[A new hydroxyapatite cement for craniofacial surgery].

Current surgical practices require reliable bone substitutes for craniofacial reconstruction. While existing materials offer some benefits, they often come with limitations like unpredictable setting behavior or insufficient mechanical stability. Prior research has shown that calcium phosphate cements can be useful in bone repair, but their clinical application remains limited by factors like pH fluctuations or structural instability. No prior work had resolved the need for a cement that sets predictably and remains stable post-setting. This gap motivated the development of a new hydroxyapatite cement. The need for a material that avoids excessive heat generation or dimensional changes is clear. Existing options may not fully meet the requirements for craniofacial applications. The challenge is to create a cement that is both biocompatible and structurally stable. This paper addresses these limitations through a novel formulation.

The aim of this study is to introduce a new hydroxyapatite cement suitable for craniofacial surgery. The specific problem addressed is the lack of a bone substitute that sets predictably and maintains structural integrity. The motivation stems from the clinical need for a material that avoids excessive heat and dimensional changes during setting. The study focuses on a cement composed of dicalcium phosphate and tetra-calcium phosphate. This formulation is intended to provide a stable implant post-setting. The goal is to achieve a material that is chemically stable and suitable for non-load-bearing applications. The proposed solution involves a precise stoechiometric mixture of two phosphate compounds. The study evaluates the cement's performance in a clinical setting.

The study describes the preparation of a cement by mixing dicalcium phosphate and tetra-calcium phosphate in a 27:73 ratio. This mixture is combined with water intraoperatively to form a paste. The setting process is monitored for time and pH changes. Mechanical properties like compressive and tensile strength are measured. The conversion of the cement to hydroxyapatite is observed in a physiological environment. The cement's non-redissolvability in body fluids is tested. Clinical application involves using the cement in craniofacial reconstructions. Nine out of ten patients received successful outcomes with this material.

The cement sets in approximately 20 minutes with a pH range of 6.5 to 8.5. It achieves a compressive strength of about 50 MPa and a tensile strength of about 8 MPa. The cement converts to hydroxyapatite within four hours in physiological conditions. This conversion makes the material non-redissolvable in normal body fluids. Clinical use in nine patients showed successful craniofacial reconstructions. The material is suitable for non-load-bearing applications. It is effective in treating cranial defects from tumors or trauma. The cement's isothermic reaction and osteoconductive properties are notable.

The authors state that the new hydroxyapatite cement offers reliable performance for craniofacial surgery. The material's setting time and pH stability are suitable for clinical use. The conversion to hydroxyapatite ensures long-term stability. The cement's mechanical properties meet the requirements for non-load-bearing applications. Clinical success in nine out of ten patients supports its effectiveness. The material's isothermic reaction and osteoconductive nature are advantageous. The study suggests potential for using the cement as a carrier for osteogenic proteins. The authors propose further applications in sinus and dental defect reconstructions.