Journal of Oral Science Research

Avoiding Risks of Temporomandibular Disorders in Orthodontic Treatment

HU Min, JIA Yifan

2021, 37(7): 583-587. DOI: 10.13701/j.cnki.kqyxyj.2021.07.001

Abstract ( 315 )

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Temporomandibular joint disorder is one of the common causes of non-odontogenic pains in the oral-facial region, but its etiology has not been fully elucidated. The old gnathologic perception believes that occlusion is one of the causes, which made orthodontic treatment that changes occlusion appears to cause temporomandibular joint disorders. Furthermore, a doctor-patient dispute may occur once symptoms of temporomandibular disorders happen to a patient during his/her orthodontic treatment lasting for two years or so. Therefore, it is critical for orthodontists to avoid the risks of temporomandibular disorders as more and more patients are seeking orthodontic treatment.

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Concept of Microbiological Diagnosis and Value Analysis of Chair-side Direct Microscopy in Oral Candidiasis

YANG Miao, ZHOU Hongmei

2021, 37(7): 588-591. DOI: 10.13701/j.cnki.kqyxyj.2021.07.002

Abstract ( 221 )

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Oral candidiasis is the most common oral fungal infection with complex clinical manifestations. At present, most physicians make diagnosis and treatment according to clinical impression only, but sometimes it is difficult to distinguish due to insufficient evidence. Therefore, it is necessary to combine with microbiological detection to further clarify the etiology and diagnosis. Direct chair-side microscopy, with the advantages of being fast, effective, non-invasive, and easy to repeat, is suitable for busy outpatient work, and can provide necessary etiological evidence for clinical diagnosis and treatment of oral candidiasis. This paper introduces the concept of microbiological diagnosis and integrate with long-term practical experience of oral candidiasis in clinic, and analyze and evaluate the application value of direct chair-side microscopy.

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Bone Metabolism and Immune Regulation of Statins in Craniofacial Defects Regeneration

HUANG Jiaqian, MA Guowu

2021, 37(7): 592-594. DOI: 10.13701/j.cnki.kqyxyj.2021.07.003

Abstract ( 190 )

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Statins are known for their beneficial effects on lowering cholesterol, which contribute to the treatment of cardiovascular diseases. In recent years, more and more experimental results have demonstrated that statins modulate inflammation, immune response, bone metabolism, and bacterial clearance through several pathways. Local delivery systems combining an osteoconductive biomaterial with statins is a popular approach in the regeneration of craniofacial defects. In this paper we review the direct and indirect mechanism of statins by affecting the immune system in bone metabolism.

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Research Progress of Secretion in Mesenchymal Stem Cell-derived Conditioned Medium with Periodontal Regeneration

ZHOU Xuechun, SUN Xinhua

2021, 37(7): 595-597. DOI: 10.13701/j.cnki.kqyxyj.2021.07.004

Abstract ( 184 )

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Periodontitis is the leading cause of tooth loss in adults. Rebuilding the defected periodontal tissue and restoring the tooth function are the ideal goal. In recent years, it has been found that the ability of stem cells to induce tissue regeneration is derived from paracrine characteristic. Various biological factors secreted by them exist in the conditioned medium (MSC-CM), exert immune regulation and anti-inflammatory function, regulate cell migration, proliferation, and differentiation, and promote angiogenesis and periodontal tissue repair. This article reviews the basic concepts of MSC-CM and its application for periodontal tissue regeneration.

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Effects of Different Implant-supported Prostheses on Residual Alveolar Ridge Remodeling in Edentulous Jaws

JIA Shengnan, LIN Ye

2021, 37(7): 598-601. DOI: 10.13701/j.cnki.kqyxyj.2021.07.005

Abstract ( 195 )

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With the development of implantology, full-arch implant-supported prostheses for edentulous jaws have become important treatments. Effects of different implant-supported prostheses on residual alveolar ridge remodeling in edentulous jaws have been hot topics in recent years. Also, the difference in the remodeling pattern of edentulous residual alveolar ridge directly affects clinicians' choice of implant-supported prostheses. By reviewing previous literatures, this article reviews the changes of residual alveolar ridge after teeth extraction, as well as the effects of different implant-supported prostheses on residual alveolar ridge remodeling in edentulous jaws.

