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25 August 2022, Volume 31 Issue 4 Previous Issue    Next Issue

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CONTENTS 2022, 31 (4):  336-336.  Abstract ( 55 )   PDF (746KB) ( 75 )   Related Articles | Metrics

Original Articles

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Effect evaluation on different treatment methods of the gap of immediate implantation in canine posterior mandible ZHANG Yi-wen, ZOU Duo-hong, ZHANG Zhi-yuan 2022, 31 (4):  337-342.  doi: 10.19439/j.sjos.2022.04.001 Abstract ( 318 )   PDF (2212KB) ( 211 )   PURPOSE: This study was aimed to explore the formation of new bone after different methods of filling the gap between the extraction socket and the implant in immediate implantation of the canine mandibular molar area. METHODS: Six Labrador dogs aged 1.5-2.0 years were used as the experimental subjects. The fourth premolar and the first molar were extracted from the mandible of each dog, and then 4 dental implants (Astra Tech®, 4.0 mm × 10 mm) were implanted respectively. The mesial and distal gaps between dental implants and the walls of extraction socket were treated in three methods: blank group (group NN), gelatin sponge with colloidal silver (Gelatamp) group (group EN), Gelatamp + absorbable collagen membrane (CM) group (group EG). At 12 weeks, the dogs were euthanized, and specimens were collected for micro-CT scanning and histological analysis. SPSS 25.0 software package was used for statistical analysis. RESULTS: The survival rate at 12 weeks after implantation was 100%. Micro-CT scan results showed no significant differences in new bone height, bone mineral density (BMD), bone volume fraction (BV/TV), bone surface area bone volume ratio (BS/TV), bone trabecular thickness (Tb.Th), bone trabecular number (Tb.N) and bone trabecular separation (Tb.Sp) among different groups. Histological analysis showed no significant differences in the area of new bone formation and bone-implant contact (BIC). CONCLUSIONS: After different treatments are performed on the gap between implants and extraction sockets, Gelatamp alone or in combination with CM has no significant effect on new bone formation, BIC, BMD, BV/TV, BS/TV, Tb.Th, Tb.N and Tb.Sp around implant. References | Related Articles | Metrics

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Maintenance of the stemness in CD133+ primary oral squamous cell carcinoma cells under different culture conditions WEN Xu-tao, MA Zhen, ZHANG Chong, Tao Shi-cheng, CHEN Xing-jin, MAI Hua-ming 2022, 31 (4):  343-348.  doi: 10.19439/j.sjos.2022.04.002 Abstract ( 192 )   PDF (1561KB) ( 125 )   PURPOSE: CD133+/- cells were isolated and purified from primary oral squamous cell carcinoma(OSCC) to explore the effects of different culture conditions on the maintenance and biological characteristics of CD133+ primary OSCC. METHODS: CCK-8 was used to detect the ability of proliferation and cisplatin resistance between CD133+/- cell subsets. Transwell assay was used to compare the invasive ability of two cell subsets under the action of cisplatin. Flow cytometry was used to detect the proportion of CD133+ cells cultured by serum free medium(SFM) (with or without leukemia inhibitory factor, LIF) or serum supplied medium (SSM). Subcutaneous tumor model in nude mice was used to verify the difference in tumorigenicity of CD133+/- cell subsets. The transplanted tumor was removed for H-E staining and immunohistochemistry (IHC). SPSS 25.0 software package was used for statistical analysis. RESULTS: Compared with CD133- cell subsets, CD133+ cell subsets had stronger ability of proliferation in vitro(P<0.05) and cisplatin tolerance(P<0.001). Cisplatin had a stronger effect on the invasive ability of CD133- cell subsets than CD133+ cell subsets (P<0.01). No significant difference in the proportion of CD133+ cell between LIF-SFM and no-LIF-SFM was found (P>0.05); but compared with SSM culture method, SFM culture method could maintain the proportion of CD133+ cell better(P<0.05). CD133+ cell subsets showed stronger tumorigenic ability with fewer cells than CD133- cell subsets in nude mice(P<0.05). CONCLUSIONS: Serum free culture method can better maintain the characteristics of primary OSCC stem cells, but the addition of LIF has no significant effect on the maintenance of stemness of primary OSCC cells. References | 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 2022, 31 (4):  349-353.  doi: 10.19439/j.sjos.2022.04.003 Abstract ( 744 )   PDF (3074KB) ( 185 )   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. References | Related Articles | Metrics

