One of the mechanisms underlying the inhibitory effect of PDGF-BB on ankylosis could be the suppression of osteoblastic differentiation from PDL cells; PDGF-BB suppressed osteocalcin-positive cells in vivo (Fig. 5A), and Wnt3a induced bone marker expressions in PDL cells in vitro (Fig. 8A). Here, WNT3A is linked to ankylosis.