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25 August 2021, Volume 30 Issue 4 Previous Issue    Next Issue

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The orthodontic therapeutic principles for malocclusions concurring with temporomandibular joint disorders SHEN Gang 2021, 30 (4):  337-343.  doi: 10.19439/j.sjos.2021.04.001 Abstract ( 545 )   PDF (2978KB) ( 549 )   The biological nature of temporomandibular joint (TMJ) featuring adaptive remodeling allows for TMJ structural changes in response to external stimuli, including alterations in occlusion and in mandibular posture. Correlative susceptibility exists between malocclusions and TMJ disorders (TMD), evidenced by high incidence of TMD coinciding with skeletal originated malocclusion with facial prognathsim (Angle Class I skeletal II high angle). Clinical manifestations include markedly retruded mandible together with increased overjet, or mandibular transverse deviation, due to condylar pathological resorption. It is critically imperative to execute differential diagnosis between the routine malocclusions and those infringed with TMD. The prime stipulations governing the orthodontic procedures include the patient's notification of the existential TMD conditions prior to any orthodontic interventions, close inspections of TMD developments during the treatment, and a specially designed retention protocol aftermath. For the cases where severe overjet and mandibular displacement occur as a result of TMD, some specific orthopedic modalities can be implemented to improve the occlusion by restoring the shifted mandible. TMD conditions are also expected to be relieved with mandibular repositioning, which encourages new bone formation in the degraded condyles. The newly developed clear version of orthopedic appliances, namely, S8-SGTB, S8-SGHB, S9 and S10 are of promising efficacy in treating this category of patients. References | Related Articles | Metrics

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Experimental study of repairing rabbit femur defect with NPP/C-HA/ rhBMP-2 YANG Yan-lan, XU Pu, ZHANG Wen-bo, CHEN Zhuo-geng, LI Xiao-ni 2021, 30 (4):  344-349.  doi: 10.19439/j.sjos.2021.04.002 Abstract ( 207 )   PDF (1581KB) ( 168 )   PURPOSE: To investigate the osteogenic effect of nano-grade pearl powder(NPP)/chitosan-hyaluronic acid (C-HA)/recombinant human bone morphology protein-2 (rhBMP-2) artificial bone. METHODS: A bone defect model with a diameter of 7 mm and a height of 10 mm was made at the distal end of the femur. NPP/C-HA stent containing rhBMP-2 was prepared according to the shape of the defect. No material was implanted in the defect as blank group. NPP/C-HA was used as the control group, NPP/C-HA/rhBMP-2 was implanted into the experimental group. At 4 weeks, 8 weeks, and 12 weeks, the bone effects of each component were detected by cone-beam CT(CBCT), H-E and Masson staining. Serum ALP activity and OCN in tissues to determine the osteogenic differentiation and osteogenesis maturity were detected. SPSS 18.0 software package was used for statistical analysis. RESULTS: At 12 weeks, the defect was completely repaired in the experimental group. No immunological side effects such as inflammation and rejection were observed. At 8 and 12 weeks, CBCT showed that the experimental group had a higher CT value (Hounsfield units, HU) compared with the control group and the blank group(P<0.05). H-E and Masson staining showed that the experimental group had obvious new bone formation compared with the control group and the blank group at 8 weeks and 12 weeks, and ALP activity of the experimental group was significantly different from the control group and the blank group at 8 weeks. OCN immunohistochemical scoring of the experimental group was significantly different from the control group and the blank group(P<0.05). CONCLUSIONS: NPP/C-HA/rhBMP-2 has good tissue fusion, osteoinductivity, osteoconductivity and osteogenicity, which is expected to provide more effective treatment for bone repair. References | Related Articles | Metrics

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Effect of inhibition of Porphyromonas endodontalis on osteoblast differentiation WANG Rui, YANG Di, YU Ya-qiong, GUO Jia-jie, QIU Li-hong 2021, 30 (4):  350-354.  doi: 10.19439/j.sjos.2021.04.003 Abstract ( 194 )   PDF (744KB) ( 177 )   PURPOSE: Porphyromonas endodontalis (P.e) is the dominant bacterium in the infected canal of pulpal and periapical disease.Lipopolysaccharides (LPS) in the outer membrane of the cell wall is an important toxicity factor of P.e. In this study, the effect of P.e-LPS on osteoblast differentiation was studied, and the pathogenic mechanism of P.e-LPS in periapical bone resorption disease was explored. METHODS: Porphyromonas endodontalis was cultured under anaerobic conditions. P.e-LPS was extracted by thermophenol water method, and then the extracted LPS was qualitatively analyzed by gel limulireagent method. Preosteoblast cell line MC3T3-E1 were induced to differentiate into osteoblasts by osteoblast differentiation medium (50 μg/mL ascorbic acid,6 mmol/L beta-glycerphosphate). Expressions of osteogenic differentiation genes including distal-less homeobox 5（DLX5）, runt-related transcription factor 2(Runx2), Osterix, bone sialoprotein (BSP), OCN(osteocalcin) and Collagen were detected by RT-PCR. The activity of alkaline phosphatase(ALP), alizarin red staining and Von Kossa staining were used to determine the mineralization level of osteoblasts.The expression of TOLL-like receptor-4 (TLR-4), the receptor of P.e-LPS, was silenced by siRNA transfection. SPSS 11.0 software package was used for statistical analysis of the data. RESULTS: The mRNA expressions of osteogenic differentiation genes including DLX5, Runx2, Osterix, OCN, BSP, and Collagen were significantly decreased after treated with P.e-LPS (10 μg/mL) for 3 d, compared with the control group（P< 0.05）.After treated with P.e-LPS (10 μg/mL) for 7 d or 14 d, respectively, ALP and alizarin red staining intensity was decreased. P.e-LPS was applied to the si-TLR-4 transfection group and the control group for 7,14 and 21 d, respectively. Compared with the control group, the expression level of osteogenic differentiation genes, ALP, alizarin red staining and Von Kossa staining intensity of si-TLR-4 group were significantly higher than those of the control group (P< 0.05). CONCLUSIONS: P.e-LPS inhibits the differentiation of osteoblasts through TLR-4 receptor, thus participating in bone resorption process of periapical lesions. References | Related Articles | Metrics