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Effect of continuous flushing out of root canal on fluid replacement in root canal during mechanical preparation using Ni-Ti instrument GUO Lin-xi, LI Xiang-fen, ZHAO Yuan-xi, SU Qin 2022, 31 (4):  354-358.  doi: 10.19439/j.sjos.2022.04.004 Abstract ( 182 )   PDF (1246KB) ( 199 )   PURPOSE: To evaluate the effect of continuous flushing out of the canal on fluid exchange in the root canal during mechanical preparation. METHODS: Sixty resin blocks with standardized root canals were divided into 5 experimental groups according to whether continuous flushing was performed during mechanical preparation. Injecting pure black ink into the root canals before each file preparation,the liquid exchange was calculated by measuring the absorbance value of the remaining liquid after performing different preparation and irrigation schemes. Meanwhile, computational fluid dynamics model was established which simulated the flow field in the canal when the file moved up-and-down. SPSS 19.0 software package was used for statistical analysis of the data. RESULTS: The absorbance value of the remaining fluid in the root canal of the three groups in which continuous flushing was performed during mechanical preparation differed significantly from the group without continuous flushing(P<0.05), but no significant difference among the three groups (P>0.05). Computer simulation confirmed that the “efficient regurgitation area” existed in the middle part of the root canal and fluid could be gradually transported to the apical area by the file's up-and-down motion. CONCLUSIONS: Continuous flushing out of the canal during mechanical preparation can replace the original solution in the canal partly, which is beneficial to conventional irrigation for cleaning of the root canal. References | Related Articles | Metrics

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Damage on paracellular pathway and effect on tight junction protein claudin-4 in rat parotid glands caused by ionizing radiation YAO Qing-ting, WU Yan-hui, LIU Shao-hua, XU Hui, LI Jun, SHI Liang 2022, 31 (4):  359-366.  doi: 10.19439/j.sjos.2022.04.005 Abstract ( 179 )   PDF (2063KB) ( 155 )   PURPOSE: To investigate the effect and the potential mechanism of ionizing radiation on secretory function and tight junction (TJ) protein claudin-4 in paracellular pathway of rat parotid glands. METHODS: Twenty four 8-week-old male Wistar rats were randomly divided into one control group(n=6) and three irradiation groups (i.e., 1-week group post-irradiation, 4-week group post-irradiation, and 12-week group post-irradiation, 6 rats in each group). The experimental glands of irradiation groups were exposed to X-radiation in one-time single doses of 20 Gy. The residual salivary secretion of parotid glands was measured by Schirmer's test. The pathological changes of gland tissues were observed under light microscope after hematoxylin-eosin(H-E) staining. The changes of TJs ultrastructure were observed under transmission electron microscopy (TEM). Immunofluorescence staining and Western blot were used to detect the expression levels of muscarinic acetylcholine M3 subtype receptor, aquaporin 5 (AQP5), and claudin-4 proteins. The experimental results were analyzed with SPSS 23.0 software package for one-way analysis of variance. RESULTS: The residual salivary secretion of irradiation group glands at 1, 4, and 12 weeks after irradiation was reduced compared with that of the control group(P<0.05), and the residual salivary secretion of irradiation group at 12 weeks was significantly lower than that at 4 weeks(P<0.05). Histologically, the dilation and congestion of interstitial vessels were observed at early stage after irradiation, and significant reduced number of acinar cells was found at late stage(P<0.05). In the irradiation groups, the ultrastructures of TJ were fuzzy, the electron density was decreased, and the TJ width at 1, 4, and 12 weeks was reduced compared with that in the control group. Immunofluorescence staining and Western blot indicated that the protein expression levels of M3 and AQP5 were down-regulated; however, the protein expression levels of claudin-4 were significantly increased at 1, 4, and 12 weeks after irradiation. CONCLUSIONS: After ionizing radiation, decreased secretory function of paracellular pathway, alterations in TJ structures, and up-regulation of claudin-4 expression may be involved in the mechanism of hyposecretion in rat parotid glands after irradiation. References | Related Articles | Metrics

