IADR Abstract Archives
Conical Connection: Correlation Analysis of Torque, Preload and Settling
Objectives: A screw-retained dental implant system is tightened to a specified torque, which during tightening, is converted to a tensile force in the screw called preload. Preload is a clamping force which when sufficiently maintained holds the modular system together and reduces the risk of screw loosening. In conical connections, tightening additionally leads to settling of the abutment which may alter occlusal alignment. Preload and settling are influenced by system parameters (e.g. tightening torque, connection geometry, surface characteristics) and affect the system`s clinical performance.
The purpose of this study was to evaluate the relationships between tightening torque and preload, tightening torque and settling and any correlation between preload and settling. Additionally, the effect of color anodization of the implant interior on preload and settling was investigated.
Methods: Two implant systems (abutment, screw and implant) were investigated. In the test group, the implant`s interior was anodized, whereas in the control group it was machined. Preload was measured (6 samples/group) while the system was continuously tightened to 35Ncm. Settling was measured (10 samples/group) at tightening torques of 5, 10, 20 and 35Ncm. Correlations are reported as Spearman’s rank correlation coefficient and between group comparisons by Wilcoxon rank sum test.
Results: Within each group, significant correlations (all p<0.001) between tightening torque and preload (test: rs=0.9448, control: rs=0.9443), between tightening torque and settling (test: rs=-0.9467, control: rs=-0.9447), and between preload and settling (test: rs=-0.8768; control: rs=-0.9421) were observed. Preload was significantly higher (p<0.005) whereas settling was significantly lower (p<0.001) in the color anodized group.
Conclusions: Higher tightening torque resulted in higher preload, lowering screw loosening risk, but greater settling. Color anodization further increased preload but decreased settling, limiting the risk of occlusal misalignment. These findings suggest that color anodization of the implant interior may positively affect the clinical performance of the system.
The purpose of this study was to evaluate the relationships between tightening torque and preload, tightening torque and settling and any correlation between preload and settling. Additionally, the effect of color anodization of the implant interior on preload and settling was investigated.
Methods: Two implant systems (abutment, screw and implant) were investigated. In the test group, the implant`s interior was anodized, whereas in the control group it was machined. Preload was measured (6 samples/group) while the system was continuously tightened to 35Ncm. Settling was measured (10 samples/group) at tightening torques of 5, 10, 20 and 35Ncm. Correlations are reported as Spearman’s rank correlation coefficient and between group comparisons by Wilcoxon rank sum test.
Results: Within each group, significant correlations (all p<0.001) between tightening torque and preload (test: rs=0.9448, control: rs=0.9443), between tightening torque and settling (test: rs=-0.9467, control: rs=-0.9447), and between preload and settling (test: rs=-0.8768; control: rs=-0.9421) were observed. Preload was significantly higher (p<0.005) whereas settling was significantly lower (p<0.001) in the color anodized group.
Conclusions: Higher tightening torque resulted in higher preload, lowering screw loosening risk, but greater settling. Color anodization further increased preload but decreased settling, limiting the risk of occlusal misalignment. These findings suggest that color anodization of the implant interior may positively affect the clinical performance of the system.