1.Biomechanics in terms of rotation angles and torques of implant-abutment screw tightening and loosening: Effects of implant types, contamination and sandblasting
Jiwoo LEE ; Seong-Kyun KIM ; Jai-Young KOAK ; Ji-Man PARK ; Jaejin CHO
The Journal of Korean Academy of Prosthodontics 2025;63(2):103-113
Purpose:
. The purpose of this study is to analyze the biomechanical differences in rotation angle-torque according to the type of implant and to compare the effects of contamination and sandblasting on the removal torque value (RTV) of abutment screws.
Materials and methods:
. For this study, an automated device for tightening and loosening implant screws was developed, and each 15 implant-abutment complexes of external and internal connection type were prepared, divided into three groups according to the surface treatment of the screw:control group (no treatment), experimental group-1 (artificial saliva contamination and chlorhexidine (CHX) rinsing), and experimental group-2 (artificial saliva contamination, CHX rinsing, and subsequent 50 µm Al 2 O 3 sandblasting). FirstRTV was measured for each group, followed by different post-treatment procedures for the screws, and then Second-RTV was measured. During the procedure, the removal torque value and rotation angle vs. time were recorded at a 20 data/s.A standardized protocol was followed for all the tightening and loosening procedures: screw was tightened with 30 Ncm torque and maintained for 5 s, and then rotated in the reverse direction until the torque value reached 0 Ncm. After 10min of rest period, the screws were loosened to initial point.
Results:
. Statistical analysis of measured data revealed that the internal connection type showed significantly higher First-RTV compared to the external connection type, however, no significant differences in Second-RTV were found. Both experimental groups 1and 2 showed a decrease in RTVs for both implant types, while the control group showed a decrease in RTV only for the internal type. The internal connection type required a significantly larger rotation angle during the tightening and loosening process.
Conclusion
. Within the limitations of this study, both artificial saliva contamination and CHX cleansing, as well as sandblasting, decreased RTV in both internal and external connection types. Internal connections were more susceptible to the effects of contaminants.
2.Biomechanics in terms of rotation angles and torques of implant-abutment screw tightening and loosening: Effects of implant types, contamination and sandblasting
Jiwoo LEE ; Seong-Kyun KIM ; Jai-Young KOAK ; Ji-Man PARK ; Jaejin CHO
The Journal of Korean Academy of Prosthodontics 2025;63(2):103-113
Purpose:
. The purpose of this study is to analyze the biomechanical differences in rotation angle-torque according to the type of implant and to compare the effects of contamination and sandblasting on the removal torque value (RTV) of abutment screws.
Materials and methods:
. For this study, an automated device for tightening and loosening implant screws was developed, and each 15 implant-abutment complexes of external and internal connection type were prepared, divided into three groups according to the surface treatment of the screw:control group (no treatment), experimental group-1 (artificial saliva contamination and chlorhexidine (CHX) rinsing), and experimental group-2 (artificial saliva contamination, CHX rinsing, and subsequent 50 µm Al 2 O 3 sandblasting). FirstRTV was measured for each group, followed by different post-treatment procedures for the screws, and then Second-RTV was measured. During the procedure, the removal torque value and rotation angle vs. time were recorded at a 20 data/s.A standardized protocol was followed for all the tightening and loosening procedures: screw was tightened with 30 Ncm torque and maintained for 5 s, and then rotated in the reverse direction until the torque value reached 0 Ncm. After 10min of rest period, the screws were loosened to initial point.
Results:
. Statistical analysis of measured data revealed that the internal connection type showed significantly higher First-RTV compared to the external connection type, however, no significant differences in Second-RTV were found. Both experimental groups 1and 2 showed a decrease in RTVs for both implant types, while the control group showed a decrease in RTV only for the internal type. The internal connection type required a significantly larger rotation angle during the tightening and loosening process.
Conclusion
. Within the limitations of this study, both artificial saliva contamination and CHX cleansing, as well as sandblasting, decreased RTV in both internal and external connection types. Internal connections were more susceptible to the effects of contaminants.
