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Research Advances on Effect of Photobiomodulation Therapy on Root Resorption in Orthodontic Treatment ZHANG Jiaxi, ZHANG Xizhong 2024, 40(8): 665-669.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.001 Abstract ( 84 )   PDF (838KB) ( 42 )   Root resorption is one of the most dangerous complications during orthodontic treatment. Mild root resorption can be repaired after removing force. However, there is no effective measure for severe root resorption. Photobiomodulation therapy, as a new physical therapy, has the advantages of small size, non-invasion, wide wavelength, limited scope of action, and biological safety. The range of its wavelength covers the range of mitochondrial absorption wavelength, and the biological activity of tissues or cells changes after being irradiated by red or near-infrared light, upregulating the anti-inflammatory and other related factors, promoting cellular ATP production, accelerating local blood microcirculation, promoting the repair of soft and hard tissues, and inhibiting or repairing resorbed tooth. The effect of photobiomodulation therapy depends on four elements, i.e. the parameter of the wavelength, energy density, power density, and irradiation frequency, obeying the "biphasic dose effect". Biological efficacy is parameter dependent, making it difficult to obtain optimal parameters. However, the unique advantages of photobiomodulation therapy make it have great application potential in the field of orthodontics. References | Related Articles | Metrics

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An Update on Research Progress of Chlorhexidine Reduced Susceptibility in Oral Bacteria and Relative Mechanisms REN Jingyi, ZHOU Wenjuan 2024, 40(8): 670-675.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.002 Abstract ( 57 )   PDF (898KB) ( 46 )   Chlorhexidine (CHX) is the most widely applicated biocide for clinical surface disinfection, however, there is a lack of regulations on its usage. The long-term and extensive utilization of CHX has led to the reduced susceptibility against CHX and cross-resistance towards an array of critical antibiotics in clinical isolates of multiple essential pathogens related to nosocomial infections. However, the potential resistance risk in oral bacteria has been overlooked even though CHX has been applied as the gold standard in dentistry for over 50 years. Hence, the current review aims to summarize the evidence of the reduced susceptibility to CHX in oral bacteria and elucidate the relative mechanisms to raise the concern about its potential risk in dental practice. References | Related Articles | Metrics

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Research Progress of Optical Coherence Tomography on Evaluating Soft Tissue Quality in Oral Implantion Area YU Mengqin, ZHANG Zhihong 2024, 40(8): 676-681.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.003 Abstract ( 33 )   PDF (7255KB) ( 5 )   The quality of soft tissue in the oral implantation area can be used to preliminarily predict the aesthetic effect, marginal bone resorption, and the occurrence of peri-implant lesions after implantation. In recent years, the evaluation of soft tissue quality has been in constant exploration and practice. Optical coherence tomography uses the optical principle to project the examined object, and the light penetrates through the gum and backscatteringly obtains soft tissue data, which is converted into 2D or 3D images through computer software to clearly show the soft tissue structure. The quality of the proposed implantation area can be preliminarily evaluated. This article reviews the application and research progress of OCT in evaluating gingival thickness, keratinized mucosa width, supracrestal tissue height, and gingival soft tissue inflammation before oral implantation. References | Related Articles | Metrics