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Clinical Study on Immediate Implantation of 3D Printing Titanium Alloy Root Analogue Implant in Mandibular Molar Area

HUANG Shuo, GUO Fang, LIU Ning, LI Yongfeng, WANG Chao, HU Min, LIU Changkui

2021, 37(7): 602-606. DOI: 10.13701/j.cnki.kqyxyj.2021.07.006

Abstract ( 242 )

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Objective: To evaluate the clinical effect of 3D printing personalized root titanium alloy implant in mandibular molar area. Methods: Twelve patients with mandibular molar extraction were selected. The cone beam CT was used to design the surface porous root analogue implant (RAI) and 3D printing using titanium alloy powder. After minimally invasive tooth extraction, RAI was immediately implanted into the alveolar socket. All patients were reexamined for complications such as implant loosening and pain at 3, 6, and 12 months after operation. All-ceramic crowns were restored after 3 months, and the clinical and imaging effects were evaluated at 3, 6, and 12 months after operation. Results: All 12 patients were operated successfully. There was no loosening, no pain or sensitivity, and no suppurative exudation after operation. The soft tissue around the implant showed good marginal adhesion, and there was no obvious loss of attachment. All patients were restored with all-ceramic crown at 3 months after operation. The success rate of the implant was 100% during the 1-year observation period. After functional loading, there was no significant change in the bone level of the neck of the implant and no transmission image of the root of the implant. Conclusion: 3D printing titanium root analogue alloy implant has a good clinical effect in the immediate implantation of the mandibular molar area, which can be used as one of the options for the immediate restoration of the missing molar. However, the long-term evaluation of the success rate and survival rate of the implant is needed.

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Effects of Edentulous Space on Lateral Bone Augmentation with Delayed Implantation in Aesthetics Area

GUAN Qishuai, XU He, YU Tiantian, XU Sheng, ZHOU Wenjuan, LIU Zhonghao

2021, 37(7): 607-611. DOI: 10.13701/j.cnki.kqyxyj.2021.07.007

Abstract ( 170 )

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Objective: To evaluate the effect of edentulous space on lateral bone augmentation with delayed implantation in the maxillary anterior area. Methods: A retrospective analysis was performed, and patients with consecutive missing maxillary anterior teeth who were treated in the department of implant dentistry in Yantai stomatological hospital from January 2013 to June 2019 were included. All patients were treated with lateral bone augmentation and delayed implantation. They were divided into two groups according to the edentulous space, group A with 2 missing teeth space, and group B with 3-6 missing teeth space. A 3D bone model derived from CBCT was established. The augmented bone width and volume were measured and analyzed by using Mimics. Image J software was used to measure the bone loss height around the edge of the implant in periapical radiology. Results: A total of 44 patients were included with 122 missing teeth and 94 implants, of which, 44 implants were in group A and 50 implants in group B. There was no statistically significant difference as regarding to the average augmented bone volume between groups (P>0.05). The average augmented bone width in group A was significantly smaller than that in group B (P＜0.05). Marginal bone level was significantly decreased at the follow-up time in both groups (P<0.05). No statistically significant difference was observed on marginal bone loss between groups (P>0.05). Conclusion: Delayed implantation with lateral bone augmentation in the aesthetic zone can achieve satisfactory clinical results. The missing tooth gap has no influence on the bone augmentation volume and the stability of the bone around the implant.

