Objective To construct a swallowing dynamic model for simulating dysphagia caused by reduced tongue movement am-plitude.Methods A swallowing dynamic model was established based on medical imaging data from CT and videofluoroscopic swallowing study(VFSS).The finite element method was used to simulate soft tissues,while the smoothed parti-cle hydrodynamics method(SPH)was used to simulate bolus.The model's posture at each time point was com-pared with the imaging data of VFSS from twelve patients with dysphagia,and a normalization method was used for quantitative evaluation of the model's validity.By adjusting the tongue movement amplitude under different viscosity conditions,the role of tongue movement in the swallowing process was investigated,and the swallow-ing safety and efficiency were assessed.Results The tongue posture and bolus trajectory presented by the swallowing dynamic model were consistent with the VFSS imaging.The brightness in the epiglottis area in VFSS images correlated with the equivalent brightness of SPH particles in the simulation results(r=0.97).As the tongue movement amplitude reducing by 20%,the num-ber of aspirated particles,swallowing efficiency and the average velocity of bolus particles in the oropharyngeal cavity all performed well.Pudding-like fluids exhibited favorable swallowing characteristics even when tongue movement amplitude reducing significantly.Conclusion The swallowing dynamic model can simulate the human swallowing process,providing good support for re-habilitation training of patients with dysphagia and the development of specialized medical foods,demonstrating significant potential for clinical applications.

Objective To investigate the effects of implant length,diameter,and abutment angle on bone stress distributions around maxillary central incisors,and determine the optimal parameter combination.Methods A three-dimensional(3D)model of the maxilla was reconstructed based on CBCT data.Using an orthogonal table,a total of 16 dental implant 3D models were established,varying in length,diameter,and abutment angle.These models were assembled with the maxillary and rigid-body models.Finite element analysis was performed using the transient dynamics module of ANSYS.Orthogonal experiments and one-way analysis of variance(ANOVA)were conducted on the obtained stress data.Results The implant diameter showed a statistically significant effect on the maximum von Mises stress in cortical bone(P=0.010),while implant length(P=0.229)and abutment angle(P=0.844)did not demonstrate a statistical significance.The optimal parameter combination for cortical bone stress was 5.0 mm implant diameter,12 mm implant length,and 0° abutment angle.In cancellous bone,implant length(P=0.001),diameter(P=0.011),and abutment angle(P=0.013)all had statistically significant effects on the maximum von Mises stress.The optimal parameter combination for cancellous bone stress was 14 mm implant length,5.0 mm implant diameter,and 5° abutment angle.Conclusions Implant diameter significantly affects the stress of both cortical and cancellous bone.Clinically,a larger diameter should be preferred to reduce the stress peak.Implant length is the next most important factor,while abutment angle has the least effect.

Objective To construct a swallowing dynamic model for simulating dysphagia caused by reduced tongue movement am-plitude.Methods A swallowing dynamic model was established based on medical imaging data from CT and videofluoroscopic swallowing study(VFSS).The finite element method was used to simulate soft tissues,while the smoothed parti-cle hydrodynamics method(SPH)was used to simulate bolus.The model's posture at each time point was com-pared with the imaging data of VFSS from twelve patients with dysphagia,and a normalization method was used for quantitative evaluation of the model's validity.By adjusting the tongue movement amplitude under different viscosity conditions,the role of tongue movement in the swallowing process was investigated,and the swallow-ing safety and efficiency were assessed.Results The tongue posture and bolus trajectory presented by the swallowing dynamic model were consistent with the VFSS imaging.The brightness in the epiglottis area in VFSS images correlated with the equivalent brightness of SPH particles in the simulation results(r=0.97).As the tongue movement amplitude reducing by 20%,the num-ber of aspirated particles,swallowing efficiency and the average velocity of bolus particles in the oropharyngeal cavity all performed well.Pudding-like fluids exhibited favorable swallowing characteristics even when tongue movement amplitude reducing significantly.Conclusion The swallowing dynamic model can simulate the human swallowing process,providing good support for re-habilitation training of patients with dysphagia and the development of specialized medical foods,demonstrating significant potential for clinical applications.

Objective To investigate the effects of implant length,diameter,and abutment angle on bone stress distributions around maxillary central incisors,and determine the optimal parameter combination.Methods A three-dimensional(3D)model of the maxilla was reconstructed based on CBCT data.Using an orthogonal table,a total of 16 dental implant 3D models were established,varying in length,diameter,and abutment angle.These models were assembled with the maxillary and rigid-body models.Finite element analysis was performed using the transient dynamics module of ANSYS.Orthogonal experiments and one-way analysis of variance(ANOVA)were conducted on the obtained stress data.Results The implant diameter showed a statistically significant effect on the maximum von Mises stress in cortical bone(P=0.010),while implant length(P=0.229)and abutment angle(P=0.844)did not demonstrate a statistical significance.The optimal parameter combination for cortical bone stress was 5.0 mm implant diameter,12 mm implant length,and 0° abutment angle.In cancellous bone,implant length(P=0.001),diameter(P=0.011),and abutment angle(P=0.013)all had statistically significant effects on the maximum von Mises stress.The optimal parameter combination for cancellous bone stress was 14 mm implant length,5.0 mm implant diameter,and 5° abutment angle.Conclusions Implant diameter significantly affects the stress of both cortical and cancellous bone.Clinically,a larger diameter should be preferred to reduce the stress peak.Implant length is the next most important factor,while abutment angle has the least effect.