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Impact of Setd2 Knockout in Osteocytes on Mouse Bone Mass NIU Jiaxin, YUAN Guohua 2024, 40(8): 682-686.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.004 Abstract ( 32 )   PDF (4480KB) ( 22 )   Objective: To elucidate the regulatory impact of Setd2 within osteocytes on bone formation. Methods: Setd2flox/flox mice were crossed with the Dmp1Cre strain to generate Dmp1Cre, Setd2flox/flox mice. All mice analyzed were maintained on the C57BL/6 background. Immunohistochemical staining was used to confirm the specific deletion of Setd2 in osteocytes. Micro-CT and three-dimensional reconstruction were used to analyze cortical and trabecular bone mass variations in bone tissues from same-litter mice at 6 months of age. Differences in bone morphology parameters, such as trabecular number, thickness, and separation, were conducted using CTAn software. Additionally, safranine O/fast green staining was utilized to observe changes in the blue-stained bone tissue regions in Setd2 cKO and control mice. Immunohistochemical staining was used to observe trimethylation of lysine 36 on histone 3 (H3K36me3). Results: With successful Setd2 deletion in osteocytes, Setd2 cKO mice exhibited smaller body size compared to littermate controls. Micro-CT and bone morphometry analysis revealed that, at 6 months of age, Setd2 cKO mice displayed thinner cortical bone, decreased bone density, reduced trabecular thickness, lower trabecular number, and increased trabecular separation compared to control mice (P<0.05). Safranine O/fast green staining further indicated a reduced blue-stained bone tissue area in Setd2 cKO mice compared to controls. Compared to the control group mice, there was a loss of H3K36me3 modification in Setd2 cKO mice. Conclusion: The loss of Setd2 in osteocytes affected the trimethylation modification of H3K36, resulting in a decrease in mouse bone mass. References | Related Articles | Metrics

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Effects of Local Injection of Different Doses of Anti-RANKL Antibody on Alveolar Bone Osteoporosis in Rats ZHOU Jing, ZHANG Jing, WANG Lu, MA Ling, SU Jingyang, ZHANG Zhao 2024, 40(8): 687-692.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.005 Abstract ( 33 )   PDF (8289KB) ( 13 )   Objective: To explore the effect of local injection of different doses of anti-receptor activator of nuclear factor kappa-B ligand (RANKL) antibody on alveolar bone osteoporosis in rats. Methods: A total of 30 SD rats were selected, with 9 in the control group and 21 in the experimental group. The rat alveolar bone osteoporosis model was established by subcutaneous injection of dexamethasone. The model was verified 5 weeks later. After successful verification, the experimental group was randomly divided into 3 groups. Experimental group Ⅱ and Ⅲ were injected with 0.1 μg/site and 1 μg/site of rabbit anti-rat RANKL antibody in the palatine side of the upper right first molar of rats on day 1, 3, and 7, and experimental group Ⅰ was injected with equal volume of saline. Bone mineral density (BMD) and bone volume fraction (BV/TV) of alveolar bone in the right upper first molar region were measured by micro-CT after 1 week. The changes of histomorphology and the number of osteoclasts were observed by histopathological staining of alveolar bone. Enzyme linked immunosorbent assay (ELISA) was used to detect the RANKL/osteoprotegerin (OPG) ratio in gingival tissue. Results: The rat alveolar bone osteoporosis model was established successfully. Micro-CT and histopathology showed that after antibody injection, alveolar bone BMD and BV/TV were increased, the number of osteoclasts were decreased, osteoblasts were actived, and bone marrow cavity were decreased, but there was no significant change between high and low doses of antibody. ELISA results showed that the ratio of RANKL/OPG in gingival was significantly decreased after high dose antibody injection, however, it was decreased without significance after low dose antibody injection. Conclusion: Local injection of anti-RANKL antibody can improve the alveolar bone osteoporosis in rats, and low dose could reach the improvement effect. References | Related Articles | Metrics

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Mechanical Properties and Microstructure of Pure Titanium through Adding Trace Ti-6Al-4V Powder in SLM Manufacturing SAIMI·Ayisen, HE Junjie, ZHANG Wenna, LUO Xiaoping 2024, 40(8): 693-699.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.006 Abstract ( 22 )   PDF (7389KB) ( 5 )   Objective: To investigate the mechanical properties of pure titanium by adding trace Ti-6Al-4V powder in SLM printing manufacturing at two different heat treatment temperatures (650 ℃,2 h and 700 ℃,2 h) and different scanning speeds (1000 mm/s and 500 mm/s). Methods: SLM samples with two different scanning speed (GA:1000 mm/s,GB:500 mm/s) were prepared and heat treated with 650 ℃,2 h (HT1) and 700 ℃,2 h (HT2). The mechanical properties of the materials were tested, and the fracture morphology and microstructure were observed with LSCM and SEM. Results: The tensile strength of SLM printed pure titanium samples was higher at 1000 mm/s(>20%), and the elongation was higher at 500 mm/s. Consistent annealing revealed that the 650 ℃, 2 h treatment yielded outstanding mechanical performance at both scanning speeds. Conclusion: SLM-ed pure titanium material by adding trace Ti-6Al-4V powder can better meet the requirements of oral restorations compared to SLM-ed Ti-6Al-4V alloy. References | Related Articles | Metrics