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Effect of Er:YAG laser in pulp revascularization in miniature pigs MA Zhi-fei, ZHOU Meng-qi, WANG Li-zhen, CHENG Qing, HONG Jin 2022, 31 (4):  367-373.  doi: 10.19439/j.sjos.2022.04.006 Abstract ( 277 )   PDF (1998KB) ( 170 )   PURPUSE: To compare the effectiveness of Er:YAG laser and Ca(OH)2 in pulp revascularization in miniature pigs. METHODS: The second and third premolars of three 14-15-month-old miniature pigs were randomly divided into three groups: laser group, medication group and negative control group. After establishment of pulp necrosis model in each group, the negative control group had no more procedures, while the laser group and medication group were treated with pulp revascularization. Intracanal antisepsis operation was conducted using Er:YAG laser in laser group and Ca(OH)2 in medication group. The maxillary first premolars, as a positive control group, were left untreated and grew naturally. Three months after surgery, X-ray and cone-beam CT(CBCT) were taken. The animals were sacrificed, and the teeth were used to make H-E staining sections. The development of the teeth and the histological manifestations in the root canals of both groups were compared and evaluated by radiographic and histological assessment. SPSS 24.0 software package was used for statistical analysis of the data. RESULTS: Radiographic results showed that 3 months after surgery, apical foramen was closed in the laser group and the medication group. It also showed that intracanal calcification, and some specimens manifested root absorption. There was no significant difference between the two groups in the aspects of increase of root length, root thickness, or decrease of apical foramen size(P>0.05). Histological results showed that there was dentin-like and cementum-like tissue deposition along the root canal walls; apical closure was apparent; and fibrous connective tissue and cementum-like tissue or bone-like tissue formation in the root canal space were evident in the laser group and the medication group 3 months after surgery. There was no significant difference in the histological findings between the two groups(P>0.05). CONCLUSIONS: Er: YAG laser can be applied to pulp revascularization in miniature pigs, and the effect is equivalent to that of intracanal medication using Ca(OH)2. References | Related Articles | Metrics

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Expression and significance of Treg/Th17 and CD4+/CD8+ T lymphocytes in experimental periodontitis in rats MO Peng, LI Xiao-yue, LIU Yao-hui 2022, 31 (4):  374-378.  doi: 10.19439/j.sjos.2022.04.007 Abstract ( 214 )   PDF (1013KB) ( 160 )   PURPOSE: To explore the expression of helper T cell 17/regulatory T cell (Th17/Treg) and CD4+/CD8+ T lymphocyte in experimental periodontitis in rats, and analyze its clinical significance. METHODS: Twenty SPF male SD rats were randomly divided into experimental group (inoculate Porphyromonas gingivalis suspension into gingival sulcus) and control group, with 10 rats in each group. The experimental group was smeared with Porphyromonas gingivalis suspension every other day within 1 week after operation, and the two groups were caged for 8 weeks. After the rats were sacrifical under anesthesia, the jaw tissue of the left maxillary second molar was stained with methylene blue to observe and measure the loss of alveolar bone (ABL). Hematoxylin-eosin (H-E) staining was used to observe the histopathological changes of the jaw. Rat peripheral blood mononuclear cells (PBMC) and T cells were isolated and cultured, Treg, Th17 cells and CD4+, CD8+ T lymphocytes in peripheral blood were detected by flow cytometry. The levels of serum interleukin-17(IL-17), IL-10 and IL-4, INF-γ were detected by enzyme-linked immunosorbent assay (ELISA). Expression changes of retinoic acid related orphan nuclear receptor (RORγt), forkhead wing like transcription factor 3 (Foxp3) and gap junction protein(Cx40) in jaw tissue were detected by Western blot. The data were statistically analyzed by SPSS 19.0 software package. RESULTS: Compared with the control group, ABL, peripheral blood Th17 ratio, Th17/Treg ratio, CD4+ ratio, CD4+/CD8+ T lymphocyte ratio, serum IL-17, IL-10 and IL-4 level, Foxp3 and Cx40 protein in jaw tissue were signifinantly increased in the experimental group(P<0.05), while Treg ratio, INF-γ, RORγt protein in jaw tissue significantly decreased(P<0.05) in the experimental group. CONCLUSIONS: Imbalance of Treg/Th17 and CD4+/CD8+ T lymphocytes leads to the abnormal high expression of inflammatory factors IL-17, IL-10 and IL-4, which may be closely related to the pathogenesis of experimental periodontitis. References | Related Articles | Metrics

