A case-control study was performed was performed following the STROBE statement from 1996 to 2016 including patients who were diagnosed with early apical peri-implantitis. Data were collected at the time of implant placement, and once the patients developed signs and symptoms consistent with early apical peri-implantitis, to determine the frequency and etiology of this pathology.

A case-control study was performed following the STROBE statement (17) at the Oral Surgery Department, Faculty of Medicine and Dentistry (University of Valencia, Spain) from 1996 to 2016, in which patients with early peri-implantitis diagnosed were included (Figure 1). All patients were informed about the study design and procedures. Prior to participating, they were requested to sign an informed consent document. The study design was approved by the Ethical Committee of the University of Valencia (H1478255958653).

Two groups were established: Test group (patients diagnosed with early apical peri-implantitis diagnosed) and Control group (patients whose implants had not developed any inflammatory/infectious process and were osseointegrated).

Inclusion Criteria:

• The following inclusion criteria were applied: patients ≥18 years old and controlled medical conditions who received treatment with implants. Additionally, for the test group, inclusion criteria were: symptoms and signs suggesting early apical peri-implantitis after implant placement; absence of implant mobility; dull percussion of nonsurmerged implants; presence or absence of radiolucency apically.

Exclusion Criteria:

• for the both groups: implants placed with guided bone regeneration or inadequate follow-up for failing to maintenance visits.

patients who received at least one dental implant

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