Papers by Keyword: Calcium Alkali Orthophosphates

Abstract: The setting behaviour, the compressive strength and the porosity of four calcium alkali orthophosphate cements were examined under laboratory conditions (dry) and under conditions similar to those during clinical application (37°C, contact with body fluid). The results showed an increase of the setting times when specimens were covered with simulated body fluid. Especially, the final setting time (FHZ) was significantly higher for three of the four cements. Furthermore, when specimens were stored in SBF for 16h, an extensive decrease of the compressive strength was noted. The porosity was more than twice as high after 16h in SBF and this may be the cause for the great decrease of the compressive strength.

Abstract: This paper deals with calcium phosphate cements containing alkali to achieve higher solubility. Until now normally for all cements also if alkali was integrated the self-setting process leads to hydroxyapatite (HA) or calcium deficient HA (CDHA). In cases where fluid dispersions of HA were used for bone defect treatment the HA remains and do not acts self-hardening. The selfsetting cements show high compressive strength in comparison to the HA supplied as a paste. They show latent hydraulic behavior during the self-hardening process. The following storage in SBF for four weeks also did not lead to a strong change of the starting materials that were Ca2KNa(PO4)2 or Ca10[K/Na](PO4)7.