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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 （234）      PDF （759KB）（125）       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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Effect of polishing method and time on the fitness of CAD/CAM zirconia ceramic crown ZHAO Chen, BAI Yue-hui, LIU Yang, JIANG Shan-shan, SHANG Qing-long, ZHAO Tian-tian, YUAN Shuo, LI Ning, JIAO Jian-ping Shanghai Journal of Stomatology    2023, 32 (3): 236-240.   DOI: 10.19439/j.sjos.2023.03.003 Abstract （229）      PDF （870KB）（113）       Knowledge map    PURPOSE: To compare the effect of different polishing methods and time treatment on the fitness of CAD/CAM zirconia ceramic crowns. METHODS: Sixteen intact maxillary premolars were randomly divided into two groups, group A was treated with silicon carbide burs, while group B was treated with tungsten steel burs. At different polishing time points of the same tooth, digital impressions of each group were obtained, which were used to manufacture CAD/CAM zirconium ceramic crowns. After trial fitting, the gap impressions were obtained by using silicone rubber replication method, and the marginal and internal discrepancies were assessed. The data were statistically analyzed with SPSS 21.0 software package. RESULTS: The difference between the gap values of the marginal and internal markers of group A and group B was not statistically significant(P>0.05). Compared with the no-polishing process, the differences of the marginal gap (39.67±8.35) μm and internal gap (45.18±7.16) μm of group A polished for 4 min, and the marginal gap (51.25±14.73) μm, and internal gap (48.56±6.45) μm of group B polished for 3 min, as well as the marginal gap (48.87±8.90) μm, and internal gap (45.99±7.12) μm of group B polished for 4 min, were all significant(P<0.05). CONCLUSIONS: CAD/CAM zirconia ceramic crowns treated with silicon carbide bur for polishing 4 min and tungsten steel for 3 min has the best fitness. Reference | Related Articles | Metrics

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Imaging findings of carcinoma ex pleomorphic adenoma in minor salivary glands ZHU Wen-Jing, YU Qiang, TAO Xiao-feng, WANG Shao-ying, TIAN Tao, ZHANG Chun-ye Shanghai Journal of Stomatology    2023, 32 (3): 255-260.   DOI: 10.19439/j.sjos.2023.03.007 Abstract （206）      PDF （1392KB）（112）       Knowledge map    PURPOSE: To summarize the CT and MR imaging features of carcinoma ex pleomorphic adenoma(Ca-ex-PA) in minor salivary gland, and analyze the correlation between various features and pathological classification. METHODS: Forty-three patients with Ca-ex-PA in minor salivary gland were collected. The CT and MRI findings were retrospectively analyzed and correlated with their pathological types. Fisher's exact test was used to analyze the correlation between various imaging features (tumor morphology, boundary, internal structure, bone invasion, cervical lymph node metastasis) and pathological types with SPSS 25.0 software package. RESULTS: Among the 43 patients with Ca-ex-PA, 83.7%(36/43) of the tumors were lobulated; 81.4%(35/43) showed cystic degeneration or necrosis, with heterogeneous enhancement. Coarse calcification or mixed calcification was found in 37.2%(16/43), 25.6%(11/43) had compressive absorption of adjacent bone. 75%(12/16) of type Ⅰ/Ⅱ tumors had regular morphology (round or oval), and 77.8%(21/27) of type Ⅲ tumors had irregular morphology, 93.8%(15/16) of type Ⅰ/Ⅱ tumors had well-defined margin and 66.7%(18/27) of type Ⅲ tumors had ill-defined margin. Osteolytic bone resorption occurred in 59.3%(16/27) of type Ⅲ tumors. The average maximum diameter of type Ⅰ/Ⅱ tumors was significantly shorter than that of type Ⅲ(P<0.05). Fisher's exact test showed the characteristics of tumor morphology, boundary and osteolytic bone resorption were related to pathological grouping(P<0.001). CONCLUSIONS: Most Ca-ex-PA in minor salivary glands is characterized by lobular and heterogeneous enhanced neoplasm on CT and MR imaging. A round or oval tumor with well-defined margin usually correlates with typeⅠ and Ⅱ, contrarily, an irregular mass with ill-defined margin and osteolytic bone destruction usually correlates with type Ⅲ. Combining the three characteristics of morphology, boundary and osteolysis is more helpful to distinguish type Ⅰ/Ⅱ and type Ⅲ tumors. Reference | Related Articles | Metrics

