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In the etiology study of epidemiology, selection bias will lead to the fact that the research sample cannot represent the general population, the association between exposure and outcome among those selected for analysis differs from the association among those eligible, and the true causal association cannot be inferred. Directed acyclic graphs (DAGs) could visualize complex causality, introduce the Collider-stratification bias using simple graphics language, provide a simple and intuitive way to identify Selection bias, different types of selection bias are verified by the graphic structure of the Collider-stratification bias. In practical studies, there may be multiple biases at the same time, improper adjustment of the collider will lead to Collider-stratification bias, open a backdoor path, even change the size and direction of the confounding bias. In order to obtain an unbiased estimate of the exposure to the outcome, it is necessary to identify the collider and avoid the adjustment to prevent the occurrence of Collider-stratification bias by using DAGs.
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OBJECTIVE@#This study evaluates the effects of different endodontic access methods and full-ceramic crown on the stress distribution in the maxillary central incisor by using three-dimensional finite element analysis.@*METHODS@#Computed tomography scans of the maxillary central incisor were used to construct a three-dimensional finite element model of the maxillary central incisor. According to the different methods of endodontic and the prosthetic treatments, four models were established, namely, group A (traditional access cavity preparation with resin filling), group B (traditional access cavity preparation restored full-ceramic crown), group C (minimally invasive endodontics with resin filling) and group D (minimally invasive endodontics restored full-ceramic crown). A static force of 100 N and a direction of 45° was applied to the long axis of the tooth at the junction of the incisal section one-third and middle section one-third. The maximum principal stress, the von Mises stress and the modified von Mises stress of the tooth tissue were analyzed using the finite-element analysis software.@*RESULTS@#1) Stress peaks: the stress peaks of the maximum principal stress, the von Mises stress and the modified von Mises in group A were the largest, except that the stress peak of von Mises stress in group D was slightly lower than that in group C. The stress peaks of the maximum principal stress and the modified von Mises in group C were the lowest. The stress peaks of the maximum principal stress and the modi-fied von Mises stress in group D were lower than those in groups A and B. 2) Stress distribution: compared with group A, the stress distribution of cervical dentin and the area of stress concentration in group C was lower and smaller. In the root dentin, the stress distribution in group C was more uniform than that in group A, and the stress was dispersed to several areas of the root apex. After crown restoration, no significant difference was observed in stress distribution between groups B and D in the root region. The stress distribution state of group B was not significantly different from that of group A. No significant difference was observed in the stress distribution state between groups D and C.@*CONCLUSIONS@#1) From the perspective of biomechanics, the minimally invasive access was adopted for the maxillary central incisor. 2) Full crown restoration is recommended after traditional access cavity preparation. No obvious advantage is observed in stress analysis for minimally invasive endodontics-restored full-ceramic crown.
Subject(s)
Crowns , Dental Stress Analysis , Dentin , Finite Element Analysis , Incisor , Post and Core Technique , Stress, Mechanical , Tooth CrownABSTRACT
Objective To research and analyze nursing measures of phlebitis caused by vein medication Amiodarone Hydrochloride. Methods 150 arrhythmias patients in the Traditional Chinese. Medicine Hospital of Wenling were selected as the subjects. The control group was given routine transfusion nursing, the experimental group was given comprehensive nursing intervention on the basis of the control group, saline irrigation before and after transfusion, observed the local reaction of patients, and controlled the concentration and external application of potato chips. Results After the corresponding nursing measures, in the control group, accounting for 46.7%. 35 cases of phlebitis occurred in the experimental group. The incidence of phlebitis in the experimental group was 16.0%, which was significantly lower than that (46.7%) in the control group, which was statistically significant (P<0.05). In the experimental group, the number of patients with I degree phlebitis was 8, and the proportion was 66.67%. In the control group, there were 7 cases of I degree phlebitis, accounting for 20%, which was statistically significant (P<0.05). In the experimental group, there were 4 cases of II degree phlebitis, the proportion was 33.33%, significantly lower than that (54.28%) of the control group (19 cases of II degree phlebitis) with statistical significance (P<0.05). Conclusion The application of comprehensive nursing measures in arrhythmia patients treated with Amiodarone Hydrochloride vein medication, could significantly reduce the occurrence of phlebitis and improve the curative effect with high safety and clinical significance.
