Objective To investigate the damage characteristics of peri-implant bones with varying densities under impact and occlusal forces using numerical simulation.Methods A finite element model of the microstructure of an implant and bones with different densities was established.Impact and occlusal forces were applied sequentially to the implant.A user material subroutine was created for failure judgment using stress-based failure criteria,enabling the analysis of bone damage caused by impact and occlusal forces.Results No cortical bone damage was observed in bones of varying densities under impact force.Damage primarily occurred in the trabecular bone at the base of the implant,with the extent of damage worsening as bone density decreased.Additionally,the number of failed bone elements generated by the damage increased with reduced bone density.Bone tissues with pre-existing impact damage sustained secondary damage when subjected to occlusal force:the bonding interface between the implant and cortical bone was damaged,leading to implant displacement and fracture of peri-implant trabecular bone.The damage caused by occlusal force also worsened as bone density decreased.Conclusions The degree of damage from impact and occlusal forces is correlated with bone density,with damage worsening as bone density decreases.This underscores the protective role of cortical bone.The application of occlusal force exacerbates bone tissue damage,leading to implant displacement when the cortical bone is damaged.In clinical practice,patients with a history of impact damage should undergo thorough examination and evaluation.The occlusal force borne by damaged bones should be reduced;if necessary,the implant should be removed and reinserted after re-establishment of osseointegration.

Objective To investigate the damage characteristics of peri-implant bones with varying densities under impact and occlusal forces using numerical simulation.Methods A finite element model of the microstructure of an implant and bones with different densities was established.Impact and occlusal forces were applied sequentially to the implant.A user material subroutine was created for failure judgment using stress-based failure criteria,enabling the analysis of bone damage caused by impact and occlusal forces.Results No cortical bone damage was observed in bones of varying densities under impact force.Damage primarily occurred in the trabecular bone at the base of the implant,with the extent of damage worsening as bone density decreased.Additionally,the number of failed bone elements generated by the damage increased with reduced bone density.Bone tissues with pre-existing impact damage sustained secondary damage when subjected to occlusal force:the bonding interface between the implant and cortical bone was damaged,leading to implant displacement and fracture of peri-implant trabecular bone.The damage caused by occlusal force also worsened as bone density decreased.Conclusions The degree of damage from impact and occlusal forces is correlated with bone density,with damage worsening as bone density decreases.This underscores the protective role of cortical bone.The application of occlusal force exacerbates bone tissue damage,leading to implant displacement when the cortical bone is damaged.In clinical practice,patients with a history of impact damage should undergo thorough examination and evaluation.The occlusal force borne by damaged bones should be reduced;if necessary,the implant should be removed and reinserted after re-establishment of osseointegration.

Objective To investigate the association between nutritional status and serum hepcidin and pentraxin 3(PTX3)levels in patients undergoing maintenance hemodialysis(MHD).Methods A total of 76 patients with MHD who met the inclusion criteria were recruited from the hemodialysis center at the Affiliated Hospital of Chengde Medical University.Nutritional status was assessed using the Subjective Global Assessment(SGA),which categorizes patients into three grades:SGA-A,SGA-B,and SGA-C.Serum levels of PTX3 and hepcidin were mea-sured by enzyme-linked immunosorbent assay(ELISA).Statistical analyses were conducted using SPSS software.One-way analysis of variance(ANOVA)was applied to compare differences across the three SGA groups.Logistic regression analysis was performed to identify influencing factors,and receiver operating characteristic(ROC)curve analysis was used to evaluate diagnostic value.Among the participants,45 patients were classified as malnourished based on SGA-B and SGA-C scores,while those with SGA-A constituted the well-nourished control group.Results Among the 76 MHD patients,59.2%were malnourished.We then compared clinical characteristics across the three groups.The results showed that the malnourished group was older and exhibited significantly higher levels of hs-CRP,PTX3,and hepcidin(P<0.05),while serum albumin,creatinine,and phosphorus levels were significantly lower(P<0.05).Pearson correlation analysis revealed positive correlations between SGA grades and hs-CRP,PTX3,and hepcidin levels(all P<0.05).Logistic regression analysis with"malnutrition"as the dependent variable indicated that elevated hs-CRP,PTX3,and hepcidin levels,along with age and male gender,were associated with increased risk of malnutrition in MHD patients,whereas higher serum phosphorus and creatinine levels were protec-tive factors.Further multivariate logistic regression analysis demonstrated that serum PTX3 level was an independent risk factor for malnutrition(P=0.032),while higher creatinine level was an independent protective factor(P=0.047).ROC curve analysis showed that the combination of serum PTX3 and creatinine levels had a high diagnostic value for identifying malnutrition in MHD patients,yielding an AUC of 0.789(P<0.001),a Youden index of 0.448,sensitivity of 77.8%,and specificity of 71.0%.Conclusions Elevated levels of PTX3 and hepcidin,along with reduced serum creatinine levels,are associated with an increased risk of malnutrition in patients undergoing MHD.Notably,elevated serum PTX3 and decreased serum creatinine independently predict malnutrition in this population and demonstrate high predictive value.

