Introduction To investigate the biomechanical characteristics of innate occlusal contact patterns in cracked teeth (CT) using T-Scan analysis combined with finite element analysis (FEA), and to establish a theoretical foundation for clinical prevention and restorative strategies. Methods Twelve patients with cracked maxillary first molars (MFMs) exhibiting mesial marginal ridge cracks and twelve controls were enrolled. Occlusal contacts were recorded using T-Scan, with categorical variables analyzed via Fisher’s exact test (p < 0.05). Patient-specific finite element models were constructed from CBCT data of three cracked and three intact MFMs. Stress distribution under different loadings was compared using two-way ANOVA (p < 0.05). Results T-Scan analysis demonstrated a significantly higher incidence of abnormal occlusal contact points in the CT group compared with controls (p < 0.05), along with bilateral occlusal imbalance. FEA revealed that maximum von Mises stress values on the mesial surfaces were consistently higher than those on the distal surfaces in the CT group under vertical loading (p < 0.05). Abnormal contact sites contributed to increased stress on the mesial surfaces in both CT and controls. A significant intergroup difference in maximum von Mises stress was observed on the mesial surfaces (p < 0.05), whereas no significant difference was detected on the distal surfaces. Conclusions Patients with CT exhibited bilateral occlusal imbalance, characterized by abnormal occlusal contact points on the affected teeth. Congenital morphological discrepancies represent the primary etiological factor for CT, whereas aberrant contact points further exacerbate crack progression. Early occlusal adjustment and crown-supported protection is recommended to compensate for underlying morphological abnormalities.

Introduction:Osteoarthritis (OA) is a chronic degenerative joint disease accompanied by an elevated macrophage proinflammatory phenotype, which is triggered by persistent pathologically elevated calcium ion levels in mitochondria. However, existing pharmacological compounds targeting the inhibition of mitochondrial calcium ion (m[Ca2+]) influx are currently limited in terms of plasma membrane permeability and low specificity for ion channels and transporters. In the present study, we synthesized mesoporous silica nanoparticle-amidated (MSN)-ethylenebis (oxyethylenenitrilo)tetraacetic acid (EGTA)/triphenylphosphine (TPP)-polyethylene glycol (PEG) [METP] nanoparticles (NPs), which specifically target mitochondria and block excess calcium ion influx.Methods:m[Ca2+] overload in OA mouse bone marrow-derived macrophages (BMDMs) was detected by a fluorescence probe. A tissue in situ fluorescence colocalization assay was used to evaluate METP NP uptake by macrophages. BMDMs from healthy mice were pretreated with a concentration gradient of METP NPs followed by lipopolysaccharide (LPS) stimulation and detection of m[Ca2+] levels in vitro. The optimal METP NP concentration was further applied, and the endoplasmic reticulum (ER) and cytoplasm calcium levels were detected. The inflammatory phenotype was measured by surface markers, cytokine secretion and intracellular inflammatory gene/protein expression. A Seahorse cell energy metabolism assay was performed to elucidate the mechanism by which METP NPs reverse the BMDM proinflammatory phenotype.Results:The present study identified calcium overload in BMDM mitochondria of OA mice. We demonstrated that METP NPs reversed the increased m[Ca2+] levels in mitochondria and the proinflammatory phenotype of BMDMs, with both in vivo and in vitro experiments, via the inhibition of the mitochondrial aspartate-arginosuccinate shunt and ROS production.Conclusion:We demonstrated that METP NPs are effective and highly specific regulators of m[Ca2+] overload. In addition, we demonstrated that these METP NPs reverse the macrophage proinflammatory phenotype by restoring m[Ca2+] homeostasis, thereby inhibiting the tissue inflammatory response and achieving a therapeutic effect for OA.

外泌体是体内活细胞分泌的一种膜性小囊泡,其良好的生物相容性、稳定性和低免疫原性使其在组织再生领域备受青睐.在牙髓再生过程中,外泌体可通过促进干细胞迁移和分化诱导牙髓组织的新生,但不易长期维持牙髓组织再生的有效浓度.生物支架可对外泌体实现有效包裹,保护其活性且减少流失,通过支架自身降解来缓慢释放外泌体,保证外泌体不断与干细胞接触,诱导牙髓组织的生成.文章就生物支架搭载干细胞来源外泌体在牙髓再生中应用的研究进展做一综述.

