Ultrastructural and immunoelectron microscopic studies of the peri-implantepithelium-implant (Ti-6Al-4V) interface of rat maxilla

Background: The role played by the internal basal lamina (IBL) and hemidesm osomes between an implant and the periimplant epithelium (PIE) in the adher ence of the epithelium to the implant is controversial. This study used rat maxilla implantation models to clarify the ultrastructure of the PIE-impla nt interface. Methods: Ti-6Al-4V implants were inserted either immediately or 2 weeks aft er the extraction of the upper left first molar of 6- or 4-week-old rats, r espectively. The junctional epithelium (JE) of the upper right molars in th e same animals was used as a control. Four weeks after implantation, the an imals were sacrificed to prepare specimens for light and immunoelectron mic roscopy. Results: Under light microscopy, the PIE appeared to attach to the implant surface. Ultrastructurally, IBL, consisting of the lamina densa and lamina lucida, and hemidesmosomes were formed only in the lower region, and rarely in the middle region, of the PIE-implant interface. In control teeth, the IBL and hemidesmosomes formed throughout the dento-JE interface. Laminin-1 was found in the IBL and also in the vesicles and vacuoles of the PIE and J E cells. Statistical analysis showed that there was also a significant diff erence in the amount of IBL between the PIE-implant and dento-JE interfaces . Conclusions: PIE attached to the implant via hemidesmosomes and IBL in the lower region of the PIE-implant interface. Although PIE cells may secrete l aminin-1, which contributes to epidermal cell adhesion, the PIE which attac hes to implants only in the lower region of the interface is considered to be the poorly adhered epithelium.