Instrument separation is a critical complication during root canal therapy, impacting treatment success and long-term tooth preservation. The etiology of instrument separation is multifactorial, involving the intricate anatomy of the root canal system, instrument-related factors, and instrumentation techniques. Instrument separation can hinder thorough cleaning, shaping, and obturation of the root canal, posing challenges to successful treatment outcomes. Although retrieval of separated instrument is often feasible, it carries risks including perforation, excessive removal of tooth structure and root fractures. Effective management of separated instruments requires a comprehensive understanding of the contributing factors, meticulous preoperative assessment, and precise evaluation of the retrieval difficulty. The application of appropriate retrieval techniques is essential to minimize complications and optimize clinical outcomes. The current manuscript provides a framework for understanding the causes, risk factors, and clinical management principles of instrument separation. By integrating effective strategies, endodontists can enhance decision-making, improve endodontic treatment success and ensure the preservation of natural dentition.
Humans ; Root Canal Therapy/adverse effects* ; Consensus ; Root Canal Preparation/adverse effects*

Fused teeth are usually formed by the partial or complete fusion of two normal tooth germs during the development process and belong to dental developmental abnormalities. Fused teeth are relatively rare clinically, and those occurring in the posterior tooth area are even rarer. This article reports a case of fused teeth between the first permanent molar and the second permanent molar in the right mandible. This fused tooth had a complex root canal anatomical structure (seven root canals). The number and location of the root canals were analyzed by cone beam computed tomography, and root canal treatment was successfully completed with the assistance of microscope.
Humans ; Molar/diagnostic imaging* ; Mandible ; Dental Pulp Cavity/abnormalities* ; Cone-Beam Computed Tomography ; Root Canal Therapy/methods* ; Fused Teeth/surgery*

Objective To explore the influencing factors of frailty among the health check-up elder-ly participants from our outpatient clinic.Methods A total of 710 elderly individuals(≥60 years old)who taking health check-up in our outpatient department between April and August 2022 were consecutively enrolled,and according to the results of Fried Frailty Phenotype Scale,they were divided into non-frailty group(422 cases),pre-frailty group(225 cases)and frailty group(63 cases).Their general clinical data,laboratory indicators and echocardiographic parameters were collected,and multivariate logistic regression analysis was applied to identify the independent in-fluencing factors for pre-frailty and frailty.Results The overall prevalence of pre-frailty and frail-ty was 31.7％and 8.9％,respectively.The pre-frailty and frailty groups had obviously larger left atrial anterior-posterior diameter and left ventricular end diastolic diameter and lower left ventric-ular ejection fraction when compared with the non-frailty group(P＜0.05).Multivariate logistic regression analysis showed that Hb was a protective factor for pre-frailty in the elderly partici-pants(OR=0.984,95％CI:0.966-0.992,P=0.048),while age(OR=1.064),CCI(OR=1.387)and LAAP(OR=1.059)were risk factors for pre-frailty in them(P＜0.05,P＜0.01).Serum albumin was a protective factor for frailty(OR=0.823,95％CI:0.728-0.931,P=0.002),but age(OR=1.081),CCI(OR=1.458),left atrial anterior-posterior diameter(OR=1.249)and NT-proBNP(OR=1.652)were independent risk factors for frailty(P＜0.05,P＜0.01).Conclusion There are differences in influencing factors for frailty of different severity,and the status of frailty is related to factors such as age,comorbidity,cardiac function and nutritional sta-tus.Therefore,comprehensive interventions should be implemented as early as possible for the elderly occurrence of pre-frailty so as to prevent and reverse frailty at the same time.