Objective To investigate the distribution characteristics and functional genes of cariogenic bacteria in oral microorganisms of patients with type 2 diabetes mellitus and to improve the understanding of the relationship between type 2 diabetes mellitus and dental caries. Methods The experimental group included 10 patients with type 2 diabetes treated in the Department of Endocrinology, the First Affiliated Hospital of Air Force Medical University. The normal control group included healthy oral subjects without type 2 diabetes in the community population (10 cases). Samples of supragingival plaque from patients with type 2 diabetes mellitus and normal controls were collected and sequenced. Bioinformatics and statistical analysis of cariogenic bacteria such as Streptococcus mutans, Lactobacillus, Actinomyces viscosus and Candida albicans were carried out. Results There were slightly fewer cariogenic bacteria such as Streptococcus mutans, Lactobacillus, Actinomyces viscosus and Candida albicans in supragingival plaque samples of type 2 diabetic patients than in normal controls, but the difference was not statistically significant (P>0.05). The results of KEGG pathway functional metabolic differences showed that the metabolic pathways of D-arginine and D-ornithine metabolism, biofilm formation-Escherichia coli, carolactam degradation and arginine biosynthesis were more abundant in the T2DM group than in the normal control group, while metabolic pathways such as tyrosine metabolism, selenocompound metabolism and pyruvate metabolism showed the opposite trend. Conclusion There was no significant difference in the content of cariogenic microorganisms between type 2 diabetic patients and normal control group. The differential metabolic pathways of the functional genes indicated that an increase in the arginine metabolic pathway was beneficial to the maintenance of acid-base balance in the oral microecological environment.

Objective:The aim of this retrospective study was to evaluate the prevalence of taurodontism in a group of adult dental patients in Northwest China with the aid of cone-beam computed tomography (CBCT). Methods:This study used Shifman and Chanannel's criteria to statistically analyze the prevalence of taurodontism in the premolars and molars of the Chinese population. CBCT images of 5488 teeth from 580 subjects of Chinese origin were evaluated. The measured data were statistically analyzed and the chi-square test was also used to compare the prevalence of taurodontism between male and female subjects and between the upper and lower jaws (P < 0.05). Results:Taurodontism was detected in 169 patients, with a prevalence of 29.14%, of which 27.24% were males and 30.65% were females. The chi-square test showed that there was no significant difference between males and females (P > 0.05). Taurodontism was found in 7.45% of all teeth examined. Taurodonts were significantly more common in the maxilla (9.06%) than in the mandible (5.15%) (P < 0.001), and the maxillary second molar (25.18%) was the most common tooth affected. According to morphology, hypotaurodonts were the most common (60.39%) among taurodontic teeth. Conclusions:Taurodontism was relatively common in the Chinese population and was almost equally distributed between males and females. The maxillary second molar was the most common tooth of all taurodonts measured, and taurodonts were significantly more common in the maxilla than in the mandible. Hypotaurodontism was the most common form of taurodontism. Our study provides a reference for dental deformities in the Chinese population and the diagnosis and treatment of taurodontism.

目的 探讨根管治疗术对牙髓炎患者外周血炎性因子的改善及焦虑抑郁情绪的影响.方法 选取2021年6月至2022年6月在第四军医大学口腔医院牙体牙髓病科收治的155例牙髓炎患者为试验组,采用根管治疗术治疗;另选同期接受健康体检且口腔健康的155例人员为对照组,比较两组的广泛性焦虑障碍量表(Generalized Anxiety Disorder-7,GAD-7)评分、抑郁症筛查量表(Patien Health Questionnare-9,PHQ-9)评分;同时观察试验组治疗前与治疗第3、6周后的GAD-7评分、PHQ-9评分与疼痛评分,其中疼痛用视觉模拟量表(visu-al analogue scale,VAS)评定;比较试验组治疗前与治疗第3、6周后外周血的炎性细胞因子白细胞介素-8(inter-leukin-8,IL-8)、白细胞介素-1β(interleukin-1β,IL-1β)、肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)、C反应蛋白(C-reactive protein,CRP)水平.结果 试验组治疗前GAD-7评分、PHQ-9评分均高于对照组(P<0.05);试验组治疗第3、6周后的GAD-7评分、PHQ-9评分均低于治疗前(P<0.05),治疗第3周后与治疗第6周后的GAD-7评分以及PHQ-9评分差异无统计学意义(P>0.05);试验组治疗第3、6周后的疼痛评分均低于治疗前(P<0.05),治疗第6周的疼痛评分比治疗第3周低(P<0.05);试验组治疗第3、6周后外周血的IL-8、IL-1β、TNF-α、CRP水平均低于治疗前(P<0.05),治疗第6周后外周血的IL-8、IL-1β水平低于治疗第3周后(P<0.05),治疗第6周后外周血的TNF-α、CRP水平与治疗第3周后差异无统计学意义(P>0.05).结论 牙髓炎患者外周血存在较高的炎症水平与明显的焦虑、抑郁情绪,根管治疗术能降低牙髓炎患者的炎症水平,改善焦虑、抑郁情绪.