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Long-term Clinical Effect of Implantoplasty Combined with Er:YAG Laser on Peri-implantitis

YANG Chunshan, XU Wei, LIU Ying, FAN Zhe, MENG Qi, YANG Chunjiang, ZHENG Jia

2021, 37(7): 612-616. DOI: 10.13701/j.cnki.kqyxyj.2021.07.008

Abstract ( 192 )

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Objective: To evaluate the long-term clinical efficacy of implantoplasty combined with Er:YAG laser in the treatment of peri-implantitis. Methods: From January 2015 to January 2017, 114 patients which diagnosed as peri-implantitis were selected from the Department of Stomatology, Tangshan Union Medical College Hospital, including 120 implants (molar, using the Switzerland ITI implant). The patients were randomly divided into three groups (40 implants in each group), in which the implants of group A were treated with the combination of implantoplasty and Er:YAG laser, the implants of group B were treated with the implantoplasty, and the implants of group C were treated with Er:YAG laser. The implant plaque index (PLI), sulcus bleeding index (SBI), periodontal probing depth (PD), and intraoperative pain of patients in the three groups before and 1, 6, 12, and 36 months after treatment were evaluated, recorded, and compared. Results: After different treatments, PLI, SBI, and PD in the three groups were significantly improved. After 36 months treatment, the improvement of PLI, SBI, and PD in group A was significantly better than those in group B and group C, and there was no significant difference between group B and group C. In addition, intraoperative pain occurred in all three groups, and the incidence of intraoperative pain in group C was significantly lower than those in group A and group B, but there was no significant difference between groups A and B. Conclusion: The long-term clinical effect of the surface implantoplasty combined with Er:YAG laser on peri-implantitis is better than that of the single application of implantoplasty or Er:YAG laser.

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Clinical Application of Dynamic Navigation in Acurate Dental Implant Placement

FENG Dajun, XU Peng, SUN Yunfeng

2021, 37(7): 617-621. DOI: 10.13701/j.cnki.kqyxyj.2021.07.009

Abstract ( 213 )

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Objective: To preliminarily evaluate the precision of guidance by computer dynamic navigation in dental implant placement. Methods: Seventeen patients (25 implants) were selected as the experimental group and implanted under the guidance of computer dynamic navigation. Eighteen patients (25 implants) who received freehand dental implant placement were selected as the control group. The entry position and angle of the planned implantation and actual implantation were measured, respectively. The deviation value was calculated for comparison. Results: The average deviation values of lingual(buccal)-tongue(palate) and proximal-distal directions in the experimental group were 0.210 mm and 0.318 mm, respectively, and average deviation of angle was 3°. The average deviation values in the control group were 0.339 mm and 1.059 mm, respectively, and average deviation of angle was 6.12°. The implantation accuracy of experimental group was better than that of control group (P<0.001). Conclusion: The dynamic navigation system can significantly improve the precision of dental implant placement.

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EGCG and Baicalin Inhibit M1 Polarization of Macrophages in Mice Periodontitis through mTOR Synergistically

ZHOU Yi, CHEN Zhen, LIU Yangruoxuan, HU Liqun, YUAN Minyan, YAN Lu, HUANG Shengfu, LI Yuhong

2021, 37(7): 622-627. DOI: 10.13701/j.cnki.kqyxyj.2021.07.010

Abstract ( 247 )

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Objective: To explore whether Epigallocatechin Gallate (EGCG) and baicalin have synergistic effects in the treatment of mice periodontitis and potential mechanisms. Methods: C57/BL6 mice were randomly divided into blank control group, periodontitis group, EGCG group, EGCG+ baicalin group. The changes of periodontal histology and alveolar bone absorption were observed by HE staining. TRAP staining was used to observe the number of osteoclasts. Immunohistochemistry was used to observe the number of macrophages in all subtypes and the expression of mTOR. Results: Experimental periodontitis was successfully induced by ligation of silk thread combined with local inoculation of Porphyromonas gingivalis. The use of EGCG alone or baicalin in combination reduced periodontal inflammation and alveolar bone absorption, reduce the number of osteoclasts, M1 macrophages, and the ratio of M1 and M2, inhibited the expression of mTOR in periodontal tissues, and the combined use of EGCG and baicalin was more effective than the use of EGCG alone. Conclusion: EGCG and baicalin can synergistically treat periodontitis, which may be related to the down-regulation of mTOR signaling pathway and the reduction of macrophage polarization toward M1.