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Effect of DKK1 on the biological behaviors of dental pulp cells exposed to lipopolysaccharide XU Fang-fang, JIANG Bei-zhan 2021, 30 (4):  355-359.  doi: 10.19439/j.sjos.2021.04.004 Abstract ( 186 )   PDF (1303KB) ( 167 )   PURPOSE: To detect the effect of DKK1 on biological behaviors of human dental pulp cells exposed to lipopolysaccharide (LPS). METHODS: The dental pulp cells were isolated and cultured by modified enzyme-tissue block method and identified by immunofluorescence staining. The effect of DKK1 on proliferation and migration of human dental pulp cells exposed to LPS were measured by cell counting kit (CCK-8) and Transwell assay. Meanwhile, the effect of DKK1 on differentiation of human dental cells exposed to LPS were studied by alizarin red staining and real-time PCR experiment, statistical analysis was performed using SPSS 20.0 software package. RESULTS: The results of immunofluorescence showed that the cultured cells were in consistent with the mesenchymal stem cells. The result of CCK-8 indicated that DKK1 had no significant effect on proliferation of dental pulp cells exposed to LPS; The result of transwell assay showed that DKK1 significantly promoted the cell migration of dental pulp cells exposed to LPS. The results of Alizarin red staining and real-time PCR revealed that DKK1 could promote cytodifferentiation of dental pulp cells exposed to LPS. CONCLUSIONS: DKK1 promotes the ability of cell migration and cytodifferentiation of LPS treated dental pulp cells, which may be resulted from inhibition of Wnt/β-catenin pathway. References | Related Articles | Metrics

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Effect of high-concentration fluoride on apoptosis of human periodontal ligament stem cells TANG Ying, SHEN Yi-fen, LIU Chao, QIU Yin-feng, GU Yong-chun, YU Jin-hua 2021, 30 (4):  360-366.  doi: 10.19439/j.sjos.2021.04.005 Abstract ( 208 )   PDF (2281KB) ( 183 )   PURPOSE: To explore the effects of high-concentration fluoride(F) on apoptosis of human periodontal ligament stem cells (PDLSCs). METHODS: PDLSCs were isolated from periodontal ligament tissues of extracted third molars, and treated with different concentrations (0-40 ppm F) of NaF for indicated period of time. CCK-8 assay was performed to detect cell viability. After stained with Annexin V-PI and JC-1, cell apoptosis and mitochondrial membrane potential were analyzed by flow cytometry. Immunofluorescence staining and confocal microscopic assay were used to detect the protein expression level of cyt-c, cleaved-caspase-9 and -3. The mRNA level of caspase -9 and -3 were examined by RT-PCR. The protein expression level of total and phosphate-ERK, JNK and p38 were analyzed by Western blot. SPSS 13.0 software package was used for statistical analysis. RESULTS: Fluoride treatment inhibited cell viability (CCK-8 assay) and induced apoptosis of PDLSCs (Annexin V-PI staining) in a dose- and time-dependent manner. Immunofluorescence assay showed that fluoride with a dose ≥10 ppm significantly induced release of cyt-c from the mitochondria to cytosol, and up-regulation of expression of cleaved-caspase -9 and -3. RT-PCR confirmed that the mRNA level of caspase-9 and -3 increased with the dose of fluoride. Western blot assay confirmed that fluoride induced up-regulation of p-ERK, but not that of p-JNK and p-p38, and specifically blocking ERK pathway with U0126 could partially rescue the fluoride-induced cell apoptosis. CONCLUSIONS: High concentrations of fluoride induces apoptosis of PDLSCs via intrinsic mitochondrial pathway, and phosphation of MAPK/ERK is involved in the F-induce cell apoptosis. References | Related Articles | Metrics

