The kinetics of the thermal decomposition of stoichiometric hydroxylapatite (HA) has been studied up to 1500°C for the purpose of determining the maximum admissible combinations of temperature and time for sintering HA. The influence of the sintering temperature on shrinkage, density and grain growth is then investigated in the temperature range from 1000 to 1450 °C. Nearly theoretical density was achieved above 1300 °C. A maximum fracture toughness is obtained for the samples sintered at 1300°C whereas hardness increases up to a sintering temperature of 1400 °C. These results are discussed in terms of the roles of porosity and grain size.

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