Objective To investigate the association between nutritional status and serum hepcidin and pentraxin 3(PTX3)levels in patients undergoing maintenance hemodialysis(MHD).Methods A total of 76 patients with MHD who met the inclusion criteria were recruited from the hemodialysis center at the Affiliated Hospital of Chengde Medical University.Nutritional status was assessed using the Subjective Global Assessment(SGA),which categorizes patients into three grades:SGA-A,SGA-B,and SGA-C.Serum levels of PTX3 and hepcidin were mea-sured by enzyme-linked immunosorbent assay(ELISA).Statistical analyses were conducted using SPSS software.One-way analysis of variance(ANOVA)was applied to compare differences across the three SGA groups.Logistic regression analysis was performed to identify influencing factors,and receiver operating characteristic(ROC)curve analysis was used to evaluate diagnostic value.Among the participants,45 patients were classified as malnourished based on SGA-B and SGA-C scores,while those with SGA-A constituted the well-nourished control group.Results Among the 76 MHD patients,59.2%were malnourished.We then compared clinical characteristics across the three groups.The results showed that the malnourished group was older and exhibited significantly higher levels of hs-CRP,PTX3,and hepcidin(P<0.05),while serum albumin,creatinine,and phosphorus levels were significantly lower(P<0.05).Pearson correlation analysis revealed positive correlations between SGA grades and hs-CRP,PTX3,and hepcidin levels(all P<0.05).Logistic regression analysis with"malnutrition"as the dependent variable indicated that elevated hs-CRP,PTX3,and hepcidin levels,along with age and male gender,were associated with increased risk of malnutrition in MHD patients,whereas higher serum phosphorus and creatinine levels were protec-tive factors.Further multivariate logistic regression analysis demonstrated that serum PTX3 level was an independent risk factor for malnutrition(P=0.032),while higher creatinine level was an independent protective factor(P=0.047).ROC curve analysis showed that the combination of serum PTX3 and creatinine levels had a high diagnostic value for identifying malnutrition in MHD patients,yielding an AUC of 0.789(P<0.001),a Youden index of 0.448,sensitivity of 77.8%,and specificity of 71.0%.Conclusions Elevated levels of PTX3 and hepcidin,along with reduced serum creatinine levels,are associated with an increased risk of malnutrition in patients undergoing MHD.Notably,elevated serum PTX3 and decreased serum creatinine independently predict malnutrition in this population and demonstrate high predictive value.

Objective:To investigate the prevalence and influencing factors of depression,anxiety and comorbid depression-anxiety symptoms among college freshmen,providing a theoretical basis for promoting their mental health.Methods:From Jan to Feb 2022,an online questionnaire survey was conducted,involving 483 online questionnaires from college freshmen(184 males,299 females).The depression-anxiety-stress self-rating scale,smartphone dependence self-rating scale for adolescents,and Pittsburgh sleep quality index(PSQI)were used for online surveys.The influencing factors of depression,anxiety,and their comorbidity among college freshmen were analyzed by multivariable logistic regression analysis.Results:The detection rates of smartphone dependence,sleep disorders,depression,anxiety and comorbid depression-anxiety symptoms among college freshmen were 26.1%,12.8%,26.3%,32.1%,and 23.6%,respectively.The detection rates of depression,anxiety and comorbid depression-anxiety symptoms in male students were significantly higher than those in female students(P＜0.05).Multivariable logistic regression analysis showed that self-perceived poor mental health,smartphone dependence and sleep disorders were risk factors for depression,anxiety and comorbid depression-anxiety symptoms.Low satisfaction with college life was a risk factor for depression.Medical specialty was a risk factor for anxiety and comorbid depression-anxiety symptoms(P＜0.05).Conclusions:Male college freshmen show higher rates of depression,anxiety,and their comorbidity.Low satisfaction with college life,self-perceived poor mental health,high academic pressure,smartphone dependence,medical specialty,and sleep disorders may be risk factors for depression,anxiety and comorbid depression-anxiety symptoms among college freshmen.

Objective:To investigate the prevalence and influencing factors of depression,anxiety and comorbid depression-anxiety symptoms among college freshmen,providing a theoretical basis for promoting their mental health.Methods:From Jan to Feb 2022,an online questionnaire survey was conducted,involving 483 online questionnaires from college freshmen(184 males,299 females).The depression-anxiety-stress self-rating scale,smartphone dependence self-rating scale for adolescents,and Pittsburgh sleep quality index(PSQI)were used for online surveys.The influencing factors of depression,anxiety,and their comorbidity among college freshmen were analyzed by multivariable logistic regression analysis.Results:The detection rates of smartphone dependence,sleep disorders,depression,anxiety and comorbid depression-anxiety symptoms among college freshmen were 26.1%,12.8%,26.3%,32.1%,and 23.6%,respectively.The detection rates of depression,anxiety and comorbid depression-anxiety symptoms in male students were significantly higher than those in female students(P＜0.05).Multivariable logistic regression analysis showed that self-perceived poor mental health,smartphone dependence and sleep disorders were risk factors for depression,anxiety and comorbid depression-anxiety symptoms.Low satisfaction with college life was a risk factor for depression.Medical specialty was a risk factor for anxiety and comorbid depression-anxiety symptoms(P＜0.05).Conclusions:Male college freshmen show higher rates of depression,anxiety,and their comorbidity.Low satisfaction with college life,self-perceived poor mental health,high academic pressure,smartphone dependence,medical specialty,and sleep disorders may be risk factors for depression,anxiety and comorbid depression-anxiety symptoms among college freshmen.

