POSTN and periodontitis: Periostin is used as biomarker for multiple diseases (Ben et al., 2009; Izuhara et al., 2016; Sung et al., 2017; Azharuddin et al., 2019; Massy et al., 2021), and it is part of the pathogenesis of periodontitis (Yamada et al., 2014) and osteoarthritis (Honsawek et al., 2015; Attur et al., 2021; Duan et al., 2021).