Histopathological and microbiological findings associated with retrograde peri-implantitis of extra-radicular endodontic origin: a systematic and critical review.

The aim of this study was to systematically review the aetiology, in particular histopathological and microbiological factors, of retrograde peri-implantitis of endodontic origin. The review is registered in the PROSPERO database (CRD42017063898). An electronic search for publications was performed in two databases, from their inception up to October 2018. Subsequently a hand search of the reference lists was conducted. Articles in English and other languages using Latin characters were included. Two independent reviewers selected the studies, extracted and synthesized the data, and assessed the quality. The methodology of the included articles was evaluated using the relevant Joanna Briggs Institute tools. Six studies fulfilled the eligibility criteria and were included in the systematic review. Histopathological examination in the component studies reflected that the presentation of retrograde peri-implantitis involves cyst formation or chronic inflammation. Bacteria found in these lesions included Porphyromonas gingivalis, Corynebacterium, Streptococcus, and Klebsiella pneumoniae. Two studies were judged as having a low possibility of bias and four were judged as having a moderate possibility of bias. This review determined that endodontic complications associated with adjacent teeth, residual infection at the extraction site due to previous apical periodontitis, or refractory apical periodontitis might be considered likely aetiological factors, although the evidence is limited.