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Effect of Quercetin on Periodontal Tissues and Serum AGEs Levels in Rats with Diabetic Periodontitis

GUO Xiaoyu, LI Shujuan, LIANG Xiangyang, QI Yali, LI Ya, YANG Dongru

2021, 37(7): 628-631. DOI: 10.13701/j.cnki.kqyxyj.2021.07.011

Abstract ( 187 )

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Objective: To observe the periodontal tissue morphology, alveolar bone resorption, blood glucose, and the differences in the content of serum advanced glycation end products (AGEs) through quercetin treatment in type Ⅱ diabetic periodontitis rats, and explore the protective effect of quercetin on the periodontal tissue of diabetic periodontitis rats. Methods: Forty male SD rats were randomly divided into 4 groups: blank control group (N group), periodontitis control group (P group), diabetic periodontitis non-treatment group (DP group), and diabetic periodontitis quercetin treatment group (DP+ Q group). The N group was fed normally, the P group was established a periodontitis model, and the DP group and DP+Q group were established diabetic periodontitis models, with 10 rats in each group. After successful modeling, the DP+Q group was gavaged with quercetin liposomes, and the DP group was gavaged with blank liposomes. After 6 weeks, blood glucose was measured, serum AGEs content was measured by ELISA method, periodontal tissue section of maxilla was taken to observe the pathological changes of periodontal tissue, and the amount of alveolar bone absorption was measured. Results: The amount of alveolar bone resorption and periodontal inflammation in P group were higher than those in N group (P<0.05). The blood glucose level, serum AGEs content, periodontal tissue inflammation, and alveolar bone absorption in the DP group were higher than those in the N group and P group (P<0.05). Compared with the DP group, the rats in the DP+Q group had lower blood glucose levels, lower serum AGEs content, lower alveolar bone absorption, and significantly lighter periodontal tissue inflammation (P<0.05). Conclusion: Quercetin has a protective effect on the periodontal tissues of diabetic periodontitis rats, and the mechanism is related to the lowering of blood glucose and the content of serum AGEs.

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Bioinformatics Analysis of Alternative Splicing Events during Mouse Cementoblast Mineralization

HUANG Hantao, WANG Xiaoxuan, JIANG Chenxi, MA Li, YAO Siqi, LIU Huan, CAO Zhengguo

2021, 37(7): 632-636. DOI: 10.13701/j.cnki.kqyxyj.2021.07.012

Abstract ( 206 )

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Objective: To bioinformational analyze the alternative splicing events and biofunctions and significant signaling pathways of differential alternative splicing genes during mouse cementoblasts (OCCM30) mineralization. Methods: OCCM30 were cultured in mineralized medium for 0, 7, and 14 days. The relative gene expression levels of bone gamma-carboxyglutamate protein (Bglap) and Osterix (Osx) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed to enrich potential biofunctions and significant signaling pathways. Results: Compared with those on day 0, 1702 and 1682 alternative splicing events were detected on day 7 and 14, respectively. Differential alternative splicing genes were associated with protein serine/threonine kinase activity, peptidyl-lysine modification, Wnt signaling pathway, and VEGF (vascular endothelial growth factor) signaling pathway and so on. Conclusion: Cementoblasts were successfully induced by mineralized medium. Using bioinformatics analysis, alternative splicing events were identified and differential alternative splicing genes may exert functions on cementoblast mineralization, which may provide a novel insight for cementogenesis and periodontal regeneration in the future.

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Effect of PMX205 on Osteoclastic Differentiation of RAW264.7 Cells induced by Anaphylatoxin C5a

JIN Ting, CUI Leihua, WANG Huining, HOU Yubo

2021, 37(7): 637-640. DOI: 10.13701/j.cnki.kqyxyj.2021.07.013

Abstract ( 193 )

