Background A virtual system that simulates the complete process of orthodontic bracket placement can be used for pre-clinical skill training to help students gain confidence by performing the required tasks on a virtu...Background A virtual system that simulates the complete process of orthodontic bracket placement can be used for pre-clinical skill training to help students gain confidence by performing the required tasks on a virtual patient.Methods The hardware for the virtual simulation system is built using two force feedback devices to support bi-manual force feedback operation.A 3D mouse is used to adjust the position of the virtual patient.A multi-threaded computational methodology is adopted to satisfy the requirements of the frame rate.The computation threads mainly consist of the haptic thread running at a frequency of>1000Hz and the graphic thread at>30Hz.The graphic thread allows the graphics engine to effectively display the visual effects of biofilm removal and acid erosion through texture mapping.Using the haptic thread,the physics engine adopts the hierarchy octree collision-detection algorithm to simulate the multi-point and multi-region interaction between the tools and the virtual environment.Its high efficiency guarantees that the time cost can be controlled within 1 ms.The physics engine also performs collision detection between the tools and particles,making it possible to simulate paint and removal of colloids.The surface-contact constraints are defined in the system;this ensures that the bracket will not divorce from or embed into the tooth during the adjustment of the bracket.Therefore,the simulated adjustment is more realistic and natural.Results A virtual system to simulate the complete process of orthodontic bracket bonding was developed.In addition to bracket bonding and adjustment,the system simulates the necessary auxiliary steps such as smearing,acid etching,and washing.Furthermore,the system supports personalized case training.Conclusions The system provides a new method for students to practice orthodontic skills.展开更多
Residual atrioventricular valve regurgitation after correction of complete atrioventricular septal defect(cAVSD)is still not ideal.As a modification of the double-patch method,our technique comprises a suture-bite-wid...Residual atrioventricular valve regurgitation after correction of complete atrioventricular septal defect(cAVSD)is still not ideal.As a modification of the double-patch method,our technique comprises a suture-bite-wide strip of a third patch that is incorporated to the upper margin of the left side of the ventricular septal defect(VSD)patch.This third patch counteracts not only the valvular tissue loss caused by the suture bites but also the rightward displacement of the VSD patch in a bulged fashion that occurs with increased left ventricular pressure after weaning from cardiopulmonary bypass.This unfavorable outcome was addressed with the current technique through augmentation of the left-sided bridging leaflets serving to prevent the separation of them from their corresponding mural leaflets.The concept was applied in two cases with Down syndrome aged 5 months and 6 months,respectively,as a rescue procedure in the same session just after a failed cAVSD repair.Since the immediate-and short-term outcomes of the atrioventricular valves in regard to regurgitation are satisfying,we believe that the technique proposed herein holds promise for the future in terms of tackling residual atrioventricular valve regurgitation.展开更多
文摘Background A virtual system that simulates the complete process of orthodontic bracket placement can be used for pre-clinical skill training to help students gain confidence by performing the required tasks on a virtual patient.Methods The hardware for the virtual simulation system is built using two force feedback devices to support bi-manual force feedback operation.A 3D mouse is used to adjust the position of the virtual patient.A multi-threaded computational methodology is adopted to satisfy the requirements of the frame rate.The computation threads mainly consist of the haptic thread running at a frequency of>1000Hz and the graphic thread at>30Hz.The graphic thread allows the graphics engine to effectively display the visual effects of biofilm removal and acid erosion through texture mapping.Using the haptic thread,the physics engine adopts the hierarchy octree collision-detection algorithm to simulate the multi-point and multi-region interaction between the tools and the virtual environment.Its high efficiency guarantees that the time cost can be controlled within 1 ms.The physics engine also performs collision detection between the tools and particles,making it possible to simulate paint and removal of colloids.The surface-contact constraints are defined in the system;this ensures that the bracket will not divorce from or embed into the tooth during the adjustment of the bracket.Therefore,the simulated adjustment is more realistic and natural.Results A virtual system to simulate the complete process of orthodontic bracket bonding was developed.In addition to bracket bonding and adjustment,the system simulates the necessary auxiliary steps such as smearing,acid etching,and washing.Furthermore,the system supports personalized case training.Conclusions The system provides a new method for students to practice orthodontic skills.
文摘Residual atrioventricular valve regurgitation after correction of complete atrioventricular septal defect(cAVSD)is still not ideal.As a modification of the double-patch method,our technique comprises a suture-bite-wide strip of a third patch that is incorporated to the upper margin of the left side of the ventricular septal defect(VSD)patch.This third patch counteracts not only the valvular tissue loss caused by the suture bites but also the rightward displacement of the VSD patch in a bulged fashion that occurs with increased left ventricular pressure after weaning from cardiopulmonary bypass.This unfavorable outcome was addressed with the current technique through augmentation of the left-sided bridging leaflets serving to prevent the separation of them from their corresponding mural leaflets.The concept was applied in two cases with Down syndrome aged 5 months and 6 months,respectively,as a rescue procedure in the same session just after a failed cAVSD repair.Since the immediate-and short-term outcomes of the atrioventricular valves in regard to regurgitation are satisfying,we believe that the technique proposed herein holds promise for the future in terms of tackling residual atrioventricular valve regurgitation.