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Application of sulfylated calcium alginate composite hydrogel loaded with zinc-based zeolite imidazole for the treatment of periodontitis OUYANG Ming, WANG Guo-hua 2022, 31 (4):  379-383.  doi: 10.19439/j.sjos.2022.04.008 Abstract ( 181 )   PDF (1637KB) ( 208 )   PURPOSE: To explore the feasibility of adhesive thiomer calcium alginate composite hydrogel (ZIF-8@CHA-SH) containing metal-organic framework for the treatment of periodontitis in rats. METHODS: Preparation and characterization of ZIF-8@CHA-SH were performed, and the morphology and chemical composition were observed. The antibacterial properties were detected by plate coating method and scanning electron microscope. CCK-8 and live/dead cell fluorescence staining were used to evaluate the toxicity of ZIF-8@CHA-SH on gingival fibroblasts. The anti-inflammatory and tissue repair promoting effects of ZIF-8@CHA-SH were verified by animal experiments. GraphPad Prism 7.0 software was used for statistical analysis. RESULTS: The successful synthesis of ZIF-8@CHA-SH was proved by scanning electron microscopy, energy spectrum analysis, Fourier transform infrared spectroscopy and X-ray diffraction. ZIF-8@CHA-SH had excellent antibacterial ability, and the antibacterial rates against Escherichia coli, Staphylococcus aureus and Streptococcus mutans were (99.88±0.12)%, (99.81±0.32)% and (95.53±3.08)%, respectively（P<0.001）. The cell viability rate of ZIF-8@CHA-SH was (91.64±3.66)% after 5 days of co-culture with human gingival fibroblasts (P=0.6). In vivo experiments showed that ZIF-8@CHA-SH could reduce the infiltration of inflammatory cells and the expression of pro-inflammatory factor IL-6 in rats with periodontitis. CONCLUSIONS: ZIF-8@CHA-SH has excellent biological performance, which can effectively treat periodontitis caused by bacteria, and provids a new strategy for the treatment of periodontal diseases in the future. References | Related Articles | Metrics

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Analysis of multimodal ultrasound in differential diagnosis of salivary gland tumors LYU Huan, XIONG Ping, ZHANG Wei-qian, GONG Xia, LI Jia, DING Ang-ang 2022, 31 (4):  384-388.  doi: 10.19439/j.sjos.2022.04.009 Abstract ( 164 )   PDF (1166KB) ( 123 )   PURPOSE: To explore the differential diagnosis of salivary gland tumors by multimodal ultrasound and to establish a preliminary scoring system by assigning meaningful parameters. METHODS: Seventy-seven tumors from 69 patients with salivary gland tumors were examined by two-dimensional gray-scale ultrasound, color Doppler flow imaging (CDFI), superb microvascular imaging(SMI), real time tissue elastography(RTE) and acoustic radiation force impulse (ARFI). Different scoring schemes were obtained for the assignment and combination of meaningful parameters. The ROC curve of each scheme was drawn, and the one with the largest area under the curve was taken as the best scoring scheme. SPSS 25.0 software package was used for statistical analysis of the data. RESULTS: There were significant differences in tumor shape, boundary, posterior echo, blood flow resistance index, RTE grade and ARFI average value between benign and malignant salivary gland tumors(P<0.05). The scoring scheme 7, which was composed of the above 6 parameters, was the best scoring scheme. When each parameter was assigned a score of 1, the total score was 6, and the area under the curve was 0.944. The sensitivity, specificity and accuracy of distinguishing benign and malignant salivary gland tumors with ≥4 points were 80.0%, 98.4% and 94.8%, respectively. CONCLUSIONS: Application of multimodal ultrasound and establishment of a scoring system can effectively improve the ability of ultrasound in the differential diagnosis of benign and malignant salivary gland tumors. References | 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 2022, 31 (4):  389-394.  doi: 10.19439/j.sjos.2022.04.010 Abstract ( 359 )   PDF (886KB) ( 171 )   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. References | Related Articles | Metrics

