Development of a Moldable, Resorbable Appliance for Use in Maxillofacial Surgery

Survivable, maxillofacial injuries, such as those arising from military conflicts, often require open or closed reductions that involve the use of metallic plates, screws, and wires. Because these are nonresorbable, internal-fracture-fixation plates made from poly(DL-lactide) and reinforced with calcium metaphosphate (CMP) fibers have been designed to provide initial rigidity and weaken gradually. This exercises the newly formed bone, thereby strengthening it. Also, the need for a second surgery is obviated. Because the biodegradable, composite plates are not readily comformable to closely match the contour of bone and must be cut, drilled, and beveled to the required size and shape, alternative approaches to fracture fixation are desirable. This investigation delved into the feasibility of preparing moldable, moisture- curable poly (DL-lactide)s as matrix for CMP whiskers. Various synthetic schemes were investigated to put isocyanate functionality onto alcohol-terminated prepolymers. At the time of surgery, the curable polymer may be cured by moisture or other curing agents as it is mixed with CMP whiskers. In curing with moisture, foaming can be expected to induce a porosity in the implant. It is concluded from this study that appropriate, biocompatible curing agents to be used with alcohol-terminated prepolymers represent a preferred route to resorbable, fracture fixation materials that can be quickly and simply shaped at the time of surgery.