01 March 2020, Volume 47 Issue 2 Previous Issue   
Expert Forum
The retention of severe periodontitis-involved tooth
Chen Bin,Xu Rongrong,Zhang Jiading,Yan Fuhua
Int J Stomatol. 2020, 47 (2):  125-130.  DOI: 10.7518/gjkq.2020053
Abstract ( 42 )   HTML ( 8 )   PDF(pc) (924KB) ( 66 )   Save

Severe periodontitis-involved teeth, especially those considered as “prognosis hopeless”, are a common and important problem that plagues dentists. Clinicians should not make abrupt extraction decisions but rather carefully perform clinical examination, fully communicate with the patient, explore the correct etiological factors, and analyze the favorable and unfavorable factors according to the specific conditions of the patient. Patient’s willingness, compliance, and financial ability should also be considered. This review begins with three typical cases, including simple severe periodontitis-affected teeth, primary periodontal lesion with secondary endodontic involvement teeth, and teeth with “true combined periodontal-endodontic lesion.” The decision-making process of tooth extraction or retention in patients with severe periodontitis was also discussed to serve as future reference.

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Periodontitis
Application of probiotic ecological regulation in prevention and treatment of periodontal diseases
Liu Lin,Zhou Jieyu,Wu Yafei,Zhao Lei
Int J Stomatol. 2020, 47 (2):  131-137.  DOI: 10.7518/gjkq.2020034
Abstract ( 29 )   HTML ( 8 )   PDF(pc) (469KB) ( 43 )   Save

The initiating factor of periodontal diseases is plaque biofilm. In recent years, plaque hypothesis becomes increasingly inclined to the disruption of microbial homeostasis. Classic treatment method is mechanical plaque removal. However, individual differences exist in the curative effect, and some patients need to be assisted with other treatment methods. The role of probiotics in reconstructing host microbial community and regulating immune inflammatory responses may result in certain improvement in the microecology of periodontal diseases. This review summarises the clinical effects, mechanism and clinical application of probiotics for prevention and treatment of periodontitis, gingivitis, oral malodour and periimplant diseases from the perspective of the classification of periodontal diseases.

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Progress in research of non-coding RNAs in osteogenic differentiation of human periodontal ligament stem cells
Wang Runting,Fang Fuchun
Int J Stomatol. 2020, 47 (2):  138-145.  DOI: 10.7518/gjkq.2020018
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Periodontitis is a common inflammatory disease that is characterised by progressive damage to dental supporting structure. Periodontitis is the main cause of tooth loss in adults in China. The aim of periodontal treatment is not only to control inflammation and prevent disease development but also to obtain periodontal regeneration. Human periodontal ligament stem cells (PDLSCs), which are capable of osteogenic differentiation, are expected to play important roles in clinical application of periodontal tissue repair and regeneration. Non-coding RNAs (ncRNAs) generally refer to RNAs that do not encode proteins. The continuous development of high-throughput detection techniques has allowed the identification of a large number of ncRNAs and their biological functions. Increasing numbers of ncRNAs have been reported to function in the pathogenesis of diseases at molecular and cellular levels. Therefore, research on ncRNAs can provide new insights into periodontal regeneration. This review focuses on the regulatory mechanism of several ncRNAs in the osteogenic differentiation of human PDLSCs.

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Research progress of exosomes derived from different stem cells in periodontal regeneration
Wu Xiaonan,Ma Ning,Hou Jianxia
Int J Stomatol. 2020, 47 (2):  146-151.  DOI: 10.7518/gjkq.2020020
Abstract ( 27 )   HTML ( 2 )   PDF(pc) (420KB) ( 28 )   Save

Periodontitis is a chronic infectious disease caused by dental plaque and the primary reason for tooth loss in adults because it damages periodontal supporting structures. Microbial plaque biofilm control is an effective method to prevent further disease progression. However, a reliable treatment that can lead to stable and satisfactory periodontal regeneration in clinical practice has not been reported to date. Exosome is a specific class of lipid-membrane-bound extracellular vesicle. Exosomes are secreted from cells through paracrine mechanism and participate in tissue regeneration. Considering that the application of exosomes provides a new strategy for tissue regeneration, this review presents the current status of exosomes derived from different kinds of cells for potential therapeutic use in periodontal regeneration.

