Implants with peri-implantitis lesions will be surgically exposed, followed by mechanical cleansing using curettes and gauzes and cotton pellets soaked in saline followed by either 1 minute of rinsing with a placebo solution (saline with appearance of chlorhexidine) (control group) or 1 minute of chemical cleansing using 0,12% chlorhexidine + cetylpyridinium chloride (CPC) without alcohol (Perio-aid®) (test group). After 1 minute of saline rinsing the gingival flap will be returned slightly apical (in order to reduce pockets) and will be firmly sutured. For both groups the surgery is followed by 2 weeks of mouthrinses with 0,12% chlorhexidine + Cetylpyridinium Chloride (CPC) without alcohol (Perio-aid®) two times daily during 30 seconds.