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Effect of enamel matrix protein on osteogenic and adipogenic differentiation of dental pulp stem cells of deciduous teeth through miR-32 LI Xiao-yan, ZHENG Lei, MA Peng-tao, ZHANG Yan-xi 2021, 30 (4):  367-373.  doi: 10.19439/j.sjos.2021.04.006 Abstract ( 187 )   PDF (1298KB) ( 144 )   PURPOSE: To explore the effect of enamel matrix proteins(EMPs) on osteogenesis and adipogenesis of stem cells from human exfoliated deciduous teeth SHED), and explore its molecular mechanism. METHODS: SHEDs were used to detect the expression of its surface antigens CD73, CD146, CD34 and CD45 by flow cytometry. SHED was induced by OB osteogenic induction liquid, and then the osteogenic differentiation ability was measured by alizarin red staining. SHEDs were divided into 4 groups, NC group had invalid sequence shRNA interfered with SHED, EMPs group had invalid sequence shRNA interfered with SHED. Then 100 μg/L EMPs was used to interfere with SHED. In miR-32 inhibitor group, miR-32 shRNA plasmid was used to interfere with SHED; while in EMPs+miR-32 inhibitor group, 100 μg/L EMP was used to intervene SHED after silencing miR-32. QPCR was used to detect the expression of miR-32, dentin sialophosphoprotein (DSPP), dentin matrix protein 1, DMP-1, peroxisome proliferators-activated receptor γ (PPARγ) and CCAAT enhancer binding protein α (C/EBPα) gene expression; Western blot was used to detect the expression of DSPP, DMP-1, PPARγ and C/EBPα protein expression; Alizarin red staining was used to detect SHED osteogenic capacity; Oil red O staining was used to detect adipogenetic capacity of SHED. RESULTS: The results of flow cytometry showed that SHED had positive expression of CD146 and CD73, and negative expression of CD34 and CD45, which was consistent with the characteristics of stem cell surface markers. Alizarin red staining and oil red O staining showed mineralized nodules and oil droplets increased significantly, consistent with the multi-directional differentiation characteristics of stem cells. Compared with NC group, the expression of miR-32 gene in EMPs group was significantly increased(P<0.05), and the expression of miR-32 in miR-32 inhibitor group and EMPs+miR-32 inhibitor group was significantly decreased(P<0.05). Compared with NC group, the expression of DSPP and DMP-1, the number of mineralized nodules in EMPs group were significantly increased(P<0.05), the expression of PPARγ and C/EBPa and the number of lipid droplets were significantly decreased (P<0.05), while the result of miR-32 inhibitor group was the opposite (P<0.05). Compared with miR-32 inhibitor group, there was no significant difference in the expression of DSPP, DMP-1, PPARγ and C/EBPα, number of mineralized nodules and oil droplets in EMPs+miR-32 inhibitor group(P>0.05). Compared with EMPs group, the expression of DSPP and DMP-1 and the number of mineralized nodules in EMPs+miR-32 inhibitor group were significantly reduced(P<0.05), while the expression of PPARγ and C/EBPα and the number of lipid droplets were significantly increased(P<0.05). CONCLUSIONS: EMPs can regulate osteogenic and adipogenic differentiation of SHED by promoting the expression of miR-32. References | Related Articles | Metrics

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Effect of triple antibiotic paste on microorganisms in root canals of deciduous teeth CAI Wen-yan, ZHOU Shu, LIN Liang-yuan 2021, 30 (4):  374-378.  doi: 10.19439/j.sjos.2021.04.007 Abstract ( 268 )   PDF (640KB) ( 247 )   PURPOSE: To analyze the effect of triple antibiotic paste on root canal microorganisms in periapical periodontitis of different stages. METHODS: Eighty-nine children with periapical periodontitis of deciduous teeth in Department of Stomatology, Children's Hospital of Nanjing Medical University from April 2017 to April 2020 were enrolled, and divided into two groups according to the clinical symptoms and root X-ray films, i.e., acute inflammation group and chronic inflammation group. Samples of infected root canals were collected for bacterial identification, isolation and purification. The detection of microorganisms in the infected root canal and the composition of anaerobic microorganisms were analyzed in both groups. Disk diffusion method was used to observe antimicrobial effects of triple antibiotic paste and calcium hydroxide against common anaerobic bacteria, and the sensitivity of different anaerobic bacteria to triple antibiotic paste. Statistical analysis was completed by SPSS 20.0 software package. RESULTS: The microorganisms in both groups were mainly anaerobic bacteria. The detection rates of aerobes and anaerobic bacteria in the infected root canals had no significant difference between the two groups (P>0.05). The top five anaerobes detected in infected root canals were Peptostreptococcus, Bacteroidetes, Enterococcus faecalis, Porphyromonas gingivalis and Fusobacterium nucleatum. The detection rates of Porphyromonas gingivalis, Fusobacterium nucleatum and Bacteroidetes in infected root canal of acute inflammation group were significantly higher than those of chronic inflammation group, and the detection rate of Enterococcus faecalis was significantly lower than that of chronic inflammation group(P<0.05). The bacteriostatic circle diameter of triple antibiotic paste against Peptostreptococcus, Bacteroidetes, Enterococcus faecalis, Porphyromonas gingivalis and Fusobacterium nucleatum was significantly larger than that of calcium hydroxide(P<0.05). The sensitivity of different anaerobic bacteria to triple antibiotic paste was highest in Enterococcus faecalis, followed by Peptostreptococcus, Porphyromonas gingivalis, Fusobacterium nucleatum, and Bacteroidetes(P<0.05). CONCLUSIONS: Triple antibiotic paste has good antimicrobial effect on the common bacteria in the infected root canal of acute and chronic periapical periodontitis. References | Related Articles | Metrics