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Torque Loss in Abutment Screw at Ten Minutes and One Month after Implant Restoration: A Cross-sectional Study XU Yingxin 2024, 40(8): 700-703.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.007 Abstract ( 28 )   PDF (1329KB) ( 17 )   Objective: To investigate torque loss in the abutment screw of single posterior implant restoration at 10 minutes and 1 month after initial tightening of the screw in premolar or molar position with 4 different implant systems. Methods: From July 2021 to June 2023, 268 patients who underwent single posterior tooth implant surgery at the Implant Department of Peking University Shenzhen Hospital were transferred to the Prosthetic Department for restoration three months after the surgery. The patients were worn a cement-retained zirconia crown with an opening hole in the occlusal surface for the convenient of detachment. After adjustment, the central screws of the abutments were tightened through opening hole according to the preload suggested by the manufacturer. At 10 minutes and 1 month after the initial tightening, when tightening the central screw of the abutment again to the manufacturer’s suggested preload, the clockwise rotation angle of the torque wrench from the starting point to the end point was recorded. Results: At 10 minutes after the initial tightening, the rotation angle of torque wrench for all experimental groups was 0 degrees. However, at 1 month after the initial tightening, no matter which group, tooth, or implant, the rotation angle of torque wrench was greater than 0 degrees. Among them, 29 cases (10.82%) were greater than 90 degrees, however, no significant differences were found between groups (P>0.05). No case reached or exceeded 180 degrees. Conclusion: In some implant systems, 1 month after a single posterior implant restoration, the loss of torque in the central screw of the abutment is more significant in some cases, and the proportion is not related to whether the central screw of the abutment has been tightened again 10 minutes after the initial tightening, as well as the premolar or molar site and the implant system used. References | Related Articles | Metrics

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Quantitative Digital Assessment of Vertical Mucosal Thickness and Its Correlation with Cortical Bone Thickness in Proposed Implant Area ZHANG Ke, CHEN Xubing 2024, 40(8): 704-709.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.008 Abstract ( 24 )   PDF (2056KB) ( 12 )   Objective: To assess the accuracy of digital measurement of vertical mucosal thickness in the proposed implant area and to investigate the correlation between vertical mucosal thickness and the corresponding cortical bone thickness. Methods: Forty-eight patients who underwent digital tooth-supported guide implant surgery from January 2020 to June 2023 were selected for this study, and all the patients completed the collection of cone beam CT (CBCT) data and 3Shape mouth scan data, and the vertical mucosal thickness of the proposed implantation area was measured after the completion of the fitting in the 3Shape Implant Studio software and the corresponding cortical bone thickness (recorded as digital technometric method). Vertical mucosal thickness was measured intraoperatively using a modified periodontal probe embedded in a digitally guided plate guide ring (recorded as modified gingival puncture method). Differences and consistency between the two measurements of vertical mucosal thickness in the proposed implant area were assessed by paired t-tests and Bland-Altman analyses, and the correlation between vertical mucosal thickness and cortical bone thickness was analysed using the Pearson correlation coefficient. Results: The digital technique and the modified gingival puncture method had not significant difference in measuring vertical mucosal thickness in the proposed implant area (P>0.05) and showed good agreement. There was no significant correlation between vertical mucosal thickness and cortical bone thickness (P>0.05). Conclusion: The digital technique is an accurate method for measuring vertical mucosal thickness in the proposed implant area, and there is no significant correlation between vertical mucosal thickness and the corresponding cortical bone thickness. References | Related Articles | Metrics