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Research for the influencing factors affecting the long-term survival time of implants: a retrospective cohort study YANG Zhi-jie, TANG Ting, LIU Kun, ZHANG Lei, ZHAI Qin-kai Shanghai Journal of Stomatology    2023, 32 (3): 292-297.   DOI: 10.19439/j.sjos.2023.03.014 Abstract （177）      PDF （680KB）（97）       Knowledge map    PURPOSE: To investigate the timing of implant failure events and their relationship with the dental position and the factors affecting the survival time of implants. METHODS: A retrospective cohort study was conducted to analyze the patients who had implants removed due to implant failure in the Department of Dental Implantology of Hefei Stomatological Hospital from January 2019 to December 2021. The predictor variables were surgical age, gender, smoking habit, oral hygiene, glucose value, jaw and dental position, implant type, implant number, surgeon, implant placement timing, implant loading timing, and antibiotic use timing. The outcome measurement was the implant survival time and implant failure events. Chi-square test, Kaplan-Meier(Log-rank test), and Cox proportional hazards model were used to identify and stepwise determined potential risk factors for implant survival time with SPSS 21.0 software package. RESULTS: A total of 89 patients(95 implants) had to remove implants. The mean survival time of the failed implants was 31(95%CI :24.2-39.1) months. Implant number (P=0.038), implant loading timing (P=0.050), and tooth position (P=0.024) were significantly correlated with the implant survival time. The risk of failure with 2 implants was 2.709 (HR=3.709, 95%CI: 1.075-12.795) times higher than that with 1 implant, and the risk of failure with late implant loading was 0.551(HR=1.511, 95%CI: 0.999-2.406) times higher than that with early implant loading. The risk of anterior teeth implant failure was 1.384 times higher than that of molars(HR=2.384, 95%CI:1.327-4.283). For patients with implant failure, about 50% of the patients removed the failed implant within 1 year after surgery, and the rate of removal of the failed implant gradually slowed down in the following 2-10 years. Peri-implantitis most commonly occurred in molars(50%). Implant fracture lastly occurred at 55(95%CI: 42.2-67.9) months postoperatively（P=0.000）. CONCLUSIONS: The number of implants, implant loading timing, and dental position were considered as the influencing factors for the survival time of implants. Follow-up in the first year after implantation seems to be particularly important for timely detection of problems and timely intervention. The occurrence of implant failure events was related to dental position and time. Reference | Related Articles | Metrics

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The clinical value of multislice CT for measuring the anatomical position of the mandibular nerve canal TAN Zhi, SHEN Li, YANG Jing, LIU Ping Shanghai Journal of Stomatology    2023, 32 (3): 314-317.   DOI: 10.19439/j.sjos.2023.03.018 Abstract （176）      PDF （456KB）（77）       Knowledge map    PURPOSE: To investigate the clinical value of multislice CT(MSCT) for measuring the anatomical position of the mandibular nerve canal during implantation in the posterior mandibular regions. METHODS: A total of 109 patients with mandibular posterior dental implants were included,and the linear distance between the alveolar ridge and the mandibular nerve canal in the posterior mandibular region to be implanted was measured by MSCT and CBCT before implantation. All 109 patients were divided into the MSCT navigation group and CBCT navigation group, and the imaging data from both groups were imported into the dynamic real-time navigation system for implant design, in parallel and in real time. The patients in both groups underwent MSCT or CBCT to measure the deviation of the actual position of the implant from the preoperative design position, including the deviation of the cervical centrum and apical part of the implant and the deviation of the distance between the implant and the mandibular nerve canal, and to assess their clinical results after treatment. The data were statistically analyzed with SPSS 21.0 software package. RESULTS: The deviations from the linear spacing between the top of the alveolar ridge and the upper arm of the mandibular nerve canal of the different dental implants in the area to be implanted were detected by MSCT as well as CBCT methods with no significant difference. In addition, there was no significant difference in the cervical deviation, tip deviation, depth deviation, angular deviation and deviation of the spacing between the implant and the mandibular nerve canal in the postoperative implant position in MSCT navigation group compared to the preoperative implant design position in CBCT navigation group. There was also no significant difference in the incidence of functional impairment of the inferior alveolar nerve between CBCT-guided and MSCT-guided group of patients. CONCLUSIONS: MSCT can achieve precise localization of the anatomical structures of the mandibular nerve canal, and the operation according to MSCT navigation during dynamic real-time guided dental implant surgery can avoid damage to the inferior alveolar nerve. Reference | Related Articles | Metrics