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Correlation analysis of supragingival microbiome and host blood lipid levels ZHAO Fen, DONG Ting, YUAN Ke-yong, JIN Qiao-qiao, HUANG Zheng-wei, MA Rui 2022, 31 (4):  395-399.  doi: 10.19439/j.sjos.2022.04.011 Abstract ( 181 )   PDF (1257KB) ( 155 )   PURPOSE: To analyze the correlation between microbiome of supragingival plaque and host blood lipid levels. METHODS: Samples of supragingival plaques from 68 volunteers aged 45-60 years were collected. The total DNA was extracted, and 16S rDNA V3-V4 regions were amplified via PCR. The amplified products were sequenced by Illumina MiSeq PE300. After that, OTU clustering and species annotation were carried out. Then, the correlation of annotated species (genus level) and host blood lipid level were calculated with Spearman correlation analysis. SPSS 16.0 software package was used for statistical analysis. RESULTS: The average number of sequences obtained from the supragingival plaque samples was 41 929, and the number of OTUs obtained by clustering was 1 037. A total of 25 phyla, 45 classes, 92 orders, 155 families and 330 genera were annotated. Species heat maps showed a high degree of consistency in the species composition abundance of 68 samples. Spearman correlation analysis showed that among the supragingival microorganisms, Alloprevotella spp., Dialister spp., Peptostreptococcus spp. and Prevotella 7 spp., were negatively correlated with the host serum total cholesterol/low density lipoprotein cholesterol level. Neisseria spp. was positively correlated with host serum high-density lipoprotein cholesterol, but negatively correlated with Prevotella 2 spp.. CONCLUSIONS: The compositional structure of the supragingival microbiome is relatively stable and has a correlation with the host blood lipid levels. Profiles of supragingival microbiome can be promising biomarkers of the lipid metabolism of the host. References | Related Articles | Metrics

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Effects of oral propranolol on urine bFGF, MMP-2, MMP-9 expression in children with proliferative infantile hemangioma YUAN Wei-li, WANG Xu-kai 2022, 31 (4):  400-405.  doi: 10.19439/j.sjos.2022.04.012 Abstract ( 220 )   PDF (1122KB) ( 146 )   PURPOSE: To investigate the effect of propranolol on urine bFGF, MMP-2, MMP-9 expression of children with proliferative infantile hemangioma(IH), so as to clarify the mechanism of propranolol in treating IH. METHODS: From June 2018 to June 2019, thirty-four children with proliferative IH were treated with oral propranolol. In addition, twenty-one normal children (age <12 months) were chosen as the control group. 10 mL of sterile morning urine were collected before and 2 months after oral administration of propranolol in infants with IH. All blood samples were placed in ordinary disinfection test tubes, centrifuged at 1 000 r/min for 10 min, the supernatant of urine was collected and stored separately. The urine samples of normal control group were processed in the same way. The expression levels of bFGF in the urine of children with proliferative IH before and 2 months after oral administration of propranolol and in the normal control group were detected by enzyme-linked immunosorbent assay (ELISA). The expression levels of MMP-2 and MMP-9 in the urine of children with proliferative IH before and 2 months after treatment and in the control group were detected by gelatin zymography. SPSS 22.0 software package was used to analyze the data. RESULTS: Two months after oral propranolol treatment, the concentration of bFGF in urine was significantly lower than that before treatment (P<0.01), but still significantly higher than that in the control group (P<0.05). The expression levels of MMP-2 and MMP-9 were significantly lower than those before treatment(P<0.01), but still higher than those in the control group (P<0.05). CONCLUSIONS: One of the mechanisms of propranolol in the treatment of children with proliferative IH may be through inhibiting the expression levels of bFGF, MMP-2 and MMP-9, and then inhibiting the proliferation and angiogenesis of vascular endothelial cells in IH, so as to achieve the effect of treating hemangioma. The detection of the expression levels of bFGF, MMP-2 and MMP-9 in urine can be used as the index for oral propranolol treatment of children with proliferative IH. References | Related Articles | Metrics

