos.2022.04.015 Abstract （903）      PDF （606KB）（279）       Knowledge map    PURPOSE: To study on the accuracy of implant-borne single restoration by two production processes with Ti-base to provide experimental data for proper processes of single implant-borne restoration. METHODS: Thirty patients were selected with single posterior teeth missing from the Department of Oral Implantology of Shanghai Putuo District Eye Disease and Dental Disease Prevention and Treatment Institute. The patients were taken 2 traditional impressions clinically for two plaster model equipped with implant analogue. These models were then divided into 2 groups according to different production processes. The experimental group was scanned with the scan body installed in the model implant analogue, while the control group was scanned directly on the Ti-base abutment installed in the model implant analogue. The implant-borne single restorations of the two groups were cut along the buccal-lingual side and the distance between the measuring point to the Ti-Base abutment was observed by electron microscopy. In addition, the breaking limit of zirconia crown was observed, universal test machine was used to load direct force to the crown. SPSS 22.0 software package was used for data analysis. RESULTS: The gap between the implant-borne single restoration to the Ti-base abutment of the experimental group was significantly smaller than that of the control group. The difference between the two groups was statistically significant (P<0.05). However, by testing the breaking limit of zirconia crown, there was no significant difference(P>0.05). CONCLUSIONS: Using scan body to transfer the implant position and Ti-base abutment data information to the digital dental design software is more accurate and reliable than directly scanning the Ti-base on the model analogue. Using scan body is recommended for processing and manufacture of implant-borne singe restoration. Reference | Related Articles | Metrics

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Effect of zoledronic acid on mandibular socket healing process of mice at an early stage JIANG Run-yang, KANG Fei-wu Shanghai Journal of Stomatology    2022, 31 (4): 349-353.   DOI: 10.19439/j.sjos.2022.04.003 Abstract （842）      PDF （3074KB）（233）       Knowledge map    PURPOSE: To investigate how bisphosphonates affect early process of socket healing in mice model. METHODS: Eighteen 8-9 weeks C57BL/6 male mice were randomly divided into control and experimental group. Bisphosphonate-related osteonecrosis of the jaw（BRONJ）model was conducted by intraperitoneal injection of zoledronate（ZOL） and extraction of lower left first molar in mice. Three, five, seven day after surgery, the mice were sacrificed and paraffin-embedded slides were made. H-E staining was used to evaluate the gross condition. The distribution and amounts of osteoclasts were measured by TRAP staining. Finally, immunochemical staining was used to detect RUNX2 and CTSK level. All experiments were duplicated thrice, ImageJ was used for transformation of pictures and SPSS 20.0 software package was used for statistical analysis. RESULTS: In comparison with the control group, early process of socket healing in the experimental group was generally delayed. RUNX2,CTSK,TRAP expression level was decreased. On the whole, early bone remodeling process in ZOL injection group was suppressed. CONCLUSIONS: Zoledronic acid inhibited the migration of fibroblasts into socket, and reduced the expression of Runx2, hindering new bone formation. It also can reduce the expression of TRAP 3,5,7 days after tooth extraction and CTSK expression three days after operation, thus inhibiting the bone resorption function of osteoclasts. Reference | Related Articles | Metrics

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Imaging characteristic of Stafne bone cavity：a retrospective study based on cone-beam CT HUANG Jin-cheng, ZHAO Hua-qiang, LI Guo-ju Shanghai Journal of Stomatology    2022, 31 (4): 439-444.   DOI: 10.19439/j.sjos.2022.04.020 Abstract （702）      PDF （1500KB）（325）       Knowledge map    PURPOSE: To guide clinical decision-making more efficiently via collecting and analyzing the imaging data of patients with Stafne bone cavity(SBC). METHODS: Six patients with SBC were retrospectively reviewed in Stomatological Hospital of Shandong University. By assessing cone-beam CT (CBCT) data, age, sex, complaint, cavity location, diameter at three dimension, maximal cross-sectional area of multi-planar reconstruction planes, content gray scale, morphological classification and its relationship with mandibular canal were recorded respectively. RESULTS: A total of 6 cases were inadvertently found on CBCT, with no symptoms. The locations of SBC were between mandibular molar region and mandibular angle, inferior border of mandible and mandibular canal, mostly at lingual side. Three were on the left and three were on the right. The bone cavity was elliptic and its long axis was consistent with the long axis of the mandible, with an average long axis diameter of (16.43±4.54) mm, horizontal axis diameter of (6.91±1.48) mm, vertical axis diameter of (10.24±2.10) mm. According to the multi-planar reconstruction planes readings, the maximal cross-sectional area of the bone cavity was (91.93±25.52) mm2, the maximal coronal area was (57.26±23.23) mm2, and the maximal sagittal area was (127.80±51.22) mm2. In view of the classification in the relationship between SBC marginal line and buccal cortical bone, there were 2 cases of type I cavity, 3 cases of type II cavity and 1 case of type III cavity. The connection between the bone cavity and the surrounding anatomical structure was classified into 3 conditions: covering penetration, adjacency and separation on the basis of the relative position between the cavity boundary with the mandibular inferior margin and the mandibular canal in sagittal plane. In addition, the content type could be primarily identified depending on estimation of corrected grey scale in the center of bone cavity. CONCLUSIONS: CBCT can make an intuitive and clear diagnosis of Stafne bone cavity, which brings great significance into the early clinical decision-making, thus not only avoiding unnecessary surgery, reducing the waste of additional medical resources, but also decreasing the physical and mental trauma of patients. Reference | Related Articles | Metrics

