Anaerobic Adhesive Effect on the Counter-Torque of Zirconia Implant Abutment Screws: In Vitro Study

Implantology has become a primary solution for tooth loss due to excellent osseointegration and high long-term success rates. However, complications such as abutment screw loosening, especially in implant-supported single crowns, compromise prosthesis longevity. Anaerobic adhesives (AAs) have shown promise in mechanical fields for preventing screw loosening, but their effectiveness in dental implants, particularly zirconia, remains uncertain. This study evaluates the effect of medium-strength AA on the counter-torque and screw stability of zirconia implant abutments.

Twenty neodent Zi zirconia implants were divided into two groups: control (n = 10) without adhesive and experimental (n = 10) using medium-strength AA (Loctite 242) on the prosthetic screw. Abutment screws were torqued to 32 Ncm and underwent mechanical cycling simulating mastication. Counter-torque was measured post-cycling. Structural damage and adhesive residues were inspected using a stereomicroscope. Data were analyzed using descriptive statistics including means and standard deviations (SDs). The Shapiro-Wilk test was performed to assess data normality. The counter-torque values after cycling were compared to the installation torque value using the one-sample t-test. Comparison between groups was performed using Student's t test. Statistical significance was established as p < 0.05.

The presence of AA was detected on all screws, without causing damage and was easily removable. Both groups showed significantly lower counter-torque values than the installation torque, with no significant intergroup difference.

Medium-strength AA did not significantly affect the counter-torque values of zirconia implant abutment screws, although it was easily removable and caused no damage.