BACKGROUND:Currently,the mandibular joint prosthesis manufactured at home and abroad needs to rely on screws to fix the condylar part of the prosthesis during the replacement process,and the retention hole is reserved to facilitate the operation during the operation.However,due to the lack of personalized jaw design,the reattachment plate may not fit the jaw,resulting in screw loosening and dislocation.Therefore,personalized condylar prosthesis replacement is of great value in the repair of the temporomandibular joint.OBJECTIVE:To design a personalized condylar prosthesis with an internal GYROID for mandibular condylar repair and reconstruction.METHODS:The GYROID structure was selected in the Rhinoceros 7 software with the single cell size of 6 mm and the wall thickness of 0.2,0.3,0.4,0.5,0.6,0.7,0.8 mm.The mechanical properties of the GYROID structure were analyzed by finite element method.3D printing of GYROID structural test specimens with different wall thickness(0.2,0.3,0.4,0.5,0.6,0.7,and 0.8 mm)was performed to test the mechanical properties of the specimens through room temperature compression experiments.A wall thickness value conforming to the range of mandibular mechanical properties was selected through finite element analysis and room temperature compression test results.An adult male mandibular CT data were used for inverse modeling to design a condylar prosthesis with an internal GYROID.Finite element analysis was used to simulate the movement of the apical staggered position and the opposite-blade jaw position after condylar prosthesis replacement.RESULTS AND CONCLUSION:(1)The results of finite element analysis and room temperature compression experiment showed that the elastic modulus of the GYROID structure increased with the increase of wall thickness.The elastic modulus of the GYROID structure with wall thickness of 0.5-0.7 mm was within the range of the elastic modulus of the mandible(1.5-4.0 GPa).Therefore,the 6 mm monocellular GYROID structural model with a wall thickness of 0.6 mm was selected for the design of the condylar prosthesis.(2)The results of finite element analysis showed that the stress distribution of mandibular model was symmetrical.The stress distribution of the two types of occlusion was roughly the same,and the stress peak was not significantly different.The stress concentrated in the neck of the condylar prosthesis,and the stress on the replacement side was slightly larger than that on the healthy side.The maximum equivalent stress of the whole internal fixation model was 269.34 MPa,and the maximum equivalent stress of the screw was 20.14 MPa.The equivalent stress and equivalent strain values of the prosthesis were greater than that of the opposite edge jaw position when the tooth tip was interlaced.The equivalent stress and equivalent strain values of the screw were smaller than that of the opposite edge jaw position when the tooth tip was interlaced.(3)The results showed that the design and retention of the personalized GYROID condylar prosthesis were good,which was consistent with the mechanical conduction of the mandible.

BACKGROUND:Currently,the mandibular joint prosthesis manufactured at home and abroad needs to rely on screws to fix the condylar part of the prosthesis during the replacement process,and the retention hole is reserved to facilitate the operation during the operation.However,due to the lack of personalized jaw design,the reattachment plate may not fit the jaw,resulting in screw loosening and dislocation.Therefore,personalized condylar prosthesis replacement is of great value in the repair of the temporomandibular joint.OBJECTIVE:To design a personalized condylar prosthesis with an internal GYROID for mandibular condylar repair and reconstruction.METHODS:The GYROID structure was selected in the Rhinoceros 7 software with the single cell size of 6 mm and the wall thickness of 0.2,0.3,0.4,0.5,0.6,0.7,0.8 mm.The mechanical properties of the GYROID structure were analyzed by finite element method.3D printing of GYROID structural test specimens with different wall thickness(0.2,0.3,0.4,0.5,0.6,0.7,and 0.8 mm)was performed to test the mechanical properties of the specimens through room temperature compression experiments.A wall thickness value conforming to the range of mandibular mechanical properties was selected through finite element analysis and room temperature compression test results.An adult male mandibular CT data were used for inverse modeling to design a condylar prosthesis with an internal GYROID.Finite element analysis was used to simulate the movement of the apical staggered position and the opposite-blade jaw position after condylar prosthesis replacement.RESULTS AND CONCLUSION:(1)The results of finite element analysis and room temperature compression experiment showed that the elastic modulus of the GYROID structure increased with the increase of wall thickness.The elastic modulus of the GYROID structure with wall thickness of 0.5-0.7 mm was within the range of the elastic modulus of the mandible(1.5-4.0 GPa).Therefore,the 6 mm monocellular GYROID structural model with a wall thickness of 0.6 mm was selected for the design of the condylar prosthesis.(2)The results of finite element analysis showed that the stress distribution of mandibular model was symmetrical.The stress distribution of the two types of occlusion was roughly the same,and the stress peak was not significantly different.The stress concentrated in the neck of the condylar prosthesis,and the stress on the replacement side was slightly larger than that on the healthy side.The maximum equivalent stress of the whole internal fixation model was 269.34 MPa,and the maximum equivalent stress of the screw was 20.14 MPa.The equivalent stress and equivalent strain values of the prosthesis were greater than that of the opposite edge jaw position when the tooth tip was interlaced.The equivalent stress and equivalent strain values of the screw were smaller than that of the opposite edge jaw position when the tooth tip was interlaced.(3)The results showed that the design and retention of the personalized GYROID condylar prosthesis were good,which was consistent with the mechanical conduction of the mandible.

