No remarkable events were observed during the surgical procedures and the subsequent healing period. The relative biomechanical performance of both experimental implant surfaces is illustrated in a representative graph of removal torque versus angular displacement. The removal torque, removal energy, and connection stiffness values are described in terms of mean, standard deviation, and 95% confidence interval for mean in Fig. 5. The results of one-way ANOVA variance and Tukey’s post hoc test values of the variables for SAE-HD and SAE implant at 2 and 4 weeks postoperatively (n = 6) are demonstrated in Table 1.

The removal torque values (N cm) did not reveal significant statistical differences between SAE-HD and SAE implants at any observation period (P = 0.06), but a slight increase over time could be observed in both test and control groups (Fig. 5a). Removal torque at 2 weeks was 60.18 ± 24.12 and 54.00 ± 29.91 N cm, and at 4 weeks was 88.11 ± 14.96 and 79.05 ± 14.59 N cm for SAE-HD and SAE implants, respectively (Fig. 5b). SAE-HD showed higher removal energy [J] at 4 weeks (9.99 ± 9.25) compared to 2 weeks (4.22 ± 4.50), while SAE displayed lower values at corresponding healing times (5.21 ± 1.49 vs. 2.83 ± 2.49, respectively) (P = 0.16). Regarding connection stiffness (N cm/rad), SAE showed lower values at 2 weeks (462.57 ± 507.75) compared with 4 weeks of healing (689.01 ± 496.28), however not statistically significant (Fig. 5c). SAE-HD disclosed similar results at 2 and 4 weeks (652.98 ± 111.26 vs. 661.56 ± 369.28, respectively) without statistically significant differences neither between the groups, nor over time (P = 0.76).

A Spearman’s correlation test was run to determine the connection between maximum removal torque, removal energy, and connection stiffness values (Table 2) during the interfacial strength assessment. There was a strong, positive monotonic correlation between removal torque and removal energy (=0.722, n = 19, P < 0.001). However, there was no evidence of positive correlation between removal torque and connection stiffness (=0.352, n = 24, P = 0.092). Moreover, a negative correlation between removal energy and connection stiffness was observed (=− 0.91, n = 19, P = 0.710).