Fibrillin protein, a candidate for creating a suitable scaffold in PDL regeneration while avoiding ankylosis.

The tooth is stabilized by fiber-rich tissue called the periodontal ligament (PDL). The narrow space of the PDL does not calcify in the physiological state even thought it exists between two calcified tissues, namely, the cementum of the root and alveolar bone. Two situations that require PDL regeneration are periodontitis and dental trauma. Periodontitis induces the loss of PDL and alveolar bone due to inflammation related to infection. Conversely, in PDLs damaged by dental trauma, accelerating bone formation as an overreaction of the healing process is induced, thereby inducing dentoalveolar ankylosis at the tooth root surface. PDL regeneration following dental trauma must therefore be considered separately from periodontitis. Therefore, PDL regeneration in dental trauma must be considered separately from periodontitis. This review focuses on the components involved in avoiding dentoalveolar ankylosis, including oxytalan fibers, aggregated microfibrils, epithelial cell rests of Malassez (ERM), and TGF-β signaling. During root development, oxytalan fibers produced by PDL cells work in collaboration with the epithelial components in the PDL (e.g., Hertwig's root sheath [HERS] and ERM). We herein describe the functions of oxytalan fibers, ERM, and TGF-β signals which are involved in the avoidance of bone formation.