Few studies report long-term results after treatment of peri-implantitis. In this context, it is important to remember that the only true end point for such therapies will be the loss of implants, but most studies solely report clinical and subclinical parameters which are only surrogate markers for the disease state and true result of the performed therapy [17].

In a meta-analysis by Khoskham et al., they report a mean radiographic defect fill of 2.41 mm after regenerative treatment of peri-implant osseous defects and a minimum healing time of 36 months [18].

Recently, Schwarz et al. reported on a 7-year follow-up on a peri-implantitis surgical treatment procedure including access flap surgery, granulation tissue removal and implantoplasty combined with two different decontamination protocols and a regenerative procedure including a natural bone mineral and GTR with a collagen membrane. These authors reported clinical attachment level gains between 2.06 and 2.76 mm [19].

Mean PPD values, at the deepest site per implant, were reduced in both groups during the study period. This finding is in agreement with other studies evaluating long-term outcome of surgical peri-implantitis treatment and peri-implant defect reconstruction [20].

One implant in the PTG group, with initial, severe bone loss had a progressive radiographic bone defect after 7 years compared to baseline. The PPD registered at this site did, however, not reflect the radiographic defect depth measured, probably due to heavy calculus deposits on the implant body, which potentially may have hindered a correct probing.

Due to the removal of the prosthetic supraconstruction, access for the clinical examinations was easy at all implants. A pressure sensitive power probe was used. This resulted in minimal traumatizing of the tissue. Half of the treated implants were identified with good plaque control, which is essential for a favourable outcome.

In a study, the prognostic value of BoP [21] was evaluated related to peri-implant mucosal tissue conditions during supportive periodontal therapy. Disease progression was identified when any site bled at more than half of the recall visits over a period of 2 years. The positive predictive value for disease progression was 100% when BoP was recorded at more than 50% of recall visits. BoP was a common finding at the 7-year evaluation, and it may well be that the patients should have been followed even closer after the surgeries, and it is clearly shown that regular maintenance care is a crucial factor for lowering the risk of developing peri-implantitis [22,23,24].