Effects of Compression During Formation on the Mechanical Strengths and Physical Properties of Composite Hydroxylapatite/Plaster Implants for Bone Reconstruction

Abstract

Composite hydroxylapatite/plaster of Paris implants, preformed or formed during the surgical implantation procedure, are undergoing study for the surgical reconstruction of craniofacial bones. It is frequently necessary to accelerate setting times of the hydroxylapatite/plaster (HA/PP) mixtures by the addition of potassium sulfate; in many of these cases rapid delivery of the moistened implant mixture to the surgical site may be achieved by employing a non-tapered syringe with a plunger. This device can facilitate implantation of quick-setting moistened mixtures through soft tissue tunnels or small incisions, and can result in a less invasive surgical procedure. During experimental surgery it was found beneficial to effect maximum compression of the moistened HA/PP mixture against a sterile glass plate prior to its extrusion from the cylinder. This resulted in elimination of excess water from the mixture. Discs formed from compressed mixtures showed greater mechanical or breaking strengths after setting than discs formed without prior compression when evaluated with a Stokes Hardness-Tester. Examination by light and scanning electron microscopy confirmed the greater compactness of the compressed mixtures.