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Effect of preformed titanium mesh combined with concentrated growth factor membrane on implant restoration of insufficient bone mass in anterior teeth of 31 consecutive cases YAN Xu, MI Da-wei, ZHAO Ming, PENG Bo 2022, 31 (4):  406-409.  doi: 10.19439/j.sjos.2022.04.013 Abstract ( 319 )   PDF (524KB) ( 136 )   PURPOSE: To explore the effect of preformed titanium mesh combined with concentrated growth factor (CGF) membrane on implant restoration of insufficient bone mass in the anterior teeth. METHODS: A total of 62 patients with insufficient bone mass in the anterior teeth who visited the hospital from January 2017 to February 2020 were selected, and they were divided into experimental group(n=31) and control group (n=31) according to computer digital table method. Both groups of patients used implant restoration. In the control group, the bone defect area was covered with a preformed titanium mesh after implant restoration, while in the experimental group, the bone defect area was covered with a preformed titanium mesh and CGF membrane after implant restoration. After 12 months of follow-up, the success rate of the two groups was counted. Alveolar ridge height, bone increment, alveolar bone density, bone thickness, pink aesthetic index (PES) and complications 6 months after surgery were compared between the two groups. SPSS 19.0 software package was used for statistical analysis. RESULTS: During the 12-month follow-up, the implantation success rate in both groups was 100%, and there was no implant loosening or dropping. There was no significant difference in the height of the alveolar ridge between the two groups before operation(P>0.05). The postoperative alveolar ridge elevation and bone increment in the experimental group were significantly higher than those in the control group(P<0.05). There was no significant difference in alveolar bone density and bone thickness between the two groups before operation(P>0.05). The alveolar bone density and bone thickness of the two groups 6 and 12 months after operation were significantly lower than those before operation (P<0.05). The alveolar bone mineral density 6 months after operation in both groups was significantly lower than that 12 months after operation(P<0.05), and the alveolar bone thickness 6 months after operation in both groups was significantly higher than that at 12 months after operation (P<0.05). The alveolar bone density and bone thickness of the experimental group 6 and 12 months after operation were significantly higher than those in the control group(P<0.05). The postoperative PES score of the experimental group was significantly higher than that of the control group(P<0.05). There was no significant difference in the total incidence of complications between the two groups 6 months after operation(P>0.05). CONCLUSIONS: Preformed titanium mesh combined with CGF membrane is used in implant restorations for patients with insufficient bone mass in the anterior teeth, and the effect is definite. It can enhance the cosmetic effect of implant restorations, improve postoperative bone metabolism, and is safe and reliable. References | Related Articles | Metrics

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Risk factors for the presence of dental black stain in 82 children YANG Bin, ZHANG Hao, ZHANG Ying 2022, 31 (4):  410-413.  doi: 10.19439/j.sjos.2022.04.014 Abstract ( 228 )   PDF (491KB) ( 144 )   PURPOSE: To investigate the prevalence of dental black stain in children and analyze the risk factors of dental black stain. METHODS: We conducted this investigation through a case-control study. A total of 164 children (82 children with dental black stain and 82 children without dental black stain) were recruited from Shanghai Stomatological Hospital. Data regarding their oral hygiene habits, dietary habits, diseases and medication situations were collected by a questionnaire survey. Samples of saliva were collected for pH analysis. Statistical analysis were performed using SPSS 21.0 software package. RESULTS: Univariate analysis showed that the proportion of children in the black stain group who used bottled water as the main source of drinking water was lower than that in the control group (18.3% vs 35.4%), and the proportion of children who used Chinese herbs or eating more vegetables(≥2 times/day) was higher than that in the control group(23.2% vs 9.8%,29.3% vs 14.6%), the differences were statistically significant (P<0.05). Multivariate logistic regression analysis showed that taking Chinese herbal medicine and eating more vegetables(≥2 times/day) were risk factors for tooth black stains(P<0.05), and use of bottled water as the main source of drinking water was a protective factor. CONCLUSIONS: Taking Chinese herbal medicine and eating more vegetables(≥2 times/day) are risk factors for tooth pigmentation, while drinking more bottled water can reduce the risk of pigmentation. References | Related Articles | Metrics

