FN1 and periodontitis: Although whether these differences originated from the use of periodontal ligament [51] versus gingival tissues (the present study) yet to be cleared, it would be of great interest to fully identify the role of fibronectin isoforms in the pathogenesis of periodontitis considering the suggested role of EDA- and EDB-containing isoforms of fibronectin during embryonic development and tissue repair [23, 51].