Abstract
Periodontal ligament cells (PDLCs) remaining in the tooth-extraction socket are involved in osseointegration after immediate implantation; however, their interaction with different implant surfaces has not been investigated. The aim of this study was to compare PDLC growth on substrates composed of differently sized titanium dioxide (TiO2) nanotubes with that on flat Ti. PDLC growth on Ti nanotubes was evaluated in terms of cell adhesion, proliferation, and osteogenic differentiation based on the expression of alkaline phosphatase (ALP), type 1 collage (COL-1), osteopontin (OPN), and Runt-related transcription factor 2 (RUNX2). We found that TiO2 nanotubes of different diameters (30, 70, and 120 nm) manufactured on Ti surface by anodisation had a well-defined structure. PDLCs grown on nanotube layers demonstrated polygonal morphology with more filopodia than those on flat Ti, which was especially evident on the nanotubes of larger diameters. However, cell adhesion and proliferation was the highest on the smallest 30 nm nanotubes. Similarly, mRNA levels of the ALP, COL-1, OPN, and RUNX2 genes increased in PDLCs cultured on 30 nm TiO2 nanotube layers compared to those in the cells grown on 70 nm and 120 nm nanotubes. In conclusion, small diameter (30 nm) nanotube layers can support PDLC adhesion, proliferation, and differentiation better than larger sized nanotubes, and consequently, have higher potential to promote bone formation and integration of an immediate implant.
Highlights
Dental implants, which represent artificial tooth roots to support a dental prosthesis have been successfully used as a popular approach to dental restoration [1]
The cells cultured on flat Ti exhibited elongated shape (Figure 2a), whereas those grown on 30 nm nanotube surface were spread freely and developed extensive filipodia (Figure 2b), which facilitated cell anchorage to the nanotubular structures potentially stimulating periodontal ligament cells (PDLCs) differentiation
The cells cultured on 70 nm (Figure 2c) and 120 nm (Figure 2d) nanotube layers displayed polygonal shape with minimal spreading and increased number of filopodia compared to PDLCs grown on flat Ti or 30 nm nanotube layers
Summary
Dental implants, which represent artificial tooth roots to support a dental prosthesis have been successfully used as a popular approach to dental restoration [1]. Immediate implantation, which is the placement of the implant in the periodontium before the healing of the tooth extraction site, is followed by the formation of connective tissue by residual periodontal ligament cells (PDLCs) in the fresh extraction socket. It is known that PDLCs have the ability for multipotent differentiation and could form collagen fibers, cementum, and bone [8,9]. These cells are involved in the complex process of osseointegration, i.e., establishment of a direct bone-to-implant anchorage without intervening connective tissue, which is essential for the success of immediate implantation [10]
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