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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 2022, 31 (4):  414-417.  doi: 10.19439/j.sjos.2022.04.015 Abstract ( 747 )   PDF (606KB) ( 168 )   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. References | 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 2022, 31 (4):  418-422.  doi: 10.19439/j.sjos.2022.04.016 Abstract ( 239 )   PDF (1217KB) ( 216 )   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. References | Related Articles | Metrics

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Short-term comparison of the clinical efficacy of angulated screw-retained implant crowns and cemented implant crowns in esthetics region LYU Xiao-lei, SHI Jun-yu, QIAN Shu-jiao, LAI Hong-chang 2022, 31 (4):  423-428.  doi: 10.19439/j.sjos.2022.04.017 Abstract ( 260 )   PDF (865KB) ( 245 )   PURPOSE: To compare the clinical efficacy of angulated screw channel abutments and prefabricated titanium abutments on the restoration of single implant crowns in esthetics region. METHODS: The study was a prospective, single center, randomized controlled trial. Patients with the need of restoration of single tooth in esthetics region were included from June 2018 to June 2019. Forty patients were randomly assigned into two groups: screw-retained crowns with angulated screw channel abutments(angulated group, AG) and cemented crowns with prefabricated Ti abutments (cemented group, CG). Clinical and radiological evaluations were performed on the day of final crowns delivery and 6 months later. Implant survival rate, marginal bone loss (MBL), mechanical complications, peri-implant conditions (Probing depth, PD; bleeding on probing, BOP%), pink esthetics score/white esthetics score(PES/WES) and patients' satisfaction were assessed. The data was analyzed with SPSS 19.0 software package. RESULTS: Thirty-six patients (AG: 19, CG: 17) attended the 6-month clinical trial. Implant survival rates were both 100% in two groups. The MBL was (0.21±0.18) mm for AG and (0.38±0.40) mm for CG (P>0.05). The BOP% was significantly higher in AG than that in CG (P=0.04). No significant difference of mechanical complications, PD, PES/WES and patients’ satisfaction was found between the two groups(P>0.05). CONCLUSIONS: Based on the present results, both treatment options show acceptable clinical outcomes in the short term. Angulated screw-retained crowns may benefit the peri-implant soft tissue; however, studies with long-term follow-up are needed to verify the results. References | Related Articles | Metrics

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Characteristics of condylography during masticatory movement in patients with Class Ⅱ division 1 malocclusion and temporomandibular disorders ZHANG Chun-xiang, WANG Tian-qi, LIU Dong-qiao, DUAN Xiao-ni, ZHI Chen, WANG Jing, LIN Chen 2022, 31 (4):  429-434.  doi: 10.19439/j.sjos.2022.04.018 Abstract ( 239 )   PDF (1044KB) ( 168 )   PURPOSE: To investigate the characteristics of condylography of masticatory movement in patients of Class Ⅱ division 1 malocclusion with temporomandibular disorders (TMD), and the effects of TMD and Angle Ⅱ1 malocclusion factors on the condylography of masticatory movement. METHODS: According to the inclusion criteria of the experiment, ten normal occlusion subjects without TMD（nTMD-N）, ten Angle Ⅱ1 patients without TMD（nTMD-Ⅱ1）and 14 Angle Ⅱ1 patients with TMD（TMD-Ⅱ1）were included. Cadiax IV was used to record the condylography of the subjects during mastication, and the data of condylography was measured and analyzed by GDSW software. The results were analyzed with SPSS 26.0 software package. RESULTS: The characteristics of condylography in nTMD-Ⅱ1 and TMD-Ⅱ1 groups were different from those of nTMD-N group. During unilateral mastication on the left or right side, there was no significant difference among nTMD-N group, nTMD-Ⅱ1 group and TMD-Ⅱ1 group. During bilateral mastication, the SCI value of nTMD-Ⅱ1 group was significantly higher than that of nTMD-N group, and the S value of nTMD-N group was significantly higher than that of nTMD-Ⅱ1 group (P<0.05). CONCLUSIONS: During unilateral masticatory movement, TMD and Angle Ⅱ1 malocclusion has little effect on the masticatory movement trajectory. Angle Ⅱ1 malocclusion has influence on bilateral masticatory movement, and the amplitude of condylar movement in patients with ClassⅡdivision 1 malocclusion is smaller than that in normal mastication. TMD has no significant effect on the masticatory movement condylography of the patients. References | Related Articles | Metrics

