Screw loosening study of a internal zirconia implant abutment reinforced with a titanium insert

Abstract

Objectives Secondary component, titanium insert was developed to reinforce the implant-abutment connection, known as the weakest part of an internal zirconia abutment. The aim of this study was to evaluate the effect of titanium insert under cyclic loading on screw loosening in internal friction connection structure

titanium abutments and zirconia abutments using titanium inserts were compared.

Material and methods Two different type of abutment with internal friction connection were assessed: titanium abutment-titanium abutment screw assemblies (Ti-Ti group) and zirconia abutment-titanium insert-titanium abutment screw assemblies (Zr+Ti-Ti group). Fourteen abutments and fourteen implants were used and divided into two groups of seven specimens. Pre-load removal torque values (RTVs) were measured after each assembly was tightened to 35 Ncm with a digital torque gauge. A cyclic load of 300N at a 30 degree angle in reference to the loading axis was applied at a frequency of 15Hz until failure or 1 million cycles by universal testing machine, Instron (E300, Instron, Canton, MA, USA). After cyclic loading, post-load RTVs were measured again.

Results 1) The pre-load RTVs for Ti-Ti group and Zr+Ti-Ti group were 26±0.8 7Ncm and 25.14±0.75 Ncm. The post-load RTVs for each groups were 18.43±1.17 Ncm and 17.50±1.08 Ncm. 2) The mean removal torque difference for Ti-Ti group and Zr+Ti-Ti group were -7.57±1.61 Ncm and -7.64±1.18 Ncm. Statistical analysis by the independent t-test revealed that RT difference of both groups were not significantly different from each other (P>0.05). 3) For all specimens, there was no screw loosening identified by visual or tactile inspection during cyclic loading or after loading.

Conclusion The internally connected zirconia implant abutment reinforced with a titanium insert shows similar resistance to screw loosening under cyclic loading compared to internally connected titanium implant abutment.