Objective To explore the influencing factors of frailty among the health check-up elder-ly participants from our outpatient clinic.Methods A total of 710 elderly individuals(≥60 years old)who taking health check-up in our outpatient department between April and August 2022 were consecutively enrolled,and according to the results of Fried Frailty Phenotype Scale,they were divided into non-frailty group(422 cases),pre-frailty group(225 cases)and frailty group(63 cases).Their general clinical data,laboratory indicators and echocardiographic parameters were collected,and multivariate logistic regression analysis was applied to identify the independent in-fluencing factors for pre-frailty and frailty.Results The overall prevalence of pre-frailty and frail-ty was 31.7％and 8.9％,respectively.The pre-frailty and frailty groups had obviously larger left atrial anterior-posterior diameter and left ventricular end diastolic diameter and lower left ventric-ular ejection fraction when compared with the non-frailty group(P＜0.05).Multivariate logistic regression analysis showed that Hb was a protective factor for pre-frailty in the elderly partici-pants(OR=0.984,95％CI:0.966-0.992,P=0.048),while age(OR=1.064),CCI(OR=1.387)and LAAP(OR=1.059)were risk factors for pre-frailty in them(P＜0.05,P＜0.01).Serum albumin was a protective factor for frailty(OR=0.823,95％CI:0.728-0.931,P=0.002),but age(OR=1.081),CCI(OR=1.458),left atrial anterior-posterior diameter(OR=1.249)and NT-proBNP(OR=1.652)were independent risk factors for frailty(P＜0.05,P＜0.01).Conclusion There are differences in influencing factors for frailty of different severity,and the status of frailty is related to factors such as age,comorbidity,cardiac function and nutritional sta-tus.Therefore,comprehensive interventions should be implemented as early as possible for the elderly occurrence of pre-frailty so as to prevent and reverse frailty at the same time.

Objective:To evaluate the practical value of ultrasound, ultrasound new technologies (ultrasound elastography, contrast enhanced ultrasound) and computed tomography (CT) examination alone or the combination of both of the four in the clinical diagnosis of lymph node metastasis of thyroid cancer by meta-analysis system.Methods:This study screened relevant literature on ultrasound, new ultrasound technologies, and CT in the diagnosis of lymph node metastasis of thyroid cancer by searching Chinese and English databases from January 2006 to August 2023. Two scholars independently assessed the quality of the literatures and scored them using the QUADAS scale. Then, the diagnostic ratio of single and combined examinations was analyzed by Meta-Disc software, and the heterogeneity test and meta-analysis were performed to calculate the sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic ratio, accuracy, and area under curve (AUC). Finally, the diagnostic efficacies of different diagnostic techniques and their combination in identifying lymph node metastasis of thyroid cancer were assessed by calculating OR and P values by two-by-two comparisons. Results:Sixty-nine diagnostic studies totaling 30, 666 lesions were finally included. The meta-analysis study showed that contrast enhanced ultrasound had the highest sensitivity[0.83(0.77-0.87)], ultrasound specificity was the highest [0.84(0.79-0.88)], the highest AUC was for contrast enhanced ultrasound (0.90), and contrast enhanced ultrasound and ultrasound elastography had high accuracies (0.81, 0.80, respectively) both of them were higher than those of ultrasound (0.77) and CT (0.69). Contrast enhanced ultrasound and ultrasound elastography were both more sensitive than CT, with statistically significant differences between them ( P<0.01); contrast enhanced ultrasound + ultrasound elastography had the highest accuracy, while ultrasound + contrast enhanced ultrasound and contrast enhanced ultrasound + ultrasound elastography were both more sensitive, with no statistically significant differences between them ( P>0.05), but the latter had the highest specificity [0.90(0.88-0.92)], which were statistically significantly different from each other ( P<0.05), ultrasound+ contrast enhanced ultrasound and contrast enhanced ultrasound+ ultrasound elastography had higher sensitivities than ultrasound+ CT, which were statistically different from each other ( P<0.05), and ultrasound+ CT had the lowest specificity [0.76(0.70-0.81)]. Conclusions:The diagnostic efficacy of thyroid cancer lymph node metastasis is highest with contrast enhanced ultrasound. The new ultrasound technique for diagnosing thyroid cancer lymph node metastasis has a higher diagnostic value than CT, and it can be used as a complementary examination to conventional ultrasound.When the two techniques are used in combination, contrast enhanced ultrasound + ultrasound elastography has the highest accuracy, contrast enhanced ultrasound + ultrasound elastography and ultrasound + contrast enhanced ultrasound both have high sensitivity and specificity, and the diagnostic performance of both is higher than that of ultrasound + ultrasound elastography and ultrasound + CT, and in actual clinical practice when ultrasound elastography combined with contrast enhanced ultrasound is limited in the examination, ultrasound combined with contrast enhanced ultrasound can effectively serve as an alternative means to provide a good diagnostic support.

