Evaluation of the Effect of Different Contaminants on the Reverse Torque Values at the Implant Abutment Junction: An In Vitro Study

Abstract Screw loosening at the implant-abutment junction is the commonest failure reason of implant prosthesis. This happens mainly due to improper insertion torque and friction between the clamping surfaces. This article evaluates the effect of three different contaminants on the screw loosening at the implant abutment junction. This effect is measured as reverse torque value, that is, the force required to loosen the screw after the contamination is done. Saliva, titanium nanoparticles, and sodium fluoride are used as contaminants which were prepared as 1000 ppm solutions with artificial saliva as a solvent. Thirty Genesis Aktiv Internal hex parallel implants were divided into three groups and contaminated in their screw access channel with the respective contaminants and clamped with straight abutments at 35 Ncm. They were torqued again after 10 minutes to compensate for settling effect. After that, they are stored in artificial saliva for 14 days at 37°C. Reverse torque values were measured by a physiodispenser. The data collected was subjected to one-way analysis of variance test to determine the difference between groups. Tukey post hoc analysis was done to evaluate the intergroup mean differences. A statistically significant difference was noted in the mean reverse torque values between group 1 and groups 2 and 3. But, when intergroup comparisons were made, the difference between group 1 and group 2 only had statistical significance. The reverse torque values increased significantly when contaminated with sodium fluoride and titanium nanoparticle solutions, which can be attributed the reduced friction between the clamping surfaces, thereby negating the settling effect.