Improving surface wettability aims to increase the implant surface area achieving most favorable protein adsorption and cellular adhesion and thereby to positively regulate the biological response at the initial osseointegration process. Thus, the superior potential of superhydrophilic surfaces in enhancing osseointegration at early stages of bone formation may also enhance their load-bearing capacity and biomechanical resistance.

In the present study, both SAE-HD implants and SAE implants showed relatively high amounts of maximum removal torque values at both observation times. In contrast, the SAE-HD implants showed relatively high values in removal energy compared with SAE implants at both 2 and 4 weeks. Specifically, the test group presented consistently higher values (about 100% higher) in removal energy compared with the control group at both observation times. Further, SAE-HD implants showed high values in connection stiffness already after 2 weeks of healing, while SAE implants required 4 weeks of healing to reach a similar level. Thus, despite the fact that the differences between the two groups were not significant for any of the evaluated parameters or observation times, the results seem to indicate that differences in surface properties between SAE-HD and SAE implants, somehow influenced osseointegration and intrinsic properties of shear strength. Indeed, greater removal torque values and interfacial stiffness for hydrophilic implants (modSLA)¹ between 2 and 4 weeks, in comparison with SLA², have been previously reported [35]. In this study [35], performed in the anterior maxilla of miniature pigs, hydrophilic implants revealed, on average, 8–21 and 9–14% significantly higher removal torque and interfacial stiffness values, respectively, than those of the SLA implants. Due to the remodeling process, the biomechanical parameters decreased with time for both implant surfaces, reflecting the developing biological stability.

It has been previously reported the existence of a correlation between removal torque and %BIC values [26], although the nature of these parameters differs from one another (three-dimensional versus most often two-dimensional parameter) [36]. Indeed, the lack of differences between the groups herein reflect well the results of the histomorphometric analysis of the other half of implants in the present study, reported elsewhere [31]. In particular, similar amounts of osseointegration in terms of %BIC and bone density were observed in both groups (SAE-HD vs. SAE) at each observation time, and there were no statistically significant differences regarding the respective parameters between the two observations times [31]. In contrast, Sartoretto et al. [27] demonstrated that Acqua® implants (Neodent®), which present similar technology as the SAE-HD implants, resulted in accelerated osseointegration when placed in tibia of rabbits after 2 weeks of healing, compared with implants with the Neoporos® surface, which in turn presents similar technology with the SAE surface. The difference between the study of de Jesus et al. [31] and Sartoretto et al. [27] in terms of the impact of surface technology on histomorphometric osseointegration parameters may be due to anatomical and/or biological differences in the experimental models employed. In this context, although there is no scientific support regarding the optimal experimental model to evaluate aspects of osseointegration, the dog is one of the most commonly used animal platforms [36]. The mandible of dogs is the most frequent location; however, a high percentage of studies on implant integration have used extra-oral implant sites, including the tibia [37]. It is suggested that due to its anatomy, with a large lumen and relatively low trabecular density [38], it possesses high discriminating potential regarding the impact of implant surface technologies to enhance osseointegration. Furthermore, the tibia allows placement of a larger number of implants comparing with the mandible, thus allowing the use of fewer animals and/or multiple types of comparisons/tests (e.g., biomechanical and histological evaluation).