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Establishment and Analysis of A Mouse Model of Syndromic Cleft Lip and Palate Induced by All-trans Retinoic Acid WANG Yumeng, CHI Dandan, ZHANG Beibei, DUAN Xiaohong, HUANG Yongqing 2024, 40(8): 710-714.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.009 Abstract ( 29 )   PDF (8790KB) ( 8 )   Objective: To establish and analyze a mouse model of syndromic cleft lip and palate in mice. Methods: Pregnant mice on gestation day 10.5 (GD10.5) were gavaged with 90 mg/kg of atRA or corn oil and DMSO solvent. Upon euthanasia of pregnant mice on GD17.5, embryos were collected. Stereomicroscope, paraffin embedding and sectioning, and hematoxylin-eosin (HE) staining were used to observe the development of embryos. Immunofluorescence staining was used to verify the expression of retinoic acid receptor alpha (RARα). Results: The embryos in the atRA group showed cleft palate, limb deformities, abnormal molar development, and non-compaction of ventricular myocardium. Immunofluorescence staining showed the expression of RARα increased in molar and palate of embryos of the atRA group. Conclusion: The mouse cleft palate model induced by atRA presents as syndromic cleft lip and palate, and atRA affects the development of mice by activating of RARα receptor. References | Related Articles | Metrics

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Drug Sensitivity Analysis and Preliminary Clinical Application Based on Patient-derived Organoid in Oral Squamous Cell Carcinoma CHEN Lin, CHEN Yinyu, LI Xinran, GE Liangyu, WANG Shoupeng, MENG Jian 2024, 40(8): 715-721.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.010 Abstract ( 24 )   PDF (7424KB) ( 11 )   Objective: To perform drug sensitivity experiments on patient-derived oral squamous cell carcinoma (OSCC) organoid models and to design individualized drug therapies for the corresponding patients. Mehthods: In the present study, patient-derived organoid (PDO) models were established by obtaining fresh specimens through biopsy or radical operation. These models were used to determine the sensitivity of six drugs (cisplatin, paclitaxel, 5-FU, Cetuximab, Alpelisib, and Nutlin-3) to OSCC. Four of the biopsy patients were given individualized medication according to the experimental results and the short-term therapeutic effect was observed after two courses of treatment. Results: Ten OSCC organoids were successfully established (success rate=10/12, 83.3%) , which could be stably passaged and amplified for more than four generations. The histopathology characteristics of OSCC were highly consistent with those of their parental tumor tissues. The PDO models derived from different patients showed individual differences in the results of drug sensitivity tests. The tumor control results of 4 biopsy patients all met the partial remission criteria, which were consistent with the experimental results. Conclusion: The histopathological characteristics of the established OSCC PDO models were highly similar to those of their parental tumors. The results of the in vitro drug sensitivity tests based on these models were consistent with the clinical treatment response of the corresponding patients, laying a foundation for the establishment of a new individualized and precise drug treatment system for OSCC. References | Related Articles | Metrics

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Clinic Trial of Utilization of Palatal Island Flap in Combination with Adjacent Soft Tissue Flap for Closure of Large Acquired Oro-nasal Fistula XU Zedong, SUN Guowen 2024, 40(8): 722-726.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.011 Abstract ( 31 )   PDF (4194KB) ( 15 )   Objective: To investigate the clinical effect of a double-layer closure of large type Ⅳ acquired oro-nasal fistula (AONF) using palatal island flap combined with adjacent soft tissue flap. Methods: Eight patients with large (maximum diameter greater than 5 mm) type Ⅳ (hard palate) AONF admitted to Ward 1 of the Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Medical School, Nanjing University from January 2017 to December 2021 were collected, with age ranged from 24 to 68 years old. A retrospective analysis was performed on the double-layer closure of the defect using palatal island flap combined with palatal margin flap (and) buccal myomucosal flap, and the efficacy was prospectively evaluated at postoperative follow-up. Results: All cases were successfully repaired, and no soft tissue flap necrosis, perforation, infection, or sinusitis was found. No nasal regurgitation, or upper respiratory tract infection was found during the 24-month follow-up, and the function of speech, mastication, and deglutition recovered well. Conclusion: Palatal island flap combined with adjacent soft tissue flap is a convenient and reliable modality for large type Ⅳ AONF if used under appropriate indications, and is worthy of clinical promotion. References | Related Articles | Metrics

