With the extensive application of nuclear technology in industry, agriculture, and medicine, the safety issues associated with neutron radiation have become increasingly prominent. Due to their high penetrability and strong ionization effect, neutrons can cause serious health risks by directly damaging DNA or inducing secondary γ radiation. Therefore, the neutron radiation protection has become a core challenge in radiation protection, especially the research and development of neutron shielding materials. To ensure the safe development of nuclear technology, neutron shielding materials are indispensable and constitute a fundamental core technology for radiation protection. This paper reviews the theory of neutron radiation protection and the research progress of neutron shielding materials, with a focus on the current application status and existing problems of neutron shielding materials. This article also discusses the future development trends. This review aims to provide theoretical support and technical references for the safe application and development of nuclear technology.

As the main means of mastication, teeth can withstand countless functional contacts. The mechanical properties of teeth are closely related to their tissue structure. Enamel and dentin have a high hardness and modulus of elasticity, and their graded structure allows them to withstand bite forces without being susceptible to fracture. When tooth tissue is defective, full crown restoration is often needed to restore the normal shape and function of the tooth. Metal materials, ceramic materials, and polyetheretherketone (PEEK) materials are commonly used for crown restoration. Metal materials have certain disadvantages in terms of aesthetics and are relatively rarely used in clinical practice. Ceramic materials with different compositions exhibit differences in performance and aesthetics, but their elastic modulus and hardness are much higher than those of dental tissue, resulting in mismatching mechanical properties. In contrast, the elastic modulus of PEEK is lower than that of tooth tissue and similar to that of bone tissue, but its properties can be improved by fiber reinforcement. Notably, when the mechanical properties of a restoration material and tooth tissue are not fully matched, the interface between them often forms a potential weak link, which ultimately affects the stability and long-term effect of the restoration. This article introduces the mechanical properties and corresponding structural characteristics of enamel and dentin. On this basis, the advantages and limitations of existing restoration materials are analyzed, and the possibility of biomimetic design of full crowns is further explored.

The problems caused by proximal contact loss(PCL)of dental implants have been a mainstream research topic in recent years,and scholars are unanimously committed to analyzing their causes and related factors,aiming to identify solutions to the problems related to PCL.The effects of the anterior component of force(ACF),the lifelong re-molding of the adult craniofacial jaw and alveolar socket,and the osseointegration characteristics of dental implants are the main causes of PCL.On the one hand,the closing movement of the mandible causes the ACF of the tooth to move through the posterior molar cusp.Moreover,drifting between the upper and lower posterior teeth and mandibular anteri-or teeth can cause the anterior teeth of the upper and lower jaws to be displaced labially.On the other hand,reconstruc-tion of the jaw,alveolar socket and tooth root,the forward horizontal force of the masticatory muscles,the dynamic com-ponent of the jaw and the forward force generated by the oblique plane of the tooth cusp can cause the natural tooth to experience near-middle drift.Additionally,natural teeth can shift horizontally and vertically and rotate to accommodate remodeling of the stomatognathic system and maintain oral function.Nevertheless,the lack of a natural periodontal mem-brane during implant osseointegration,the lack of a physiological basis for near-medium drift,the small average degree of vertical motion and the integrated silence of dental implants without the overall drift characteristics of natural teeth increases the probability of PCL.The high incidence of PCL is clearly associated with the duration of prosthesis delivery and the mesial position;but it is also affected by the magnitude of the bite force,occlusion,the adjacent teeth,restora-tion design,implant location,jaw,and patient age and sex.PCL has shown a significant correlation with food impaction,but not a one-to-one correspondence,and did not meet the necessary and sufficient conditions.PCL is also associated with peri-implant lesions as well as dental caries.PCL prevention included informed consent,regular examinations,se-lection of retention options,point of contact enhancement,occlusal splints,and the application of multipurpose digital crowns.Management of the PCL includes adjacent contact point additions,orthodontic traction,and occlusal adjust-ment.Existing methods can solve the problem of food impaction in the short term with comprehensive intervention to seek stable,long-term effects.Symmetric and balanced considerations will expand the treatment of issues caused by PCL.