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A case of two-stage orthodontic treatment of skeletal ClassⅡmalocclusion with mandibular retrusion and maxillary dental arch stenosis ZHANG Yun, LI Xiao-bing Shanghai Journal of Stomatology    2023, 32 (5): 555-560.   DOI: 10.19439/j.sjos.2023.05.020 Abstract （169）      PDF （2656KB）（140）       Knowledge map    This article reviewed two-stage orthodontic treatment of a patient with skeletal ClassⅡmalocclusion with mandibular retrusion and maxillary dental arch stenosis. The patient was also accompanied by premature loss of bilateral mandibular deciduous canines and mesialization of mandibular posterior teeth. The first-stage treatment mainly corrected the maxillary dental arch stenosis, maxillary anterior teeth protrusion, mandibular retrusion and skeletal ClassⅡmalocclusion, while the second-stage treatment mainly corrected the mesialization of mandibular posterior teeth and alignment of maxillary and mandibular dentition. The two-stage orthodontic treatment finally enabled the patient to achieve good dental arch shape, tooth alignment, skeletal face pattern and soft tissue profile. Reference | Related Articles | Metrics

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Analysis of reasons and countermeasures for cancellation of oral and maxillofacial day surgery LI Yan, XU Ying, YANG Yue-lai, JI Jun, SHI Tian Shanghai Journal of Stomatology    2023, 32 (3): 328-331.   DOI: 10.19439/j.sjos.2023.03.021 Abstract （168）      PDF （801KB）（92）       Knowledge map    PURPOSE: To analyze the reasons for cancellation of oral and maxillofacial day surgery on the same day, and to propose countermeasures, so as to provide reference for improving the work efficiency and medical quality of day surgery ward. METHODS: The number of oral and maxillofacial day surgery cancellation cases in Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from June 1, 2021, to December 31, 2021 was calculated and then the relevant causes were analyzed. RESULTS: During the statistical period, a total of 3134 patients underwent oral and maxillofacial day surgery. Among them, 72 (2.30%) cases were canceled of day surgery on the same day. Cancellation of oral and maxillofacial day surgery was as followed: patient-related factors(31, 43.05%), disease-related factors (28, 38.89%), epidemic of Covid 19-related(10, 13.89%), and hospital-related factors(3, 4.17%). The top three departments of oral and maxillofacial day surgery cancellation were Department of Preventive Dentistry(7, 7.37%), Department of Oral Surgery(22, 6.56%) and Department of Oral and Craniomaxillofacial Surgery(18,2.77%). CONCLUSIONS: The cancellation rate of oral and maxillofacial day surgery can be reduced by strengthening screening in anesthesia assessment at outpatient clinic, strengthening doctor-patient communication, strengthening health education and epidemic prevention and control in day outpatient management center. Reference | Related Articles | Metrics

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Osteotome sinus floor elevation with tapered implants: a short-term evaluation LU Yu-tung, SHI Jun-yu, LAI Hong-chang Shanghai Journal of Stomatology    2023, 32 (3): 302-307.   DOI: 10.19439/j.sjos.2023.03.016 Abstract （160）      PDF （738KB）（62）       Knowledge map    PURPOSE: The aim of this study was to evaluate the short-term clinical outcome of tapered implants placed in posterior maxilla with osteotome sinus floor elevation (OSFE) technique. METHODS: The study population comprised 40 patients in whom 44 Astra tapered implants were inserted with OSFE technique from March to September in 2019. The surgical indication was that the bone height below the maxillary sinus was considered to be 2mm ~8mm. Astra tapered implants were inserted. Prosthetic restoration was completed 4 months after surgery. The implant success rate and stability, as well as osseointegration of the implant were clinically evaluated, and bone gain around the implants were measured. The data were analyzed using SPSS 19.0 software package. RESULTS: During the study period,the implant survival rate was 100%. The mean variation of implant stability quotient(ISQ) was 12.07±5.86. The mean value of ISQ ranged from 67.55±8.07 to 79.62±5.08. The average marginal bone loss was (0.32±0.29) mm. The endo-sinus bone gain(ESBG) was (1.06±0.4) mm. No mechanical complication was observed. The average probing depth around the implant was (3.2±1.51) mm, the bleeding on probing rate was(11.36±4.28)%, and the modified plaque index was 1.23±0.43. CONCLUSIONS: Astra tapered implants were found to produce predictable results in osteotome sinus floor elevation surgery. Further properly designed clinical trials are required to validate the use of tapered dental implants in sinus floor elevation technique. Reference | Related Articles | Metrics

