The leading hypothesis behind this study is that a 3-month frequency of supportive peri-implant care (SPIC) recalls after surgical therapy of implants affected by severe peri-implantitis yields better results when compared to a 6-month frequency. Thus, the primary aim of this randomized clinical trial is to compare 2 different frequencies of SPIC recalls (3 and 6 months) after surgical treatment of severe peri-implantitis in terms of treatment success (absence of implant loss, probing pocket depth (PPD) ≤ 5 mm at all aspects, bleeding on deep probing ≤1 site/implant, no suppuration at all aspects, bone loss \<0.5 mm) at early follow-up (1-year) and implant survival at the 5-year examination. Secondarily, this randomized clinical trial aims to assess the effects of the 2 different frequencies over clinical attachment levels around remaining teeth.