Effect of layered double hydroxide intercalated with fluoride ions on the physical, biological and release properties of a dental composite resin.
OBJECTIVE
The aim of this work was the preparation of a new fluoride-releasing dental material characterized by a release of fluoride relatively constant over time without any initial toxic burst effect. This type of delivery is obtained by a matrix controlled elution and elicits the beneficial effect of a low amount of fluoride on human dental pulp stem cells (hDPSCs) towards mature phenotype.


METHODS
The modified hydrotalcite intercalated with fluoride ions (LDH-F), used as filler, was prepared via ion exchange procedure and characterized by X-ray diffraction and FT-IR spectroscopy. The LDH-F inorganic particles (0.7, 5, 10, 20wt.%) were mixed with a photo-activated Bis-GMA/TEGDMA (45/55wt/wt) matrix and novel visible-light cured composites were prepared. The dynamic thermo-mechanical properties were determined by dynamic mechanical analyzer. The release of fluoride ions in physiological solution was determined using a ionometer. Total DNA content was measured by a PicoGreen dsDNA quantification kit to assess the proliferation rate of hDPSCs. Alkaline phosphatase activity (ALP) was measured in presence of fluoride resins.


RESULTS
Incorporation of even small mass fractions (e.g. 0.7 and 5wt.%) of the fluoride LDH in Bis-GMA/TEGDMA dental resin significantly improved the mechanical properties of the pristine resin, in particular at 37°C. The observed reinforcement increases on increasing the filler concentration. The release of fluoride ions resulted very slow, lasting months. ALP activity gradually increased for 28 days in hDPSCs cell grown, demonstrating that low concentrations of fluoride contributed to the cell differentiation.


CONCLUSIONS
The prepared composites containing different amount of hydrotalcite filler showed improved mechanical properties, slow fluoride release and promoted hDPSCs cell proliferation and cell differentiation.
Department of Industrial Engineering, University of Salerno, Fisciano, SA, Italy. Electronic address: ltammaro@unisa.it.
Loredana
L
Tammaro
Department of Industrial Engineering, University of Salerno, Fisciano, SA, Italy.
Vittoria
V
Vittoria
Institute of Protein Biochemistry, CNR, Naples, Italy; Institute of Biosciences and BioResources, CNR, Naples, Italy.
Anna
A
Calarco
Institute of Protein Biochemistry, CNR, Naples, Italy; Institute of Biosciences and BioResources, CNR, Naples, Italy.
Orsolina
O
Petillo
Conservative Odontostomatology and Maxillofacial Surgery, University of Naples, Naples, Italy.
Francesco
F
Riccitiello
Institute of Protein Biochemistry, CNR, Naples, Italy; Institute of Biosciences and BioResources, CNR, Naples, Italy.
Gianfranco
G
Peluso
D000293:Adolescent; D000469:Alkaline Phosphatase / Q000032:analysis; D000536:Aluminum Hydroxide / Q000737:chemistry*; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002327:Cariostatic Agents / Q000737:chemistry*; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003188:Composite Resins / Q000737:chemistry*; D003692:Delayed-Action Preparations; D003764:Dental Materials / Q000737:chemistry*; D003782:Dental Pulp / Q000166:cytology / Q000187:drug effects; D004058:Diffusion; D005459:Fluorides / Q000737:chemistry*; D006801:Humans; D006878:Hydroxides / Q000737:chemistry*; D007474:Ion Exchange; D008276:Magnesium Hydroxide / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013234:Stem Cells / Q000187:drug effects; D013314:Stress, Mechanical; D013696:Temperature; D014961:X-Ray Diffraction; D055815:Young Adult
D002327:Cariostatic Agents; D003188:Composite Resins; D003692:Delayed-Action Preparations; D003764:Dental Materials; D006878:Hydroxides; D008689:Methacrylates; D011109:Polymethacrylic Acids; C020946:triethylene glycol dimethacrylate; C010467:hydrotalcite; D011092:Polyethylene Glycols; C074277:ethoxylated bis-phenol A dimethacrylate; D017438:Bisphenol A-Glycidyl Methacrylate; D000536:Aluminum Hydroxide; C031356:hydroxide ion; D000469:Alkaline Phosphatase; D008276:Magnesium Hydroxide; D005459:Fluorides
Cell proliferation; Composite resin; Dental materials; Fluoride release; Layered double hydroxide