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Original Articles
Comparative study of the retention force of titanium-alloy clasps fabricated through selective laser melting and casting
Liu Chunxu,Lu Yuqing,Jia Luming,Dong Bo,Zhang Qianqian,Yu Haiyang
Int J Stomatol. 2020, 47 (2):  152-158.  DOI: 10.7518/gjkq.2020040
Abstract ( 10 )   HTML ( 1 )   PDF(pc) (875KB) ( 10 )   Save

Objective This study aimed to determine the effects of 3D printing and casting on the retention force of titanium-alloy clasps by simulating clasp removal and wear by patients to provide a reference for the clinical design and manufacture of clasps. Methods Preparatory abutment teeth, crowns, and clasps were designed through computer-aided design. The clasps were designed with two undercut depths of 0.25 and 0.75 mm while the other parameters were held constant. The processing technology was divided into three groups. The experimental group used EOSINT and Concept Laser to 3D print the designed data, whereas the control group used casting technology. A total of 36 groups were set. A universal mechanical tester was used to simulate the cycle test of the clasps with a total cycle of 15 000 times. The initial retention force was recorded, and the retention force was recorded every 1 500 times. Results By using the same processing technology, the retention force of the undercut depth of 0.75 mm was greater than that of 0.25 mm. The retention force of the titanium-alloy clasp formed through selective laser melting (SLM) with the same parameters was greater than that of the clasps fabricated through casting. EOSINT and Concept Laser did not have different retentive forces. Conclusion The retention force of the titanium alloy clasp produced through SLM technology was higher than that of the clasp fabricated through casting. The undercut depth of titanium-alloy clasps machined by casting should be 0.75 mm. Titanium-alloy clasps that can meet clinical requirements can be produced through using digital design, 3D printing, and an undercut depth of 0.25 mm. The retention forces of titanium-alloy clasps fabricated through EOSINT and Concept Laser SLM systems were the same.

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Expression and potential clinical significance of Transformer 2β in oral squamous cell carcinoma
Hao Fu,Ning Yi,Sun Rui,Zheng Xiaoxu
Int J Stomatol. 2020, 47 (2):  159-165.  DOI: 10.7518/gjkq.2020039
Abstract ( 25 )   HTML ( 2 )   PDF(pc) (788KB) ( 20 )   Save

Objective This study aimed to investigate the expression and clinical significance of Transformer 2β (Tra2β) in oral squamous cell carcinoma (OSCC). Methods Sixty-four samples of OSCC were subjected to immunohistochemistry to analyze the expression of Tra2β protein in OSCC and to explore the relationship between the expression of Tra2β protein and different clinical pathological parameters. Twenty-two pairs of fresh OSCC tissues and adjacent tissues were used to explore the expression of Tra2β mRNA and protein through real-time polymerase chain reaction and Western blot analyses. The Kaplan-Meier method was used to estimate and validate the effect of Tra2β protein on the survival rate of patients with OSCC. Cox multivariate regression was used to analyze the effect of Tra2β protein on the prognosis of patients with OSCC. Results Immunohistochemistry results revealed that Tra2β protein was expressed in OSCC, and the positive expression of Tra2β protein was significantly associated with the differentiation degree and clinical stage of OSCC. Moreover, the expression trends of Tra2β protein and mRNA were consistent, and the expression levels of Tra2β protein and mRNA in OSCC tissues were higher than those in adjacent tissues. Kaplan-Meier survival analysis showed that patients with OSCC and Tra2β protein expression had poor prognoses. Cox multivariate regression analysis demonstrated that the Tra2β protein was an independent prognostic factor of OSCC. Conclusion Tra2β may be a new molecular target for the treatment of OSCC.

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Survival analysis of patients with oral squamous cell carcinoma treated by radical surgery for the first time
Xue Lingli,Li Yadong
Int J Stomatol. 2020, 47 (2):  166-174.  DOI: 10.7518/gjkq.2020051
Abstract ( 18 )   HTML ( 0 )   PDF(pc) (637KB) ( 13 )   Save

Objective To analyze the overall survival (OS) and relevant risk factors for oral squamous cell carcinoma (OSCC) patients. Methods To retrospectively review the clinical, pathological, and follow-up records of 78 patients after primary radical tumor resection. Descriptive statistics were calculated for each variable, survival was calculated using the Kaplan-Meier method, differences in OS rate were analyzed via a log-rank test, and univariate and multivariate Cox proportional hazard models were performed to analyze the factors associated with overall survival and prognosis. Results A total of 68 patients were included in the final study. The five-year OS rate was 55.9%. The median survival time of the patients who died of this disease within five years was 20.5 (6-52) months. The univariate analysis showed that clinical stage, tumor size, lymph node metastasis, pathological differentiation, recurrence, and metastasis were the exposure factors affecting survival time (P<0.05). Multivariate analysis showed that pathological differentiation, recurrence, and metastasis were in-dependent factors affecting survival time (P<0.05). The patients with esophageal squamous cell carcinoma accounted for 5.1% (4/78) in total 78 OSCC. Conclusion The survival prognosis of patients with oral squamous cell carcinoma is correlated with clinical stage (TNM stage), tumor size, lymph node metastasis, pathological differentiation, recurrence, and metastasis. In this study, pathological differentiation, recurrence, and metastasis were independent factors affecting survival time. Some OSCC patients may be screened for esophageal squamous cell carcinoma.