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Effect of Chronic Fluorosis Environment on Expression of VEGF and eNOS in Periodontal Tissue During Orthodontic Tooth Movement in Rats LIU Xingyun, LI Zhongwei, JIA Ying, DING Xue 2024, 40(8): 727-734.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.012 Abstract ( 22 )   PDF (7222KB) ( 18 )   Objective: To observe the expression changes of periodontal tissue, vascular endothelial growth factor (VEGF), and endothelial nitric oxide synthase (eNOS) during tooth movement in SD rats with chronic fluorosis, and to preliminarily explore the possible effects of chronic fluorosis on the angiogenesis of periodontal tissue in orthodontic tooth movement rats. Methods: One hundred and twenty 3-week-old SPF grade SD rats weighing (60±5) g were selected and randomly divided into blank group (C), fluoride group (F), orthodontic group (O), and fluoride orthodontic group (FO), with 15 males and 15 females in each group. According to the duration of orthodontic force, they were divided into 0, 3, 7, 14, and 28 day groups. Each group of rats was euthanized at corresponding time points, and HE staining was used to observe the vascular status of periodontal tissue. Immunohistochemical staining was used to observe the expression of VEGF and eNOS proteins in rat periodontal tissue. Results: The models of chronic fluorosis rats and orthodontic tooth movement rats were successfully established. The arrangement of periodontal fibers in Group O was more disordered than that in Group C, with an increase in the number of periodontal blood vessels and irregular lumens. The distribution of angiogenesis in the FO group was less prominent than that in the O group. There was no significant gender difference in the expression of VEGF and eNOS between male and female rats in each group. There was no significant statistical difference in the expression of VEGF and eNOS on the tension side compared to the pressure side in the O and FO groups. The average protein expression levels of VEGF and eNOS in the FO group were higher than those in the F group, but lower than those in the O group (P<0.05). The expression of VEGF and eNOS proteins in the O and FO groups showed an increasing trend followed by a decreasing trend over time, with a peak on the third day. Conclusion: Chronic fluorosis can inhibit the expression of VEGF and eNOS in the periodontal tissue of rats during tooth movement. References | Related Articles | Metrics

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Shear Bond Strength of Personalized Machined Brackets YANG Ruiting, ZHANG Jie, XU Yafen, JIANG Yingqi, DAI Xiwei, ZHOU Yin, ZHANG Qi 2024, 40(8): 735-740.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.013 Abstract ( 24 )   PDF (2956KB) ( 25 )   Objective: To compare the bonding strength of four types of metal bottom plate brackets. Methods: Forty-eight extracted premolars were randomly assigned to eight main groups, with six teeth in each group. Personalized machined bottom bracket was adopted in group A and B, new net bottom bracket was adopted in group C and D, two-way barb bottom bracket was adopted in group E and F, and traditional net bottom bracket was adopted in group G and H. Among them, chemically cured resin adhesive was adopted for bonding brackets in group A, C, E, and G, light-cured resin adhesive was adopted for bonding brackets in group B, D, F, and H. Before the bonding experiment, the bottom plate was observed with the scanning electron microscope. The shear strength of each bracket was measured with a universal material testing machine, and the adhesive residue on each bracket was counted. Results: When using chemically cured resin adhesive, the bonding strength of the brackets on the two-way barb bottom bracket was lower than that of other three kinds of brackets (P<0.05). When using light-cured resin adhesive, compared with other three kinds of brackets, the two-way barb bottom bracket had the lowest bonding strength, the new net bottom bracket had the lowest bonding strength, the traditional net bottom bracket and the personalized machined bottom bracket had the highest bonding strength, and the difference was statistically significant (P<0.05). There was no significant difference in bonding strength between the traditional net bottom bracket and the personalized machined base bracket (P>0.05). There were significant differences in ARI scores among all groups (P<0.05). ARI score in group H was the smallest, and the difference between group H, group A, and group E was statistically significant (P<0.05). Conclusion: The use of chemically cured resin adhesive or light-cured resin adhesive has no obvious effect on personalized machined bottom brackets bonding strength, and the bonding strength can meet the requirements of orthodontic clinical bonding. The fracture site of group H was relatively closer to the enamel, and the risk of enamel damage in the other groups was less during the process of debonding. References | Related Articles | Metrics