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Survey on oral health knowledge, attitudes, behaviors among parents of disabled children in Shanghai area ZENG Xiao-li, ZHANG Ying, WANG Yan, ZHANG Hao, JIANG Yi-wei, DA Dong-xin, YU Jin, WANG Hu -ning 2021, 30 (4):  379-383.  doi: 10.19439/j.sjos.2021.04.008 Abstract ( 210 )   PDF (553KB) ( 225 )   PURPOSE: To analyze the oral health behaviors of disabled children and their parents' oral health knowledge, attitudes in Shanghai city, and to provide information support for designing oral health care programs and making relevant policies. METHODS: By using stratified cluster sampling method, a questionnaire was given to 1381 parents of disabled children. The data were analyzed using SPSS 21.0 software package. RESULTS: The awareness rate of oral health knowledge among parents of disabled children was 67.21%, and 78.98% of parents had positive attitudes towards oral health. 13.61% of disabled children took sweet snacks before sleep, only 45.98% of disabled children brushed their teeth twice or more daily. 42.65% of disabled children used fluoride toothpaste, and 88.12% never flossed their teeth. The percentage of disabled children who had never visited a dentist was 49.75%. CONCLUSIONS: Oral health behaviors of disabled children in Shanghai city need to be improved, and the parents' oral health knowledge level is low. Customized educational programs should be carried out for parents, in order to strengthen oral health education in the suburban areas. References | Related Articles | Metrics

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Full-zirconia single-tooth molar implant-supported restorations with angulated screw channel abutments: evaluation of short-term outcomes LIN Hou-xue, HUANG Jing, SUN Ya-xuan, XIA Jin-xing 2021, 30 (4):  384-388.  doi: 10.19439/j.sjos.2021.04.009 Abstract ( 276 )   PDF (743KB) ( 221 )   PURPOSE: To evaluate the effect of full-zirconia single-tooth molar implant-supported restorations with angulated screw channel abutments. METHODS: Seventy-six patients with a single missing tooth in the posterior region of the maxilla and mandible underwent dental implants from March 2016 to March 2018 were enrolled. After 3 months, each patient received a full-contour screw-retained zirconia restoration with angulated screw channel abutment. Modified sulcus bleeding index (MSBI), modified plaque index (mPLI), periodontal probing depth (PD), marginal bone levels (MBLs) and mid-buccal mucosal levels (MBMLs) were recorded at the implantation moment (T0), four weeks (T1), one year (T2) and two years (T3) after treatment. During the follow-up period, the incidence of implant defects, survival rate and porcelain fracture were recorded. The data were processed using SPSS 23.0 software package. RESULTS: Of the 76 patients, 9 did not have a complete follow-up record (two of the implants failed before restoration, two patients had bilateral first molars missing, and five were lost to follow-up), and the remaining 67 patients with a total of 67 implants had a complete follow-up record. The success rate of implant was 97.01%(65/67) during one-year follow-up, and the initial success rate was 100% at an interval of three months. Compared with indexes at T0, mSBI and mPLI were significantly reduced at T1, T2 and T3 (P<0.05). There was no significant difference in PD level at T0, T1, T2 and T3(P>0.05), and the effective depth averaged 1.75 mm. Compared with indexes at T0, MBLs and MBMLs were significantly increased at T1(P<0.05). A total of 4 cases had implant reconstruction at T1 due to concerns about framework fracture, veneering fracture and aesthetics. At T2 and T3, there was no implant problems and loosening of restoration. There were 2 cases of peri-implant inflammation, one case of implant loss and one case of abutment pain, which were all improved after corresponding treatments. Two cases of porcelain fracture occurred in 67 zirconia restorations (2.63%), and the implant survival rate was 100%. CONCLUSIONS: Full-zirconia single-tooth molar implant-supported restorations with angulated screw channel abutments can effectively improve the implant stability in early phase, with high success rate, good short-term effect and few complications. References | Related Articles | Metrics

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Orofacial myofunctional therapy improves facial morphology of children with obstructive sleep apnea after adenotonsillectomy SHAN Hua-qing, WANG Yu-hui, YU Li-ming, LI Xiao-yan, LIU Yue -hua 2021, 30 (4):  389-393.  doi: 10.19439/j.sjos.2021.04.010 Abstract ( 655 )   PDF (790KB) ( 331 )   PURPOSE: This study investigated the effectiveness of orofacial myofunctional therapy(OMT) in improving facial morphology of children with obstructive sleep apnea (OSA) after adenotonsillectomy (AT). METHODS: Ten children aged from 4-7 years with persistent oral breathing for more than 1 month after adenotonsillectomy were chosen to receive orofacial myofunctional therapy. The patients were required to take photos before and after orofacial myofunctional therapy. In order to compare the soft changes before and after OMT treatment, twelve representative mark points were selected and used for proportion and angle measurements. Graphpad Prism 8 statistical software was used for statistical analysis, to compare the differences in facial morphology of patients before and after treatment. RESULTS: Compared with before OMT, a significant difference was found in the proportion of Sn-Ls/Sn-Stms(P=0.0002), Sn-Stms/Sn-Me'(P<0.05), as well as in the angle of Gs-Sn-Pos (P<0.05), nasolabial angle(P=0.0005), mentolabial angle (P=0.0026) after OMT treatment. CONCLUSIONS: Orofacial myofunctional therapy can be considered as an effective complementary treatment for OSA patients with oral breathing after adenotonsillectomy. References | Related Articles | Metrics