Several previous studies have shown that oral microbial disorders may be closely related to the occurrence and development of type 2 diabetes mellitus (T2DM). However, whether the function of oral microorganisms and their metabolites have changed in patients with T2DM who have not suffered from any oral diseases has not been reported. We performed metagenomic analyses and nontargeted metabolic analysis of saliva and supragingival plaque samples from patients with T2DM who have not suffered any oral diseases and normal controls. We found that periodontal pathogens such as Porphyromonas gingivalis and Prevotella melaninogenica were significantly enriched, while the abundances of dental caries pathogens such as Streptococcus mutans and Streptococcus sobrinus were not significantly different in patients with T2DM compared to those in normal controls. Metabolomic analyses showed that the salivary levels of cadaverine and L-(+)-leucine of patients with T2DM were significantly higher than those of normal controls, while the supragingival plaque levels of N-acetyldopamine and 3,4-dimethylbenzoic acid in patients with T2DM were significantly higher than those in the normal controls. Additionally, we identified the types of oral microorganisms related to the changes in the levels of circulating metabolites, and the oral microorganisms were involved in the dysregulation of harmful metabolites such as cadaverine and n, n-dimethylarginine. Overall, our study first described the changes in the composition of oral microorganisms and their metabolites in patients with T2DM who have not suffered any oral diseases, which will provide a direct basis for finding oral biomarkers for early warning of oral diseases in T2DM. IMPORTANCE The incidence of oral diseases in type 2 diabetic patients might increase, and the severity might also be more serious. At present, the relationship between oral microorganisms and type 2 diabetes mellitus (T2DM) has become a hot topic in systemic health research. However, whether the function of oral microorganisms and their metabolites have changed in patients with T2DM who have not suffered from any oral diseases has not been reported. We found that even if the oral condition of T2DM is healthy, their oral microbes and metabolites have changed, thus increasing the risk of periodontal disease. Our study first described the changes in the composition of oral microorganisms and their metabolites in T2DM who have not suffered any oral diseases and revealed the correlation between oral microorganisms and their metabolites, which will provide a direct basis for finding oral biomarkers for early warning of oral diseases in patients with T2DM.

The root canal systems of maxillary second molar (MSM) variations are complicated, especially the prevalence of fused roots and consequent merged and C-shaped canals, which represent a clinical challenge because canal configurations can be irregular and unpredictable. The purpose of this article was to present 2 cases with a C-shaped configuration diagnosed during root canal retreatment and perform a literature review of this MSM anatomy. Case 1 reports that two palatal root canals fused into a C-shaped configuration that finally formed an apical foramen, which was classified as Type D. Case 2 reflects the fusion of the distobuccal canal and palatal canal into a C-shaped configuration and the configuration was Type C, which was first reported in a case report. Nonsurgical retreatments were proposed and conducted. Evaluation at a 24-month recall revealed that the two patients were symptom-free, and radiographic examination revealed normal periapical tissue. This report serves to remind clinicians of the complexities of the root canal system and that possible anatomic variation should always be anticipated when formulating an effective root canal treatment plan. The use of CBCT imaging coupled with an operative dental microscope will be helpful in locating and identifying supernumerary canals when a preoperative periapical radiograph shows signs of a fused-rooted MSM.

