An In Vitro Study of Fluid Contaminations Influences on Reverse Torque Values of Implant-Abutment Connections

Abstract

Purpose. To examine the effects of fluid contamination on the reverse torque value (RTV) of abutment screws. 484 titanium fixtures were mounted into the stainless-steel holders. Methods. 11 groups (44 specimens in each group) of implants were mounted in acrylic resin. Ten groups of fixture screw holes were contaminated with chlorhexidine, saliva, blood, fluoride, or combination groups, and one group served as a control without contamination. To simulate the oral environment, samples were subjected to thermal cycling and cyclic loading. Results. The RTV means were less than the initial torque in both control and contamination groups. The maximum RTV mean was observed in the fluoride group ($26.00\pm 1.02$ Ncm). In other groups, this rate for control, blood, saliva, and chlorhexidine groups were$18.00\pm 1.78$ Ncm,$22.12\pm 1.56$ Ncm,$21.56\pm 1.43$ Ncm, and$21.89\pm 1.02$ Ncm, respectively. In combination groups, the maximum RTV mean was observed in the saliva+CHX group ($23.89\pm 1.92$ Ncm). In other combination groups, this rate for the blood+CHX, blood+saliva, saliva+fluoride, fluoride+CHX, and fluoride+blood groups were$22.56\pm 1.73$ Ncm,$22.00\pm 1.54$ Ncm,$20.11\pm 1.58$ Ncm,$23.51\pm 1.19$ Ncm,$21.02\pm 1.38$ Ncm, and$20.11\pm 1.58$ Ncm, respectively. The RTV was statistically significant ($p<0.05$) for the contamination groups (except saliva) and combination groups compared to the control group. There is no statistically significant difference ($p>0.05$) between the reverse torque value mean of the blood and saliva groups and between that of the fluoride and chlorhexidine groups. Conclusion. Implant-abutment specimens are suggested to be placed in a saliva environment and should be subjected to cyclic loading.