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The effect of orthognathic surgery on speech function in patients with skeletal Class Ⅲ malocclusion MENG Kun, SUN Jian, LI Ya-li, LIU Yan-shan, CHEN Chen, XU Ze-xian, SUN Ming, ZHANG Xiu-xiu, ZHOU Dong-yang 2021, 30 (4):  394-401.  doi: 10.19439/j.sjos.2021.04.011 Abstract ( 209 )   PDF (1602KB) ( 193 )   PURPOSE: To investigate the influence of the position of the upper and lower jaws on the anatomical structure of pharynx before and after orthognathic surgery in patients with skeletal Class Ⅲ malocclusion. METHODS: Craniofacial CT scan and speech data were collected from 31 patients with skeletal Class Ⅲ malocclusion before and 3 months after surgery. The collected CT data was imported into Dolphin imaging 11.95 software to establish a digital original model, and the anatomical structure of the pharynx was measured and analyzed. Speech data were analyzed objectively and subjectively by Computerized Speech Lab 4500b and professional speech specialists. Statistical analysis was performed using SPSS 24.0 software package. RESULTS: The distance from the lower edge of the soft palate to the posterior pharyngeal wall, the shortest distance from the posterior margin of the tongue to the posterior pharyngeal wall and its corresponding cross-sectional area were significantly different from those before surgery (P<0.05). The changes of SNA, SNB, ANB, OJ, and OBJ before and after surgery were significant in this series. Importantly, the speech intelligibility of orthognathic patients before and after surgery changed significantly subjectively (P<0.05). Objectively, the postoperative vowels /a/B2, B3, B4, /i/B1,B2, /u/B1,B2 and B4 of the patients were significantly different from those before surgery. There was no significant difference in the lower limit frequency of the consonants /x/, /zh/, /s/, the energy value of /zh/ and the grammatical form of /z/ before and after surgery. The maxillary advancement distance was highly correlated or significantly correlated with △S1, △VOP, and voice changes. CONCLUSIONS: Orthognathic surgery moves the upper and lower jaws to cause changes in the anatomy of the pharyngeal cavity, leading to changes of postoperative speech. References | Related Articles | Metrics

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Changes of α-SMA, type I and type Ⅲ collagen in gingival tissue and expression of MMP-2 and TIMP-2 in gingival crevicular fluid under orthodontic force JIANG Li-ping, TANG Zhen 2021, 30 (4):  402-405.  doi: 10.19439/j.sjos.2021.04.012 Abstract ( 216 )   PDF (458KB) ( 149 )   PURPOSE: To investigate the changes of α-smooth muscle actin (α-SMA), type Ⅰ and type Ⅲ collagen in gingival tissue and expression of matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) in gingival crevicular fluid under orthodontic force. METHODS: Seventy-four patients undergoing orthodontic treatment in Affiliated Stomatological Hospital of Nanchang University from April 2018 to April 2019 were enrolled, and randomly divided into three groups. Group A(n=24) received the treatment under 0 g of orthodontic force, group B (n=25) under 75 g of orthodontic force, and group C(n=25) under 150 g of orthodontic force. At the baseline and 4th week of treatment, the expression levels of α-SMA, type I collagen and type Ⅲ collagen in gingival tissues were detected by immunohistochemical staining. At the baseline, the 2nd, and 4th week of treatment, the expression levels of MMP-2 and TIMP-2 in gingival crevicular fluid were detected by enzyme-linked immunosorbent assay. Then the correlation between different orthodontic force and levels of α-SMA, type Ⅰ collagen, type Ⅲ collagen, MMP-2 and TIMP-2 was analyzed using Spearman correlation analysis. Statistical analysis was completed by SPSS 19.0 software package. RESULTS: At the 2nd and 4th week of treatment, the expression levels of MMP-2 and TIMP-2 in gingival crevicular fluid among three groups were the lowest in group A, followed by group B and group C(P<0.05). At the 4th week of treatment, the levels of α-SMA, type Ⅰ and type Ⅲ collagen in gingival tissues among three groups were the lowest in group A, followed by group B and group C(P<0.05). The orthodontic force was positively correlated with expression levels of α-SMA, type Ⅰ collagen, type Ⅲ collagen, MMP-2 and TIMP-2(P<0.05). CONCLUSIONS: The expression levels of MMP-2 and TIMP-2 in gingival crevicular fluid and myofibroblast are related to the changes of orthodontic force, which may play an important role in the reconstruction of periodontal tissue during orthodontic treatment. References | Related Articles | Metrics