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Regulation effect of serum IFN-γ and IL-4 expression on immune response in patients with oral lichen planus ZHAO Xiang, GE Hua-bing Shanghai Journal of Stomatology    2023, 32 (3): 271-275.   DOI: 10.19439/j.sjos.2023.03.010 Abstract （158）      PDF （555KB）（64）       Knowledge map    PURPOSE: To investigate the regulation effect of interferon-γ (IFN-γ) and interleukin-4 (IL-4) in the serum of patients with oral lichen planus (OLP) on immune response. METHODS: A total of 83 OLP patients in Wangfujing Branch of Beijing Stomatological Hospital, Capital Medical University from January 2019 to December 2021 were selected as the experimental group, and another 61 healthy volunteers who came to the hospital during the same period were included as the control group. The expression levels of IFN-γ and IL-4 in the serum and the expression of immune function indexes of the two groups were compared. The relationship between the expression levels of IFN-γ, IL-4 and immune function indicators in the experimental group was analyzed. SPSS 22.0 software package was used to analyze the data. RESULTS: The levels of IFN-γ and IL-4 in the experimental group were significantly higher than those in the control group(P<0.05). There was no significant difference in the levels of IFN-γ between patients with reticulated OLP and erosive OLP in the experimental group (P>0.05). The level of IL-4 in patients with erosive OLP in the experimental group was significantly higher than that in patients with reticulated OLP(P<0.05). The levels of CD3+, CD4, CD16++CD56+ and CD4+/CD8+ in the experimental group were significantly lower than those in the control group(P<0.05), the levels of CD8+ and CD19+ in the experimental group were significantly higher than those in the control group(P<0.05). The levels of IgG, IgM and CH50 in the experimental group were significantly higher than those in the control group(P<0.05), and the levels of IgA, C3 and C4 in the experimental group were significantly lower than those in the control group(P<0.05). Pearson correlation analysis showed that the level of IFN-γ in the experimental group was negatively correlated with CD16++CD56+ and CD4+/CD8+ (P<0.05), the level of IL-4 in the experimental group was negatively correlated with CD16++CD56+ and CD4+/CD8+(P<0.05), and the level of IL-4 in the experimental group was positively correlated with IgG (P<0.05). CONCLUSIONS: Serum IFN-γ and IL-4 in OLP patients are abnormally high, and IL-4 expression is significantly higher in erosive OLP patients. The cellular and humoral immune functions of OLP patients are disordered and related to the regulation of CD16++CD56+, CD4+/CD8+, and IgG immune responses. Reference | Related Articles | Metrics

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Comparative study of two novel nickel-titanium instruments for root canal preparation in curved canals on shaping ability and microcrack formation FENG Fei, CAO Li-qun, ZHANG Qi Shanghai Journal of Stomatology    2023, 32 (3): 225-229.   DOI: 10.19439/j.sjos.2023.03.001 Abstract （149）      PDF （625KB）（89）       Knowledge map    PURPOSE: To evaluate the shaping ability and microcrack formation of ProTaper Next (PTN) and XP-endo Shaper (XPS) systems in the mesial curved root canals of mandibular molars by using micro-CT scans. METHODS: Sixteen mandibular molars with two independent mesial root canals and curvature ranging from 25° to 35° were randomly divided into two groups. The preparation time was recorded. Pre-and-postoperative images were scanned by micro-CT. The following parameters were evaluated: canal transportation, centering ratio, changes in canal volume, canal/root width ratio and microcrack formation. SPSS 22.0 software package was used to analyze the data. RESULTS: Significant difference (P <0.05) was found for canal transportation at the section of 1, 3, 5, 7 mm from the apical foramen and centering ratio at the section of 1, 3, 7 mm from the apical foramen, where XPS files were superior. There was no significant difference for centering ratio at the section of 5 mm from the apical foramen(P>0.05). XPS groups significantly consumed less time during the preparation(P<0.05). There was no significant difference between the two groups for the increase amount of volume, and canal/root width ratio(P>0.05). Both instruments did not induce new microcrack after preparation. CONCLUSIONS: PTN and XPS can both shape curved canals effectively and safely. XPS showed better centering ability and reduced preparation time during preparation. Reference | Related Articles | Metrics

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Study on digital models of normal deciduous dentition in 189 children from Shanghai CAI Yue, ZHANG Man-man, SU Hong-ru, QIAN Wen-hao Shanghai Journal of Stomatology    2023, 32 (3): 308-313.   DOI: 10.19439/j.sjos.2023.03.017 Abstract （148）      PDF （886KB）（83）       Knowledge map    PURPOSE: To study the gender difference and the regulation of growth and development in normal deciduous dentition. METHODS: A total of 189 children with normal deciduous dentition aged 3 to 6 years in several kindergartens in Xuhui District in Shanghai were selected. The three-dimensional(3D) digital dental models were reconstructed by intraoral scanning. Geomagic Studio, a 3D reverse engineering software, was employed to extract the data, such as the dental arc perimeter of C(APC), the dental arc perimeter of E(APE), the dental arc length of C(LC), the dental arc length of E(LE), the dental arc width of C(C-C), the dental arc width of E(E-E), the mesiodistal width of the deciduous crown, the maxillary and mandibular space. SPSS 22.0 software package was used for data analysis. RESULTS: Parameters of deciduous dentition in boys were significantly elevated than in girls(P<0.05). All the boys and girls were divided into 4 groups by age. In 3-year-old group, significant differences were observed in maxillary APC, C-C, E-E(P<0.05) between boys and girls. In 4-year-old group, all boys' parameters were significantly greater than girls'(P<0.05) except maxillary LC. In 5-year-old group, there were significant differences in all the parameters between boys and girl(P<0.05) except maxillary APE and mandibular APC, LC, LE, C-C. No significant difference was observed in all the parameters except mandibular APE in 6-year old group. The significant difference between boys and girls were observed in the mesiodistal width of each deciduous crown except that of the maxillary lateral incisor and mandibular central incisor (P<0.05). There were significant differences in maxillary LE and E-E among children of different ages(P<0.05).The maxillary space was significantly greater than the mandibular space(P<0.01). CONCLUSIONS: There was gender difference in children's normal deciduous dentition, especially when they were 4 years old. Reference | Related Articles | Metrics

