Page 170 - Clinical relevance of current materials for cranial implants

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Chapter 8
Immersion of polymerized PMMA-based materials in a 60 °C water bath for 30 minutes during a post-polymerization heat treatment increased the degree of conversion. However, this post-treatment did not markedly affect the slight in vitro cytotoxicity observed in L-929 fibroblasts27. Endothelial cells lost their normal phenotype and adherence to one-another and to the substratum, they rounded up, and detached from the surface upon contact with MMA22. Cytotoxicity was also observed in human oral fibroblasts8. Other studies showed that 0.1-1.0 μg/mL of MMA activated tissue factor and consequently the coagulation of human blood22. Polymerized PMMA-based materials which were put into contact with platelet-rich plasma induced activation of platelets. This may contribute to the occurrence of deep venous thrombosis following arthroplasty, but may also release growth factors stimulating bone formation28.
PMMA-based materials with different compositions are currently used for similar surgical interventions. In medicine, an optimal implantation material is mandatory with respect to safety, ease-of-use, and the eventual aesthetic outcome. As reported in this study, these materials showed significantly different quantities of leached residual monomers in water over a two week period. The composition of PMMA influences the mechanical properties7,29,30 and may potentially influence cellular interactions and adverse events. Combined, this suggests that the composition of PMMA-based materials has a significant influence on the success rate. Medical professionals and the manufacturer should strive for optimal compositions for specific applications.
If possible, preoperative manufacturing of medical devices may allow for better control on the final chemical, mechanical, and biological properties. This also allows for a post-polymerization treatment by immersion in water for longer than 24 hours to decrease the release of residual monomers. Preoperatively manufacturing of the medical device reduces duration of surgery, exposure of medical professionals to MMA vapor, and burden on the surgeon.