ABSTRACT
AIM: To evaluate mineral trioxide aggregate (MTA), Biodentine and several formulations of calcium aluminate cements (CACb) in terms of their ability to release calcium ions (Ca2+ ) and form apatite-like precipitates after short-term immersion in phosphate-buffered saline (PBS) and its influence on the bond strength to the root-end cavity. METHODOLOGY: Ten samples of MTA, Biodentine, CACb and calcium-enriched aluminate cement (CACb+) were placed in contact with PBS or deionized water for 14 days. The cement surfaces were analysed using SEM, EDS-X and FTIR. Eighty standardized root-end cavities filled with the cements (ten samples of each cement) were immersed in PBS or deionized water for 14 days, and the bond strengths were measured. Data from the push-out test were analysed using two-way ANOVA and Tukey's tests (α = 0.05). RESULTS: A gradual decrease was observed in Ca2+ concentrations and pH of all solutions. FTIR bands of different phases of hydroxyapatite were identified. Crystalline formation was observed on the surface of all cements after immersion in PBS. No significant difference was observed in the bond strength of the test materials (P > 0.05); however, all cements without contact with the solution revealed significantly lower bond strength values than those in contact with the solution (P < 0.05). CONCLUSION: MTA, Biodentine, CACb e CACb+ were associated with precipitation of crystals after being in contact with PBS for 14 days, indicated by different phases of hydroxyapatite crystalline formation, which also increased dislodgment resistance of the material from root-end cavities. The CACb+ had similar bond strengths and precipitation of crystals to existing materials.
Subject(s)
Aluminum Compounds/chemistry , Calcium Compounds/chemistry , Dental Bonding , Dental Cements/chemistry , Oxides/chemistry , Silicates/chemistry , Dental Stress Analysis , Dentin , Drug Combinations , Humans , Materials Testing , Tooth RootABSTRACT
Naked foil bolometers can reflect a significant fraction of incident energy and therefore cannot be used for absolute measurements. This paper outlines a novel coating approach to address this problem by blackening the surface of gold foil bolometers using physical vapour deposition. An experimental bolometer was built containing four standard gold foil bolometers, of which two were coated with 100+ nm of carbon. All bolometers were collimated and observed the same relatively high temperature, ohmically heated plasma. Preliminary results showed 13%-15% more incident power was measured by the coated bolometers and this is expected to be much higher in future TCV detached divertor experiments.
