The present analysis was based on 39 patients diagnosed with peri-implantitis in 57 implants. The patients were divided into 2 groups according to the grafting of the site: non-grafted implant sites (29 patients/41 implants) and grafted implant sites (10 patients/16 implants).

The characteristics of the implant sites are presented in Table 1. In total, 26 implants (45.6%) were located in the maxilla and the remaining 31 (54.4%) were located in the mandible. Out of these implants, 15 (26%) were located in the anterior (incisor and canine area) and 42 (74%) were located in the posterior regions (premolars and molars). All the studied implants (100%) presented with BOP, and only 1 implant had BOP in fewer than 6 sites.

At the baseline, the maximum PD values at the grafted and non-grafted sites 6.25 ± 0.45 mm and 6.77 ± 1.61 mm, respectively (Table 1, Fig. 2). The Wilcoxon rank-sum test did not show a significant difference in the baseline maximum PD values between the groups (p = 0.353) (Table 1).

In general, disease resolution (i.e., the absence of BOP and PD ≥ 6 mm) was achieved in 19 out of 57 (33%) implants and in 11 out of 39 (28%) patients. At the patient level, disease resolution was obtained in 4 out of 10 patients (40%) at grafted sites and in 7 out of 29 patients (24.1%) at non-grafted sites. The chi-square test (χ2) demonstrated no significant difference between the two patient groups (p = 0.579, df = 1, χ2 = 0.307) (Table 2, Fig. 3a). However, the results of the implant-level analysis revealed a significant difference between the two groups, indicating a higher disease resolution at grafted implant sites (9/16 (56%) compared to non-grafted sites (10/41 (25%)) (p = 0.048, df = 1, χ2 = 3.921) (Fig. 3b).

Mean and median BOP reduction values (%) for the 2 groups are presented in Table 3. At the patient level, mean BOP reduction amounted to 77.45% (minimum 0%; maximum 100%) and 60.64% (minimum 0%; maximum 100%) at grafted and non-grafted sites, respectively.