In total, 63 implants in 63 patients were ultimately included in the analysis. Demographic information is presented in Tables 1 and 2.

Significant reductions in both PPD and mBoP were seen at all time points relative to the baseline clinical measurements (p < 0.001) in both the unadjusted and adjusted models including age, gender and past smoking experience (Figs. 2 and 3). Stable reductions in PPD and mBoP were observed after 2 weeks and up to 6 months after the initial treatment. The hypothesis of no difference in PPD values between week 2 and week 4 (p = 0.1429) could not be rejected, but from week 4 until 3 and 6 months, statistically significant reductions with p values of 0.007 and 0.0295, respectively, were detected. A relevant cluster effect at the center level was identified with variation around the center intercepts of 0.267 and 0.117 and remaining variances of 0.432 and 0.46 for PPD and mBoP, respectively.

The mean PPD and mBoP at baseline were 5.15 mm (4.97; 5.32) and 1.86 (1.78; 1.93), respectively, whereas the mean PPD and mBoP at 6 months were 4.0 mm (3.91; 4.19) and 0.64 (0.54; 0.75), respectively (Figs. 2 and 3).

A mBoP index of 1 or more and PPD ≥4 mm was recorded at 35% of the sites at the final examination. At the baseline examination, PPD ≥6 mm was recorded at 31.25% (25.53; 37.59) of the sites and 17.02% (8.14; 31.35) of the implants. These numbers were reduced to 13.25% (9.31; 18.43) of the sites and 4.35% (0.76; 16.04) of the implants at the terminal examination (Fig. 4).

At the baseline visit, a mBoP index of 2 or 3 was recorded at 73.14% (67.01; 78.52) of the included sites, while this number was reduced to 28.9% (16.3; 27.1) at the final evaluation (Fig. 5).

Statistical difference in the level of the mucosal margin was recorded between baseline and all the later time points. No further change was seen after 4 weeks (Table 3).