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Oral dexketoprofen tromethamine for preemptive analgesia in extraction of impacted teeth: a randomized controlled double-blind trial ZHAO Jun, WU Xiao-bo, LIU Na, ZHOU Yu, HAO Xin-he Shanghai Journal of Stomatology    2023, 32 (3): 298-301.   DOI: 10.19439/j.sjos.2023.03.015 Abstract （148）      PDF （528KB）（101）       Knowledge map    PURPOSE: To study the preemptive analgesic effect of dexketoprofen tromethamine in extraction of impacted teeth. METHODS: Twenty patients with bilateral mandibular impacted teeth were selected, and were randomly divided into dexketoprofen tromethamine group(experimental group) and placebo group(control group). The pain scores of patients at 0.5, 2, 4, 8, 12, and 24 hours after tooth extraction were counted by numeric rating scale(NRS), and the total dosage of emergent analgesic drugs used in 24 hours was recorded. COX analysis method was used to compare the interval time and the number of cases of first application of emergent analgesic drugs after two operations, and the survival curve was drawn. SPSS 20.0 software package was used for data analysis. RESULTS: The NRS scores of postoperative pain in the experimental group were significantly lower than those in the control group at 2, 4, 8 and 12 hours after operation (P<0.05). The dose of emergent analgesics used in the experimental group for 24 h was significantly lower than that in the control group (P<0.05). Survival curve showed that the interval time between the first application of analgesics in the experimental group was significantly longer than that in the control group(P<0.05). CONCLUSIONS: Dexketoprofen tromethamine can achieve obvious analgesic effect within 12 hours, but the analgesic effect is not obvious after 12 hours. Reference | Related Articles | Metrics

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Evaluation of red and white aesthetic effects of porcelain veneers in the restoration of developmental anterior dental gaps DENG Xiao-lin, YUAN Shuang, ZHU Dan-ting, SHI Le Shanghai Journal of Stomatology    2023, 32 (3): 276-279.   DOI: 10.19439/j.sjos.2023.03.011 Abstract （145）      PDF （873KB）（134）       Knowledge map    PURPOSE: To evaluate the red and white aesthetic effect of porcelain veneer in the restoration of developmental anterior interdental spaces. METHODS: A total of 152 anterior teeth in 64 patients with developmental anterior dental gaps were restored using porcelain veneers, the aesthetic effects before and after restoration were evaluated by pink aesthetic index (PES) and white aesthetic index(WES), the aesthetic effect of gingival papilla filling and reconstruction was evaluated by interdental gingival papilla index (PIS), and visual analogue score (VAS) was used to compare the satisfaction of patients before and after restoration. SPSS 203.0 software package was used for statistical analysis. RESULTS: The overall mean scores of PES before and after restoration of 152 developmental anterior interdental teeth were 9.63±2.23 and 13.64±0.88, respectively. The average scores of WES before and after restoration were 6.85±1.87 and 9.81±0.58, respectively. There were significant differences of PES and WES scores before and after restoration(P<0.01). According to the requirements of "near" perfect restoration(PES≥13 points, WES≥9 points), the red and white aesthetic effect after restoration was near the standard. The scores of PIS before and after restoration were 1.86±0.67 and 2.97±0.18, the interdental gingival papilla was completely filled with space, and the shape was ideal, there were significant statistical differences before and after restoration(P<0.01). Patients were more satisfied with the smile curve and morphology of the restored anterior teeth than other parameters. CONCLUSIONS: The aesthetic effect of using porcelain veneers to repair developmental anterior interdental gaps is ideal, among which the filling of the papillae between the teeth can meet the expectations of patients, and the aesthetic effect evaluation of PIS and PES/WES applied to porcelain veneers to repair developmental anterior interdental spaces has practical guiding significance in clinical practice. Reference | Related Articles | Metrics

