Zirconia surface modifications for implant dentistry

Zirconia has emerged as a versatile dental material due to its excellent aesthetic outcomes such as color and opacity, unique mechanical properties that can mimic the appearance of natural teeth and decrease peri-implant inflammatory reactions.The aim of this review was to critically explore the state of art of zirconia surface treatment to enhance the biological and osseointegration behavior of zirconia in implant dentistry.An electronic search in PubMed database was carried out until May 2018 using the following combination of key words and MeSH terms without time periods: "zirconia surface treatment" or "zirconia surface modification" or "zirconia coating" and "osseointegration" or "biological properties" or "bioactivity" or "functionally graded properties".Previous studies have reported the influence of zirconia-based implant surface on the adhesion, proliferation, and differentiation of osteoblast and fibroblasts at the implant to bone interface during the osseointegration process. A large number of physicochemical methods have been used to change the implant surfaces and therefore to improve the early and late bone-to-implant integration, namely: acid etching, gritblasting, laser treatment, UV light, CVD, and PVD. The development of coatings composed of silica, magnesium, graphene, dopamine, and bioactive molecules has been assessed although the development of a functionally graded material for implants has shown encouraging mechanical and biological behavior.Modified zirconia surfaces clearly demonstrate faster osseointegration than that on untreated surfaces. However, there is no consensus regarding the surface treatment and consequent morphological aspects of the surfaces to enhance osseointegration.