Implant survival

The cumulative survival rate was 100% at 1-year follow-up, 99.6% at 3-year follow-up, and 98.6% at 5-year follow-up. All three late failures were in the platform-switching subgroup.

Clinical parameters/soft tissue parameters

Plaque index

Mean modified plaque indices were very low at below 0.5 for all but one measurement throughout the course of the study (Fig. 2a). At loading, the overall MPI was 0.27 ± 0.49 slightly increasing to 0.38 ± 0.52 at 5-year follow-up; the increase in MPI from loading to 5-year follow-up was statistically significant (p < 0.001). The MPI for the platform-switching subgroup was significantly lower than that for platform-matching subgroup at 3-year (p = 0.025), 4-year (p = 0.001), and 5-year (p = 0.028) follow-up.

Sulcus bleeding index

At loading, the overall SBI was 0.21 ± 0.47, remaining very low throughout the study and slightly increasing to 0.32 ± 0.49 at 5-year follow-up (Fig. 2b). The increase in SBI from loading to 5-year follow-up was statistically significant (p < 0.001). At 3-year follow-up, the SBI was significantly higher in the platform-matching subgroup than in the platform-switching subgroup (0.29 vs. 0.23; p = 0.039); this difference increased at 4-year and 5-year follow-up (0.41 vs. 0.20; p = 0.001 and 0.50 vs. 0.27; p = 0.004, respectively).

Pocket probing depth

At loading, the PPD was 2.16 ± 1.05 mm; it decreased to 1.89 ± 1.04 mm at 6 months post-loading, increasing to 2.12 ± 1.04 mm at 1-year follow-up (Fig. 2c). From this point onward, the PPD increased to 2.34 ± 1.18 mm at 5-year follow-up. The increase in mean PPD from loading to 5-year follow-up was statistically significant (p = 0.032). The mean PPD for the platform-switching subgroup was significantly lower than that for the platform-matching subgroup at 4-year (2.20 mm vs. 2.77 mm; p = 0.012) and 5-year follow-up (2.23 mm vs. 2.70 mm; p = 0.011).