Nanocrystalline calcium sulfate/hydroxyapatite biphasic compound as a TGF-ß1/VEGF reservoir for vital pulp therapy.

OBJECTIVES: Vital pulp therapy aims to treat reversible pulpal injuries via protective dentinogenesis and to preserve more tooth structure. Mineral trioxide aggregate (MTA)-based capping materials demonstrate prolonged setting time increases the risk of pulpal infection during multi-visit treatment. Their non-degradable property occupies pulp space and limits dentin-pulp regeneration. This study reports an inorganic degradable biomaterial that presents a short initial setting time and acts as a growth factor reservoir to promote reparative dentinogenesis. METHODS: We synthesize nanocrystalline calcium sulfate hemihydrate (nCS), hydroxyapatite (HAp) and calcium sulfate hemihydrate (CS) as a reservoir to which transforming growth factor-beta 1 (TGF-ß1) and vascular endothelial growth factor (VEGF) are added (denoted as nCS/HAp/CS/TGF-ß1/VEGF). In vitro biocompatibility and mineralization (the activity and expression of alkaline phosphatase, ALP) were evaluated. Rat animal model was created to test in vivo efficacy. RESULTS: Cultured human dental pulp cells (HDPCs) showed that nCS/HAp/CS/TGF-ß1/VEGF cement has excellent biocompatibility and the potential to elevate the activity and expression of ALP. The in vivo efficacy (rat animal model) indicates protective dentin by micro-computed tomography (µ-CT) measurements and histological analyses. The 3D µ-CT non-destructive analysis also determines volume changes during pulpotomy, suggesting that the degraded space of the nCS/HAp/CS/TGF-ß1/VEGF cement is repaired by the formation of dentin-pulp tissue. SIGNIFICANCE: These findings demonstrate that nCS/HAp/CS cement acts as a potent reservoir for the sustained release of growth factors, and that nCS/HAp/CS/TGF-ß1/VEGF cement has a high potential to form the reparative dentinogenesis in vivo.

Development of in vitro tooth staining model and usage of catalysts to elevate the effectiveness of tooth bleaching.

OBJECTIVES: Whole blood or tea was frequently used to stain the teeth for measuring the effectiveness of different bleaching materials. However, the components of blood or tea cannot be quantitatively determined and variability might exist among different brands of tea. The purpose of this study was to develop a reproducible in vitro tooth-staining model to simulate the intrinsic discoloration of teeth and evaluate the ability of two catalysts to enhance the bleaching activity of H(2)O(2). METHODS: Rhodamine B, Orange II, Fe(III) phthalocyanine, and tea were used to stain the tooth specimens for 4-72 h and subsequently bleached by H(2)O(2) for 4-72 h. The process was photographed using a digital stereoscopic microscope and a digital camera. The image was transformed to get L*, a*, b* values of CIE Lab system with image processing software. The catalytic ability of light irradiation plus addition of Fe/Sodium-Y or Mn/Sodium-Y for specimens stained by Orange II was evaluated in test tubes and in extracted tooth model. RESULTS: The color of specimens stained by Rhodamine B could not be sufficiently recovered after bleaching by H(2)O(2). In addition, the reaction of Fe(III) phthalocyanine with H(2)O(2) in test tubes was too fast to be monitored. Light activation plus use of Fe/Sodium-Y or Mn/Sodium-Y could significantly accelerate the bleaching efficiency of H(2)O(2). SIGNIFICANCE: Orange II was the most appropriate dye for tooth staining among the dyes used in this study. Addition of Fe/Sodium-Y or Mn/Sodium-Y plus light irradiation could elevate the bleaching efficacy of H(2)O(2) for those specimens stained by Orange II.