Unlike Ca²⁺-modified dental implants, two early implant losses were observed for the same dental implants but without Ca²⁺. Moderately rough implant surface has enhanced implant osseointegration and has increased the implant secondary stability [2, 3, 19]. Hydrophilic moderately rough surfaces showed faster osseointegration compared to those with hydrophobic characteristics [20, 21]. Ca²⁺ ions have been shown to protect the hydrophilic implant surface against aging and the formation of carbon-rich species [4, 6].

Upon exposure to blood plasma, Ca²⁺-modified surface has induced surface clot formation, platelet adsorption, and activation [6]. By using a peri-implant gap model in rabbit, Ca²⁺-modified surface has significantly improved peri-implant bone volume and density at 2 weeks and bone-to-implant contact at 8 weeks [6]. Ca²⁺-modified surface presented a significantly more new bone formation at 2 and 4 weeks compared to a surface modified by nanometer-scale discrete crystalline deposition of calcium phosphate [8].

In this study, the modifications of an acid-etched surface with calcium ions have significantly decreased the marginal bone loss. Preservation of the crestal bone has been higher in Ca²⁺-modified implants compared to unmodified implants. One of the criteria of dental implant success as defined by Buser et al. [22] and modified by Albrektsson et al. [23] is the absence of persistent peri-implant bone resorption greater than 1.5 mm during the first year of loading and 0.2 mm per year during the following years. Östman et al. have documented the outcomes of dental implants modified with nanometer-scale discrete crystalline deposition of calcium phosphate [24]. The dental implants have been immediately loaded by the fixed prostheses in both maxillary and mandibular regions. The average marginal bone resorption was 0.37 ± 0.39 mm during the first year in function. This outcome might be related to the implant surface modification.

This study was limited by the retrospective design, data dependency on the accuracy of the patients’ record, and the short follow-up. Further prospective controlled studies with a long-term follow-up are required. The use of panoramic radiographs could be a source of error in measurement that was reduced by performing a 1:1 calibration of the radiograph. This would render the measurements sufficiently accurate for clinical use [25].