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Objective: To investigate the effect of PMX205 on osteoclastic differentiation of RAW264.7 cells induced by anaphylatoxin C5a. Methods: The viability of RAW264.7 treated by PMX205 was detected with MTT assays, and then RAW264.7 were divided into three groups: control group; C5a group, in which cells were induced osteoclastogenic differentiation in medium supplemented with 10 ng/mL RANKL and 1 μmol/L C5a; C5a+PMX205 group, in which cells were treated with 1 μg/mL PMX205, 10 ng/mL RANKL, and 1 μmol/L C5a. The differentiation of RAW264.7 to osteoclast-like cells was quantified by tartrate-resistant acid phosphatase (TRAP) staining, and genes expression associated with osteoclastic differentiation were assessed by real-time quantitative polymerase chain reaction (qRT-PCR). Results: PMX205 significantly inhibited the osteoclastic differentiation induced by C5a in RAW264.7 cells without cytotoxicity. The inhibitory effects of PMX205 on differentiation-related signaling molecules resulted in significant repression of c-fos, TRAF6, and NFATc1 expression, compared with the C5a group (P<0.01), which was still higher than that of control group (P<0.01). Conclusion: PMX205 decreased osteoclastic differentiation of RAW264.7 induced by C5a through C5a-C5aR axis.

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Efficacy of Spiral Tomographic Radiotherapy Combined with TPF Induction Chemotherapy for Locally Advanced Oropharyngeal Cancer and Logistic Regression of Its Influencing Factors

JIANG Cuihong, WU Xiangwei, XIAO Shuai, HE Lili

2021, 37(7): 641-645. DOI: 10.13701/j.cnki.kqyxyj.2021.07.014

Abstract ( 155 )

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Objective: To investigate the efficacy of spiral tomographic radiotherapy combined with TPF induction chemotherapy (docetaxel + cisplatin + 5-fluorouracil) in the treatment of locally advanced oropharyngeal cancer and logistic regression equation analysis of its influencing factors. Methods: The clinical data of 56 patients with locally advanced oropharyngeal cancer treated with spiral tomographic radiotherapy combined with TPF chemotherapy in our hospital from January 2015 to Oct 2017 were selected and retrospectively studied. The short-term curative effect, long-term curative effect, and the occurrence of toxic and side effects of 56 patients were statistically observed, and the factors affecting the short-term and long-term curative effect were analyzed by multivariate Logistic and Cox. Results: The ORR of spiral tomographic radiotherapy combined with TPF chemotherapy for locally advanced oropharyngeal cancer patients was 53.57%, and the 1, 3, and 5-year survival rates were 83.93%, 64.29%, and 39.29%, respectively. Univariate analysis showed that the ORR and 5-year survival rate of patients with locally advanced oropharyngeal cancer of different ages, clinical stages, and degree of differentiation were statistically significant (P<0.05). Multivariate analysis showed that with the increase of age, clinical stage, and degree of differentiation, the short-term and long-term efficacy of locally advanced oropharyngeal cancer patients gradually decreased (P<0.05). During the treatment, the incidence of white blood cell decline ≥ grade Ⅲ was 21.43%, the incidence of platelet decline ≥ grade Ⅲ was 1.79%, the incidence of oral mucositis ≥ grade Ⅲ was 7.14%, and the incidence of radiation dermatitis ≥ grade Ⅲ was 8.93%. Conclusion: Spiral tomographic radiotherapy combined with TPF chemotherapy is effective in the treatment of locally advanced oropharyngeal cancer. The toxic and side effects are mostly within the tolerable range. Age, clinical stage, and degree of differentiation are influencing factors for its short-term and long-term efficacy, and sufficient clinical attention should be paid.

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Development and Validation of Nomogram for Benign and Malignant Parotid Tumors Combined with Enhanced CT Image Features

YAN Qinghan, WANG Jiali, CHE Yinfu, YU Tao, TAO Feng, CHEN Lixin, HE Dengqi

2021, 37(7): 646-650. DOI: 10.13701/j.cnki.kqyxyj.2021.07.015

Abstract ( 173 )