BACKGROUND:Porous structures based on triple periodic minimal surfaces are one of the most promising orthopedic biostructures,among which the Gyroid structure is characterized by high specific surface area,high permeability,and zero mean curvature.OBJECTIVE:To screen the wall thickness interval of TC4 bionic bone scaffolds with 4 mm single-cell Gyroid structure matching the elastic modulus range of cancellous bone of the mandible through finite element analysis combined with mechanical compression test testing.METHODS:The finite element model of the 4 mm single-cell Gyroid structure with different wall thickths(0.1,0.2,0.3,0.4,0.5,0.6,0.7,and 0.8 mm)was established.The equivalent elastic modulus of the Gyroid structure was analyzed,and the wall thickness interval of the Gyroid structure matching the elastic modulus range of the maxillary resinous bone was selected with different wall thicknesses of 0.2,0.3,0.4,0.5,0.6,and 0.7 mm,respectively.According to finite element analysis screening results,the material selected was Ti6Al4V.Selective laser melting was used to prepare 3D printed Gyroid structure specimens.The surface treatment was carried out by large-grained sand blasting and acid etching.The elastic modulus and compressive strength of the specimen were tested by mechanical compression experiment.RESULTS AND CONCLUSION:(1)The finite element analysis results showed that the equivalent elastic modulus of the Gyroid structure increased with the increase of wall thickness,and the equivalent elastic modulus of the Gyroid structure with wall thickness of 0.2-0.7 mm was within the range of the elastic modulus of the spongy bone of the mandible(1.5-4.0 GPa),which was used for 3D printing of the Gyroid structure specimen.(2)The mechanical compression test results showed that the elastic modulus and compressive strength of the Gyroid structural specimen increased with the increase of wall thickness,and the elastic modulus of the Gyroid structural specimen with wall thickness of 0.3-0.5 mm was within the range of the elastic modulus of the cancellous bone of the mandible.The compressive strength of the Gyroid specimen with 0.3-0.7 mm wall thickness was consistent with the mechanical properties of the mandible.(3)The results show that the Gyroid structure of 0.3-0.5 mm wall thickness is compatible with the range of elastic modulus of the mandible.