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Evaluation of the effect of 3D printing resin splint based on the retention effect of orthodontic treatment in patients with periodontal disease QIAN Yi, DENG Chao, XU Xiao-bo, HU Yuan-pin, HONG Li-lin, LIU Shou-hong Shanghai Journal of Stomatology    2023, 32 (3): 323-327.   DOI: 10.19439/j.sjos.2023.03.020 Abstract （142）      PDF （919KB）（89）       Knowledge map    PURPOSE: To investigate the difference in the retention effect of 3D printing resin splint and Hawley retainer combined with lingual retention wire in periodontal disease patients after orthodontic treatment. METHODS: Forty patients who finished orthodontic treatment for periodontal disease from January 2021 to February 2022 were selected and divided into experimental group and control group according to the random number table method, with 20 patients in each group. Patients in the experimental group used 3D printing resin splint for retention, while patients in the control group used Hawley retainer combined with a lingual retention wire for retention. The chair-side operation time of the retainers was recorded for both groups. The maxillary and mandibular cuspid width, molar width, overjet, overbite and irregularity index were measured at 1 month and 6 months after orthodontic treatment in both groups. Statistical analysis was performed with SPSS 12.0 software package. RESULTS: The mean time for chair-side manipulation of experimental group and control group was 8.23, 11.17 min, respectively. The difference between the two groups was statistically significant (P<0.05) when comparing the width of the maxillary and mandibular cusps, the width of the molars, overjet, overbite and the irregularity index after 1 month and 6 months of wear of the retainers, which were significantly greater in the experimental group than in the control group at 6 months(P<0.05). CONCLUSIONS: 3D printing resin splint, with short chair-side manipulation time, was more effective than Hawley retainer combined with a lingual retention wire, and the efficacy of both groups was otherwise generally consistent. Reference | Related Articles | Metrics

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Study on the effect of alginate impression spray disinfection process on model accuracy ZHANG Jia-yuan, YU De-dong, YE Li-juan, WU Chun-lan, LIU Jing Shanghai Journal of Stomatology    2023, 32 (5): 449-454.   DOI: 10.19439/j.sjos.2023.05.001 Abstract （141）      PDF （1125KB）（153）       Knowledge map    PURPOSE: To investigate the effect of a new cleaning and disinfection process of oral impressions on the accuracy of alginate dental impression. METHODS: Sixteen young volunteers were selected to make alginate oral impression (2 times for each upper and lower jaw) and oral scandata acquisition (1 time for each upper and lower jaw) to obtain STL data. The 2 pairs of alginate impressions of each subject were numbered group 1, group 2, inwhich group 1 was not sterilized and the oral impression film in group 2 was treated with the method and steps of new oral impression cleaning and disinfection. All the oral impressions of the subjects were perfused with plaster models in the same standard way and demoulded. The obtained plaster models were examined and scanned after appropriate trimming and grinding. The plaster model data obtained from each group of each patient after warehouse scanning were compared with the orally scanned model data for alignment analysis, and root mean square(RMS) was used as a parameter to evaluate the deviation between the test model and the standard model. The chromatograms of the deviations were saved for visualization and analysis to observe the differences in model accuracy from several dimensions. Statistical analysis was performed with SPSS 23.0 software package. RESULTS: The differences in RMS of model accuracy of maxillary dental series of alginate impressions were statistically significant, in which the RMS of the group disinfecting the maxillary oral impression film with a new oral impression cleaning and disinfection process was significantly higher than that of the nonsterilized group (P=0.006), while the difference between model accuracy RMS of the mandibular disinfection group and non-disinfection group was not statistically significant(P=0.874). CONCLUSIONS: The new technical specifications for cleaning and disinfection of dental impressions recommended by the Chinese Stomatological Association have certain effects on the accuracy of dental impressions made of alginate material,and the details in its process should be further improved. Reference | Related Articles | Metrics

