Keywords : screw loosening
Evaluation Of Gingival Tissue Entrapment On Abutment Screw Loosening Of Titanium And Zirconium Abutments: An In Vitro Pilot Study
European Journal of Molecular & Clinical Medicine,
2020, Volume 7, Issue 7, Pages 431-442
The study compared the difference in removal torque values of titanium/titanium implant abutment interface and titanium/zirconium implant abutment interface with and without entrapped soft tissue, employing an in vitro model. Porcine tissue specimens were prepared to thickness of 0.5 mm. Twenty internal hex implants were embedded in acrylic block. Four groups (n = 5) were studied. Titanium and zirconium abutments were tightened with and without entrapped tissue, to each of the 20 titanium implants. Using a digital torque gauge all the abutments were torqued to 20 Ncm (Newton-Centimetre). Specimens with entrapped tissue were immersed in 1 M NaOH (Molar sodium hydroxide) for 48 hours to dissolve tissue to simulate salivary breakdown in the oral cavity. Mean and standard deviation was calculated for each group. Mann Whitney U test was used to compare reverse torque values between two groups. Statistically significant variation in reverse torque values was found between all groups with and without tissue entrapment, (p < 0.05). The difference in torque drop for Zirconium/Titanium implant abutment interface with and without tissue entrapment was found to be (12.12 Ncm) and (13.48 Ncm) respectively after 48 hours. The difference in torque drop following 48 hours noted for Titanium/Titanium interface with and without tissue entrapment was found to be (13.86 Ncm) and (15.87 Ncm) respectively. Study revealed that tissue entrapment significantly lowers the reverse torque values.