Surface treatment with airborne-particle abrasion is an essential method for improving the adhesion between restorative materials and tooth/implant surfaces. The surface topography after treatment can affect the protein and bacterial adsorption and thus the biofilm formation and eventually the plaque formation leading to dental caries or periodontal disease.  The commonly used alumina abrasive comparing with a newly developed nano-featured alumina-zirconia composite (AZC) abrasive for their blasting effect on the surface of four commercially available dental zirconias was investigated.  The tested abrasives give the surface features in different length scales from micron to nanosized. The alumina abrasive with the size of 50-70 µm and sharp edges indicates that there is a risk for creating destructive microcracks on the zirconia surface. As the zirconias are going towards high translucent along with increasing the cubic phase and decreasing the benefits of the phase transition from tetragonal to monoclinic phase, it may be beneficial to consider a less destructive abrasive for translucent zirconia surface treatment.
Dental zirconia specimens, 3Y-TZP subjected to three different surface treatments: polished, as-sintered, and airborne-particle abrasion were then incubated in human saliva with a-amylase (3/group).  The protein adsorption on the specimen surface was analysed by calculating the differences in the amount of total protein in solution before and after 24 h of incubation using BCA assay. Immunofluorescent imaging using CSLM was performed to observe and analyse surface protein adsorption. The shear bond test was conducted on zirconia discs with different surface treatments including polished, blasted with the new abrasive under 0.2 and 0.4 MPa pressures, and blasted with alumina abrasive under 0.2 MPa pressure. The shear bond test was performed using the resin cement pellet attached on the zirconia disk surface.
The results show increased protein adsorption on the as-sintered surface indicating that a proper size of nano features on the surface of implant is important for the first phase of biofilm formation or plaque accumulation.  Nanostructure alone or together with micron scale features may improve the healing and osseointegration of implants even below the gingival tissue level. The newly developed abrasive showed nanofeatures on the abrasion surface after sandblasting. The data of shear bond test had similar values to the alumina abrasive treated surface and the surface roughness measurements did not show any significant difference. The phase analysis revealed that T-M phase transformation in zirconia was decreased after nano-featured abrasive surface treatment. It indicated that surface airborne-particle abrasion treatment with AZC abrasive is more suitable for the high translucent zirconias and may increase the biocompatibility of zirconia.
 
Iqbal, M.N.; Shen, Z.J.; Bengtsson, T.; Eriksson, M. Materials 2021, 14,6412. https://doi.org/10.3390/ma14216412
Dianne Gan, Muhammad Naeem Iqbal, Qianhui Xu, Zhijian Shen, Van Ramos Jr, and Kwok-Hung Chung; The journal of prosthetic dentistry; https://doi.org/10.1016/j.prosdent.2021.12.022