BACKGROUND:Fused teeth usually involve several complications, such as the development of caries in the groove between fused crowns, tooth impaction, diastemas, aesthetic and periodontal problems, and pulpal pathosis, due to the complex anatomical structure of fused teeth. A thorough diagnosis is paramount to forming an accurate treatment plan and obtaining a favourable prognosis. With the advent of cone-beam computed tomography (CBCT), accurate 3-dimensional images of teeth and their surrounding dentoalveolar structures can now be readily obtained, and the technology can accurately provide a minimally invasive approach to acquire detailed diagnostic information. Therefore, we utilize CBCT data herein to generate a digital model for the infected region in a patient, and this model enables us to better plan the management of his case.CASE SUMMARY:This report details the diagnosis and endodontic treatment of a rare case involving a fused maxillary second molar and two paramolars with apical periodontitis. The patient experienced pain upon biting and cold sensitivity in the area of the maxillary left molar. No caries or other defects were identified in these teeth, and a normal response to a pulp electric viability test was observed. With the aid of CBCT and digital model technology, we initially suspected that the infection originated from the isthmus between the maxillary second molar and two paramolars. Therefore, we only treated the isthmus by an endodontic approach and did not destroy the original tooth structure; furthermore, the vital pulp was retained, and good treatment outcomes were observed at the 24-month follow-up.CONCLUSION:This finding may provide new insights and perspectives on the diagnosis and treatment of fused teeth.

Dental caries and pulpal diseases are common oral bacterial infectious diseases, the prevention and treatment of these diseases require the control of the causative pathogens, such as Streptococcus mutans (S. mutans) and Enterococcus faecalis. As a cationic antimicrobial peptide, Chrysophsin-3 has broad-spectrum bactericidal activity against both Gram-positive and Gram-negative bacteria which may cause a variety of oral infectious diseases. The present study evaluated the potential of chrysophsin-3 against several oral pathogens and S.mutans biofilms. The cytotoxic activity of chrysophsin-3 against human gingival fibroblasts (HGFs) was investigated for potential oral application. We use minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and time-kill assay to evaluate the killing effect of chrysophsin-3. Then scanning electron microscopy (SEM) and Transmission Electron Microscope (TEM) were used to analyze the change of morphology and membrane of the pathogens, Live/Dead staining and confocal scanning laser microscopy (CSLM) was used to observe S. mutans biofilms. The results indicate that chrysophsin-3 has varying antimicrobial activities against different oral bacteria. Chrysophsin-3 did not cause obvious cytotoxicity in HGFs at concentrations of 32-128 μg/ml for 5 min or 8 μg/ml for 60 min. SEM revealed membranous blebs and pore formation on the bacterial cell surface, and TEM showed loss of the nucleoid and dissolution of the cytoplasmic space. Furthermore, the CSLM images indicate that chrysophsin-3 can reduce the viability of the cells within the biofilms significantly and had a comparatively lethal effect against S. mutans biofilms. Taken together, our finding suggests that chrysophsin-3 has potential clinical application in oral infectious disease, especially in preventing and treating dental caries.

Abstract Objectives: The purpose of this study was to predict the fracture resistance of endodontically treated mandibular first molars (MFMs) with diverse minimally invasive endodontic access cavities using finite element models.Materials and Methods: Based on microcomputed tomographic data of an MFM, five three-dimensional finite element models representing a natural tooth (NT) and 4 endodontically treated MFMs were generated using finite element analysis software (HyperWork 14.0, Altair, USA). Treated MFM models were with a traditional endodontic cavity (TEC) and minimal invasive endodontic (MIE) cavities, including a computer-aided designed guided endodontic cavity (GEC), contracted endodontic cavity (CEC) and truss endodontic cavity (TREC). Three loading conditions were applied, simulating a maximum bite force of 600 N vertically and a normal masticatory force of 225 N vertically and laterally. The distributions of von Mises (VM) stress and peak VM stress were calculated.Results: The peak VM stresses of the NT model were the lowest under normal masticatory forces. In endodontically treated models, the distribution of VM stress in GEC model under all loads was the most similar to NT model. The peak VM stresses of the GEC and CEC models under different forces were lower than those of TREC and TEC models. The peak VM stresses of the GEC were lower than those of the CEC under normal masticatory loads but higher under maximum bite load. Under two vertical loads, the peak VM stresses of the TREC model were the highest, while under the lateral load, the peak VM stress of the TEC model was the highest. However, the VM stress in most part of the TEC model was higher than that in TREC model under all loads. Conclusions: Compared with TEC, GEC and CEC could better improve the fracture resistance of teeth. TREC may have a limited effect on fracture resistance enhancement when compared to GEC and CEC.Clinical Relevance: Our data demonstrated that compared with TEC and TREC, GEC and CEC access could better improve the fracture resistance of endodontically treated teeth, which may be an alternative balancing biomechanical properties and clinical convenience.