BACKGROUND:Condylar prosthesis replacement,as one of the surgical methods for the treatment of temporomandibular joint diseases,not only needs to restore the morphology and function,but also needs to ensure long-term stable application.OBJECTIVE:To design finite element analysis of a customized Gyroid condylar prosthesis.METHODS:Gyroid structure specimens with different wall thicknesses(250,350,450,550,650,and 750 μm)were designed by software.Finite element simulation compression experiments were carried out to test the elastic modulus of the specimens.The Gyroid structure wall thickness range that matches the elastic modulus of mandibular cancellous bone and whose pore size meets the osteogenesis conditions was screened out.This range was subdivided and Gyroid structure specimens were made using 3D printing technology.Mechanical compression experiments were carried out on a universal testing machine.The Gyroid structure wall thickness that meets the mechanical properties of mandibular bone,has an easier osteogenesis and a smaller strength was screened out by elastic modulus and compressive strength,and subsequent experiments were carried out.A three-dimensional model of a customized Gyroid condylar prosthesis was designed,and the finite element analysis of the blade jaw position and cusp interdigitation position of the model under natural occlusion was simulated.RESULTS AND CONCLUSION:(1)Finite element analysis results showed that with the increase of wall thickness,the elastic modulus of Gyroid structure specimens increased.The elastic modulus of Gyroid structure specimens with wall thickness of 350,450,550,650,and 750 μm matched the elastic modulus of mandibular cancellous bone.Since the subsequent experiments needed to be subdivided into groups and the pore size of the 550,650,and 750 μm wall thickness group(pore size 800-1 000 μm)was within the osteogenesis range.Gyroid structure specimens with wall thickness of 550,600,650,700,and 750μm were selected for mechanical compression experiments on a universal testing machine.(2)The results of mechanical compression experiments showed that with the increase of wall thickness,the elastic modulus and compressive strength of Gyroid structure specimens increased.The elastic modulus of Gyroid structure specimens with wall thickness of 550,600,and 650 μm was within the elastic modulus of the mandibular cancellous bone.Finally,the wall thickness of 650 μm and the pore size of 900 μm were selected to construct the three-dimensional model of the mandibular customized Gyroid condylar prosthesis.(3)The results of finite element analysis of three-dimensional model of the mandibular customized Gyroid condylar prosthesis showed that the stress of the articular disc in the edge-to-edge occlusion was mainly concentrated on the lower surface of the anterior middle band,and the stress of the articular disc in the interposition of tooth tips was mainly concentrated on the lateral surface of the lower surface.The maximum displacement and the maximum equivalent stress of the left and right articular discs in the edge-to-edge occlusion and the interposition of tooth tips were similar.The maximum displacement was 0.031,0.030,0.028,and 0.018 mm,and the maximum equivalent stress was 2.87,2.30,2.73,and 1.71 MPa,respectively.(4)The results showed that the Gyroid structure with a wall thickness of 650 μm was consistent with the mechanical properties of the mandible,which reduced the strength of the titanium alloy and reduced the damage of the articular disc caused by the customized Gyroid condylar prosthesis.

BACKGROUND:Condylar prosthesis replacement,as one of the surgical methods for the treatment of temporomandibular joint diseases,not only needs to restore the morphology and function,but also needs to ensure long-term stable application.OBJECTIVE:To design finite element analysis of a customized Gyroid condylar prosthesis.METHODS:Gyroid structure specimens with different wall thicknesses(250,350,450,550,650,and 750 μm)were designed by software.Finite element simulation compression experiments were carried out to test the elastic modulus of the specimens.The Gyroid structure wall thickness range that matches the elastic modulus of mandibular cancellous bone and whose pore size meets the osteogenesis conditions was screened out.This range was subdivided and Gyroid structure specimens were made using 3D printing technology.Mechanical compression experiments were carried out on a universal testing machine.The Gyroid structure wall thickness that meets the mechanical properties of mandibular bone,has an easier osteogenesis and a smaller strength was screened out by elastic modulus and compressive strength,and subsequent experiments were carried out.A three-dimensional model of a customized Gyroid condylar prosthesis was designed,and the finite element analysis of the blade jaw position and cusp interdigitation position of the model under natural occlusion was simulated.RESULTS AND CONCLUSION:(1)Finite element analysis results showed that with the increase of wall thickness,the elastic modulus of Gyroid structure specimens increased.The elastic modulus of Gyroid structure specimens with wall thickness of 350,450,550,650,and 750 μm matched the elastic modulus of mandibular cancellous bone.Since the subsequent experiments needed to be subdivided into groups and the pore size of the 550,650,and 750 μm wall thickness group(pore size 800-1 000 μm)was within the osteogenesis range.Gyroid structure specimens with wall thickness of 550,600,650,700,and 750μm were selected for mechanical compression experiments on a universal testing machine.(2)The results of mechanical compression experiments showed that with the increase of wall thickness,the elastic modulus and compressive strength of Gyroid structure specimens increased.The elastic modulus of Gyroid structure specimens with wall thickness of 550,600,and 650 μm was within the elastic modulus of the mandibular cancellous bone.Finally,the wall thickness of 650 μm and the pore size of 900 μm were selected to construct the three-dimensional model of the mandibular customized Gyroid condylar prosthesis.(3)The results of finite element analysis of three-dimensional model of the mandibular customized Gyroid condylar prosthesis showed that the stress of the articular disc in the edge-to-edge occlusion was mainly concentrated on the lower surface of the anterior middle band,and the stress of the articular disc in the interposition of tooth tips was mainly concentrated on the lateral surface of the lower surface.The maximum displacement and the maximum equivalent stress of the left and right articular discs in the edge-to-edge occlusion and the interposition of tooth tips were similar.The maximum displacement was 0.031,0.030,0.028,and 0.018 mm,and the maximum equivalent stress was 2.87,2.30,2.73,and 1.71 MPa,respectively.(4)The results showed that the Gyroid structure with a wall thickness of 650 μm was consistent with the mechanical properties of the mandible,which reduced the strength of the titanium alloy and reduced the damage of the articular disc caused by the customized Gyroid condylar prosthesis.