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Effect of children's oral health cognition and behavior on oral health status LI Li, JIN Hao, SHENG Kai, JI Ping-ping, DING Qin, HOU Li-li 2021, 30 (4):  406-409.  doi: 10.19439/j.sjos.2021.04.013 Abstract ( 230 )   PDF (533KB) ( 197 )   PURPOSE: To investigate the current status of oral health cognition behavior and oral health status of children, and to provide countermeasures for the prevention and treatment of oral diseases in children. METHODS: A total of 387 primary school students in the urban area of Shanghai from December 2018 to February 2019 were surveyed using Children's Oral Health Questionnaire and child oral health impact profile（COHIP）. SPSS 24.0 software package was used to conduct statistical analysis of the results through descriptive, univariate and multivariate analysis. RESULTS: The cognition of oral health of children aged 6-9 years old in Shanghai urban area was generally good, but their oral health behavior was average. The caries rate of 387 children reached 57.4%, and the oral health status was not good. Correlation analysis and regression analysis showed that children's oral health behavior was positively correlated with oral health cognition（r=0.260,P<0.05）, and negatively correlated with positive and negative effects of oral health status（r=-0.333,-0.181,P<0.05）, while children's oral health cognition had no significant effect on their oral health status（P>0.05）. CONCLUSIONS: The better the oral health behavior habits of children, the greater the positive impact on oral health status; the development of oral health education for children requires more attention to the cultivation of oral health behavior patterns. References | Related Articles | Metrics

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Anatomical limits of distal displacement of bony maxillary molars in patients with skeletal Class Ⅱ malocclusion LIU Li-ping, YANG Tong-tong, CHENG Jia-xiu 2021, 30 (4):  410-413.  doi: 10.19439/j.sjos.2021.04.014 Abstract ( 418 )   PDF (720KB) ( 269 )   PURPOSE: To compare the posterior space of the maxillary molar with osseous dislocation and investigate the retromolar space available for molar distalization in patients with maxillary prognathism. METHODS: Cone-beam CT (CBCT) data of 136 posterior maxillary segments in 32 patients with skeletal Class I malocclusion and 36 patients with skeletal Class Ⅱ malocclusion were analyzed. The functional tip of the maxillary first and second molars was connected as the measuring reference line, the reference plane for measurement parallel to the reference line, which passed the furcation of the mandibular second molar root, was set as the “0 mm” plane. Four additional planes, which were parallel to the 0 mm-plane and located at 2, 4, 6 mm apical to the 0 mm-plane, cemento-enamel junction (CEJ) and root tip, were named the"2 mm, 4 mm, 6 mm, CEJ and TIP", in order to measure the distance from the maxillary second molar to maxillary tubercle bone cortex in the edge. SPSS 23.0 software package was used to analyze the data. RESULTS: At all levels of measurement, the retromolar space of the values in male and female patients was not significantly different, ClassⅡ malocclusion were significantly greater than those in ClassⅠmalocclusion, with the minimum values at the CEJ level, (4.18±1.40) and (5.12±2.16) mm, respectively. As the measured level moved up, the measured clearance value increased and reached the maximum at the root tip, which was (8.64±2.41) and (10.02±2.27) mm, respectively. CONCLUSIONS: Compared with ClassⅠmalocclusion, patients with ClassⅡmalocclusion have greater retromolar space for maxillary molar distalization along the posterior line of occlusion. More attention should be paid to the anatomical limit of maxillary second molar at the CEJ level along the bite line in the distal direction when maxillary molar is pushed backward. References | Related Articles | Metrics

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Clinical study of the effect of fixed Twin-block on adolescent skeletal ClassⅡmalocclusion MA Xiao-qing, ZHAO Ning, XIANG Fei, ZHOU Man-li, QIAN Wen-hao 2021, 30 (4):  414-418.  doi: 10.19439/j.sjos.2021.04.015 Abstract ( 317 )   PDF (969KB) ( 227 )   PURPOSE: To evaluate the retention ability of fixed Twin-block appliance and its clinical effect on adolescent skeletal ClassⅡmalocclusion. METHODS: Twenty-six skeletal ClassⅡdivision 1 adolescents (M:12, F: 14; age:11~13 years, average: 11.8 years) were chosen and fixed Twin-block appliance was used to guide the mandibular protrusion for one year. Before and after treatment, cephalometric films were taken to observe the skeletal, dental and soft tissue changes. Graphpad Prism 6.0 software was used for Student's t test. RESULTS: There was no loosening or destruction of the appliance during the treatment and the profile of all cases was improved significantly. The indexes that showed significant difference(P<0.05) included the mandibular length and position (Co-Gn, SNB, ANB, Pog-VL, Pos-VL), the inclination and position of the maxillary incisors(U1-VL, U1-SN), the sagittal position of the mandibular dentition(L1-VL, L6-VL). The indexes that showed insignificant difference(P>0.05) included the mandibular plane(MP-SN), the length and position of the maxilla (SNA, A-VL), the vertical position of the maxillary incisor(U1-HL), the position of the maxillary posterior teeth(U6-VL, U6-HL), the mandibular incisor inclination(IMPA) and the vertical position of the mandibular dentition(L6-MP,L1-MP). CONCLUSIONS: Fixed Twin-block appliance can enhance the mandibular anchorage, effectively promote the mandibular growth and improve the facial profile. References | Related Articles | Metrics

