Phase II Periodontal Therapy 4 weeks after the initial periodontal treatments, for the treatment of the sites with pocket depth deeper than 5mm, flap operation was performed to achieve a direct reach to implant surfaces. Around affected implants, intrasulcular incisions were performed and mucoperiostal flaps with full thickness were raised both buccally and palatally. Implant surface decontamination is performed using with either plastic curettes or ultrasonic scaler (Figure 3); In control group, plastic curettes (Hue-Friedy Co., Chicago, IL, USA) were used for debridement and implant surfaces were decontaminated by klorhegsidin solution. In test group, sub-gingival operations with ultrasonic scaler was for nearly 20s per site (EMS Master Piezon LED, implant care system, Nyon, Switzerland). A special design disposable thermoplastic elastomer nozzle (Perio-flow Nozzle EMS Electro Medical Systems, Nyon, Sweden.), which horizontally gives out the glycine powder, was utilized.