Abrasion of Abutemt Screw Coated with TiN

Objectives: The purpose of this study was to evaluate surface changes and abrasion of the implant fixture and TiN coated abutment screw after repeated delivery and removal under SEM and universal measuring microscope. Methods: Seven pairs of implant fixture, abutment and abutment screws for each system were selected. Titanium abutment screws of Osstem and 3i were assigned to Group 1 and Group 2 respectively. TiN coated Abutment screws of Osstem and 3i were classified to Group 3 and Group 4. After 20 times of repeated closing and opening test, the evaluation for the change of inner surface of implant and TiN-coated abutment screw, and measurement of weight loss were performed. Mann-Whitney test with SPSS statistical software for Window was applied to analysis the measurement of weight loss.

Results:

1. Mean weight loss of abutment screws for four groups was 0.181± 0.145mg in Group 1, 0.069±0.023mg in Group 2, 0.056± 0.026mg in Group 3 and 0.043±0.016mg in Group 4.

2. In the comparison of weight loss of Group 1 and Group 3, there was a statistically significant difference between Group 1 and Group 3 (P<0.05, Mann-Whitney test).

3. In the comparison of weight loss of Group 2 and Group 4, Group 2 revealed a statistically higher mean value than Group 4(P<0.05, Mann-Whitney test).

4. Abrasion and defect of mating thread surface of abutment screw were considerable in both Group 1 and Group 2, while only slight abrasion and defect were founded in Group 3 and Group 4.

Conclusions: Conclusively, TiN coating of abutment screw showed better resistance to abrasion than titanium abutment screw. It was concluded that TiN coating of abutment screw would reduce the loss of preload with good abrasion resistance and low coefficient of friction, and help to maintain screw joint stability.