Evaluation of a low-temperature calcium phosphate particulate implant material: Physical-chemical properties and in vivo bone response

A study was conducted to evaluate the osteoconductive ability of a particulate, low-temperature hydroxylapatite (HA^LT) material (OsteoGen; Impladent, Holliswood, NY). An implantable chamber model was used to determine the ability of this material to encourage bone ingrowth into channels lined with either roughsurfaced titanium or rough-surfaced plasma-sprayed hydroxylapatite. The HA^LT material increased bone ingrowth into the titanium-lined channels comparable with that in plasma-sprayed hydroxylapatite-coated channels. It was incorporated into ingrowing bone without intervening soft tissue, with the bone bonding directly to the material surface in much the same fashion as it bonds at the plasma-sprayed hydroxylapatite surface. Mechanical testing of the ingrown bone showed no weakness because particles were incorporated. At 12 weeks, the particles began to show signs of dissolution. It was concluded that the HA^LT material is a biocompatible, osteoconductive material that conducts bone ingrowth in much the same way as high-temperature particulate hydroxylapatite ceramics. This material has the additional desirable property of being slowly resorbable, a beneficial characteristic for many bone-filling applications.