Dental implants are nowadays the treatment of choice to replace missing teeth due to their high predictability and long-term success [1]. This success is the outcome of several cellular and molecular events that take place at the implant-bone interface. Although the process of osseointegration is not fully understood, research is ongoing to enhance and accelerate this process. Moderately rough implant surface has enhanced implant osseointegration and has increased the implant secondary stability [2, 3]. Recently, elements of the extracellular cellular matrix have been introduced to bio-activate the dental implant surface [4, 5].

Calcium is one of these elements that has been studied to enhance the osseointegration process [6, 7]. Recently, Favero et al. have compared modifications of an acid-etched surface with calcium ions (UnicCa®) against a surface modified by a nanometer-scale Discrete Crystalline Deposition (DCD™) of Calcium Phosphate [8]. The patterns of sequential healing have been similar for the two surfaces, although the UnicCa® surface showed a statistically significant higher new bone formation at 2 and 4 weeks. Moreover, the osseointegration process of UnicCa® and the SLActive® surfaces has been very similar without statistically significant differences [9].

A research is needed to study if these enhancements to the dental implant surface would improve the outcome of dental implants. It has been reported that 40% of the implant failures occur during the period of osseointegration (early failures) [10]. The presence of low-density bone is a challenging situation to achieve the success of dental implants and requires specific treatment plan and surgical protocol to minimize the risk of implant failure [11, 12]. The rehabilitation of posterior maxilla with an implant-supported prosthesis could be complicated by the presence of low-density bone [13].

For that, the aim of this study is to evaluate the early survival of UnicCa® dental implants placed in transalveolarly augmented maxillary sinus. The null hypothesis of the study is that the UnicCa® surface does not enhance implant survival nor the marginal bone stability. The principal outcome has been the marginal bone stability and as secondary outcome the implant survival.