Jemt papilla score

At loading, the Jemt papilla score was 1.93 ± 1.01, significantly increasing to 2.14 ± 0.95 at 5-year follow-up (p = 0.023) (Fig. 2d). For the platform-switching subgroup, a significant difference was observed between baseline and 5-year follow-up (p < 0.001); however, no significant difference was observed for the platform-matching group over the same time period. Furthermore, at loading, the Jemt papilla score was significantly lower for the platform-switching subgroup than for the platform-matching subgroup (1.78 vs. 2.28; p = 0.009).

Bone level changes

Evaluable radiographs were available from 13 participating sites: eleven sites with periapical and two sites with orthopantographic radiographs. At loading and at 5-year follow-up, respectively, 148 and 119 evaluable radiographs were available. The mean bone level change from loading (baseline) to 5-year follow-up was (mean ± SD) − 0.28 ± 0.60 mm. No significant differences in the mean bone level change from loading to 5-year follow-up were observed between the platform-switching and platform-matching subgroups (− 0.32 ± 0.60 mm vs. − 0.13 ± 0.29 mm). From loading to 5-year follow-up, no bone loss or even bone gain was observed in 38% of evaluable implants. Figure 3 shows the frequency distribution of bone level changes from loading to 5-year follow-up for all implants.

Patient satisfaction

Patient satisfaction was reported as excellent by over 60% of all patients for each category at each time point during the course of the study, with almost all remaining patients reporting good outcomes (Fig. 4). No more than three patients reported an outcome of fair for any category at any time point, and no patients reported an outcome of poor for any category at any time points. No differences were observed between the platform-switching and platform-matching subgroups for any category at any time point (data not shown).

Prosthetic complications

With regard to prosthetic complications, there were two cases of ceramic chipping in two patients; the restorations were corrected and no further complications were seen. There were three cases of crown loosening which resolved after re-cementing the crowns, and there were two cases of abutment screw loosening leading to crown mobility, which resolved after screw tightening.