The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases （amounting to a to...The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases （amounting to a total of 1 005 root canals） were examined. The anatomy risk factors assessed in each case included： tooth type （tooth location）, root canal curvature, and root canal calcification, as well as endodontic retreatment. The investigation examined the correlation between each of these anatomic factors and the working length, with statistical analysis consisting of Chi-square tests and multiple logistic regression analysis. In an independent factor analysis, tooth type （tooth iocation）, root canal curvature, canal calcification, and endodontic retreatment were determined to be the primary risk factors. In a multiple-factor regression model, root curvature and canal calcification were found to most significantly influence root canal working length accessibility （P〈0.05）. Root canal anatomy increases the difficulty of root canal preparation. Appropriate consideration of tooth anatomy will assist in accurate determination of preparation difficulty before instrumentation. This study alerts clinical therapists to anatomical factors influencing the working length accessibility, and allows for a direct estimate of success rate given in situ measurements of tooth factors during the root canal treatment procedure.展开更多
Objective The aim of this study was to explore the influence of working length(determined by the screw position)on the stiffness and interfragmentary strain(IFS)of femoral locking compression plate(LCP)external fixato...Objective The aim of this study was to explore the influence of working length(determined by the screw position)on the stiffness and interfragmentary strain(IFS)of femoral locking compression plate(LCP)external fixators for lower tibial fractures under full weight-bearing conditions,with the goal of providing a reference basis for clinical applications.Methods Finite element analysis software was used to construct a model of a lower tibial fracture with external femoral LCP fixation.The models were divided into four groups according to the different working lengths(external femoral locking plate fixation 1[EF1],EF2,EF3,and EF4).Stress distribution clouds,fracture end displacements,stiffness and IFS were tested for each model group at different loads.Results Compared with those in the EF1 group,the stiffnesses in the EF2,EF3,and EF4 groups decreased by 28%,31%,and 37%,respectively,under axial compression loading.Compared with those in the EF1 group,the stiffnesses in the EF2,EF3,and EF4 groups decreased by 19%,33%,and 35%,respectively,under axial torsion loading.Compared with those in the EF1 group,the stiffnesses in the EF2,EF3,and EF4 groups decreased by 32%,33%,and 35%,respectively,under a three-point bending load.The IFS of the four finite element models increased with the working length of the plate,with EF1(76%)<EF2(107%)<EF3(110%)<EF4(122%).Finite element analysis revealed that under full weight-bearing conditions,the structural stiffness of the femoral LCP external fixator decreased with increasing working length,leading to an increase in the IFS,which resulted in an IFS that exceeded the ideal range required for secondary healing.Conclusion For unstable lower tibial fractures,screws in the femoral LCP external fixator should be placed as close to the fracture end as possible to increase stability and promote fracture healing.展开更多
基金supported by State Key Laboratory of Oral Diseases and Department of Endodontics and Operative Dentistry, West China School of Stomatology, Sichuan Universitysupported by the Key Clinical Program of the Ministry of Health of China (2010)National Key Clinical Program of China (2010)
文摘The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases （amounting to a total of 1 005 root canals） were examined. The anatomy risk factors assessed in each case included： tooth type （tooth location）, root canal curvature, and root canal calcification, as well as endodontic retreatment. The investigation examined the correlation between each of these anatomic factors and the working length, with statistical analysis consisting of Chi-square tests and multiple logistic regression analysis. In an independent factor analysis, tooth type （tooth iocation）, root canal curvature, canal calcification, and endodontic retreatment were determined to be the primary risk factors. In a multiple-factor regression model, root curvature and canal calcification were found to most significantly influence root canal working length accessibility （P〈0.05）. Root canal anatomy increases the difficulty of root canal preparation. Appropriate consideration of tooth anatomy will assist in accurate determination of preparation difficulty before instrumentation. This study alerts clinical therapists to anatomical factors influencing the working length accessibility, and allows for a direct estimate of success rate given in situ measurements of tooth factors during the root canal treatment procedure.
基金supported by the Health Commission of Guizhou Province(No.gzwkj2024-400)the“Open Competition Project”of Bijie Science and Technology Bureau(BST Major Project No.1,2022).
文摘Objective The aim of this study was to explore the influence of working length(determined by the screw position)on the stiffness and interfragmentary strain(IFS)of femoral locking compression plate(LCP)external fixators for lower tibial fractures under full weight-bearing conditions,with the goal of providing a reference basis for clinical applications.Methods Finite element analysis software was used to construct a model of a lower tibial fracture with external femoral LCP fixation.The models were divided into four groups according to the different working lengths(external femoral locking plate fixation 1[EF1],EF2,EF3,and EF4).Stress distribution clouds,fracture end displacements,stiffness and IFS were tested for each model group at different loads.Results Compared with those in the EF1 group,the stiffnesses in the EF2,EF3,and EF4 groups decreased by 28%,31%,and 37%,respectively,under axial compression loading.Compared with those in the EF1 group,the stiffnesses in the EF2,EF3,and EF4 groups decreased by 19%,33%,and 35%,respectively,under axial torsion loading.Compared with those in the EF1 group,the stiffnesses in the EF2,EF3,and EF4 groups decreased by 32%,33%,and 35%,respectively,under a three-point bending load.The IFS of the four finite element models increased with the working length of the plate,with EF1(76%)<EF2(107%)<EF3(110%)<EF4(122%).Finite element analysis revealed that under full weight-bearing conditions,the structural stiffness of the femoral LCP external fixator decreased with increasing working length,leading to an increase in the IFS,which resulted in an IFS that exceeded the ideal range required for secondary healing.Conclusion For unstable lower tibial fractures,screws in the femoral LCP external fixator should be placed as close to the fracture end as possible to increase stability and promote fracture healing.
