Calcium and phosphate release from resin‐based materials containing different calcium orthophosphate nanoparticles

Abstract

The study compared ion release from resin-based materials containing calcium orthophosphates. Amorphous calcium phosphate (ACP), dicalcium phosphate anhydrous (DCPA), dicalcium phosphate dihydrate (DCPD), and tricalcium phosphate (β-TCP) nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and surface area (nitrogen adsorption isotherms, BET method). Nanoparticles were added to a dimethacrylate-based resin and materials were tested for degree of conversion (DC) and calcium/phosphate release up to 28 days under pH 5.5 and 7.0. Data were analyzed by ANOVA/Tukey test (alpha: 0.05).The crystallinity of DCPA, DCPD, and β-TCP were confirmed, as well as the ACP amorphous nature. DCPD and β-TCP presented larger agglomerates than DCPA and ACP. The surface area of ACP was 5-11 times higher than those of the other nanoparticles. Materials showed similar DC. The material containing ACP released significantly more ions than the others, which released similar amounts of calcium and, in most cases, phosphate. Ion release was not affected by pH. Calcium release decreased between 7 and 21 days, while phosphate levels remained constant after 14 days. In conclusion, ACP higher ion release can be ascribed to its high surface area. DCPA, DCPD, and β-TCP had similar performances as ion-releasing fillers.

Poly(ethylene glycol)-alendronate coated nanoparticles for magnetic resonance imaging of lymph nodes

“…Interestingly, TEM micrographs showed that the particles had a spherical morphology and a diameter of about 50-60 nm ( Figure 3(a,b)), and they appeared as interconnected structures of a small number of NPs. The resulting cumulative size of the aggregates correlated with the hydrodynamic diameter measured by DLS (%150 nm), indicating that the particles form small clusters in solution, as previously described for amorphous CaP [23,36]. Empty round spaces were found in the interior of the particles, which is a typical pattern for amorphous CaP (Figure S6a and S6b) [36,37].…”

“…The resulting cumulative size of the aggregates correlated with the hydrodynamic diameter measured by DLS (%150 nm), indicating that the particles form small clusters in solution, as previously described for amorphous CaP [23,36]. Empty round spaces were found in the interior of the particles, which is a typical pattern for amorphous CaP (Figure S6a and S6b) [36,37]. A more defined and uniform spherical structure was observed for the particles that were hydrothermally treated (Figure 3(b)), while not treated particles had an irregular geometrical distribution (Figure 3(a)).…”

“…The physical state of CaP in colloidal delivery systems was shown to have a significant effect on the dissolution rate of the material. A faster leakage of Ca 2þ and PO 4 3À ions was indeed reported for NPs containing amorphous CaP vs. more crystalline structures of equivalent size, as well as in CaP with a higher degree of porosity [36,37,40]. For MRI applications, amorphous Gd-DTPA/CaP NPs could, in theory, represent an advantageous system for short-term imaging after injection as, due to their favourable bioresorbable properties, the particles would not accumulate in the body and the released Gd-DTPA would be quickly excreted via the urinary route.…”

The effect of calcinated hydroxyapatite and magnesium doped hydroxyapatite as fillers on the mechanical properties of a model BisGMA/TEGDMA dental composite initially and after aging

“…One possible approach to reduce the risk of secondary caries development is to add bioactive agents that promote remineralization of tooth structure through calcium and phosphate ion release. In this regard, a wide range of calcium phosphates (CaP) such as hydroxyapatite (HAp), amorphous calcium phosphate (ACP), tetracalcium phosphate (TTCP) and mono-and dicalcium phosphates (MCPM and DCPA) have been studied as fillers in dental composites [7][8][9][10][11][12][13][14][15][16][17][18]. Nanostructured calcium-hydroxyapatite (HAp) presents as a desired component in dental materials due to its biocompatibility, bioactivity and chemical similarity to inorganic component of the teeth [19].…”

Efeito da adição de fosfato dicálcico dihidratado (DCPD) sobre as propriedades mecânicas e liberação de íons após imersão prolongada de compósitos experimentais

“…A liberação de íons apresenta uma relação exponencial com conteúdo de partículas no material[28] e concentrações significativamente maiores de Ca 2+ e PO4 3foram observadas em materiais contendo partir de 37,5% em peso de partículas[12].O tamanho das partículas está inversamente relacionado com a liberação de íons, dado que partículas de menor tamanho possuem uma área de superfície maior e, dessa maneira, uma maior interface com a matriz resinosa. A área superficial da partícula parece ser um fator mais relevante para a liberação de íons do que a fase de ortofosfato de cálcio utilizada no material[7]. Portanto, partículas nanométricas são preferidas em relação às partículas micrométricas, uma vez que liberam altas concentrações de íons mesmo em baixas concentrações[25].…”