Abstract: Objective To assess the impact of different tapers and materials of abutments on peri-implant soft tissue attachment in vivo, and to select the best abutment taper. Methods Ti6Al4V and zirconia abutments with different tapers were prepared using CAD/CAM technology. The abutments underwent surface treatment and were placed into the oral cavities of animals. The animals were executed four weeks after healing, and the gingival attachment to abutments with different materials and tapers was observed using HE staining and immunohistochemistry (IHC). Results Roughness Ti6Al4V Ra= 0.16 μm, zirconia Ra=0.34 μm. HE staining showed that there were more inflammatory cells in the 35° group than in the other groups, while there was no significant difference in the number and distribution of inflammatory cells in the 20°~ 30° groups, and the inflammation in zirconia group was more obvious than that in Ti6Al4V group. IHC staining demonstrated an immune response to laminin-5 at the interface between the abutment and the surrounding epithelium. The expression intensity reached its peak at 30° with the increase of the emergency taper. The expression in the zirconia group was weaker than that in the Ti6Al4V group. The MOD values (Mean Optical Density) of 20° to 40° were 0.27 ± 0.00, 0.29 ± 0.00, 0.35 ± 0.00, 0.24 ± 0.01 and 0.25 ± 0.01, respectively. The MOD values of Ti6Al4V and zirconia were 0.29 ± 0.00 and 0.20 ± 0.01, respectively. Conclusion The soft tissue attachment ability of the restorative abutment with 30° emergency taper was better, and the 3D-printed Ti6Al4V abutment was better than the digitally cut zirconia abutment.

Key words: Implant restorative abutment, Emergence taper, Digital cutting, 3D printing