Setting Reactions and Compressive Strengths of Calcium Phosphate Cements

Abstract

Setting reactions and compressive strengths of a self-hardening calcium phosphate cement (CPC) were investigated. The CPC consists of tetracalcium phosphate (TTCP) and anhydrous dicalcium phosphate (DCPA). The cement specimens were prepared by mixing 0.7 g of the powder (TTCP 72.9 wt% + DCPA 27.1 wt%) with 0.175 mL of the liquid (25 mmol/L H3PO4 and 1.32 mmol/L sodium fluoride). The specimens were removed from the molds at pre-determined time intervals after being mixed, and their compressive strengths were measured. Immediately afterward, the fractured specimens were rapidly frozen in ethanol (-80 degrees C), lyophilized, and examined by powder x-ray diffraction and scanning electron microscopy (SEM). The results showed that (1) hydroxyapatite was the only reaction product; (2) the reaction was nearly completed within four h, during which both the reaction product and compressive strength increased linearly with time, resulting in a strong correlation between the two; and (3) fully set CPC consisted primarily of small rod-like crystals and some platy crystals.

Dental Cements

“…[1] Hydrolysis reactions of these materials result in H 3 Since, after a long time since the reactions described above, the phosphocalcic compounds used as reactants (e.g., calcium phosphate) are found to be excess in solution, the composition of the solution remains on the isothermal solubility of these reactants. [1] However, the accumulation of H 3 PO 4 in time, in reaction solution, will decrease the pH value and also to reduce the degree of supersaturation with hydroxyapatite.…”

“…[3] In fact the crystalline phase consists of small flat formations consisting of hydroxyapatite, which is formed during the setting reaction of the cement and, at the same time, the property to adhere to one another during the setting process.…”

Effects of added mannitol on the setting reaction and mechanical strength of apatite cement

“…Then, the specimen was placed between steel platens that were covered with one thickness of wet filter paper and crushed at a loading rate of 1 mm/min. Each mean DTS value was obtained from at least six specimens [18][19][20][21] .…”

Bone formation ability of carbonate apatite-collagen scaffolds with different carbonate contents

“…Last century, sintered ceramics such as calcium phosphates were the most commonly used hard tissue biomaterials from the viewpoint of mechanical strength; however, they are fundamentally less biodegradable and not easy to process. To obtain better handling properties, apatite-collagen/ gelatin composites [7][8][9] in addition to various kinds of calcium phosphate cements [10][11][12] have been developed. Recently, tissue engineering has been developed.…”