3.Biomechanics in terms of rotation angles and torques of implant-abutment screw tightening and loosening: Effects of implant types, contamination and sandblasting
Jiwoo LEE ; Seong-Kyun KIM ; Jai-Young KOAK ; Ji-Man PARK ; Jaejin CHO
The Journal of Korean Academy of Prosthodontics 2025;63(2):103-113
Purpose:
. The purpose of this study is to analyze the biomechanical differences in rotation angle-torque according to the type of implant and to compare the effects of contamination and sandblasting on the removal torque value (RTV) of abutment screws.
Materials and methods:
. For this study, an automated device for tightening and loosening implant screws was developed, and each 15 implant-abutment complexes of external and internal connection type were prepared, divided into three groups according to the surface treatment of the screw:control group (no treatment), experimental group-1 (artificial saliva contamination and chlorhexidine (CHX) rinsing), and experimental group-2 (artificial saliva contamination, CHX rinsing, and subsequent 50 µm Al 2 O 3 sandblasting). FirstRTV was measured for each group, followed by different post-treatment procedures for the screws, and then Second-RTV was measured. During the procedure, the removal torque value and rotation angle vs. time were recorded at a 20 data/s.A standardized protocol was followed for all the tightening and loosening procedures: screw was tightened with 30 Ncm torque and maintained for 5 s, and then rotated in the reverse direction until the torque value reached 0 Ncm. After 10min of rest period, the screws were loosened to initial point.
Results:
. Statistical analysis of measured data revealed that the internal connection type showed significantly higher First-RTV compared to the external connection type, however, no significant differences in Second-RTV were found. Both experimental groups 1and 2 showed a decrease in RTVs for both implant types, while the control group showed a decrease in RTV only for the internal type. The internal connection type required a significantly larger rotation angle during the tightening and loosening process.
Conclusion
. Within the limitations of this study, both artificial saliva contamination and CHX cleansing, as well as sandblasting, decreased RTV in both internal and external connection types. Internal connections were more susceptible to the effects of contaminants.
4.Biomechanics in terms of rotation angles and torques of implant-abutment screw tightening and loosening: Effects of implant types, contamination and sandblasting
Jiwoo LEE ; Seong-Kyun KIM ; Jai-Young KOAK ; Ji-Man PARK ; Jaejin CHO
The Journal of Korean Academy of Prosthodontics 2025;63(2):103-113
Purpose:
. The purpose of this study is to analyze the biomechanical differences in rotation angle-torque according to the type of implant and to compare the effects of contamination and sandblasting on the removal torque value (RTV) of abutment screws.
Materials and methods:
. For this study, an automated device for tightening and loosening implant screws was developed, and each 15 implant-abutment complexes of external and internal connection type were prepared, divided into three groups according to the surface treatment of the screw:control group (no treatment), experimental group-1 (artificial saliva contamination and chlorhexidine (CHX) rinsing), and experimental group-2 (artificial saliva contamination, CHX rinsing, and subsequent 50 µm Al 2 O 3 sandblasting). FirstRTV was measured for each group, followed by different post-treatment procedures for the screws, and then Second-RTV was measured. During the procedure, the removal torque value and rotation angle vs. time were recorded at a 20 data/s.A standardized protocol was followed for all the tightening and loosening procedures: screw was tightened with 30 Ncm torque and maintained for 5 s, and then rotated in the reverse direction until the torque value reached 0 Ncm. After 10min of rest period, the screws were loosened to initial point.
Results:
. Statistical analysis of measured data revealed that the internal connection type showed significantly higher First-RTV compared to the external connection type, however, no significant differences in Second-RTV were found. Both experimental groups 1and 2 showed a decrease in RTVs for both implant types, while the control group showed a decrease in RTV only for the internal type. The internal connection type required a significantly larger rotation angle during the tightening and loosening process.
Conclusion
. Within the limitations of this study, both artificial saliva contamination and CHX cleansing, as well as sandblasting, decreased RTV in both internal and external connection types. Internal connections were more susceptible to the effects of contaminants.
5.Biomechanics in terms of rotation angles and torques of implant-abutment screw tightening and loosening: Effects of implant types, contamination and sandblasting
Jiwoo LEE ; Seong-Kyun KIM ; Jai-Young KOAK ; Ji-Man PARK ; Jaejin CHO
The Journal of Korean Academy of Prosthodontics 2025;63(2):103-113
Purpose:
. The purpose of this study is to analyze the biomechanical differences in rotation angle-torque according to the type of implant and to compare the effects of contamination and sandblasting on the removal torque value (RTV) of abutment screws.
