Dental implants are a well-accepted and predictable treatment modality for the rehabilitation of partially and completely edentulous patients. Ten-year survival rates > 95% and 15-year survival rates > 92% have been reported [
1]. To achieve long-term success, rigid fixation of the implants within the host bone site is required [
2]. This biological concept of osseointegration was first introduced by Branemark et al. in the 1960s [
3]. Since its introduction the term osseointegration has been successively redefined, the common denominator being an inanimate metallic structure anchored long-term in living bone under functional loading [
4]. Nowadays, commercially pure (cp) titanium and its alloys are the materials most often used in implant manufacturing because of their excellent biocompatibility, favourable mechanical properties and well-documented beneficial results. When exposed to air titanium immediately develops a stable oxide layer which forms the basis of its exceptional biocompatibility. The properties of the oxide layer, i.e. its chemical purity and surface cleanliness, are of great importance for the biological outcome of the osseointegration of titanium implants [
5]. According to Albrektsson et al., the quality of the implant surface is one major factor that influences wound healing at the implantation site and subsequently affects osseointegration [
6]. In recent years, much effort has been made to improve implant anchorage in bone tissue by modifying the surface characteristics of titanium implants. Various studies have demonstrated that the success of integration of implants into bone tissue correlates positively with a special roughness of the implant surface [
7]. Another advantage of a roughened titanium surfaces is a shorter healing period and the option of utilizing shorter implants, still with a good long-term prognosis because of the better bone anchorage [
8]. Therefore, many surface modifications of titanium implants have been developed to achieve better osseointegration (machined, plasma-sprayed, grit blasted and/or acid etched).
In recent years, high-strength ceramics have become attractive as new materials for dental implants. They are considered to be inert in the body and exhibit minimal ion release compared to metallic implants. Zirconium oxide partially stabilized with yttrium (yttrium-stabilized tetragonal polycrystals [Y-TZP]) appears to offer advantages over aluminium oxide for dental implants due to its higher fracture resilience and higher flexure strength [
9]. Zirconia ceramics have also been successfully used in orthopedic surgery to manufacture ball heads for total hip replacements and this is still the current main application of this biomaterial [
10,
11].
Up to now, only few studies have investigated the osseointegration of dental implants made of zirconia ceramics. As the surface topography of zirconia implants seems to influence the bone implant interface, the aim of this study was to investigate the osseointegration of zirconia implants with modified ablative surfaces at the ultrastructural level.