The aim of this study was to evaluate the effect of using a synthetic bone substitute with or without simvastatin on regenerative surgical treatment of bone defects associated with peri-implantitis in a 6- months randomized controlled clinical trial.

A total of 30 patients diagnosed with peri-implantitis were randomly assigned to one of two surgical treatment groups (group I: synthetic bone substitute (NanoBone), group II: NanoBone with simvastatin). Clinical measurements included probing pocket depth (PPD), clinical attachment level (CAL), plaque index (PI), modified sulcus bleeding index (mSBI) and mucosal recession (MR). Radiographic bone fill was evaluated at baseline and after 6- months.

The study was designed as a prospective single-center, parallel group, 6 month randomized clinical trial evaluating the effect of a bone substitute; NanoBone® (Artoss GmbH, Rostock, Germany) (group 1, control group) compared to the same bone substitute with simvastatin (Corvast 80 mg, Egyphar, Egypt) (group 2, test group) for RST of peri-implantitis. A total of 30 patients suffering from peri-implantitis who needed regenerative treatment of at least one peri-implant bone defect were selected and only one implant per patient (the most severe) was evaluated in the treatment groups. The criteria for diagnosing peri-implantitis is based on the consensus report of the eighth European Workshop on Periodontology [34] ; the presence of a peri-implant marginal bone loss ≥2 mm based on baseline periapical radiographs after delivery of the final restoration and bleeding on probing (BOP) and/or suppuration with or without concomitant deepening of peri-implant pockets.

Clinical and radiographic evaluation were conducted at baseline and 6 months postoperatively. Grouping was done using a random number table generated by a third party. They were numbered according to the order of enrolment and assigned to group I or group II. The grouping results were sealed in an opaque envelope and kept by an independent third party. For each patient, cards opened immediately before the surgical procedures. Treatment assignment in each patient was registered by the clinician who assisted in the operations and kept concealed until the completion of the study.

Inclusion Criteria:

1. age > 18 years,
2. having at least one implant demonstrating bone defect ≥3 mm, which presented a probing depth of ≥5 mm with BOP and/or suppuration, implants had to be in function for >12 months,
3. no implant mobility and no evidence of occlusal overload,
4. no evidence of occlusal overload
5. presence of at least 2 mm of keratinized attached mucosa .

Exclusion Criteria:

1. serious systemic diseases, medications or conditions that would contraindicate periodontal surgery and compromise wound healing,
2. history of taking systemic antibiotic during the past 3 months,
3. smoking,
4. pregnant or lactating females,
5. implants previously augmented with bone substitute or placed in grafted bone,
6. implants previously treated for peri-implantitis,
7. a mobile implant.

A single examiner blinded to the treatment assignment was responsible for evaluating the clinical parameters