BACKGROUND:Porous structures based on triple periodic minimal surfaces are one of the most promising orthopedic biostructures,among which the Gyroid structure is characterized by high specific surface area,high permeability,and zero mean curvature.OBJECTIVE:To screen the wall thickness interval of TC4 bionic bone scaffolds with 4 mm single-cell Gyroid structure matching the elastic modulus range of cancellous bone of the mandible through finite element analysis combined with mechanical compression test testing.METHODS:The finite element model of the 4 mm single-cell Gyroid structure with different wall thickths(0.1,0.2,0.3,0.4,0.5,0.6,0.7,and 0.8 mm)was established.The equivalent elastic modulus of the Gyroid structure was analyzed,and the wall thickness interval of the Gyroid structure matching the elastic modulus range of the maxillary resinous bone was selected with different wall thicknesses of 0.2,0.3,0.4,0.5,0.6,and 0.7 mm,respectively.According to finite element analysis screening results,the material selected was Ti6Al4V.Selective laser melting was used to prepare 3D printed Gyroid structure specimens.The surface treatment was carried out by large-grained sand blasting and acid etching.The elastic modulus and compressive strength of the specimen were tested by mechanical compression experiment.RESULTS AND CONCLUSION:(1)The finite element analysis results showed that the equivalent elastic modulus of the Gyroid structure increased with the increase of wall thickness,and the equivalent elastic modulus of the Gyroid structure with wall thickness of 0.2-0.7 mm was within the range of the elastic modulus of the spongy bone of the mandible(1.5-4.0 GPa),which was used for 3D printing of the Gyroid structure specimen.(2)The mechanical compression test results showed that the elastic modulus and compressive strength of the Gyroid structural specimen increased with the increase of wall thickness,and the elastic modulus of the Gyroid structural specimen with wall thickness of 0.3-0.5 mm was within the range of the elastic modulus of the cancellous bone of the mandible.The compressive strength of the Gyroid specimen with 0.3-0.7 mm wall thickness was consistent with the mechanical properties of the mandible.(3)The results show that the Gyroid structure of 0.3-0.5 mm wall thickness is compatible with the range of elastic modulus of the mandible.

Objective:To investigate the effect of internal fixation of medial support and lateral wall on initial weight-bearing stability of femoral intertrochanteric fracture after reconstruction of intertrochanteric fracture.Methods:Based on the digital model of Sawbones femur, intertrochanteric fracture models with different medial support and lateral wall states were constructed. Combined with various intramedullary and extramedullary fixation methods, the mechanical models after fixation were simplified, and seven mechanical simplified models were obtained. The individual body weight load (70 kg) was simulated by applying concentrated force (700 N) to the end nodes of the femoral head. Through the analysis and calculation of each model in StrucMaster software, the axial force, shear force, bending moment, displacement deformation, and support reaction force of each bar in each mechanical model were obtained, and the results were output through the supporting SMConsole.Results:The median bending moment of model 1 was 11.55(5.57, 18.00) N·m, and the median bending moment was 2.89(2.81, 2.94) rad. The median bending moment of model 2 was 13.72(9.30, 20.05) N·m, and the median bending moment was 2.93(2.77, 3.05) rad. The median bending moment of model 3 was 19.65(10.23, 26.11) N·m, and the median bending moment was 2.93 (2.77, 3.05) rad. The median bending moment of model 4 was 25.95(25.14, 36.70) N·m, and the median bending moment was 4.38(3.16, 5.15) rad. The median bending moment of model 5 was 13.66(7.99, 25.62) N·m, and the median bending moment was 3.50(3.32, 3.56) rad. The median bending moment of model 6 was 24.60(9.33, 29.37) N·m, and the median bending moment was 3.90(3.69, 4.10) rad. The median bending moment of model 7 was 41.14(0.16, 41.30) N·m, and the median bending moment was 5.50(5.50, 7.05) rad. The mechanical properties of model 1 were better than those of the other six models.Conclusion:The simplified mechanical model and its mechanical calculation analysis based on the lever reconstruction balance theory can be used to preliminarily reveal the mechanical characteristics of femoral intertrochanteric fractures after internal fixation. The internal fixation methods of the medial support and lateral wall of femoral intertrochanteric fracture reconstruction can improve the initial stability of the weight bearing after internal fixation of femoral intertrochanteric fractures and have guiding significance for the functional rehabilitation of early postoperative weight bearing.

