One patient (control group) expressed minimally changed extraoral sensation in the chin region at both the 1- and 2-week follow-up. However, the extra- and intraoral clinical examination revealed no sensory disturbances. The patient was not affected by this and described the same changed sensation at the final clinical follow-up after 29 months.

Another patient (PRF group) experienced sensory disturbances at the mucosa of the alveolar sulcus at the recipient site, which was confirmed clinically. The disturbance decreased over time, but the patient was still affected by this at the final clinical follow-up 28 months later.

Implant placement

All implants could be placed 6 months after the bone block augmentation procedure. Buccal bone thickness after implant installation was less than 2 mm in two patients (one in each group); therefore, additional localised alveolar ridge augmentation was performed using locally harvested autogenous bone chips (Safescraper, Divisione Medical Meta, Italy) covered by Geistlich Bio-Oss® and a Geistlich Bio-Gide® membrane.

Technical and biological complications following implant placement

All patients were included in a maintenance care programme after placement of the implant crown by the referring dentist. No technical or biological complication was reported during the follow-up period by the referring dentist or at the final follow-up examination.

Patient-reported outcome measures (PROMs)

The overall treatment satisfaction was characterised as high at both the baseline examination and the follow-up examination for both groups (Table 4 and Fig. 3). At baseline, the mean PROM was 0.13 (95% CI: − 0.40 to 0.66, p = 0.61) higher in the control group than in the PRF group, while at the follow-up examination the control group was 0.10 (95% CI: − 0.66 to 0.46) lower than the PRF group. Within both groups, the mean PROM outcome was 0.22 (95% CI: − 0.19 to 0.63, p = 0.27) units higher at the follow-up examination than at the baseline examination in the PRF group and 0.02 (95% CI: − 0.48 to 0.44, p = 0.93) units lower for the control group. No statistical differences were observed between or within the groups. The change from baseline to follow-up examination was 0.24 (95% CI: − 0.37 to 0.85, p = 0.43) units higher for the PRF group than the control group.

Reproducibility

The interobserver repeatability of the assessment of the radiographic peri-implant marginal bone level revealed a positive correlation between the two observers (r² = 0.67, p = 0.001). Furthermore, a strong correlation between the first and second evaluation of the radiographic peri-implant marginal bone level was also revealed (r² = 0.76, p < 0.001).