A Preliminary Study of Osseointegration in the Dental Implant Therapy in vitro-culture of-Culture of Mouse KUSA/A1 Cells on Titanium Plates with Different Surface Modifications

To sustain an extensive osseointegration with optimal bone-to-implant contact (BIC) is one of the essentials for a successful oral implant therapy. In the present in vitro study, we have preliminarily elucidated that KUSA/A1 cells actively proliferated and have differentiated into osteocalcin-producing osteoblast-like cells (Obs) since day 3 of culture. We then cultured the Obs on titanium (Ti) and Ti alloy plates (discs), which have commercially available surface texture and modifications (i.e., anodic oxidization: AO, hydroxyapatite coating: HA, precision blasting: SPI) as same as the current dental implants. The histology of proliferating Obs cultured on discs (Disc-AO, Disc-HA and Disc-SPI; for 180 minutes) was investigated to study the microenvironment mimic initial osseointegration of the dental implant therapy. The present SEM of 60-min Disc-AO, Disc-HA and Disc-SPI specimens demonstrated a loose distribution of spherical-to-ovoid (10 μm in diameter, avg.) Obs migrating towards concavities of the substrate. The proliferating Obs had the bulging cell body sending out many minute filopodia and some lamellipodia to attach with the substrate; few Obs with intercellular junctions were dispersedly found. In contrast, in the 180-min Disc-AO, Disc-HA and Disc-SPI specimens, we observed the cultured KUSA/AI cells actively proliferated and spread into flat, large polygonal (20 μm × 30 μm, approx.) Obs with several prominent lamellipodia and many dendritic filopodia to employ cell-to-disc and intercellular attachments; a few scattered small spherical-to-spindle shaped Obs were also observed interposing the large polymorphic Obs. On the other hand, the present immunohistochemistry of the attached Obs demonstrated the expression of F-actin (actin filaments of the cytoskeleton) in both 60-min and 180-min specimens, and CD51 ( α V integrin) only in 180-min. specimens. Hence, the present study revealed that the condition-induced KUSA/A1 cells actively proliferated and extensively adhered on different substrates yet showed similar histology. We confirmed that the present GBR engineered KUSA/AI cells to obtain extensive cell attachment on different microtextured Ti discs within 180 min, thereby we surmised that the Obs might be further regulated to precipitate mineralization matrix for contact and distant osseointegration.