Setting reactions and compressive strengths of calcium phosphate cements.
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.
Fukase
Y
Y
American Dental Association Health Foundation, Paffenbarger Research Center, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
Eanes
E D
ED
Takagi
S
S
Chow
L C
LC
Brown
W E
WE
D002130:Calcium Phosphates / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003738:Dental Cements / Q000737:chemistry*; D005069:Evaluation Studies as Topic; D016018:Least-Squares Analysis; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011312:Pressure; D013718:Tensile Strength; D013997:Time Factors; D014961:X-Ray Diffraction
D002130:Calcium Phosphates; D003738:Dental Cements