Background::Clinical opportunistic screening is a cost-effective cancer screening modality. This study aimed to establish an easy-to-use diagnostic model serving as a risk stratification tool for identification of individuals with malignant gastric lesions for opportunistic screening.Methods::We developed a questionnaire-based diagnostic model using a joint dataset including two clinical cohorts from northern and southern China. The cohorts consisted of 17,360 outpatients who had undergone upper gastrointestinal endoscopic examination in endoscopic clinics. The final model was derived based on unconditional logistic regression, and predictors were selected according to the Akaike information criterion. External validation was carried out with 32,614 participants from a community-based randomized controlled trial.Results::This questionnaire-based diagnostic model for malignant gastric lesions had eight predictors, including advanced age, male gender, family history of gastric cancer, low body mass index, unexplained weight loss, consumption of leftover food, consumption of preserved food, and epigastric pain. This model showed high discriminative power in the development set with an area under the receiver operating characteristic curve (AUC) of 0.791 (95% confidence interval [CI]: 0.750–0.831). External validation of the model in the general population generated an AUC of 0.696 (95% CI: 0.570–0.822). This model showed an ideal ability for enriching prevalent malignant gastric lesions when applied to various scenarios.Conclusion::This easy-to-use questionnaire-based model for diagnosis of prevalent malignant gastric lesions may serve as an effective prescreening tool in clinical opportunistic screening for gastric cancer.

Bladder cancer is one of the most common malignancy in the urinary system over the world. Urine cytology and cystoscopy are important tools for bladder cancer diagnosis and recurrence monitoring. However, due to the limited sensitivity and invasive procedure, there is an urgent need to develop new non-invasive and highly sensitive liquid biopsy approaches. Urine biopsy is a research focus in the field and has great potential. This review focused on protein-based urine markers (including NMP22, BTA and UroVysion etc.) and DNA or RNA-based urine markers (including cfDNA, AssureMDx and Xpert BC Monitor etc.), which were used for bladder cancer diagnosis and recurrence monitoring, and summarized the sensitivity and specificity of each biomarker as well as their characteristics in the diagnosis and recurrence surveillance of bladder cancer. This study provides theoretical and empirical support for further optimization and application of these biomarkers in clinical practice.

Objective : To investigate the effects of angiopoietin 4 (ANGPT4) on the odontogenic differentiation of human dental pulp stem cells. Methods : This study has been reviewed and approved by the Ethics Committee, and informed consent has been obtained from patients. Human premolars were fixed, decalcified, dehydrated, embedded, and sectioned. Immunofluorescence staining was used to observe the expression and localization of ANGPT4. Human dental pulp stem cells (hDPSCs) were isolated and cultured in vitro. The growth state and morphology of hDPSCs were observed under an inverted phase contrast microscope. The expression of cell surface-related molecular markers was detected by flow cytometry. Alkaline phosphatase and alizarin red S staining were used to detect the odontogenic differentiation potential of hDPSCs. Oil-red O staining was used to detect the adipogenic differentiation potential of hDPSCs. RNA was extracted from hDPSCs at different time points after odontogenic induction, and RT-qPCR was used to analyze the mRNA expression of ANGPT4 and odontogenic-related genes during the odontogenic differentiation of hDPSCs in vitro. siRNA gene silencing technology was used to silence the expression of ANGPT4 in hDPSCs, and the silencing efficiency was detected by RT-qPCR and Western Blot. After silencing ANGPT4 in hDPSCs for 24 h, odontogenic induction was performed. Alkaline phosphatase and alizarin red S staining were performed on the 7th and 14th of induction to detect the odontogenic differentiation ability of hDPSCs after silencing ANGPT4 Results : Immunofluorescence staining of human premolars showed that ANGPT4 was expressed in odontoblasts and sub-odontoblastic cell-rich zone. hDPSCs were in good condition after 14 days of isolation and culture. Under the microscope, multiple cell colonies were observed, and the cell morphology was uniform and long spindle-shaped. The results of flow cytometry showed that hDPSCs expressed mesenchymal stem cell markers CD105 (90.42%) and CD90 (97.15%), but did not express hematopoietic cell markers CD45 (0.01%) and CD34 (0.08%). After odontogenic and adipogenic induction of hDPSCs, alkaline phosphatase staining, alizarin red S staining and oil red O staining were positive. The results of RT-qPCR after the odontogenic induction of hDPSCs showed that ANGPT4 was highly expressed on the 5th, 7th, 11th and 14th days of differentiation of hDPSCs (P<0.05), with the highest expression level on the 5th day. After hDPSCs were transfected with si-ANGPT4, the expression of ANGPT4 mRNA and protein was significantly down-regulated (P<0.05). The results of alkaline phosphatase staining showed that ALP staining intensity and area in the si-ANGPT4 group were significantly lower than those in the negative control. Alizarin red S staining showed that the formation of calcium nodules in the si-ANGPT4 group was significantly lower than that in the negative control. Conclusion ANGPT4 was expressed in odontoblasts and sub-odontoblastic cell-rich zone of human premolars. ANGPT4 may be a factor to promote the odontogenic differentiation of hDPSCs.