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Clinical efficacy of the combination of miniscrew with clear aligner in controlling the roller coaster effect MA Xiao-qing, XIANG Fei, FAN Ming-yue, SONG Yi, WANG Xiao-hui, ZHANG Ling, QIAN Wen-hao Shanghai Journal of Stomatology    2022, 31 (2): 193-197.   DOI: 10.19439/j.sjos.2022.02.015 Abstract （652）      PDF （1173KB）（597）       Knowledge map    PURPOSE: To investigate the clinical efficacy of miniscrew in controlling the roller coaster effect in long-distance space closure with clear aligner. METHODS: Sixteen adult patients with bimaxillary protrusion were selected. All cases were treated with clear aligner and their four first premolars were extracted. G6 was designed in all cases. In the experimental group, four miniscrews were inserted at the beginning of treatment to control the teeth in three dimensions; while in the control group, the miniscrews were not applied until obvious roller coaster effect appeared. Paired t test was used to analyze the data with Graphpad Prism 6.0 software package. RESULTS: All the extraction space was closed successfully and the lateral profile was improved significantly. The torque of the upper incisor was under well control and no roller coaster effect happened in the experimental group; while in the control group, the lingual inclination of the upper incisors and open bite of the posterior teeth developed(P<0.05). After the miniscrews intrusion of the upper anterior teeth, the occlusion relationship improved significantly. CONCLUSIONS: Miniscrews effectively prevents and eliminates the roller coaster effect in the process of long-distance space closure with clear aligner. Reference | Related Articles | Metrics

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Effect of three mixing methods on air bubbles and solidification state of alginate impression materials ZHOU Yi-an, XIAO Song, XIE Xue-mei, WANG Yu-hua Shanghai Journal of Stomatology    2023, 32 (1): 12-16.   DOI: 10.19439/j.sjos.2023.01.003 Abstract （598）      PDF （658KB）（209）       Knowledge map    PURPOSE: To evaluate the effect of full-automatic mixing machine method, clockwise manual mixing and combined eight-shaped manual mixing on air bubble content, flowability, temperature, working time and setting time of alginate impression materials. METHODS: With the same condition, alginate impression materials were mixed by three different methods. The number of bubbles, area, flowability, temperature, working time and setting time were evaluated with SPSS 24.0 software package. RESULTS: The number of bubbles in the automatic mixing group was (2.30±2.50), and the area was (0.17±0.18) mm2, which was less than the number of clockwise manual mixing group (59.60±14.19), and the total area (7.41±2.24) mm2 (P<0.01). The flowability of the clockwise manual mixing group [(39.52±0.85) mm] was less than that of the full-automatic mixing group [(50.78±0.90) mm] and the combined eight-character manual mixing group [(50.36±1.75) mm](P<0.01).The setting time of the material mixed by three methods was eligible for clinical use. CONCLUSIONS: The mixing method of alginate impression material has an effect on material's bubble content, flowability and temperature changes. The impression materials mixed by full-automatic mixing method are better in terms of bubble content, flowability and other properties. If manual mixing is used, combined eight-shaped manual mixing method can help reduce impression bubbles and deformation, and improve flowability. Reference | Related Articles | Metrics