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Evaluation of the upper airway and maxillary and mandibular characters in adult skeletal Class Ⅱ malocclusion MAO Xiao-yan, YANG Jia-yin, LI Jia, XU Rui 2021, 30 (4):  419-423.  doi: 10.19439/j.sjos.2021.04.016 Abstract ( 309 )   PDF (821KB) ( 255 )   PURPOSE: To analyze the relationship between upper airway and mandible morphology in patients with skeletal Class Ⅱ malocclusion with cone-beam CT (CBCT). METHODS: Thirty-three volunteers with individual normal occlusion and thirty-three patients with skeletal Class Ⅱ malocclusion were selected to undergo CBCT. All samples were outputted to Dicom and reconstructed using Mimics 19.0 medical software. SPSS 19.0 software package was used to analyze the differences between the two groups. Correlation between the two groups was evaluated using Pearson's coefficient analysis. RESULTS: Fifteen parameters showed significant difference between individual normal occlusion and the skeletal Class Ⅱ malocclusion(P<0.05). There were 10 significant correlational parameters between mandible length and upper airway of the skeletal Class Ⅱ malocclusion group. There were 13 significant correlational parameters between the arch width of the maxilla and upper airway of the skeletal Class Ⅱ malocclusion group. There were 3 significant correlational parameters between the arch width of the mandible and upper airway of the skeletal Class Ⅱ malocclusion group. CONCLUSIONS: The upper airway morphology of skeletal Class Ⅱ malocclusion is correlated with maxillary and mandibular parameters. References | Related Articles | Metrics

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Survey of dentists' knowledge and behavior of medications used during pregnancy in Beijing area LYU Jiao, ZHANG Xue-mei, REN Xiao-li, NIE Xiao-han 2021, 30 (4):  424-428.  doi: 10.19439/j.sjos.2021.04.017 Abstract ( 136 )   PDF (595KB) ( 151 )   PURPOSE: To investigate dentists' knowledge and behavior of drugs used during pregnancy in Beijing and analyze sources of influence. METHODS: A cross sectional survey was undertaken among 259 dentists in Beijing. The percentage frequency distributions of correct responses regarding medication safety during pregnancy and the use of drugs were calculated. Logistic regression model was used to explore factors associated with dentists' knowledge of medications used during pregnancy with SAS 9.4 software package. RESULTS: The correct rate on medication safety during pregnancy ranged from 1.93%-57.92%. The percentage of knowledge scores exceeding 8 point was only 10.42% (out of 16 points). In addition, the percentage of drugs prescribed and used during pregnancy was generally low(2.8%-27.09%). CONLUSIONS: Dentists in Beijing do not have sufficient knowledge about medication used during pregnancy. Continuing education is needed and professional authorities should develop unified guidelines to standardize their clinical practice. References | Related Articles | Metrics

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A comparative study of tongue appliance combined with chin-cup and facemask in the treatment of anterior crossbite LIU Ming-jin, LI Le, CHEN Ju-fang, HAO Xin, YANG Ru, TIAN Yu-lou 2021, 30 (4):  429-434.  doi: 10.19439/j.sjos.2021.04.018 Abstract ( 814 )   PDF (816KB) ( 208 )   PURPOSE: To compare the efficacy of tongue appliance combined with chin-cup and facemask in the treatment of anterior crossbite, as well as the effects on the position of hyoid bone and airway, so as to provide reference for clinic. METHODS: Sixty cases with anterior crossbite were selected after treatment, using tongue appliance combined with chin-cup (n=30) and facemask (n=30). Cephalometric radiographs were taken before and after treatment, skeletal, dental, hyoid, and airway space measurements were analyzed with Winceph 9.0 and AutoCAD 2016. SPSS 21.0 software package was used for statistical analysis. RESULTS: Both appliances had a good effect on anterior crossbite. After treatment, SNA, ANS-PNS significantly increased(P<0.05), and SN-MP significantly increased(P<0.05). The upper anterior teeth showed a buccal inclination(P<0.01), the lower anterior teeth had a lingual inclination, and the overjet became normal(P<0.01). UL-E increased in both groups(P<0.05), PLA significantly increased in tongue appliance combined with chin-cup group(P<0.05). H-C3 decreased in both groups(P<0.05), while H-S, H-Ar increased(P<0.01), suggesting that the hyoid bone moved backward and downward. PNS-UPW increased in both groups(P<0.01), and U-MPW increased in facemask group(P<0.01). CONCLUSIONS: Facemask and tongue appliance combined with chin-cup can both promote the development of the maxilla, cause a clockwise rotation of the mandible, and effectively correct the anterior crossbite. Both methods can cause a backward and downward displacement of hyoid bone. Facemask can enlarge the width of nasopharynx and palatopharynx airway, while only the width of nasopharynx can be increased by tongue appliance combined with chin-cup. References | Related Articles | Metrics

