Mica-apatite glass-ceramics

Figure 2-30 Three glassy phases in the base glass for mica-apatite glass-ceramic. SEM. TEM/replica. Fractured surface etched (HCI, 5 sec).

The reactive behavior of the mica-apatite glass-ceramic was thoroughly examined in in vitro and in vivo studies to establish its biocompatibility. Also, bone implants were studied to establish the bioactivity of BIOVERIT I glass-ceramics (Section 4.4.1). The two examples of... 

Figure 2-32 Mica-apatite glass-ceramic after one week in Ringer s solution. TEM/replica.

The following bioactive glass-ceramics are used for implants in human medicine CERABONE (apatite-wollastonite glass-ceramic), CERAVITAL (apatites devitrite glass-ceramic), and BIOVERJT I (mica-apatite glass-ceramic). 

Phospha.tes. Many phosphates cl aim unique material advantages over siUcates that make them worth the higher material costs for certain apphcations. Glass-ceramics containing the calcium orthophosphate apatite, for example, have demonstrated good biocompatibiUty and, in some cases even bioactivity (the abiUty to bond with bone) (25). Recent combinations of fluorapatite with phlogopite mica provide bioactivity as well as machinability and show promise as surgical implants (26). 

Fluorapatite and mica crystallization are examples of a twofold controlled mechanism to develop a glass-ceramic having a combination of diflFerent properties, such as machinability and bioactivity. The microstructure of the final glass-ceramic comprising mica and apatite crystals embedded in a glass matrix is shown in Fig. 2-32. 

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