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Effect of different kinds of gingival retraction agents on the polymerization inhibition of polyvinyl siloxane impression materials HOU Qian-qian, GE huan, GAO Yi-ming Shanghai Journal of Stomatology    2023, 32 (3): 251-254.   DOI: 10.19439/j.sjos.2023.03.006 Abstract （140）      PDF （1023KB）（80）       Knowledge map    PURPOSE: To evaluate the effect of different kinds of gingival retraction agents after directly contacted with polyvinyl siloxane impression materials on polymerization inhibition and the inhibition degree. METHODS: Five kinds of gingival retraction agents (0.1% epinephrine hydrochloride, 0.05% oxymetazoline, 15.5% ferric sulfate, 25% aluminum chloride and 5% aluminum chloride) were chosen, normal saline was as control group, and two kinds of polyvinyl siloxane impression materials (ExpressTM, ImprintTM Ⅱ) were combined into 12 groups. There were 12 specimens in each group and 144 specimens in total. Silicone rubber impression materials were mixed by the same operator using a dispensing gun into the acrylic mold, so that they could directly contact the gingival retraction agents on the densely woven cotton fabrics. The samples were removed when the polymerization time arrived according to the manufactures’ recommendations and then placed under a stereomicroscope with a magnification of 10 times to observe whether polymerization inhibition occurred, the degree of inhibition was compared afterwards. SPSS 22.0 software package was used for statistical analysis. RESULTS: The polymerization inhibition of two kinds of silicone rubber impression materials occurred in 15.5% ferric sulfate group and 25% aluminum chloride group, and the inhibition occurrence rate was 100%, the difference was statistically significant (P<0.05) compared with normal saline group. Inhibition was not found in 0.1% epinephrine hydrochloride group, 0.05% oxymetazoline group and 5% aluminum chloride. The effect of 15.5% ferric sulfate and 25% aluminum chloride on polymerization inhibition degree of ImprintTM Ⅱ was greater than ExpressTM, and the difference was statistically significant(P<0.05). CONCLUSIONS: When silicone rubber impression material is used during impression procedure, attention should be paid to the effect of the gingival retraction agent containing 15.5% ferric sulfate and 25% aluminum chloride on its polymerization. The gingival retraction agent should be washed before impression to avoid the residue directly contacting the silicone rubber to prevent polymerization. Reference | Related Articles | Metrics

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Effect of surface treatment on the three-point bend bonding strength between pure titanium fabricated by selective laser melting and porcelain HU Dan-dan, Ren Can-xia, LUO Xiao-ping Shanghai Journal of Stomatology    2023, 32 (3): 230-235.   DOI: 10.19439/j.sjos.2023.03.002 Abstract （138）      PDF （2374KB）（90）       Knowledge map    PURPOSE: To evaluate the effect of surface treatment on bonding strength between pure titanium formed by selective laser melting and porcelain. METHODS: Pure titanium strips (64) and cobalt-chromium alloy strips (16) were laser machined to meet ISO 9693 standards. The pure titanium specimens were divided into 4 groups according to the sandblasting pressure and interlayer material. The sandblasting pressure of 0.25 MPa of bonder porcelain group was TB1, the sandblasting pressure of 0.25 MPa of gold coating group was TG1, the sandblasting pressure of 0.45 MPa of bonder porcelain group was TB2, and the sandblasting pressure of 0.45 MPa of the gold coating group was TG2(n=16). After porcelain fusing, half of the specimens in each group were tested for three-point bend bonding strength, and the other half were tested after 10 000 cycles of thermal cycling(n=8). The bonding strength of cobalt-chromium alloy after sandblasting at 0.25 MPa and 0.45 MPa was taken as the control group and recorded as group C1, C2(n=8). The bonding strength was tested using classical three-point bending experiment. The surface roughness of pure titanium was measured by laser scanning confocal microscope(LSCM). Field emission scanning electron microscopy(FE-SEM) was used to observe the interface morphology of titanium-ceramic. The surface morphology of titanium after porcelain stripping was observed with stereomicroscope and fracture modes were analyzed by it. Graphpad Prism 8.0 software package was used for statistical analysis of the data. RESULTS: The bonding strength of group TG2 was (40.16±3.97) MPa and (37.38±2.39) MPa of group TG1, which were significantly higher than that of group TB2 (36.32±1.44) MPa and group TB1 (33.75±2.31) MPa (P<0.05). The bonding strength of group TB2 with 0.45 MPa sandblasting was significantly higher than that of group TB1 with 0.25 MPa sandblasting (P<0.05). There was no significant decrease in titanium-ceramic bonding strength before and after thermal cycling. When the sandblasting pressure increased from 0.25 MPa to 0.45 MPa, the roughness increased significantly (P<0.05). The fracture modes were mixed. CONCLUSIONS: Under the conditions of this study, gold coating can significantly improve the bonding strength of Ti22 porcelain and SLM pure titanium than bonder porcelain, and increase of sandblasting pressure can further improve the bonding strength of titanium-porcelain. After 10 000 cycles of thermal cycling, the titanium-porcelain bonding strength did not decrease significantly. Reference | Related Articles | Metrics