Background::Carotid intima-media thickness (IMT) and diameter, stiffness, and wave reflections, are independent and important clinical biomarkers and risk predictors for cardiovascular diseases. The purpose of the present study was to establish nationwide reference values of carotid properties for healthy Chinese adults and to explore potential clinical determinants.Methods::A total of 3053 healthy Han Chinese adults (1922 women) aged 18-79 years were enrolled at 28 collaborating tertiary centers throughout China between April 2021 and July 2022. The real-time tracking of common carotid artery walls was achieved by the radio frequency (RF) ultrasound system. The IMT, diameter, compliance coefficient, β stiffness, local pulse wave velocity (PWV), local systolic blood pressure, augmented pressure (AP), and augmentation index (AIx) were then automatically measured and reported. Data were stratified by age groups and sex. The relationships between age and carotid property parameters were analyzed by Jonckheere-Terpstra test and simple linear regressions. The major clinical determinants of carotid properties were identified by Pearson’s correlation, multiple linear regression, and analyses of covariance.Results::All the parameters of carotid properties demonstrated significantly age-related trajectories. Women showed thinner IMT, smaller carotid diameter, larger AP, and AIx than men. The β stiffness and PWV were significantly higher in men than women before forties, but the differences reversed after that. The increase rate of carotid IMT (5.5 μm/year in women and 5.8 μm/year in men) and diameter (0.03 mm/year in both men and women) were similar between men and women. For the stiffness and wave reflections, women showed significantly larger age-related variations than men as demonstrated by steeper regression slopes (all P for age by sex interaction <0.05). The blood pressures, body mass index (BMI), and triglyceride levels were identified as major clinical determinants of carotid properties with adjustment of age and sex. Conclusions::The age- and sex-specific reference values of carotid properties measured by RF ultrasound for healthy Chinese adults were established. The blood pressures, BMI, and triglyceride levels should be considered for clinical application of corresponding reference values.

Purpose Early diagnosis of Alzheimer's disease is lack of objective imaging marker.This study evaluates characteristics of cerebral blood flow (CBF) and gray matter atrophy in patients with mild Alzheimer's disease (AD) by using 3D arterial spin labeling (3D ASL) and thin slice 3D T1 weighted images of voxel-based method (VBM).Materials and Methods Sixteen mild AD patients (mild AD group) and sixteen normal control subjects (control group) were recruited.3D ASL and T1WI SPGR sequences were performed.By using voxel-based method,the whole brain CBF and T1WI images were analyzed.CBF and volume of gray matter were compared between two groups,and correlation analysis was done.Results Compared with control group,CBF hypoperfusion was detected in bilateral precuneus,cunei,middle temporal cortex,superior temporalcortex,left parahippocampal gyrus,left superior temporal pole and right superioroccipital gyrus in mild AD group (t=3.84,Pcorrected＜0.05).Compared with control group,gray matter atrophy was found in bilateral hippocampi,amygdalae,superior temporal pole,left parahippocampal gyrus,left inferior temporal cortex in mild AD group (t=4.12,Pcorrected＜0.05).There was a correlation in left parahippocampal gyrus and left upper pole of the temporal between changes of CBF and volume of gray matter in mild AD patients (r=0.50,P＜0.05).Conclusion Voxel-based VBM and ASL can evaluate AD patients' cerebral atrophy and CBF change in early stage,and there is a correlation between changes of CBF and gray matter atrophy in some overlap areas.

Objective To investigate the brain gray matter atrophy in behavioral variant of frontotemporal dementia (bvFTD) in order to provide an objective basis for early diagnosis. Methods High-resolution 3D structural brain images of 39 probable bvFTD and 46 controls were acquired by 3.0 Tesla MRI scanner. Neuropsychiatric Inventory (NPI), MMSE, Logical Memory Subtest of the Wechsler Memory Scale-Chinese Revision, Consortium to Establish a Registry for Alzheimer''s Disease drawing and WCST were administered to assess cognitive function and psychological and behavioral symptoms. Then voxel-based morphometry and diffeomorphic anatomical registration through exponentiated lie algebra (VBM-DARTEL)was used to compare the structural difference between bvFTD and control groups. Partial correlation analysis was deployed to examine the relationship between the whole brain volume and the total score of the NPI. Results Compared with the control group, bvFTD patients showed abnormalities in most of the neuropsycological tests (all P<0.01), including the higher scores in NPI(Z=-6.545), and the poor performance in global cognitive function(t=-8.621), execution function(t=4.776), episodic memory (t=-7.990)and visuospatial skills(Z=-4.909). In addition, the volume of specific regions, including notably bilateral prefrontal and pre-temporal cortex, insula and subcortical structures, were significantly reduced in bvFTD group (t=4.89-10.95,P<0.05,FWE-corrected). Most prominent atrophy was observed in bilateral caudate nucleus, amygdala, pallidum, putamen, insula, and rectus gyrus. Moreover, the atrophy of left precuneus (cluster size=193 voxels, peak MNI coordinates x=-7.5, y=-66.0, z=67.5) was significantly associated with the total score of NPI (ρ=-0.515,P<0.05,AlphaSim corrected). Conclusions It indicates that the structure of cortico-striatal-thalamic circuits is compromised in bvFTD. The atrophy of bilateral striatum may be most prominent. Besides, the volume of left precuneus may be associated with the severity of psychological and behavioral symptoms. These findings suggest the atrophy of bilateral striatum and left precuneus might be considered as potential imaging markers of bvFTD.

