The investigators have hypothesized that control of inflammation and repair of pathologically damaged peri-implant tissues requires a comprehensive mechanical plus chemical surface decontamination therapy. The aims of this study are to 1) determine the most effective surface decontamination protocol that can lead to control of peri-implant inflammation and 2) delineate the microbial and immunological mediators that are associated with the changes in peri-implant inflammation. The investigators propose to compare conventional implant surface contamination techniques to a comprehensive mechanical plus chemical protocol. This randomized controlled clinical trial seeks to enroll 68 participants with at least one implant diagnosed with moderate to severe peri-implantitis. Pre-op parameters to be assessed include: probing pocket depth, bleeding on probing, suppuration, plaque index, marginal inflammation, recession, clinical attachment level, inflammatory biomarkers and microbial sampling, and digital intra-oral peri-apical radiograph. Subjects will be randomly assigned to one of the four surgical debridement intervention groups: (A) gauzes soaked in sterile saline and chlorhexidine; (B) Titanium brush; (C) Air power abrasion; (D) comprehensive surface decontamination, including titanium brush, air powder abrasion and surface etching with 9.6% hydrofluoric acid gel. At 3-months post-operative, the initial clinical assessment will be repeated. The clinical examination will be used to analyze the efficacy of each treatment in controlling peri-implant mucosal inflammation. The ultimate objective of this research is not only to identify an effective method for control of peri-implant inflammation, but also to lay the foundation to detect biomarkers of peri-implantitis that can potentially be helpful in future studies as risk factors of this disease.