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Genetic and environmental effects on craniofacial depth and upper airway in cephalograms of twins
Lü Jing,Peng Jing,Li Pu
Int J Stomatol. 2020, 47 (2):  175-181.  DOI: 10.7518/gjkq.2020008
Abstract ( 13 )   HTML ( 1 )   PDF(pc) (485KB) ( 8 )   Save

Objective This study aimed to investigate the influences of genetic and environmental factors on craniofacial depth and upper airway width in a mixed dentition period and to provide a theoretical basis for functional correction plans. Methods The relative indexes of the craniofacial depth and the upper airway width in the lateral cephalic radiographs of 183 twin girls aged 6-12 years were measured. The influences of genetic and environmental factors on craniofacial depth and upper airway width were subjected to longitudinal statistical analysis by using the twin research method. Results The influence of environmental factors on craniofacial depth was greater than that of genetic factors. The effect of environmental factors on mandibular depth (L4-L7) was stronger than that on maxillary depth (L1-L3). The influence of environmental factors on the upper airway width (d1-d6) was greater than that of genetic factors. The role of genetic factors in oropharyngeal and laryngopharynx airways was insignificant (P<0.05). Conclusion The craniofacial depth and airway width of cephalometric measurements in twin girls are strongly affected by environmental and genetic factors.

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Analysis of upper lip profile features in 300 dentate subjects of different ages via three-dimensional measurement of cone beam computed tomography
Zhang Tingting,Hu Changhong,Peng Yan,Zhou Wenqiao,Zhang Huicong,Liu Die
Int J Stomatol. 2020, 47 (2):  182-188.  DOI: 10.7518/gjkq.2020050
Abstract ( 17 )   HTML ( 0 )   PDF(pc) (580KB) ( 8 )   Save

Objective To measure and analyze upper lip profile features in dentate subjects among different age groups using cone beam computed tomography (CBCT) to provide an objective reference for facial esthetics in complete denture restoration. Methods A total of 300 CBCT images were selected and divided into one of the following three groups accor-ding to age: youth group (20-39 years), middle-aged group (40-59 years), and elderly group (more than 60 years). The length and thickness of the upper lip of each image were measured, and a morphological analysis of the upper lip profile was performed. Results The upper lip lengthened with aging. Moreover, the exposure of lip vermilion and the thickness of lip vermilion gradually decreased. The distance from the edge of the upper incisor to the edge the upper lip in three groups equated to (1.962 2±1.107 1), (0.835 3±1.206 6), and (0.014 1±1.225 6) mm. Moreover, the thicknesses of the lip vermilion were (12.355 8±1.950 3), (10.634 2±1.782 4), and (9.924 9±1.951 4) mm. According to the morphological analysis of the upper lip profile, the upper lip profile was presented in the following four shapes: concave, straight, wavy, and convex. Furthermore, differences were noted between groups; that is, the young group showed the largest proportion of concave upper lip profiles (68%), the middle-aged group showed the largest proportion of concave and straight upper lip profiles (80%), and the elderly group showed the largest proportion of wavy and convex upper lip profiles (67%). Conclusion Results indicated that the upper lip changes related to aging should be fully considered when complete denture restoration is performed for edentulous patients. When arranging the artificial anterior teeth, we should pay attention to the distance from the edge of the upper incisor to the edge of the upper lip while considering patients’ ages. When plumping up the upper lip using a complete denture, we should try to make the effect consistent with that observed among dentate people of the same age.