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Objective: To develop the prediction models for begin and malignant parotid neoplasms by analyzing multiple examination indexes. Methods: A retrospective analysis was performed on 242 patients with parotid neoplasms who were treated with parotid neoplasms resection in the First Hospital of Lanzhou University from March 2013 to March 2019(group A). The independent predictors of malignancy in parotid tumor patients were screened out through logistic regression analysis, then a prediction model was built. Other 42 parotid neoplasm patients(group B)with definite pathological diagnosis from April 2019 to September 2020 were used to validate this model. Results: Through multivariate logistic regression analysis on group A, the prediction model was built as follows: Y=e^x/ (1+e^x), X=-0.18347+ (-1.29435×tumor shape) + (-1.44877×tumor boundary) + (4.34121×surrounding tissues), in which “e” was natural logarithm. The validity of this model was validated by data from group B, and the results showed that the accuracy was 95.2%, the sensitivity was 1.00, and the specificity of the model was 93.4%. Conclusion: The establishment of logistic regression prediction model can help clinicians diagnose benign and malignant parotid tumors by combining the presence or absence of regular tumor shape, clear tumor boundaries, and involvement of surrounding tissues.

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Manifestation and Analysis of Parotid Malignant Lymphoma with Spiral CT

PAN Xiao, HU Ziyang, LIANG Jiahao, ZHANG Lei, LIN Zitong

2021, 37(7): 651-655. DOI: 10.13701/j.cnki.kqyxyj.2021.07.016

Abstract ( 256 )

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Objective: To summarize the CT manifestations of malignant lymphoma in parotid region and analyze the CT imaging characteristics of different pathological types. Methods: Twenty cases of parotid malignant lymphoma in our hospital were collected, and the clinical characteristics, CT manifestations, histopathology, and immunohistochemical results were reviewed. CT manifestations included the number, size, boundary, density, and regional lymph node involvement of lesions. Pathological classification was performed combining histopathological observations and immunohistochemistry analysis, and tumor cell proliferation analysis was performed by immunohistochemistry analysis of Ki-67. Results: All 20 cases of malignant lymphoma were non-Hodgkin's lymphoma (NHL), 9 cases were mucosal associated lymphoid tissue lymphoma (MALT), 8 cases were diffuse large B cell lymphoma (DLBCL), 2 cases were follicular lymphoma (FL), 1 case was angioimmunoblastic T-cell lymphoma (AITL). Of 9 MALTs, 7 cases manifested unclear boundaries, 6 cases were plasticized along the parotid contour, and 8 cases manifested uneven density. Of 8 DLBCLs, 7 cases manifested clear boundary, 4 were single nodules and 4 were multiple nodules, 4 presented uniform density, and 4 presented uneven density. 14 of the 20 cases had lymph node involvement. Ki-67(+) was distributed in 20%~90%, and 4 DLBCLs had Ki-67(+) higher than 50%. Conclusion: Most of parotid malignant lymphoma is MALT or DLBCL, both of them have some radiographic manifestations in spiral CT images.

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Radiographic Study of PRF Combined with MTA for Direct Pulp Capping of Rabbit Teeth

HU Yuping, YANG Xue, YAN Zhihao, XING Huiyan, LU Jin, LI Shufang

2021, 37(7): 656-660. DOI: 10.13701/j.cnki.kqyxyj.2021.07.017

Abstract ( 232 )

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Objective: To investigate the ability for pulp to form hard tissue when PRF membrane combined with MTA was used as a new compound pulp capping agent for direct pulp capping. Methods: 32 New Zealand rabbits were randomly divided into 4 groups with 8 experimental rabbits in each group and central mandibular incisors of each rabbit were used as experimental teeth and received the same treatment. According to the different capping materials, they were divided into three experimental groups (PRF+MTA group, MTA group, PRF group) and blank control group; establishment the dental pulp exposure model and direct pulp capping. The experimental teeth were filmed with CBCT immediately before and after surgery, on the 7th and 28th day, and Mimics19.0 software was used to reconstruct the experimental teeth and calculate the volume of dentine bridge formed at the perforating pulp hole. Results: On 7th day after surgery, the dentine bridge volumes in three experimental groups were all larger than those in the blank control group (P<0.05), but there was no significant difference among three experimental groups (P>0.05). On 28th day after surgery, the dentine bridge volume of PRF+MTA group was larger than that of PRF group and blank control group (P<0.05), but there was no statistically significant difference between the PRF+MTA group and MTA group (P>0.05). Conclusion: From the perspective of imaging, the level of PRF combined with MTA in promoting the formation of restorative dentin was not different from that of MTA, both of which were at a high level. However, the nature of the generated restorative dentin and the state of dental pulp required more study by histological observation.

