Biocompatible Nanocomposite Enhanced Osteogenic and Cementogenic Differentiation of Periodontal Ligament Stem Cells In Vitro for Periodontal Regeneration

Abstract

Decays in the roots of teeth is prevalent in seniors as people live longer and retain more of their teeth to an old age, especially in patients with periodontal disease and gingival recession. The objectives of this study were to develop a biocompatible nanocomposite with nano-sized calcium fluoride particles (Nano-CaF2), and to investigate for the first time the effects on osteogenic and cementogenic induction of periodontal ligament stem cells (hPDLSCs) from human donors.Nano-CaF2 particles with a mean particle size of 53 nm were produced via a spray-drying machine.Nano-CaF2 was mingled into the composite at 0%, 10%, 15% and 20% by mass. Flexural strength (160 ± 10) MPa, elastic modulus (11.0 ± 0.5) GPa, and hardness (0.58 ± 0.03) GPa for Nano-CaF2 composite exceeded those of a commercial dental composite (p < 0.05). Calcium (Ca) and fluoride (F) ions were released steadily from the composite. Osteogenic genes were elevated for hPDLSCs growing on 20% Nano-CaF2. Alkaline phosphatase (ALP) peaked at 14 days. Collagen type 1 (COL1), runt-related transcription factor 2 (RUNX2) and osteopontin (OPN) peaked at 21 days. Cementogenic genes were also enhanced on 20% Nano-CaF2 composite, promoting cementum adherence protein (CAP), cementum protein 1 (CEMP1) and bone sialoprotein (BSP) expressions (p < 0.05). At 7, 14 and 21 days, the ALP activity of hPDLSCs on 20% Nano-CaF2 composite was 57-fold, 78-fold, and 55-fold greater than those of control, respectively (p < 0.05). Bone mineral secretion by hPDLSCs on 20% Nano-CaF2 composite was 2-fold that of control (p < 0.05). In conclusion, the novel Nano-CaF2 composite was biocompatible and supported hPDLSCs. Nano-CaF2 composite is promising to fill tooth root cavities and release Ca and F ions to enhance osteogenic and cementogenic induction of hPDLSCs and promote periodontium regeneration.