Materials and methods:
. For this study, an automated device for tightening and loosening implant screws was developed, and each 15 implant-abutment complexes of external and internal connection type were prepared, divided into three groups according to the surface treatment of the screw:control group (no treatment), experimental group-1 (artificial saliva contamination and chlorhexidine (CHX) rinsing), and experimental group-2 (artificial saliva contamination, CHX rinsing, and subsequent 50 µm Al 2 O 3 sandblasting). FirstRTV was measured for each group, followed by different post-treatment procedures for the screws, and then Second-RTV was measured. During the procedure, the removal torque value and rotation angle vs. time were recorded at a 20 data/s.A standardized protocol was followed for all the tightening and loosening procedures: screw was tightened with 30 Ncm torque and maintained for 5 s, and then rotated in the reverse direction until the torque value reached 0 Ncm. After 10min of rest period, the screws were loosened to initial point.
Results:
. Statistical analysis of measured data revealed that the internal connection type showed significantly higher First-RTV compared to the external connection type, however, no significant differences in Second-RTV were found. Both experimental groups 1and 2 showed a decrease in RTVs for both implant types, while the control group showed a decrease in RTV only for the internal type. The internal connection type required a significantly larger rotation angle during the tightening and loosening process.
Conclusion
. Within the limitations of this study, both artificial saliva contamination and CHX cleansing, as well as sandblasting, decreased RTV in both internal and external connection types. Internal connections were more susceptible to the effects of contaminants.
6.Role of Mindfulness in the Effects of Organizational Culture on Depression in Korean Physical Therapists
Jong-Hyun LEE ; Jinwon LEE ; Jaejin HWANG ; Du-Jin PARK ; Won-Jin KIM ; Kyung-Sun LEE
Safety and Health at Work 2024;15(4):441-451
Objective:
The study aimed to investigate whether mindfulness could mitigate the impact of job and interpersonal demands arising from stressful organizational cultures in predicting depression during the COVID-19 pandemic.
Methods:
A total of 280 Korean physical therapists participated in this study. To verify the mediated moderation model, this study implemented an SPSS 26.0 PROCESS Macro (v.3.5) that was based on the verification of Hayes' conditional indirect effect.
Results:
The study confirmed the moderated mediation effect of mindfulness on the mediating relationship between stressful organizational culture, job demands/interpersonal demands, and depression. Moreover, the conditional indirect effect of mindfulness was found to be statistically significant. However, the impact on interpersonal stress differed from anticipated outcomes.
Conclusions
Mindfulness, applicable within the framework of the Job Demands-Resources model theory, served as a resource variable and moderated the impact of organizational culture on members' depression. Amidst ongoing debates on mindfulness effectiveness, this study partially confirmed its potential within the Job Demands-Resources model, suggesting a role in mitigating the influence of organizational culture on members' depression as a resource variable.
7.Role of Mindfulness in the Effects of Organizational Culture on Depression in Korean Physical Therapists
Jong-Hyun LEE ; Jinwon LEE ; Jaejin HWANG ; Du-Jin PARK ; Won-Jin KIM ; Kyung-Sun LEE
Safety and Health at Work 2024;15(4):441-451
Objective:
The study aimed to investigate whether mindfulness could mitigate the impact of job and interpersonal demands arising from stressful organizational cultures in predicting depression during the COVID-19 pandemic.
Methods:
A total of 280 Korean physical therapists participated in this study. To verify the mediated moderation model, this study implemented an SPSS 26.0 PROCESS Macro (v.3.5) that was based on the verification of Hayes' conditional indirect effect.
Results:
The study confirmed the moderated mediation effect of mindfulness on the mediating relationship between stressful organizational culture, job demands/interpersonal demands, and depression. Moreover, the conditional indirect effect of mindfulness was found to be statistically significant. However, the impact on interpersonal stress differed from anticipated outcomes.
Conclusions
Mindfulness, applicable within the framework of the Job Demands-Resources model theory, served as a resource variable and moderated the impact of organizational culture on members' depression. Amidst ongoing debates on mindfulness effectiveness, this study partially confirmed its potential within the Job Demands-Resources model, suggesting a role in mitigating the influence of organizational culture on members' depression as a resource variable.