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Comparative study on the effect of microscopic revascularization and apexification in the treatment of pulp necrosis of permanent teeth LIN Xiao-ming, SU Jiang-ling, PU Cui-ping Shanghai Journal of Stomatology    2022, 31 (3): 318-321.   DOI: 10.19439/j.sjos.2022.03.019 Abstract （578）      PDF （564KB）（305）       Knowledge map    PURPOSE: To compare the curative effect of microscopic revascularization and apexification in the treatment of pulp necrosis of permanent teeth. METHODS: Seventy-five cases of pulp necrosis in young permanent teeth were divided into two groups according to different treatment methods. Group A (n=30) underwent revascularization under microscope, while group B (n=45) underwent apexification. The treatment effect and pain improvement of the two groups were compared. The changes of the wall thickness and root canal length of the affected teeth before and after treatment were observed, and the bone-like deposition rate after treatment was recorded. SPSS 23.0 software package was used for statistical analysis. RESULTS: There was no significant difference in the length of root canal between the two groups before treatment (P>0.05); there was no significant difference in the length of root canal in group B before and after treatment (P>0.05); the length of root canal in group A was significantly longer than that in group B 6 months after treatment(P<0.05). There was no significant change in the thickness of root canal wall in group B before and after treatment (P>0.05). The thickness of root canal in group A was significantly higher than that in group A 6 months after treatment (P<0.05). Bone-like deposition rate of group A was significantly higher than that of group B 1 month and 6 months after treatment (P<0.05). The total effective rate of group A and B was 90.00% and 84.44%, the difference was not statistically significant (P>0.05). The cure rate of group A was 70.00%, which was significantly higher than that of group B (48.89%, P<0.05). COCLUSIONS: Microscopic revascularization for pulp necrosis of young permanent teeth can effectively promote root development, lengthen root canal and increase the thickness of canal wall, which is better than apexification. Reference | Related Articles | Metrics

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MRI findings of parotid acinic cell carcinoma in 19 consecutive cases XIAO Hua, TAO Xiao-feng, ZHU Wen-jing, CHEN Qian-qian Shanghai Journal of Stomatology    2022, 31 (3): 322-326.   DOI: 10.19439/j.sjos.2022.03.020 Abstract （514）      PDF （1403KB）（216）       Knowledge map    PURPOSE: To describe the MRI features of acinar cell carcinoma of parotid gland (AciCC) and to evaluate the diagnostic value of MR functional imaging. METHODS: A total of 269 cases of maxillofacial AciCC confirmed by surgery and pathology were analyzed. Among them, nineteen subjects with AciCC in the parotid gland underwent preoperative MRI examination (non-enhanced scan for one case, enhanced scan for 18 cases), seventeen patients underwent diffusion-weighted imaging scan, and 15 patients underwent dynamic contrast-enhanced scan. MRI findings of 19 patients were retrospectively analyzed. The lesion size, location, morphology, margin, internal composition, enhancement pattern and functional imaging characteristics were analyzed. SPSS 25.0 software package was used for statistical analysis. RESULTS: Among 269 cases of maxillofacial AciCC, there were 108 males and 161 females, male: female = 1:1.49, aged from 4 to 89 years, with a mean age of (45.95±17.33) years. 84.4% (227/269) were located in the parotid gland. On MRI images, 78.9% (15/19) had well-defined margin, 57.9% (11/19) were round or oval, and 36.8% (7/19) were lobed nodules. One case had irregular morphology and peripheral invasion. The range of maximum diameter was 6-56 mm, averaging (24.8±15.3) mm. Internal composition showed 57.9% (11/19) were cystic solid, 42.1% (8/19) were solid, 31.6% (6/19) had bleeding. T2-weighted MRI showed 52.6% (10/19) with envelope structure, 15.8% (3/19) with low signal separation inside, 38.9%(7/18) had uniform enhancement, and 61.1%(11/18) had uneven enhancement. Functional imaging showed the mean ADC value of tumor was (1.026±0.194)×10-3 mm2/s(n=17). 86.7%(13/15) TIC was type Ⅱ. CONCLUSIONS: Most maxillofacial AciCC are located in the parotid gland. It is difficult to distinguish AciCC from benign tumors with conventional MRI in morphology. The ADC value of AciCC is lower than that of benign tumors, and the type of TIC curve is mostly type Ⅱ. Combination of morphology and functional imaging can improve the diagnostic accuracy of this disease. Reference | Related Articles | Metrics