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A Case Report of Cleidocranial Dysplasia with 17 Supernumerary Teeth GUO Longmei, HAN Jiusong 2024, 40(8): 741-743.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.014 Abstract ( 35 )   PDF (2870KB) ( 45 )   Cleidocranial dysplasia (CCD) is a rare congenital disorder that primarily affects the development of bones and teeth, especially unusual with more than 10 supernumerary teeth. This article reports the clinical and radiological findings of a case of CCD with 17 impacted supplementary teeth, also comprises the procedure of the surgical extraction of the supernumerary teeth. References | Related Articles | Metrics

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Oral Myiasis in A Mouth Breathing Patient: A Case Report ZHANG Hongchi, LONG Jinfeng, CHEN Penghui 2024, 40(8): 744-745.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.015 Abstract ( 32 )   PDF (1310KB) ( 31 )   A case of myiasis in a mouth-breathing patient, with retrospective analysis of the onset and progression of the disease, provides insights for the clinical prevention and management. References | Related Articles | Metrics

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Clear Cell Variant of Mucoepidermoid Carcinoma of Salivary Gland in Children: A Case Report PAN Yue, ZHANG Yujie, ZHANG Shukun 2024, 40(8): 746-748.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.016 Abstract ( 31 )   PDF (3968KB) ( 16 )   Mucoepidermoid carcinoma (MEC) is the most common malignant tumor of salivary gland origin in children and young adults, with a male-to-female ratio of approximately 3∶2. Classical MEC consists of mucous cells, epidermoid cells, and mesenchymal cells in various proportions, and there are some rare subtypes in addition to the classical three cellular components, among which, the clear-cell subtype is the one in which the percentage of clear cells in the tumor exceeds that of the other three classic cellular components. In terms of molecular genetics, most mucoepidermoid carcinomas have a CRTC1/MAML2 gene fusion. In this article, we report a case of clear cell type moderately differentiated mucoepidermoid carcinoma occurring in the palatal mucosa of a child, in order to improve the diagnostic ability of this type of disease in the future, and to reduce the occurrence of misdiagnosis and underdiagnosis. References | Related Articles | Metrics

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Oral Pemphigus during Pregnancy: A Case Report HE Mingjing, SU Zhuizi, ZHOU Gang 2024, 40(8): 749-752.  DOI: 10.13701/j.cnki.kqyxyj.2024.08.017 Abstract ( 33 )   PDF (3126KB) ( 34 )   Pemphigus is a severe and chronic autoimmune blistering disorder that typically presents as cutaneous and mucosal blisters and erosions. Pemphigus in pregnancy is rarely reported and may lead to both maternal and fetal complications, so early diagnosis and management are quite crucial to improve outcomes. Herein, we presented a case of pemphigus during pregnancy with lesions confined to oral cavity. The aim of this report was to explore the clinical manifestations, diagnosis, differential diagnosis, and treatment of this rare condition, and to provide a reference for the clinical diagnosis and treatment of this condition. References | Related Articles | Metrics