8.Role of Mindfulness in the Effects of Organizational Culture on Depression in Korean Physical Therapists
Jong-Hyun LEE ; Jinwon LEE ; Jaejin HWANG ; Du-Jin PARK ; Won-Jin KIM ; Kyung-Sun LEE
Safety and Health at Work 2024;15(4):441-451
Objective:
The study aimed to investigate whether mindfulness could mitigate the impact of job and interpersonal demands arising from stressful organizational cultures in predicting depression during the COVID-19 pandemic.
Methods:
A total of 280 Korean physical therapists participated in this study. To verify the mediated moderation model, this study implemented an SPSS 26.0 PROCESS Macro (v.3.5) that was based on the verification of Hayes' conditional indirect effect.
Results:
The study confirmed the moderated mediation effect of mindfulness on the mediating relationship between stressful organizational culture, job demands/interpersonal demands, and depression. Moreover, the conditional indirect effect of mindfulness was found to be statistically significant. However, the impact on interpersonal stress differed from anticipated outcomes.
Conclusions
Mindfulness, applicable within the framework of the Job Demands-Resources model theory, served as a resource variable and moderated the impact of organizational culture on members' depression. Amidst ongoing debates on mindfulness effectiveness, this study partially confirmed its potential within the Job Demands-Resources model, suggesting a role in mitigating the influence of organizational culture on members' depression as a resource variable.
9.Role of Mindfulness in the Effects of Organizational Culture on Depression in Korean Physical Therapists
Jong-Hyun LEE ; Jinwon LEE ; Jaejin HWANG ; Du-Jin PARK ; Won-Jin KIM ; Kyung-Sun LEE
Safety and Health at Work 2024;15(4):441-451
Objective:
The study aimed to investigate whether mindfulness could mitigate the impact of job and interpersonal demands arising from stressful organizational cultures in predicting depression during the COVID-19 pandemic.
Methods:
A total of 280 Korean physical therapists participated in this study. To verify the mediated moderation model, this study implemented an SPSS 26.0 PROCESS Macro (v.3.5) that was based on the verification of Hayes' conditional indirect effect.
Results:
The study confirmed the moderated mediation effect of mindfulness on the mediating relationship between stressful organizational culture, job demands/interpersonal demands, and depression. Moreover, the conditional indirect effect of mindfulness was found to be statistically significant. However, the impact on interpersonal stress differed from anticipated outcomes.
Conclusions
Mindfulness, applicable within the framework of the Job Demands-Resources model theory, served as a resource variable and moderated the impact of organizational culture on members' depression. Amidst ongoing debates on mindfulness effectiveness, this study partially confirmed its potential within the Job Demands-Resources model, suggesting a role in mitigating the influence of organizational culture on members' depression as a resource variable.
10.Role of Mindfulness in the Effects of Organizational Culture on Depression in Korean Physical Therapists
Jong-Hyun LEE ; Jinwon LEE ; Jaejin HWANG ; Du-Jin PARK ; Won-Jin KIM ; Kyung-Sun LEE
Safety and Health at Work 2024;15(4):441-451
Objective:
The study aimed to investigate whether mindfulness could mitigate the impact of job and interpersonal demands arising from stressful organizational cultures in predicting depression during the COVID-19 pandemic.
Methods:
A total of 280 Korean physical therapists participated in this study. To verify the mediated moderation model, this study implemented an SPSS 26.0 PROCESS Macro (v.3.5) that was based on the verification of Hayes' conditional indirect effect.
Results:
The study confirmed the moderated mediation effect of mindfulness on the mediating relationship between stressful organizational culture, job demands/interpersonal demands, and depression. Moreover, the conditional indirect effect of mindfulness was found to be statistically significant. However, the impact on interpersonal stress differed from anticipated outcomes.
Conclusions
Mindfulness, applicable within the framework of the Job Demands-Resources model theory, served as a resource variable and moderated the impact of organizational culture on members' depression. Amidst ongoing debates on mindfulness effectiveness, this study partially confirmed its potential within the Job Demands-Resources model, suggesting a role in mitigating the influence of organizational culture on members' depression as a resource variable.

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