Changes in the distribution of laminin-5 during peri-implant epithelium formation after immediate titanium implantation in rats.

Laminin-5 (Ln-5), a component of the basement membrane (BM), regulates epithelial cell migration and adhesion. This study used anti-Ln-5 (gamma2chain) antibody to investigate the distribution of Ln-5 during the formation of peri-implant epithelium (PIE) in rats, and compared it to the distribution of Ln-5 during oral mucosa formation after tooth extraction. One day after extraction, the junctional epithelium (JE) had disappeared. After 3 days, new epithelium formed from the oral sulcular epithelium (OSE) and extended horizontally over the wound with Ln-5-positive cells at the leading edge. After 5 days, the epithelium extending from the OSE on each side of the wound joined and formed additional new epithelium. The new epithelium expressed Ln-5 in the BM. After 1-2 weeks, the oral epithelium (OE) extending from the sides of the wound joined in the center. Thereafter, OSE and new epithelium disappeared, and only OE remained covering the wound. Three days after implantation (titanium), no JE remained. New epithelium formed from the keratinized OSE extending apically with Ln-5-positive cells. After 1-2 weeks, the new epithelium became the PIE and spread further apically facing the implant surface. Ln-5 was expressed at the PIE-connective tissue interface, but not at the implant-PIE interface. Finally, after 4 weeks, Ln-5 was expressed at the implant-PIE interface, and the PIE was non-keratinized epithelium. These findings suggest that Ln-5 induces cell migration during PIE formation, and that PIE originates from OSE. Furthermore, they support the hypothesis that Ln-5 contributes to the attachment of PIE to titanium, regardless of the delay in the synthesis and deposition of Ln-5 at the titanium-PIE interface.