Surgical regenerative treatment of peri-implantitis lesions using a nanocrystalline hydroxyapatite or a natural bone mineral in combination with a collagen membrane: a four-year clinical follow-up report

Objectives: The present case series aimed at investigating the 4‐year clinical outcomes following surgical regenerative therapy of peri‐implantitis lesions using either a nanocrystalline hydroxyapatite (NHA) or a natural bone mineral in combination with a collagen membrane (NBM+CM). Materials and Methods: Twenty patients suffering from moderate peri‐implantitis (n=20 intrabony defects) were randomly treated with (1) access flap surgery (AFS) and the application of NHA (n=9), or with AFS and the application of NBM+CM (n=11). Clinical and radiographic (R) parameters were recorded at baseline (R) and after 36 and 48 (R) months of non‐submerged healing. Results: One patient from the NBM+CM group was discontinued from the study due to severe pus formation at 36 months. Compared with NHA, the application of NBM+CM resulted in higher mean PD reductions (NBM+CM: 2.5 ± 0.9 mm versus NHA: 1.1 ± 0.3 mm) and clinical attachment‐level gains (NBM+CM: 2.0 ± 1.0 mm versus NHA: 0.6 ± 0.5 mm) at 48 months. A radiographic bone fill was observed for five sites in the NHA group, and eight sites in the NBM+CM group. Conclusion: While the application of NBM+CM resulted in clinical improvements over a period of 4 years, the long‐term outcome obtained with NHA without barrier membrane must be considered as poor.