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Evaluation of the effect of invisible correction and SGTB in the treatment of mandibular retrusion CHEN Shuang-xi, GAO Mei-qin Shanghai Journal of Stomatology    2023, 32 (5): 513-518.   DOI: 10.19439/j.sjos.2023.05.012 Abstract （137）      PDF （1464KB）（112）       Knowledge map    PURPOSE: To compare the clinical effects of invisible correction and SGTB in two-stage treatment of mandibular retrusion. METHODS: Eighty-five patients with bony mandibular regression who did not pass the peak of growth and development were selected. Among them, 40 cases were guided by invisible correction and 45 cases were guided by SGTB functional correction. Lateral head X-rays before and after treatment were measured, and the effect before and after treatment was compared by SPSS 16.0 software package. RESULTS: After treatment, the SNB angle and NP-FH (face angle) increased and the ANB angle decreased in both groups, all of which had significant changes(P<0.001). At T1, the changes of SNB angle, ANB angle and NP-FH angle in the invisible group were smaller than those in the SGTB group(P<0.05). The difference between MP-FH angle and MP-SN angle before and after treatment was greater in the SGTB group than in the invisible group(P<0.001). CONCLUSIONS: In patients with receding mandible before the peak of growth and development, the mandible was significantly moved forward after orthodontics. Both invisible orthodontics and SGTB promote changes in the position of the mandible, improves coordination between the upper and lower jaws. In the control of the posterior teeth in the vertical direction, the invisible group is stronger than the SGTB group. Reference | Related Articles | Metrics

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In vitro study on cytotoxicity, osteogenic potential and antibacterial activity of silicate root canal sealers YANG Xi-liang, ZHENG Tian-xia, LI Wen, WANG Wu-liang, YIN Zi-han, BAI Yu-hong Shanghai Journal of Stomatology    2023, 32 (3): 246-250.   DOI: 10.19439/j.sjos.2023.03.005 Abstract （133）      PDF （1442KB）（93）       Knowledge map    PURPOSE: To evaluate the in vitro biocompatibility and antibacterial activity of a new type of strontium silicate-based C-Root SP root canal sealer, and to provide a reference for clinical selection of sealers. METHODS: C-Root SP, iRoot SP and AH Plus extracts were prepared, L929 cells and MC3T3-E1 cells were cultured in vitro, and the cytotoxicity and osteogenic potential of the three sealers were compared. Fresh sealers were mixed with Enterococcus faecalis solution and the antibacterial activity of the sealer was determined by direct contact text (DCT). SPSS 25.0 software package was used for statistical analysis. RESULTS: At 24, 48, and 72 h, the cytotoxicity of the sealers in each group were significantly different (P<0.01). Compared with AH Plus, the cytotoxicity of C-Root SP was lower (P<0.01). C-Root SP was superior to AH Plus in promoting the activity of alkaline phosphatase(ALP) (P<0.01). iRoot SP was the strongest in promoting the formation of mineralized nodules, followed by C-Root SP, and the weakest was AH Plus(P<0.01). C-Root SP inhibited the growth of Enterococcus faecalis, and its antibacterial rate was significantly higher than AH Plus(P<0.01). CONCLUSIONS: The strontium silicate root canal sealer C-Root SP has low cytotoxicity, certain osteogenic potential and antibacterial activity against Enterococcus faecalis, so it can be used for root canal filling. Reference | Related Articles | Metrics

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Evaluation of low intensity Nd: YAG laser and traditional drugs in the treatment of myofascial pain LI Xu, ZHAO Ning, LIU Zong-lin, ZHANG Shan-yong, CAI Zhen, ZHU Chao Shanghai Journal of Stomatology    2023, 32 (3): 261-265.   DOI: 10.19439/j.sjos.2023.03.008 Abstract （131）      PDF （537KB）（87）       Knowledge map    PURPOSE: To evaluate the efficacy of low intensity Nd: YAG laser and traditional drugs in the treatment of myofascial pain (MP). METHODS: Eighty patients with MP were divided into laser group(n=40) and traditional medicine group(n=40) according to the principle of randomization and double-blindness. The patients in the laser group were treated with low intensity Nd :YAG laser(1 064 nm, 8 J/cm2, 250 mW) , with an interval of 48 h between the two laser treatments. The whole course of treatment was 10 times. Patients in the traditional medicine group uesd celecoxib capsules, 1 capsulet each time(0.2 g), twice a day for 2 weeks. Before and after each treatment, mouth opening, protrusion excursion, lateral movement of the affected side and lateral movement of the contralateral side were measured, and pain visual analogue scores (VAS) were measured and recorded. The data were statistically analyzed with SPSS 22.0 software package. RESULTS: Patients in laser group had significantly improved mandibular function and movement status(P<0.05) and pain symptoms(P<0.05); patients in traditional medicine group had the same significant improvement on mandibular functional movement status(P<0.05) and pain symptoms (P<0.05). The total effective rate of the two groups had no significant difference(P>0.05). The VAS score of patients in laser group was lower than that of traditional medicine group, but the difference was not significant(P>0.05). CONCLUSIONS: Low intensity Nd: YAG laser and traditional medicine can effectively relieve the symptoms of myofascial pain and improve mandibular function and movement. Laser treatment has the advantages of short course of treatment, high efficiency, no pain and fewer side effects, which is worthy of clinical application. Reference | Related Articles | Metrics