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Effect of different adduction methods of maxillary incisor in adolescents on the shape of alveolar bone XIE Qin, LIN Shan, LIN Li, LI Duo Shanghai Journal of Stomatology    2022, 31 (3): 290-294.   DOI: 10.19439/j.sjos.2022.03.013 Abstract （507）      PDF （595KB）（252）       Knowledge map    PURPOSE: To explore the influence of different adduction methods of maxillary incisor in adolescents on the shape of alveolar bone. METHODS: Three hundred and twenty-eight maxillary incisors were collected from 82 patients with jaw protrusion deformity treated in Union Hospital of Fujian Medical University from June 2018 to June 2019. 135 incisors were included in the oblique adduction group, and 193 incisors were included in the root control adduction group. All patients took cone-beam CT(CBCT) to measure the adduction of the maxillary incisor and the changes in alveolar bone height, thickness, and bone density. Statistical analysis was performed with SPSS 18.0 software package. RESULTS: The length of the maxillary incisor to the mid-palatine vertical surface(IE-MP), the long axis of the maxillary incisor and the posterior inferior angle of the palatal plane (LAI-PP) in oblique adduction group were significantly greater than root control adduction group(P<0.05). The length of the maxillary incisor from the apex of the maxillary incisor to the mid-palatine vertical surface(RA-MP) in the oblique adduction group was significantly smaller than the root control adduction group (P<0.05). Postoperative L1, L2, L3, P1, T1 of the oblique adduction group were significantly lower than preoperative values(P<0.05), and postoperative P2, P3, T2, and T3 were significantly higher than preoperative value(P<0.05). Postoperative L1, L2, and L3 of the root control adduction group were significantly higher than those before operation (P<0.05), and postoperative P1, P2, P3, T1, T2, and T3 were significantly lower than those before operation(P<0.05). The changes of L2, L3, P3, T3 of the oblique adduction group were significantly higher than the control root adduction group(P<0.05), and the changes of L1, P1, P2, T1, T2 of the oblique adduction group were all significantly lower than the control root adduction group(P<0.05). There was no significant difference in bone mineral density of the upper and lower jaws between the two groups before and 6 months after operation(P>0.05). CONCLUSIONS: When adolescents' maxillary incisors are retracted in a wide range, the labial apical area, the palatal alveolar ridge area of the oblique adduction group, and the palatal root neck of the root control adduction group are all high-risk areas for alveolar bone resorption. Reference | Related Articles | Metrics

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Effects of two implant systems on peri-implant soft tissue CAO Wei-yu, CAO Jie, LIU Bin-yi, XU Zhou Shanghai Journal of Stomatology    2022, 31 (3): 305-308.   DOI: 10.19439/j.sjos.2022.03.016 Abstract （484）      PDF （535KB）（182）       Knowledge map    PURPOSE: To investigate the effect of different implant systems on peri-implant soft tissue. METHODS: Forty patients requiring single implant therapy in posterior teeth at Dental and Ophthalmic Clinic of Putuo District from December 2020 to February 2021 were selected. Ten patients were implanted with bone level implants and 30 patients with soft tissue level implants. Periodontal exploration was performed at the buccal side, lingual side, mesial and distal axial angle of the implants, and the gingival crevicular fluid of these locations were taken to detect the enzyme level. The probing depth, aspartate aminotransferase (AST) and alkaline phosphatase (ALP) level of the two groups were compared at the day, 3 months, 6 months and 12 months after crown restoration. Statistical analysis was completed by SPSS 17.0 software package. RESULTS: The probing depth and ALP level of soft tissue level implants were significantly lower than those of bone level implants at the day, 3 months, 6 months and 12 months after crown restoration(P<0.05). At the day when crown restoration was accomplished, AST of soft tissue implant was significantly lower than that of bone level implant(P<0.05). AST in gingival crevicular fluid of bone level implants decreased rapidly in the following three time periods, and close to that of the soft tissue level implants(P>0.05) at last. CONCLUSIONS: Both bone level implants and soft tissue level implants have good clinical effects, but peri-implant soft tissues of the soft tissue level implants show better stability. Reference | Related Articles | Metrics

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Study of the mandibular changes after treatment of Class Ⅱ division 2 malocclusion in adolescents ZHOU Ming-zhi, WANG Lin, WANG Liang, WU Ke, QIN Yan-jun, ZHAO Chun-yang Shanghai Journal of Stomatology    2022, 31 (4): 389-394.   DOI: 10.19439/j.sjos.2022.04.010 Abstract （464）      PDF （886KB）（294）       Knowledge map    PURPOSE: To evaluate the mandibular and dentoalveolar changes in Class Ⅱ division 2 malocclusion adolescents after treatment. METHODS: Thirty-six patients treated in our hospital were selected. Twelve skeletal Class Ⅱ division 2 adolescents were served as the experimental group, while 12 skeletal Class Ⅱ division 2 adults were selected as the control group 1, 12 skeletal Class Ⅰ adolescents were selected from those who have undergone fixed orthodontic treatment as the control group 2. Cone-beam CT (CBCT) was taken before and after treatment. The lateral cephalometric radiographs generated from CBCT data were committed to explore the changes of the mandible and dentoalveolar bone before and after orthodontic treatment among three groups. Statistic analysis was completed by SPSS 21.0 software package. RESULTS: After orthodontic treatment, the mandibular length (Go-Gn), mandibular ramus height (Co-Go), mandibular protrusion (SNB), mandibular dentoalveolus protrusion (SNId), lower facial height (S-Go, ANS-Me, ANS-Me/N-Me) increased and the fossa of chin decreased significantly in Class Ⅱ division 2 adolescents (P<0.05). The differences of SNB, SNId, ANS-Me/N-Me between Class Ⅱ division 2 and Class Ⅰ adolescents decreased. CONCLUSIONS: The growth potential of the mandible is released after treatment of Class Ⅱ division 2 malocclusion adolescents, promoting mandibular growth and reconstruction. Reference | Related Articles | Metrics