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Microtribological behaviour of human tooth enamel treated by gamma irradiation
Qing Ping,Gao Shanshan,Qian Linmao,Yu Haiyang
Int J Stomatol. 2020, 47 (2):  189-195.  DOI: 10.7518/gjkq.2020021
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Objective This study aimed to understand the effect of gamma irradiation on the microstructure, composition and microfriction and wear properties of human tooth enamel. Methods Nanoscratch tests, surface profilometer and scanning electron microscope analysis were used to evaluate the friction behaviour of human tooth enamel slabs before and after gamma irradiation. X-ray diffraction and Fourier transform infrared spectroscopy were performed to analyse changes in crystallography and chemical composition induced by irradiation. Surface microhardness alteration was also evaluated. Results After irradiation, additional partial packing and delamination with high friction coefficient were observed in the enamel. The Knoop hardness number (KHN) of the enamel significantly decreased from (420±20) KHN before irradiation to (333±11) KHN (P<0.000 1) after irradiation. The crystallinity decreased from 82.42%±2.01% to 71.11%±2.62% (P<0.05). The crystal size increased from (24.35±1.00) nm before irradiation to (26.72±1.88) nm (P<0.05) after irradiation. The carbonate:mineral ratio increased from 0.034±0.005 to 0.052±0.010 (P<0.05). Conclusion Gamma irradiation decreased the wear resistance of enamel. Results should be considered when performing clinical restorations.

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Reviews
Effects of different registration methods on the accuracy of navigation registration in dental implants
Tian Tian,Zhang Zhihong,Liu Honghong
Int J Stomatol. 2020, 47 (2):  196-201.  DOI: 10.7518/gjkq.2020046
Abstract ( 32 )   HTML ( 1 )   PDF(pc) (489KB) ( 27 )   Save

The dynamic navigation system (DNS) is an auxiliary system for dental implant surgery that utilizes precise infrared positioning technology through the visualized operation of 3D digital images. The system is aimed at realizing the precise fusion of 3D images and actual anatomical positions and achieving the real-time tracking of surgical instruments. The DNS is suitable for preoperative planning and precise intraoperative guidance for dental implant surgery. The key factor that affects the accuracy of the DNS is the accurate registration of the actual anatomical structure of the operation area and its virtual 3D digital image. The indications, registration characteristics, and registration accuracies with different registration methods vary. The present work introduces the registration methods used in clinical practice, including bone marker registration, occlusal splint registration, U-tube registration, facial frame registration, anatomical mark registration, and unmarked registration. The factors affecting registration errors are also summarized to enable clinicians to effectively understand the characteristics and indications of different registration methods, reduce registration errors, and achieve accurate implantation.

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Interproximal open contacts between implant restorations and adjacent teeth
Xiao Yuhan,Yu Haiyang
Int J Stomatol. 2020, 47 (2):  202-205.  DOI: 10.7518/gjkq.2020035
Abstract ( 26 )   HTML ( 4 )   PDF(pc) (416KB) ( 35 )   Save

Implant-supported protheses are considered a predictable option for dentition defects. Many researchers have observed the loss of proximal contact between implant-supported protheses and adjacent natural tooth. Food impaction, which mainly caused by proximal contact loss, is one of the main complications of dental implants. This article reviews research advancements on the prevalence, contributing factors and treatments of this complication.

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Clinical advances of periodontally accelerated osteogenic orthodontics
Li Hanyue,Xia Lulu,Hua Xianming
Int J Stomatol. 2020, 47 (2):  206-211.  DOI: 10.7518/gjkq.2020047
Abstract ( 26 )   HTML ( 0 )   PDF(pc) (422KB) ( 39 )   Save

Periodontally accelerated osteogenic orthodontics (PAOO) involves alveolar bone corticotomy and particulate bone grafting. Regional acceleratory phenomena (RAP) induced by corticotomy stimulates osteoclast activity and alveolar bone remodeling. The stimulation results in orthodontic tooth movement acceleration, reduced treatment duration, and decreased root resorption. Alveolar augmentation expands tooth moving boundaries and benefits periodontal conditions. The present article reviews the evaluation of the clinical effects of PAOO on tooth movement acceleration, bone augmentation, and root resorption to provide references for clinical application.

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Research progress on stability of mini-implants in orthodontic treatments
Tian Qinglu,Zhao Zhihe
Int J Stomatol. 2020, 47 (2):  212-218.  DOI: 10.7518/gjkq.2020010
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Anchorage is indispensable for the loading during orthodontic treatments. Temporary anchorage devices (TADs) are widely used for such treatment. The stability of these devices is closely linked to treatment efficiency and quality and can be affected by several factors, such as the patient’s individual condition, the design of TADs, the preparation before implantation, implantation techniques, and the loading after implantation. These factors are reviewed in this study. TAD implanting failures can worsen patients’ suffering and increase the cost, prolong treatment time, and hinder the progress of orthodontic treatment. The success rate of implantation can be improved to a certain degree by controlling the adverse factors influencing TAD stability to achieve a precise and professional-grade orthodontic treatment.

