The Study of Initiation Systems and Formulations for the Development of a Novel Silorane Biomaterial

Abstract

There are approximately one million hip and knee replacements each year in the United States alone and over 70% are cemented for stabilization. The number of these replacements is expected to rise to 3.5 million per year by 2030 and result in an estimated several fold increase of the current global market of a billion to multi-billion dollars over the next fifteen years. The current commercially available polymethyl methacrylate (PMMA) based bone cements have been used since the 1960’s with little change to their composition. They provide strength and longevity for total joint replacements, however they are not without their disadvantages. Issues such as polymerization shrinkage, high curing temperatures, and component toxicity have been reported. In order to address these problems, we replaced the methacrylate-based resin with a silorane-based system, which are novel monomers previously used for dental composites. Our goal is to develop a new bone cement that would have handling times between 10 – 20 min, curing temperatures under 45 °C, good mechanical strength, and biocompatibility. An important part of this effort centered on the identification and investigation of silorane initiation systems, which can be tailored for specific uses including internal bone cements. The initial screening process utilized the neat resin system followed by differing formulations including modified and unmodified fillers. The tests were based in part on the ISO standard 5833 used for acrylic resin cements and included exothermicity, degree of cure, biocompatibility, and mechanical strength. From these studies, we identified alternative bone cement formulations, which met or exceeded our desired properties as compared to commercially available bone cement.