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Short-term efficacy of three root canal filling methods in endodontic treatment of chronic periapical inflammation GUO Jing-jing, TANG Yi-qun, HE Hong, XU Zhen Shanghai Journal of Stomatology    2022, 31 (5): 544-549.   DOI: 10.19439/j.sjos.2022.05.018 Abstract （452）      PDF （684KB）（362）       Knowledge map    PURPOSE: To provide a reference basis for clinical selection of a reasonable and effective root canal treatment by comparing the short-term clinical efficacy of three root canal filling methods in the treatment of chronic periapical inflammation. METHODS: One hundred and twenty patients with chronic periapical inflammation who received root canal filling between October 2019 and October 2020 were randomly divided into 3 groups, with 40 patients in each group. All patients received root canal filling, group A was filled with iRoot SP paste by matched-taper single cone obturation technique, group B was filled with AH-plus paste by warm vertical condensation, and group C filled with AH-plus paste by cold lateral condensation. Root canal filling time in the three groups was calculated, pain score 24 h after treatment was determined using visual analogue scale/score(VAS), and periapical index(PAI) was used to evaluate radiographs. SPSS 22.0 statistical software was applied for data analysis. RESULTS： Root canal filling times in the three groups were (75.50±7.44) s in group A, (85.38±3.46) s in group B and (102.33±3.32) s in group C, the differences were statistically significant (P<0.05); the incidence of postoperative pain in the three groups was 25% in group A, 25% in group B and 32.5% in group C, the difference was not statistically significant(P>0.05). There was no significant difference between group A and group B, but significant difference existed between group A, group B and group C. The results of comparison of PAI scores showed a time effect was F=498.93, P<0.001, suggesting significant difference in total PAI scores at different time points; a group effect was F=0.91, P=0.406, suggesting no significant difference in total PAI scores of the 3 groups; an interaction effect of time and group was F=0.44, P=0.777, suggesting that there was no significant difference in total PAI scores of the 3 groups at the time points. The total effective rate at 3 and 12 months was 97.5%, 97.3% in group A, 97.5%, 97.2% in group B and 90%, 91.9% in group C, the difference was not statistically significant(P>0.05). CONCLUSIONS: Compared with the other 2 root canal filling methods, the iROOT SP paste matched-taper single cone obturation technique is clinically effective in terms of time saving and increasing the comfort of the patients' visit. Reference | Related Articles | Metrics

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Research on the pathogeny of black tooth stain and association between black tooth stain and primary dentition caries in children MIAO Fen, MA Hao-ran, LIU Zi-han Shanghai Journal of Stomatology    2022, 31 (3): 282-285.   DOI: 10.19439/j.sjos.2022.03.011 Abstract （451）      PDF （544KB）（297）       Knowledge map    PURPOSE: To investigate the related factors of black tooth stain in primary teeth of 3~5 years old children and caries status of primary dentition in these children. METHODS: From December 2019 to August 2020, 182 3~5 years old children with black tooth stain and 200 children without pigmentation were investigated by oral examination and questionnaire survey to their guardians, while caries status , distribution range of the pigment, factors associated with black tooth stain were evaluated. SPSS 20.0 software package was used for data analysis. RESULTS: Children with black tooth stain had fewer dental caries. The lingual surfaces of the mandibular anterior teeth were the most affected sites. Factors associated with black tooth stain were foods with soy sauce and brushing teeth with parents' help. CONCLUSIONS: There is a negative correlation between the occurrence of primary dentition caries and blacktooth stain, but there is no significant correlation between formation of black tooth stain and most environmental factors. Reference | Related Articles | Metrics