Objective To investigate the brain gray matter atrophy in behavioral variant of frontotemporal dementia (bvFTD) in order to provide an objective basis for early diagnosis. Methods High-resolution 3D structural brain images of 39 probable bvFTD and 46 controls were acquired by 3.0 Tesla MRI scanner. Neuropsychiatric Inventory (NPI), MMSE, Logical Memory Subtest of the Wechsler Memory Scale-Chinese Revision, Consortium to Establish a Registry for Alzheimer''s Disease drawing and WCST were administered to assess cognitive function and psychological and behavioral symptoms. Then voxel-based morphometry and diffeomorphic anatomical registration through exponentiated lie algebra (VBM-DARTEL)was used to compare the structural difference between bvFTD and control groups. Partial correlation analysis was deployed to examine the relationship between the whole brain volume and the total score of the NPI. Results Compared with the control group, bvFTD patients showed abnormalities in most of the neuropsycological tests (all P<0.01), including the higher scores in NPI(Z=-6.545), and the poor performance in global cognitive function(t=-8.621), execution function(t=4.776), episodic memory (t=-7.990)and visuospatial skills(Z=-4.909). In addition, the volume of specific regions, including notably bilateral prefrontal and pre-temporal cortex, insula and subcortical structures, were significantly reduced in bvFTD group (t=4.89-10.95,P<0.05,FWE-corrected). Most prominent atrophy was observed in bilateral caudate nucleus, amygdala, pallidum, putamen, insula, and rectus gyrus. Moreover, the atrophy of left precuneus (cluster size=193 voxels, peak MNI coordinates x=-7.5, y=-66.0, z=67.5) was significantly associated with the total score of NPI (ρ=-0.515,P<0.05,AlphaSim corrected). Conclusions It indicates that the structure of cortico-striatal-thalamic circuits is compromised in bvFTD. The atrophy of bilateral striatum may be most prominent. Besides, the volume of left precuneus may be associated with the severity of psychological and behavioral symptoms. These findings suggest the atrophy of bilateral striatum and left precuneus might be considered as potential imaging markers of bvFTD.

BACKGROUND:Stem celltumorigenicity is a practical issue concerning stability in the clinical application of stem cells. Therefore, it is particularly important to clear whether stem cells have tumorigenic ability or not. Nude mice occupy an increasingly important position in oncology, immunology, and safety evaluation of drugs and biological products.
OBJECTIVE:To observe the tumorigenicity of neural stem cells and mesenchymal stem cells in Balb/c nude immunodeficient mice.
METHODS:Balb/c nude mice were randomly divided into control group, negative group, positive group, neural stem cellgroup and mesenchymal stem cellgroup. HepG-2 cells, RPE cells, passage 4 neural stem cells and mesenchymal stem cells were injected subcutaneously into nude mice from different groups, respectively. After 12 weeks of injection, anatomical observation was performed to detect the tumor formation in the transplantation site. Meanwhile, soft agar colony formation assay was applied to investigate neural stem celland mesenchymal stem cellclone in vitro.
RESULTS AND CONCLUSION:After 12 weeks of injection, the tumorigenicity study results showed that no tumor developed in the transplantation site in the control group, negative group, neural stem cellgroup and mesenchymal stem cellgroup. Histopathologic examinations also showed no abnormality in these groups. Soft agar colony formation assay showed in soft agar resistance medium, neural stem cells and mesenchymal stem cells did not exhibit clone ability. These findings indicate that neural stem cells and mesenchymal stem cells undergoing short-term passages have no tumorigenic growth.