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Research progress on shape memory polymers in bone defect repair and regeneration
Liu Yuhao,Zhang Tao
Int J Stomatol. 2020, 47 (2):  219-224.  DOI: 10.7518/gjkq.2020011
Abstract ( 23 )   HTML ( 1 )   PDF(pc) (529KB) ( 26 )   Save

As novel stimuli-responsive biomaterials, shape memory polymers (SMPs) have been used in bone defect repair. The 3D shape of these biomaterials can be switched between initial and temporary states under external stimuli, such as temperature changes and water contact, making them suitable for tightly filling bone defects and advantageous over traditional materials featuring shape mismatch and complicated implantation. In addition, modified SMPs can be used as porous bone tissue engineering scaffolds to load various bioactive factors and stem cells for new bone formation. Recently, SMPs have shown promising prospects in minimal invasiveness, repairing irregular bone defects, and promoting bone defect regeneration. This review will discuss the current progresses of SMPs in bone tissue engineering, including their mechanism, biological effects, and performance optimization.

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Progress in pathogenic factors and mechanisms of Enterococcus faecalis in oral and systemic diseases
Shui Yusen,Lü Xiaoying,Li Jingya,Yang Ran
Int J Stomatol. 2020, 47 (2):  225-234.  DOI: 10.7518/gjkq.2020048
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Enterococcus faecalis (E. faecalis) is the main pathogen of root canal reinfection and persistent periapical periodontitis in human oral cavity. This species can survive for a long time in the harsh environment of a root canal. E. faecalis has a certain resistance to most root canal therapy drugs, as well as cleaning and disinfection methods. This species presents a major challenge in root canal therapy at present. In addition, E. faecalis is associated with some systemic infections, such as gastrointestinal and urinary tract infection. Its pathogenesis is related to its initial adhesion to the host, biofilm formation, invasive infection, and immune escape. E. faecalis expresses various proteins, glycolipids, and other adhesion to achieve initial adhesion. This species can regulates the expression of various biofilm-associated genes to form a mature biofilm to fight against the body’s deterioration, and realize the communication between cells subsequently. Eventually, E. faecalis colonizes a local area or even the whole body to cause infection. The present review focuses on the pathogenic factors and pathogenesis of E. faecalis.

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Application and research progress on concentrated growth factor in oral clinic
Wei Zhongwu,Huang Xieshan,Chen Zhuogeng
Int J Stomatol. 2020, 47 (2):  235-243.  DOI: 10.7518/gjkq.2020013
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Concentrated growth factor (CGF) is a new generation of platelet concentrate prepared by differential centrifugation. Compared with the two previous generations of platelet concentrates, CGF contains more growth factors in the same volume. It has a fibrin matrix with high tensile strength and viscosity and long application time in the body and exhibits good tissue regeneration ability. CGF has been widely used in oral implant and maxillofacial surgery because of its simple and efficient preparation by autologous blood. Moreover, CGF contains a large number of growth factors that exert an osteoinductive effect and a fibrin matrix that plays a role in bone guidance. Furthermore, CGF can activate angiogenesis and effectively induce and accelerate soft and bone tissue. CGF can also shorten the healing time without the risk of cross-infection and immune rejection and has a certain anti-inflammatory effect. This article reviews the application of CGF in oral cavity and related research progress. We hope to provide a theoretical basis for the further application of CGF in oral clinics.

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Novel Coronavirus Pneumonia
Nursing prevention and control of the novel coronavirus pneumonia in oral and maxillofacial surgery
Bi Xiaoqin,Xiong Maojing,Chen Lixian,Bai Yuanyan,Tian Li,Yang Hui
Int J Stomatol. 2020, 47 (2):  244-248.  DOI: 10.7518/gjkq.2020054
Abstract ( 154 )   HTML ( 9 )   PDF(pc) (563KB) ( 81 )   Save

A great challenge to the treatment and nursing of oral and maxillofacial surgery is due to the outbreak of novel coronavirus pneumonia. In order to effectively prevent the spread of the epidemic situation caused by the novel coronavirus pneumonia and minimize the risk of transmission of the novel coronavirus pneumonia in medical institutions, according to the general requirements of the State for the prevention and control of the novel coronavirus and the characteristics of maxillofacial surgery specialty, the related prevention and control measures of oral and maxillofacial surgery nursing management were formulated, the contents include pre-examination and triage, grading protection, health education, key points of prevention and control in relevant departments, as well as prevention and control strategies in nursing operation, so as to ensure the orderly progress of nursing work in maxillofacial surgery, in order to provide reference for the management of oral and maxillofacial surgery in epidemic period and the research in the future, the authors put forward some suggestions on the management of oral and maxillofacial surgery during the epidemic period.

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