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Segmentation, accuracy validation of mandibular molar, pulp cavity on cone-beam CT images by U-net neural network LIN Xiang, FU Yu-jie, REN Gen-qiang, WEN Jia-huan, CHEN Yu-fei, ZHANG Qi Shanghai Journal of Stomatology    2022, 31 (5): 454-459.   DOI: 10.19439/j.sjos.2022.05.002 Abstract （442）      PDF （912KB）（388）       Knowledge map    PURPOSE: To realize the automatic segmentation of mandibular molar and pulp cavity on cone-beam CT (CBCT) images by U-net convolutional neural network, and to use the 3D models reconstructed by Micro-CT data as the ground truth to validate its accuracy. METHODS: Twenty groups of small field of view(FOV) CBCT data containing complete mandibular molars were collected from the Department of Radiology, Affiliated Stomatology Hospital of Tongji University. After preprocessing, an endodontic specialist labeled teeth and pulp cavities by MITK Workbench software. These data were used as the training set for training U-net neural network. In addition, five mandibular molars and corresponding small FOV CBCT data were collected. These five CBCT were processed in the same way and used as the testing set. Then, teeth and pulp cavities on CBCT images of the testing set were segmented and reconstructed by U-net neural network and the same specialist. The isolated teeth were scanned by a Micro-CT machine after preprocessing and the results were reconstructed to 3D models, which were used as the ground truth. Then the 3D models reconstructed by the specialist’s labeling, U-net network segmentation results, and the ground truth in the testing set were compared. Dice similarity coefficient(DSC), average symmetric surface distance (ASSD), Hausdorff distance (HD), and morphological analysis were used to evaluate the results. SPSS 20.0 software package was used for statistical analysis. RESULTS: Compared with the ground truth, the segmentation accuracy of the U-net neural network measured by DSC, ASSD, and AHD was (95.30±1.01)%, (0.11±0.02) mm, and (1.05±0.31) mm in teeth and (81.21±2.27)%, (0.15±0.05) mm, and (3.29±1.85) mm in the pulp cavity, respectively. Morphological analysis results showed that the U-net network segmentation results were similar to the ground truth in tooth and pulp chamber. As for the segmentation results of root canals, only thick root canals could be segmented rather than the thin root canals, such as the canals in the apical third and lateral root canals. CONCLUSIONS: Under the experimental conditions, the U-net neural network trained by the specialist’s labeling realized the automatic and accurate segmentation of mandibular molar and their pulp chamber on CBCT images. For the segmentation of root canals, the results need to be further improved. Reference | Related Articles | Metrics

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Influence of bilateral coronoidectomy on temporomandibular joint stress distribution after costochondral graft reconstruction: a finite element analysis MAO Yi, CHEN Xu-zhuo, QIN Hai-yi, ZHEN Jin-ze, QIU Ya-ting, HUO Liang, ZHANG Shan-yong Shanghai Journal of Stomatology    2022, 31 (2): 126-131.   DOI: 10.19439/j.sjos.2022.02.003 Abstract （426）      PDF （1861KB）（194）       Knowledge map    PURPOSE: To explore the effect of bilateral coronoidectomy on stress distribution after reconstruction of temporomandibular joint (TMJ) by costochondral graft. METHODS: Ten groups of models were established to simulate costochondral graft reconstruction with simultaneously different distances (0, 2, 4, 6, 8 mm) of mandibular advancement, with or without coronoidectomy. Force and stress distribution in the rib-cartilage area were analyzed by finite element analysis. RESULTS: In the process of bilateral joint reconstruction with simultaneously mandible advancement ranging from 0 mm to 8 mm, when the coronoid processes were retained, the forward deformation of the cartilage occurred and the shear force decreased in turn, from 113.2 N to 26.7 N on the left side and from 133.7 N to 1.9 N on the right side. When the coronoid processes were removed, the cartilage deformed backward and the shear force increased successively, from 94.6 N to 188.5 N on the left and 70.1 N to 157.7 N on the right. The stress in the neck was obviously concentrated when mandible advanced 8 mm. CONCLUSIONS: Coronoidectomy has an important impact on stress distribution in the TMJ area, and keeping the coronoid process is beneficial to maintain the mechanical balance. Bilateral CCG reconstruction with coronoidectomy for lengthy mandible advancement (≥ 8 mm) may lead to prominent increase in shear force beyond CCG resistance, resulting in a costal-cartilage junction fracture. Reference | Related Articles | Metrics

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A reflectional insight into orthodontic theoretical renovation and technological innovation SHEN Gang Shanghai Journal of Stomatology    2023, 32 (2): 113-119.   DOI: 10.19439/j.sjos.2023.02.001 Abstract （415）      PDF （867KB）（373）       Knowledge map    Orthodontics, among other specialties in dentistry, remains most dynamic and vigorous in upgrading and reforming its fundamental doctrines and clinical technologies. Orthodontic specialty in China has played a leading role in recent years in reshaping fundamental theories and in creating cutting-edge therapeutic modalities. The newly developed diagnostic classification system, a complementary addition to that of Angle's, not only defines the natures, but also identifies the developmental mechanisms of malocclusions. Orthopedic therapy aiming to relocate the mandible before correcting the dentition is emerging as an indispensable treatment mode to malocclusions concurring with mandibular deviation. Whilst correlations exist between malocclusion and TMD susceptibility and incidence, the specifically designed orthopedic and orthodontic approaches have proven effective in managing cases inflicted by TMD conditions. Innovative efforts that create the GS products, have redefined the clear appliances much more beyond merely clear aligners, thus further pushing the boundaries of both the indications and clinical use for clear appliances. Reference | Related Articles | Metrics

