In 2012, the same group of researchers presented results from a randomized parallel arm case-control clinical study, using porous titanium granules as a bone substitute in the corrective surgical treatment of peri-implant osseous defects. Grafting of the defects with PTG was compared with open flap debridement alone. No clinical differences between groups were found after 12 months, but a better defect fill was seen on radiographs in the PTG group [12]. A multicentre study [15] reported similar results.

The aim of the present study was to evaluate the long-term clinical and radiographic results from a study on peri-implant osseous defect reconstruction.

Data from patients having participated in a randomized case-control clinical trial was screened with the aim to re-examine all treated implants. The present study was approved by the Regional Committee for Medical and Health Research Ethics, South East Norway (REK 2015/90).

Wohlfahrt and co-workers [12] described the study population and the 12-month results. In brief, 32 subjects diagnosed with peri-implantitis, fulfilling the inclusion criteria of having an implant demonstrating an intrabony component ≥ 4 mm, probing pocket depth (PPD) of at least 5 mm at one site with bleeding on probing (BoP) and/or suppuration were included, randomized to either the case or control group, treated accordingly and followed for 12 months. The prosthetic supraconstruction was removed and evaluated with respect to occlusal adjustments; in some cases, renewal was performed. Access for oral hygiene was evaluated and corrected if necessary. After the oral hygiene phase and any necessary active periodontal treatment, the study participants received surgical therapy. Sixteen individuals were randomly assigned to the case group and received reconstructive treatment of one implant each with PTG additional to surgical open flap mechanical and chemical debridement with titanium curettes and EDTA gel (PrefGel, Straumann Inc., Basel, Switzerland). The other 16 individuals were treated with open flap debridement alone. Implants were submerged for 6 months; thereafter, the prosthetic supraconstructions were repositioned. Results from the evaluation at 12 months were presented in a publication by Wohlfahrt et al. in 2012. Thereafter, the patients were discharged from the university clinic and maintenance, and follow-ups were handled by the referring dentists.