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Clinical effectiveness evaluation of gingival recession by using perioscope as an adjunct to non-surgical periodontal therapy LU Wei-qing, ZHANG Wei-liang, XIANG Wen-jing, LIU Bin-yi, CAO Wei-yu, YANG Yi-ming 2022, 31 (4):  435-438.  doi: 10.19439/j.sjos.2022.04.019 Abstract ( 233 )   PDF (530KB) ( 205 )   PURPOSE: To investigate the effects of ultrasonic scaling and root planning(SRP) assisted by perioscope on gingival recession of maxillary lateral incisor. METHODS: Thirty-six outpatients with moderate to advanced chronic periodontitis from the Department of Periodontology at Dental and Ophthalmic Clinic of Putuo District from June 2020 to December 2020 were collected as research objects. Periodontal treatment was carried out according to a single-blind split-mouth self-control design randomly with(experimental group, namely perioscope group) or without(control group, namely SRP group) periodontal endoscope.The labial periodontal probing depth (PD), labial attachment loss (AL) and gingival recession(GR) in the maxillary lateral incisors were recorded at baseline, 3 and 6 months, and compared among groups by SPSS 22.0 software package. RESULTS: There was no significant difference between perioscope group and SRP group at baseline. ΔGR (the recession extent of gum within two observation time) in perioscope group was significantly smaller than that in SRP group at 3 months（P<0.05）. There was no significant difference in other periodontal indicators at 3 and 6 months between the 2 groups after treatment, but it can be found that the degree of PD reduction and AL improvement in perioscope group was more than those in SRP group, this trend was most obvious at 3 months. PD and AL were significantly different between baseline and 3 months or 6 months in the two groups. There were significant differences in ΔGR at 3 months and 6 months between the two groups. CONCLUSIONS: Compared with routine SRP, the extent of root surface debridement with perioscope-assisted SRP is thorough and less invasive, and the reduction of gingival recession of labial surface of maxillary lateral incisor at 3 months is significantly less; thus, the aesthetic effect is prominent. References | 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 2022, 31 (4):  439-444.  doi: 10.19439/j.sjos.2022.04.020 Abstract ( 580 )   PDF (1500KB) ( 244 )   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. References | Related Articles | Metrics

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Practice and thinking of promoting ideological and political education in system integrated curriculum of stomatology YU Song, ZHANG Wen-hui 2022, 31 (4):  445-448.  doi: 10.19439/j.sjos.2022.04.021 Abstract ( 224 )   PDF (613KB) ( 198 )   System integrated curricula are based on organs and systems. They closely combine basic medicine theory with clinical practice, aiming to stimulate students' subjective initiative and improve their ability to analyze and solve problems. In order to implement moral education concept in the teaching process of professional courses for dental students, dental teaching teams of Shanghai Jiao Tong University School of Medicine has carried out teaching reforms including constructing a stronger team of teachers, making ideological and political achievement goals of curriculum, finding out and writing ideological and political materials. Taking advantages of the various teaching forms of integrated curricula, the curriculum ideological and political education is run through the whole process of professional teaching, in order to cultivate dental talents with both ideological and humanistic ability. References | Related Articles | Metrics