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Effect of collagen sponge on the healing process of alveolar fossa after tooth extraction in rats LI Jun-fu, ZHU Jia, JIANG Juan, WANG Xu-xia, CHEN Dai-yun, ZHAO Zuo-qin Shanghai Journal of Stomatology    2023, 32 (3): 241-245.   DOI: 10.19439/j.sjos.2023.03.004 Abstract （414）      PDF （759KB）（209）       Knowledge map    PURPOSE: To investigate the effect of collagen sponge on early bone healing process of alveolar fossa after tooth extraction in rats. METHODS: A total of 16 healthy female SD rats were selected. Animal models with tooth extraction were established. The right alveolar fossa inserted with collagen sponge was as the experimental group, and the left alveolar fossa was as the control group with treatment. The rats were sacrificed 1, 2, 4 and 8 weeks after tooth extraction, and the osteogenesis of alveolar fossa was observed. Real-time quantitative PCR (qt-PCR) was used to detect the changes of osteogenesis related gene expression. SPSS 19.0 software package was used for statistical analysis. RESULTS: After surgery, alveolar cavity healing was significantly better in the experimental group than in the control group. Osterix, Runx2 and Vegf genes were expressed in the experimental group and the control group, and the expression levels of related genes in the experimental group were significantly higher than the control group 1, 2, 4 and 8 weeks after surgery(P<0.05). CONCLUSIONS: Collagen sponge could promote early alveolar bone healing, possibly related to the expression level of osteogenic genes regulated by collagen sponge. Reference | Related Articles | Metrics

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Evaluation of the effect of digital crown extension guide in aesthetic restoration of anterior teeth WANG Xue-chun, WANG Yong, XU Xiao-bo, HAO Xin-he Shanghai Journal of Stomatology    2022, 31 (3): 260-264.   DOI: 10.19439/j.sjos.2022.03.007 Abstract （414）      PDF （749KB）（496）       Knowledge map    PURPOSE: To evaluate the clinical effect of three-dimensional digital smile design (3D-DSD) combined with double positioning crown extension guide in aesthetic restoration of anterior teeth. METHODS: Twenty patients who needed aesthetic crown lengthening and full crown restoration of upper anterior teeth were selected and randomly divided into the experimental group and control group, with 10 cases in each group. The experimental group carried out 3D-DSD, after confirming the plan, 3D printed double positioning crown extension guides were used to guide aesthetic crown lengthening, and full crown was completed 3 months after operation. The control group used traditional aesthetic crown lengthening and full crown restoration. PES/WES evaluation was performed before operation, three months and six months after operation. Visual analogue scales(VAS) were used to evaluate patient satisfaction 6 and 7 months after surgery, and the repeatability evaluation of VAS was conducted. The correlation between PES/WES score and overall satisfaction was analyzed 6 months after operation. SPSS 23.0 software package was used for statistical analysis. RESULTS: The PES/WES scores of the two groups of patients at 3 months and 6 months after operation were higher than those before operation(P<0.05). The two groups showed that the scores of the experimental group were significantly higher than those of the control group for PES 3 months after operation, PES and WES 6 months after operation(P<0.05).Satisfaction survey results showed that the intra-group correlation coefficient of the two VAS results was 0.956(P<0.05),and crown length-to-width ratio, smile curve, personality characteristics, patient participation and overall satisfaction in the experimental group were better than those of the control group(P<0.05).The results of Speraman correlation analysis showed that PES and WES scores at 6 months after operation were positively correlated with overall satisfaction (rs1=0.905, P<0.001; rs2=0.460, P=0.041). CONCLUSIONS: 3D digital smile design combined with double positioning crown extension guide guides the anterior aesthetic crown lengthening and restoration treatment, which can improve the effect of pink and white aesthetics after treatment and patient satisfaction. Reference | Related Articles | Metrics

