Processing of gelatine coated composite scaffolds based on magnesium and strontium doped hydroxyapatite and yttria-stabilized zirconium oxide

This study presents technological process for obtaining strontium enriched calcium silicate based dental ceramics and testing their microstructural and chemical properties. In brief, the influence of different radiopacifiers on microstructural properties of calcium-silicate (CaSi) and calcium-aluminate (CaAl) dental ceramics was evaluated. For synthesis of CaSi-based ceramics, calcium chloride pentahydrate (CaCl2?5H2O) and silica sol obtained by hydrothermal treatment were used. CaSi+barium-sulphate (BaSO4), CaSi+bismuth-oxide (Bi2O3), CaAl+zirconium-dioxide (ZrO2), CaAl+strontium-carbonate (SrCO3), CaAl+strontium-fluoride (SrF2),pure CaSi, pure CaAland mineral trioxide aggregate (MTA) (control material) were used. The wettability, surface free energy (SFE), microporosity, nano-porosity and micro-gap size between the material and tooth root canal were evaluated. There was no difference in total SFE among tested cements (p<0.05), while CaSi+BaSO4, CaAl+SrCO3 and CaAl+SrF2 experienced superior wetting than other cements (p<0.05). The highest microporosity was observed in CaAl, whilst adding radiopacifiers into it decrease cements microporosity (p<0.05). The lowest nanoporosity was found for CaAl+ZrO2. The gap size was not statistically different among tested ceramics (p>0.05). Altogether, strontium containing radiopacyfiers result in improved microstructural characteristics of dental ceramics.

The influence of different radiopacifying agents on hermetical sealing ability of calcium silicate and calcium aluminate dental cements

Cetkovic,

Zhiyu,

Vukovic

et al. 2024

Consolidation and characterization of Cu, Mg substituted hydroxyapatite by cold sintering

Hmood,

Sabri,

Najim

2024

Cold sintering method is an effective route to consolidate powders at temperatures below 300?C. In this study, pure and (Cu, Mg) substituted hydroxyapatite were sintered at 250?C. Ultrapure and substituted hydroxyapatite powders were synthesized by wet precipitation method. Sintering pressure of 250 MPa was used to compact the powders while they were heated simultaneously. 10% (H3PO4) solution was used as a transsolvent for the ionic-substituted hydroxyapatite while distillated water was supplied to the pure one. The yield geometries were characterized for density, thermal stability, microstructure, and the biodegradation in Tris-HCl buffer. The findings indicate that the pure hydroxyapatite compacts has a density of 2.876 g/cm3 (86% TD). Owing to the low sintering temperature the resulting hydroxyapatites have not experienced thermal decomposition, besides no additional phases have appeared. Biologically, the sintered sample (Cu0.25Mg0.75Ca9(PO4)6(OH)2) showed larger degradability (0.0001 g/mm2) than to others after one day of immersion.

Synthesis and mechanical characterization of hydroxyapatite-based biomaterials reinforced with nickel-titanium-magnesium alloys for use in cortical bone implants

Refugio-García,

Miranda-Hernández,

Gallardo-Mendez

et al. 2024

In this work, biomaterials consisting of bioactive hydroxyapatite-based ceramic and nickel-titanium-magnesium alloys were made. The biomaterials were obtained through powder techniques involving mechanical milling, uniaxial pressing and pressureless sintering. The purpose of the study was to evaluate the effect of alloys on the mechanical properties of hydroxyapatite, the alloy additions were 0, 20, 30, 40, 40, 50 and 60 wt.%. The results were compared with cortical bone samples of bovine origin. From the results, it is possible to comment that, with increasing alloy contents in the hydroxyapatite, the mechanical properties increase considerably. The behavior of the composites reinforced with 50 and 60 wt.% NiTiMg alloy is similar to that of bovine cortical bone. The microstructures of the biomaterials are fine, homogeneous, and similar to those of bovine cortical bone. From the study it can be commented that given the mechanical characteristics of the biomaterials obtained, they could be used as possible bone implants.