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Objective To research and analyze nursing measures of phlebitis caused by vein medication Amiodarone Hydrochloride. Methods 150 arrhythmias patients in the Traditional Chinese. Medicine Hospital of Wenling were selected as the subjects. The control group was given routine transfusion nursing, the experimental group was given comprehensive nursing intervention on the basis of the control group, saline irrigation before and after transfusion, observed the local reaction of patients, and controlled the concentration and external application of potato chips. Results After the corresponding nursing measures, in the control group, accounting for 46.7%. 35 cases of phlebitis occurred in the experimental group. The incidence of phlebitis in the experimental group was 16.0%, which was significantly lower than that (46.7%) in the control group, which was statistically significant (P<0.05). In the experimental group, the number of patients with I degree phlebitis was 8, and the proportion was 66.67%. In the control group, there were 7 cases of I degree phlebitis, accounting for 20%, which was statistically significant (P<0.05). In the experimental group, there were 4 cases of II degree phlebitis, the proportion was 33.33%, significantly lower than that (54.28%) of the control group (19 cases of II degree phlebitis) with statistical significance (P<0.05). Conclusion The application of comprehensive nursing measures in arrhythmia patients treated with Amiodarone Hydrochloride vein medication, could significantly reduce the occurrence of phlebitis and improve the curative effect with high safety and clinical significance.
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<p><b>OBJECTIVE</b>To investigate whether RhoA/Rho-kinase contributes to the occurrence of chronic post-thoracotomy pain (CPSP) by up regulation of glutaminase 1 (GLS1) expression in the spinal dorsal cord.</p><p><b>METHODS</b>Twenty five male Sprague Dawley (SD) rats were divided into control group (n=5) and model group (n=20). The rats in the model group were randomized into two sub groups (n=10) for observation on day 10 and day 21 after thoracotomy, and each group was further divided into CPSP and non CPSP groups according to the behavioral test results. All the rats were sacrificed after behavioral test for examination of GLS1 and RhoA expressions in the spinal cord using Western blotting and RT PCR. We also compared the effect of the Rho kinase inhibitor fasudil and saline, both injected intraperitoneally daily at 10 mg/kg for 7 consecutive days following thoracotomy, on CPSP and GLS1 expression in 30 male SD rats on day 21 after thoracotomy.</p><p><b>RESULTS</b>Compared with the control group, the rats with CPSP showed significantly increased expressions of GLS1 and RhoA mRNA in the spinal cord on both day 10 and day 21 following thoracotomy (P<0.01), but the rats without CPSP did not show obvious changes in GLS1 and RhoA expressions. In fasudil treated rats, the mechanical pain threshold was obviously increased and the expressions of GLS1 and RhoA were significantly reduced as compared with those in saline treated rats (P<0.01).</p><p><b>CONCLUSION</b>RhoA plays an important role in the occurence of CPSP by up-regulating the expression of GLS1 in the spinal dorsal cord of rats.</p>
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<p><b>OBJECTIVE</b>To evaluate the effect of alprazolam use on psychological status and hospitalization cost in patient with paroxysmal supraventricular tachycardia underwent electrophysiology studies or radiofrequency catheter ablation.</p><p><b>METHODS</b>In this prospective, randomized, double-blind, placebo-controlled study, 142 inpatients [77 males, mean age (43.1 +/- 14.5) years] were randomly assigned to receive alprazolam (0.4 mg qd at 10PM for 3 days, n = 72) or placebo (n = 70) 3 days before scheduled electrophysiology studies or radiofrequency catheter ablation. All patients were examined by the Chinese version of Symptom Checklist-90 (SCL-90) at 24 hours before the procedure.</p><p><b>RESULTS</b>Compared with the placebo group, the scores of somatization (1.38 +/- 0.40 vs. 1.65 +/- 0.56, P < 0.01), anxiety (1.50 +/- 0.39 vs. 1.69 +/- 0.50, P < 0.05), phobic anxiety (1.24 +/- 0.36 vs. 1.47 +/- 0.57, P < 0.01), psychotism constructs (1.24 +/- 0.34 vs. 1.35 +/- 0.30, P < 0.05) and global severity index (1.36 +/- 0.35 vs. 1.49 +/- 0.37, P < 0.05) were significantly decreased in alprazolam group. The hospitalization costs were also significantly lower in alprazolam group (32 498 +/- 1170) yuan compared to placebo group (32 947 +/- 1096) yuan, P < 0.05.</p><p><b>CONCLUSION</b>The alprazolam use before electrophysiology studies and radiofrequency catheter ablation can improve the patients' psychological status and reduce the hospitalization costs.</p>