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Short-term and long-term effects of all-ceramic onlay on restoration of premolars and its influence on dental function XIAO Sha, GAO Cheng-zhi, ZHOU Dong-ping Shanghai Journal of Stomatology    2022, 31 (3): 300-304.   DOI: 10.19439/j.sjos.2022.03.015 Abstract （409）      PDF （597KB）（301）       Knowledge map    PURPOSE: To investigate the short-term and long-term effects of all-ceramic onlay on restoration of premolars and its influence on dental function. METHODS: Ninety-five premolars receiving root canal treatment in People's Hospital of Peking University from January 2017 to January 2018 were enrolled, and randomly divided into two groups based on different repairing methods. Patients in the control group (n=47) received full crown restoration, while patients in the experimental group(n=48) received all-ceramic onlay restoration. The success, survival and failure rates of the teeth were compared. The United States Public Health Service(USPHS) and occlusal function of the prosthesis were compared 6, 12 and 36 months after treatment. The data were processed using SPSS 19.0 software package. RESULTS: The success and survival rate of the experimental group were higher than those of the control group, but without significant difference (P>0.05). The morphology, marginal integrity, marginal coloration, surface texture, secondary caries, gingival health and proximal contacts showed no significant difference between the two groups 12 months after treatment(P>0.05). Thirty-six months after treatment, the marginal integrity, marginal coloration and surface texture showed no significant difference between the two groups (P>0.05), while the morphology, secondary caries, gingival health and proximal contacts were significantly better in the experimental group than in the control group (P<0.05). The occlusal function between the affected side and contralateral side of both groups showed no significant difference 6, 12 and 36 months after treatment(P>0.05). CONCLUSIONS: All-ceramic onlay restoration of premolars has high success and survival rate, and good short-term and long-term restoration effect, which is beneficial to improve the occlusal function of the affected teeth. Reference | Related Articles | Metrics

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Experimental study of the gap ossification in the double-barrel technique in rabbit tibia WANG Xiao-lin, SU Ming, LI De-long, HAN Zheng-xue Shanghai Journal of Stomatology    2022, 31 (5): 497-500.   DOI: 10.19439/j.sjos.2022.05.009 Abstract （408）      PDF （1099KB）（182）       Knowledge map    PURPOSE: Double-barrel vascularized fibula graft is one of the most common surgical techniques to augment or maintain the height of the neo-mandible. The purpose of this study was to investigate whether the gap completely disappeared and gap ossification ultimately achieved between the double barrels. METHODS: Six rabbits were used in the study. Each animal's tibia was vertically osteotomized at its midpoint, folded onto each other and fixed by mini-titanium plate, thus an animal model of “double barrel” was established. Specimens were obtained at 3 months and 6 months postoperatively, then the gap ossification between the double barrels was evaluated by radiography and histomorphology. Measurements of the gap width between the two tibial struts on X-ray films were performed 3 months after the operation at three sites: distal, middle and proximal site. Measurements were compared with those obtained immediately after operation using SPSS 19.0 software package. RESULTS: Three months after operation, radiography demonstrated that the gap between the double barrels gradually became vague. Histological study showed that irregular new woven bone formed in the gap between the two struts. There was significant difference in mean gap width at the distal and proximal site (P<0.05), but there was no significant difference at the middle site(P=0.552). Radiological and histological study showed cortical bone resorption in the contact area and two thin tubular bones fused into a thicker one 6 months postoperatively. CONCLUSIONS: The double-barrel tibia fixed with titanium microplate can fuse into a large, unique, continuous bone barrel. Reference | Related Articles | Metrics

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Evaluation of the effect of Er:YAG laser combined with guided bone regeneration in the treatment of peri-implantitis with osseous defects TU Hui-juan, LI Ling-yu, LI Yi-dan, LUO Zhen-lan, YU Ming Shanghai Journal of Stomatology    2022, 31 (4): 418-422.   DOI: 10.19439/j.sjos.2022.04.016 Abstract （407）      PDF （1217KB）（344）       Knowledge map    PURPOSE: To evaluate the clinical benefits of Er:YAG laser combined with guided bone regeneration (GBR) in the treatment of peri-implantitis-assocaited osseous defects. METHODS: Twenty-six patients (34 implants in total) who underwent implant restoration in Dental Disease Prevention and Treatment Institute, Jiading District, from 2017 to 2019 and were diagnosed with peri-implantitis with osseous defects, and randomly divided into the experimental group and control group. The two groups of patients received open flap surgery, debridement and GBR treatment. The only difference in the experimental group was the use of Er: YAG laser to modulate and remove inflammatory tissue as well as to decontaminate the implant surface, instead of traditional mechanical treatment in the control group. The probing depth (PD), bleeding on probing (BOP), and plaque index (PI), the height of the bone defect around the implant (reduce of marginal bone level, RBL) were recorded and compared. SPSS 20.0 software package was used to analyze the data. RESULTS: The PD, BOP, PI and RBL of the two groups of patients were significantly improved after treatment with different methods. There was no significant difference in the improvement of PD, BOP and PI between the two groups 6, 12 and 24 months after treatment, while the improvement of RBL in the experimental group was significantly better than that of the control group 12 and 24 months after treatment. CONCLUSIONS: In the treatment of GBR with peri-implantitis and osseous defects, Er: YAG laser therapy is more effective than traditional mechanical methods, and is more conducive to the regeneration of new bone. Reference | Related Articles | Metrics