Objective:To investigate the change of chemical exchange saturation transfer (CEST) imaging in the bilateral substantia nigra (SN) and red nucleus (RN) of Parkinson disease (PD), and to explore the value of CEST-MRI for the clinical application of PD.Methods:This was a cross-sectional study. A total of 45 PD patients (PD group) and 21 sex-, age-, and cognitive-function matched normal control subjects (NC group) were retrospectively enrolled from December 2012 to July 2015 in Beijing Hospital. All subjects underwent brain CEST-MRI and routine MRI. Based on the MATLAB software package, the 4-pool Lorentz fitting model was applied to analyze the signal change of CEST imaging, which could acquire the mean amplitudes of the 4-pool parameters including Amide, nuclear overhauser enhancement (NOE), direct water saturation (DS) and magnetization transfer (MT) in the bilateral SN and RN. Independent samples t test and Mann-Whitney U test were used to compare CEST parameters between the PD group and the NC group and controlled by Bonferroni correction. The combined model was constructed based on parameters with inter-group differences after correction. The receiver operating characteristic curve and area under the curve (AUC) were used to evaluate the diagnostic efficiency of the CEST parameters and the combined model. Results:Compared with the NC group, the left SN Amide value, left RN Amide value, and right SN NOE value were reduced in the PD group, and the difference was statistically significant ( t=-3.59, corrected P=0.026; t=-3.77, corrected P=0.016; Z=-3.27, corrected P=0.017). The left SN Amide value, the left RN Amide value, the right SN NOE value, and the combined model all had good diagnostic efficacy in the differentiation of the PD group from the HC group (AUCs of 0.78, 0.79, 0.75, and 0.81, respectively). The combined model had the highest AUC value (0.81) and specificity (97.78%), the Amide value of left SN had the highest sensitivity (93.33%). Conclusions:Quantitative analysis of CEST-MRI based on the 4-pool Lorentz fitting model shows significant differences in the CEST quantitative indicators of the SN and RN between the PD group and the NC group, demonstrating good potential for clinical application in the diagnosis of PD.

Objective To investigate the dynamic mechanical responses and damage characteristics of peri-implant bone structures subjected to impact load.Methods A finite element model of the peri-implant bone microstructure was established,and an initial velocity was applied to the rigid body to simulate the impact load.A stress failure criterion was employed and a user-material subroutine was developed to assess failure.Subsequently,bone damage after the impact load was analyzed according to the material subroutine.Results After the impact load,the stress on the cortical bone increased rapidly,reaching a peak value(16.01 MPa)immediately.In contrast,the stress on the trabecular bone at the bottom of the implant reached its peak value(5.85 MPa)at 0.1 μs.The impact load resulted in stress waves that propagated and diffused within the bone structure,causing changes in the bone structure damage over time.The generated impact energy could be absorbed and dissipated by the trabecular bone through deformation.The deformed trabecular bone experienced damage and failure upon reaching the yield limit,whereas the cortical bone did not experience damage or failure under an impact load.Conclusions Structural changes in the trabecular bone should be considered in patients with impact damage.The numerical model established in this study can effectively predict bone impact damage by combining the structural mechanical properties and geometric characteristics of the bones.These findings can serve as a reference for assessing bone damage and post-damage treatment in patients subjected to impact loads in clinical practice.

Lymphoma is a malignant tumor of the lymphatic system, including Hodgkin's lymphoma and non-Hodgkin's lymphoma. Lymphoma is the fourth most common primary malignant tumor during pregnancy and one of the major malignant diseases affecting maternal and infant outcomes. This review summarizes the clinical features, diagnosis, maternal and fetal outcomes, and clinical lymphoma treatment during pregnancy. It is suggested that clinicians should pay attention to the symptoms, including unexplained lymphadenectasis, systemic symptoms, extranodal lesions, and the　symptoms of pressure exerted on the involved local organs, especially those in the breast and reproductive system, and make a timely diagnosis in line with the biopsy or puncture results. Management should be based on the classification, stage, and clinical manifestations of lymphoma. Besides, the gestational age at diagnosis, maternal and child conditions, and the willingness to continue the pregnancy should also be considered. Most mothers and their children can have good outcomes after individualized treatment through multidisciplinary cooperation and close perinatal management.

Prosthodontics is an important undergraduate course in stomatology. It's an unprecedented challenge for teachers to give theoretical lectures completely by online teaching methods. After several months of online teaching practice, a complete closed-loop online teaching mode of "pre-class, in-class and after-class" has been formed by using online teaching tools such as Tencent meeting, Superstar learning platform and WeChat. A comprehensive feedback and assessment mechanism has also been established. On the premise of the teaching quality, online teaching has also promoted the exploration and reform of the information-based teaching of prosthodontics course.