The purpose of this study is to evaluate the clinical efficacy of ultrasonic instrumentation versus the use of an erythritol jet in the treatment of peri-implantitis.

To carry out this study, the investigators considered a treatment protocol for periimplantitis consisting of 2 phases. The first phase corresponds to the non-surgical treatment of periimplantitis, which can be performed using various techniques. In the present study, it will be carried out using manual instrumentation (with ultrasound and curettes) or with an erythritol jet. In both cases, systemic antibiotic therapy with metronidazole will be performed. The results obtained during the follow-ups will allow the evaluation of the effectiveness of the treatment carried out. If this does not prove to be successful, through an evaluation of clinical and radiographic criteria, patients will be advised to undergo a second phase of treatment, in this case a surgical treatment of peri-implantitis, but which will no longer be part of the interventions carried out and documented in this study. Patients for whom the unsatisfactory treatment was considered effective will be allocated to a periimplant support treatment program, which means that they will be advised to carry out maintenance consultations at the FMDUP clinic with a specific and individualized periodicity in order to maintain the health of the periimplant tissues and the remaining oral cavity. The study will be carried out by the students of the Specialization in Periodontology and Oral Implantology 2021-2024 of the Faculty of Dental Medicine of the University of Porto (FMDUP).

Inclusion Criteria:

• At least 1 osseointegrated implant diagnosed with peri-implantitis (according to the new Classification of Periodontal and Peri-implant Diseases and Conditions) and rehabilitated with screw-retained crown
• Patients of legal age (≥18 years old)

Exclusion Criteria:

• Uncontrolled systemic pathologies, namely diabetes mellitus (HbA1c > 7% or >53 mmol/mol)
• Pregnant or lactating patients
• Severe smoking (>20 cigarettes/day)
• Systemic pathologies, medication or treatments that cause alterations in bone metabolism (for example: osteoporosis, bisphosphonates, radiotherapy of the head and neck)
• Patients who missed study control visits
• Patients who have received systemic antibiotic therapy in the last 2 months
• Patients with allergies to any of the components used in the study, namely to erythritol
• Implants that have previously undergone surgical treatment for peri-implantitis
• Implants with bone loss greater than 2/3 of their length and/or mobility