Lateral epicondylitis is a common clinical disease with characteristics of lateral elbow pain, insidious onset and easy recurrence, which can cause forearm pain and decreased wrist strength, seriously affecting patients′ daily life and work. Although there are various treatment methods for lateral epicondylitis with different effects, standard treatments are still lacking nowadays. Platelet-rich plasma (PRP) has good effects on bone and tendon repair, and is now widely used in the treatment of lateral epicondylitis. However, there is a lack of a unified understanding of the technology and specifications of PRP in the treatment of lateral epicondylitis. Therefore, the Sports Medicine Branch of the Chinese Medical Association and Physical Medicine and Rehabilitation Branch of the Chinese Medical Association organized experts in the fields of sports medicine and rehabilitation medicine in China to formulate the "clinical expert consensus on platelet-rich plasma treatment for lateral epicondylitis (2022 version)", and proposed suggestions based on evidence-based medicine mainly from the concept, epidemiology and pathophysiology of lateral epicondylitis, symptoms, signs and imaging manifestations of lateral epicondylitis, PRP concept and application component requirements, quality control of PRP preparation technology, indications and contraindications of PRP in the treatment of lateral epicondylitis, PRP injection in the treatment of lateral epicondylitis, application of PRP in the operation of lateral epicondylitis, related problems after PRP treatment of lateral epicondylitis, evaluation of the results after PRP treatment of lateral epicondylitis, and health and economic evaluation of PRP treatment of lateral epicondylitis, so as to provide guidance for clinical diagnosis and treatment.

Objective:To investigate the clinical symptoms and cone-beam CT (CBCT) imaging characteristics of temporomandibular joint osteoarthritis (TMJOA) with chewing side preference (CSP).Methods:One hundred patients with TMJOA diagnosed in the Department of Stomatology, General Hospital of the Chinese PLA from January 2018 to December 2020 were enrolled, including 32 males and 68 females, with an median age of 27.5 years (16-71 years). According to the habit of CSP, 100 cases were divided into 71 cases of TMJOA with CSP group and 29 cases of TMJOA without CSP group. The clinical symptoms were observed, including pain, TMJ sounds, limited mouth opening as well as the radiograph imaging changes of condylar bone. When analyzing the radiograph imaging changes of condylar, the cases with bilateral TMJ symptoms were excluded and the remaining cases were divided into symptomatic sides and asymptomatic sides with CSP or without CSP according to the symptoms of the chief complaint. SPSS 25.0 was used to analyze the statistical data. Age data did not conform to normal distribution so that median and quartile spacing were used for description, and Mann-Whitney U test was used for nonparametric test. Qualitative data such as gender, clinical symptoms and condylar lesion types were described by composition ratio and chi-square test was performed. Results:There was no statistical significance in age and gender of TMJOA patients in the group with or without CSP ( P>0.05). The incidence of pain in CSP group [83.1% (59/71)] was marginally higher than that in non-CSP group [65.5% (19/29)] but without statistical difference (χ2 =3.71, P=0.054). There was also no significant difference in TMJ sounds and limitation of mandibular movement between the two groups (χ2 =0.11, P=0.742; χ2 =0.48, P=0.489). Among all of joints, the most common types of TMJOA were articular flattening and shortening and erosion. CBCT showed that erosion [65.0% (130/200)], flattening and shortening [73.0% (146/200)], subcortical sclerosis [42.0% (84/200)], osteophyte [30.5% (61/200)] and subcortical cystic [15.5% (31/200)]. According to the different groups of chief complaint sides, intra-group comparisons show that the proportion of erosion in symptomatic sides of CSP group [80.0% (40/50)] was significantly higher than that in asymptomatic sides of CSP group [50.0% (25/50)] (χ2=9.89, P=0.002). Inter-group comparisons show that the proportion of condyle flattening and shortening in symptomatic sides of CSP group [84.0% (42/50)] was significantly higher than that in bilateral joint of non-CSP group (8/15) (χ2=8.81, P=0.032). There was no significant difference in the proportion of subcortical sclerosis, osteophyte and subcortical cystic between the group with or without CSP ( P>0.05). Conclusions:TMJOA patients with CSP may be more prone to clinical symptoms of pain and CBCT imaging changes of condyle erosion as well as flattening and shortening. CSP may be a promoting factor for the development of TMJOA.