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Aspiration Effect of Intracanal Ejectors on 3D-printed Teeth

HAO Junyan, HU Hongcheng, HAN Yi, CAO Jia, ZHOU Haiquan, XUAN Yan, YANG Ying, HOU Xiaomei

2021, 37(7): 661-665. DOI: 10.13701/j.cnki.kqyxyj.2021.07.018

Abstract ( 161 )

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Objective: To compare the aspiration efficacy of intra-canal aspirators with different tip sizes and aspiration powers in 3D printed teeth models of upper first molar, upper first premolar and upper center incisor. Methods: Forty-eight teeth models of upper first molar (three-canals), upper first premolar (two-canals) or upper center incisor (one canal) were printed and randomly divided into 6 groups, respectively, Intra-canal aspirators with tip size 0.5mm, 1.0mm or 1.5mm connecting to high or low power, constituted 6 group (n=8). Aspirators were inserted into canals and pictures obtained using digital camera, insert depths were measured by Image J, accordingly. Radiopaque fluid were injected into teeth models and pre-suction images were scanned using CBCT. Each groups of aspirators were used to suction the canals, 5 seconds each, and the post-suction images were scanned. Volume of residual fluid were measured. Data were analyzed using one-way ANOVA with significance of 0.05. Results: The insert depths were increased significantly with the tip size increased. Particularly, tip size 1.5 mm were obstructed in upper first molar. The volume of residual fluid were increased significantly with the tip size increased. The influences of suction power were not significant. Conclusion: In the 3D printed teeth models, tip size 0.5 mm results in the least residual fluid and the influence of suction power seems not significant.

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Patent Analysis on 3D Printing Technology in Stomatology

ZHANG Lingbo, REN Liling

2021, 37(7): 666-670. DOI: 10.13701/j.cnki.kqyxyj.2021.07.019

Abstract ( 281 )

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Objective: To provide references for China's related technology research and patent layout based on the analysis on the global patent application status of 3D printing technology in stomatology. Methods: The article uses patent analysis method, adopts the Intelligent Bud Patent Analysis Platform, and combines manual indexing and statistics to systematically analyze the patents of global 3D printing technology in stomatology. Results: The patents application of 3D printing technology in the field of stomatology is growing rapidly, China, the United States and South Korea have a large number of patent applications in this field and the Chinese market has been valued by foreign institutions. Oral prosthesis manufacturing, dental implant tools, and orthodontics are hot areas. SLA, DLP and SLM, technologies are the fastest growing technologies in the field of stomatology of 3D printing technology. The processes, products, and data processing of 3D printing are also areas that have received much attention in recent years. The patent layout of 3D printed materials and special equipment for manufacturing workpieces or products from metal powder are emerging, which is worth strengthening the layout in the future. Conclusion: The application of 3D printing technology in the field of stomatology is emerging and has great potential. China has the largest number of patent applications in this field, but the quality, needs to be improved. The research trend of advanced foreign institutions should be payed much attention to. Not only the application of invention patents with high originality but also the lay out of utility model patents related to the core products should be concerned about. A comprehensive layout of patents in the process of 3D printing, products, and data processing, relevant materials and preparation equipment should be pushed forward, to ensure the safe production of core products in an all-round way. Industry-universityresearch cooperation should be promoted to improve the quality of patents. Overseas patents should be applied to guarantee the export of the products.

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Endodontic Microsurgery for Destruction of Maxillary Sinus Floor Caused by Maxillary Molar with Apical Cyst: A Case Report

LI Jiatong, FU Yujie, MAN Yi, HUANG Dingming

2021, 37(7): 671-672. DOI: 10.13701/j.cnki.kqyxyj.2021.07.020

Abstract ( 263 )

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Odontogenic maxillary sinusitis is caused by maxillary posterior teeth periapical periodontitis. This article reports a case of odontogenic maxillary sinusitis and extensive bone destruction due to apical cyst after root canal treatment failure. The tooth is preserved by endodontic microsurgery with maxillary sinus lift.

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