To evaluate in a laboratory setting, the impact of three designs of endodontic access cavities on dentine removal and effectiveness of canal instrumentation in extracted maxillary first molars using micro-computed tomography (micro-CT). A total of 30 extracted intact maxillary first molars were selected and scanned by micro-CT with a voxel size of 24 µm and randomly distributed into three groups: the traditional endodontic cavity (TEC) group, the conservative endodontic cavity (CEC) group and the guided endodontic cavity (GEC) group. The pulp chambers of teeth in the groups were accessed accordingly. After root canal preparation, the teeth were rescanned. The volume of dentine removed after canal preparation, the noninstrumented canal areas, canal transportation and centring ratio were analysed. Data were analysed statistically using one-way analysis of variance. Tukey's post hoc test was used for multiple comparisons. The significance level was set at p < .05. The total volume of dentine removed was significantly greater in the TEC group after root canal preparation ( p < .05). No significant differences in the volume of dentine removed occurred between the CEC and GEC groups ( p > .05). The volume of dentine removed in the crown, pericervical dentine and coronal third of the canal was significantly lower in CEC and GEC groups when compared to that in the TEC group ( p < .05), no difference was observed in the middle third of the canal and apical third of the canal amongst the three groups ( p > .05). There was no significant difference in noninstrumented canal area, canal transportation and centring ratio amongst the TEC, CEC and GEC groups ( p > .05). In extracted maxillary molars tested in a laboratory setting, CEC and GEC preserved more tooth tissue in the crown, pericervical dentine and coronal third of the canal compared with TEC after root canal preparation. The design of the endodontic access cavity did not impact on the effectiveness of canal instrumentation in terms of noninstrumented canal area, canal transportation and centring ratio.

目的 探讨微课结合翻转课堂的教学模式在牙体牙髓病学实践教学效果中的作用.方法 选择第四军医大学口腔医院2016级所有23名五年制口腔医学专业本科生作为实验组,2015级所有20名五年制口腔医学专业本科生作为对照组,实验组在牙体牙髓病学实践教学中采用微课结合翻转课堂的教学模式,对照组采用传统教学法,研究起始时间为2019年9月至2021年1月.课程结束后比较两组学生实践理论和实践操作的成绩,并通过问卷调查评估实验组学生对微课结合翻转课堂的教学模式的认可度和满意度.结果 实验组实践成绩和总成绩均高于对照组,两组之间差异有统计学意义(P<0.05).问卷调查结果显示实验组学生对微课结合翻转课堂的教学模式具有较高的认可度和满意度,但也认为其不能完全替代传统的教学方法.结论 微课结合翻转课堂的新型教学模式有利于调动学生的学习积极性,提高教学效率,是提升牙体牙髓病学实践教学效果的一种有效方法.

OBJECTIVE:Patients with type 2 diabetes mellitus (T2DM) are at high risk for development of atherosclerosis and cardiovascular events. Serum S100A12 levels have been reported to be associated with coronary artery disease (CAD) and T2DM. We sought to assess whether serum S100A12 levels are correlated with the presence and severity of CAD.METHODS:Type 2 diabetes mellitus levels in 188 consecutive patients with T2DM undergoing coronary angiography for the evaluation of CAD. The severity of CAD was assessed by the Coronary Atherosclerosis Index (CAI) scores.RESULTS:Serum S100A12 levels were significantly higher in patients with T2DM with CAD than in those without CAD. Multivariate logistic regression analysis revealed that serum S100A12 levels were independently associated with the presence of CAD. Serum S100A12 levels were positively correlated with the Coronary Atherosclerosis Index scores after adjusting for other clinical characteristics.CONCLUSION:High S100A12 levels are associated with the presence and severity of CAD in patients with T2DM.