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Primary school teachers' knowledge regarding tooth trauma in Putuo district, Shanghai area YANG Li, RAN Xing, LI Yan 2021, 30 (4):  435-438.  doi: 10.19439/j.sjos.2021.04.019 Abstract ( 166 )   PDF (472KB) ( 140 )   PURPOSE: This study was conducted to evaluate the knowledge of primary school teachers regarding tooth trauma in Putuo district, Shanghai. METHODS: A questionnaire involving the knowledge of tooth trauma was designed. A total of 1 020 teachers from primary schools were invited to participate in the survey. SPSS 20.0 software package was used for statistical analysis of the data. RESULTS: A total of 973 valid questionnaires were collected. 74.8% of the respondents knew the information of the nearest medical institution dealing with dental trauma; 53.8% would first inform the parents when dental trauma occurred; 59.1% chose to leave the fractured teeth to the parents for treatment; 79.5 % knew that fourth graders had permanent anterior teeth. As to the preservation medium of broken teeth, 12.7% of the participating teachers chose the wrong answer.62.7% of the teachers answered correctly about the cleaning method of contaminated broken teeth. When asked about the best time to reimplant teeth, 19.6% of the teachers chose fewer than half an hour. Teachers' gender, age and whether they were trained before affected their scores of the scene simulation questions(P<0.05), and education background was not the most important factor (P>0.05). CONCLUSIONS: Primary school teachers in Putuo district partly mastered the emergency treatment knowledge of children's tooth trauma. Medical institutions and educational institutions need to strengthen training related to children's tooth trauma. References | Related Articles | Metrics

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Incidence and risk factors of temporomandibular joint disorders in patients with bimaxillary protrusion after orthodontic treatment CHENG Jie, ZHANG Dong, XIE Li-li, WANG Pu, LI Juan, HAO Wei 2021, 30 (4):  439-443.  doi: 10.19439/j.sjos.2021.04.020 Abstract ( 965 )   PDF (586KB) ( 182 )   PURPOSE: To observe the occurrence of temporomandibular joint disorder (TMD) in patients with bimaxillary protrusion after orthodontic treatment, and to explore the possible factors causing this phenomenon, so as to guide rational prevention of TMD in clinic. METHODS: The clinical data of 80 patients with bimaxillary protrusion who received orthodontic treatment in Hebei Provincial People's Hospital from March 2019 to October 2020 were retrospectively analyzed. The patients with TMD after orthodontic treatment were included in the experimental group and the remaining patients were included in control group. The baseline data questionnaire was designed for bimaxillary protrusion patients after orthodontic treatment. The risk factors of TMD were included in the study. Through a series of univariate and multivariate analysis, the influencing factors of TMD in patients with bimaxillary protrusion after orthodontic treatment were determined. SPSS 23.0 software package was used to analyze the data. RESULTS: Among 80 patients with bimaxillary protrusion after orthodontic treatment, 15(18.75%) were included in the experimental group, while 65(81.25%) did not have TMD, and were included in the control group. After a preliminary analysis of the baseline data, the variables with significant difference were included in the independent variables for univariate analysis. After adjusting for the influence of other baseline data, the results showed that younger age, girl, high stress perception scale score, bad oral habits, dental caries, history of maxillofacial trauma, bad eating habits, and root canal treatment history were the causes of bimaxillary protrusion. CONCLUSIONS: The risk factors of TMD of patients with bimaxillary protrusion after orthodontic treatment may be closely related to girl, younger age, high stress perception score, bad eating habits, previous caries, root canal treatment history and maxillofacial trauma. Therefore, it is necessary to strengthen the standardization of orthodontic treatment, publicize oral health awareness, establish good eating habits. Patients who had a history of root canal therapy, maxillofacial trauma and dental caries should be vigilant, which may be of positive significance in reducing the incidence of TMD. References | Related Articles | Metrics

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Evaluation of the effectiveness of treatment of 16 patients with tongue microcystic lymphatic malformation using bipolar coagulation forceps combined with 1% lauromacrogol foam sclerotherapy LI Jia-peng, ZHANG Guo-run, CHEN Ju-feng, LI Jin, LIU Shi-wei, HE Xian-ming, XIAN Dan 2021, 30 (4):  444-448.  doi: 10.19439/j.sjos.2021.04.021 Abstract ( 282 )   PDF (1027KB) ( 151 )   PURPOSE: To investigate the clinical efficacy and safety of bipolar coagulation forceps combined with 1% lauromacrogol foam sclerotherapy in the treatment of microcystic lymphatic malformation of tongue. METHODS: The clinical data of 16 patients with microcystic lymphatic malformation of the tongue admitted to the Department of Stomatology of Foshan First People's Hospital from April 2017 to April 2020 were retrospectively analyzed, including 7 males and 9 females, aging from 15 months to 21 years. The average age of patients was 8.32±1.21 years. The efficacy and complications of the patients were evaluated. RESULTS: All 16 patients were followed up for 6 to 12 months. The clinical response was evaluated as eleven patients (68.75%) for grade Ⅳ, three (18.75%) for grade Ⅲ, two (12.5%) for grade Ⅱ, and the effective rate was 87.5%. Necrosis of tongue mucosa and muscle occurred in 1 patient. CONCLUSIONS: Bipolar coagulation forceps combined with 1% lauromacrogol foam sclerotherapy is a minimally invasive, safe and effective treatment for tongue microcystic lymphatic malformation. References | Related Articles | Metrics