Protective bone cement

The glass polyalkenoate cement uniquely combines translucency with the ability to bond to untreated tooth material and bone. Indeed, the only other cement to possess translucency is the dental silicate cement, while the zinc polycarboxylate cement is the only other adhesive cement. It is also an agent for the sustained release of fluoride. For these reasons the glass polyalkenoate cement has many applications in dentistry as well as being a candidate bone cement. Its translucency makes it a favoured material both for the restoration of front teeth and to cement translucent porcelain teeth and veneers. Its adhesive quality reduces and sometimes eliminates the need for the use of the dental drill. The release of fluoride from this cement protects neighbouring tooth material from the ravages of dental decay. New clinical techniques have been devised to exploit the unique characteristics of the material (McLean Wilson, 1977a,b,c Wilson McLean, 1988 Mount, 1990). 

Cranial defects can be caused by injury, infection, or tumor invasion. Large defects should be restructured to protect the brain by using cranial implants. The conventional method is to cover the defect with bone cement. Nowadays, custom-made implants designed for the individual patient are available. Rapid prototyping techniques and medical-grade plastics allow surgeons to repair large holes in skulls. 

FIGURE 5.14 (Top) Acrylates (R=H) and methacrylates (R=CH3) polymerize to form poly(acrylates) and poly(methacrylates), which have saturated hydrocarbon backbones. (Bottom) Four common (meth)acrylate monomers. (a) Methyl methacrylate is a hydrophobic monomer commonly used in bone cements. (b) 2-Hydroxyethyl(meth) acrylate is a hydrophilic monomer used in soft tissue engineering, (c) 2-Nitrobenzyl acrylate is a protected form of acrylic acid and deprotects upon exposure to UV light, (d) 2-Dimethylaminoethyl methacrylate is a pH-sensitive monomer. 

---