Nanomaterial-based drug sustainable release systems have been tentatively applied to bone regeneration. They, however, still face disadvantages of high toxicity, low biocompatibility, and low drug-load capacity. In view of the low toxicity and high biocompatibility of polymer nanomaterials and the excellent load capacity of hollow nanomaterials with high specific surface area, we evaluated the hollow polydopamine nanoparticles (HPDA NPs), in order to find an optimal system to effectively deliver the osteogenic drugs to improve treatment of bone defect. Data demonstrated that the HPDA NPs synthesized herein could efficiently load four types of osteogenic drugs and the drugs can effectively release from the HPDA NPs for a relatively longer time in vitro and in vivo with low toxicity and high biocompatibility. Results of qRT-PCR, ALP, and alizarin red S staining showed that drugs released from the HPDA NPs could promote osteogenic differentiation and proliferation of rat bone marrow mesenchymal stem cells (rBMSCs) in vitro. Image data from micro-CT and H&E staining showed that all four osteogenic drugs released from the HPDA NPs effectively promoted bone regeneration in the defect of tooth extraction fossa in vivo, especially tacrolimus. These results suggest that the HPDA NPs, the biodegradable hollow polymer nanoparticles with high drug load rate and sustainable release ability, have good prospect to treat the bone defect in future clinical practice.
Animals ; Bone Regeneration ; Indoles ; Nanoparticles ; Osteogenesis ; Pharmaceutical Preparations ; Polymers ; Rats

Currently, titanium alloys are widely used in the field of stomatology; however, owing to long-term exposure to a complex microbial environment, dental plaques easily form on the surface of the materials, affecting the use efficiency and the service life of the materials. The antibacterial titanium alloy is a new kind of titanium alloy with antimicrobials added through surface modification or overall modification. Based on the location of antibacterial agents in titanium alloy materials, antibacterial titanium alloys can be divided into coating and alloy types. The antibacterial effect of coated antibacterial titanium alloy is good, but the disadvantage is that most of the coatings are not wear-resistant. The widely-used antibacterial agent of the alloy type is metal elements, which can be evenly distributed in the alloy, and the antibacterial properties are stable and long-lasting. Based on whether antibacterial agents can be released, antibacterial titanium alloys can be further divided into active antibacterial and passive antibacterial types. Active antibacterial type titanium alloys can release loaded antibacterial agents, and the antibacterial effect is more obvious, but the release duration of antibacterial agents is relatively short. Passive antibacterial titanium alloys exhibit an antibacterial effect by contact sterilization or inhibition of bacterial adhesion instead of releasing antibacterial agents. The antibacterial titanium alloy can inhibit the adhesion of bacteria on the surface of the material and prolong the service life of oral orthodontic appliances, implants and titanium plates. Moreover, the mechanical properties of the titanium alloy after antibacterial modification are not significantly affected, and the addition of antibacterial agents such as hydroxyapatite can increase the osteogenic function of the material. Therefore, the alloy has good application prospects in the fields of dental implant, orthodontic treatment and oral and maxillofacial surgery. However, most of the current studies on antibacterial titanium alloys are in vitro experiments, and their long-term clinical effects and antibacterial mechanisms are still unclear and need further study.