Objective:To investigate the effect of mobile phone dependence on suppression control under the conditions of emotional loss and cognitive loss in college students.Methods:A total of 553 college students were recruited,and 108 in the mobile phone dependence group and 194 in the non-dependent group were screened with the Mobile Phone Addiction Tendency Scale(MPATS).Ninety-nine of them were selected to participate in experi-ment 1,and the effect of emotional loss on the inhibitory control,and 101 students were selected to participate in ex-periment 2 to investigate the effect of cognitive loss on the inhibitory control.The GO/NOGO paradigm was used to compare the correct rate and response of different mobile phones dependent on college students under different emo-tional and cognitive depletion conditions.Results:In experiment 1,the main effect of emotional loss was statistically significant[F(1,55)=6.16,178.91;Ps＜0.05],the inhibition control accuracy rates were lower and reaction tim-es were shorter in the high emotional loss group than in the low emotional loss group.In experiment 2,the main effect of the group was statistically significant[F(1,57)=17.90,19.06;Ps＜0.001],the accuracy rates of inhibi-tion control were lower and the inhibition control reaction times were longer in the mobile phone-dependent group than in the non-dependent group.The interaction between groups and cognitive loss types was statistically significant[F(1,57)=7.95,P＜0.01],and the inhibition control accuracy rates of the mobile phone-dependent group were lower under high cognitive loss.Conclusion:Emotional loss and cognitive loss could reduce the inhibition and con-trol ability of individuals,and the mobile phone dependence group is more likely to be affected in the case of cogni-tive loss.

Objective:To compare the effects of different test meals on postprandial triglycerides and to optimize the standard meal composition and the blood sampling protocol for the oral fat tolerance test.Methods:This study is a prospective, open-label, randomized, cross-over trial. In March 2023, 36 volunteers were recruited in Hebei General Hospital. They underwent a health examination and oral glucose tolerance test. Twenty-six healthy volunteers(11 males and 15 females) were included in this study, with an average age of(39.08±4.56) years. Each volunteer received 75 g protein meal, 75 g fat meal, 700 kcal fixed-calorie high-fat mixed meal, and a high-fat mixed meal with energy adjusted based on 10 kcal/kg body weight. A one-week washout period of regular diet was applied before each trial. Blood was collected at fasting status and 1, 2, 3, 4, 5, and 6 hours after a meal to detect serum triglycerides, total cholesterol, low density lipoprotein-cholesterol(LDL-C), high density lipoprotein-cholesterol(HDL-C), glucose, and insulin. The variations of postprandial metabolic indicators over time following the consumption of different test meals were analyzed. The disparities in postprandial metabolic responses between the two types of mixed meals were compared.Results:The protein meal, fat meal, fixed-calorie high-fat mixed meal, and adjusted-calorie high-fat mixed meal resulted in postprandial triglyceride increases of 22.45%, 115.40%, 77.14%, and 63.63%, and insulin increase of 560.43%, 85.69%, 554.18%, and 598.97%, respectively, and with reductions in total cholesterol, LDL-C, and HDL-C ranging from 5.64%-21.81%, respectively. The blood glucose changed slightly. Changes in metabolic indicators mainly occured within 4 hours. The comparison of the characteristics of postprandial triglycerides between the two high-fat mixed meals showed no statistically significant differences( P>0.05). Conclusion:A standardize protocol with a 700 kcal fixed-calorie high-fat mixed meal as test meal, and blood lipid levels measured at fasting and at 1, 2, 3, and 4 hours after consumption, can serve as an optimized approach for oral fat tolerance test.