Effect of Cooling Procedures over Linear dimensional changes in PMMA

Denture bases are commonly made from acrylic resins, which were introduced by Dr. Walter Wright back in 1937. Among these, polymethyl methacrylate (PMMA) is the most commonly used. PMMA material is mostly processed by wet heat and compression molding techniques, which deliver dentures with acceptable mechanical properties. However, certain dimensional changes are known to occur in acrylic resin during or after its processing. These changes hold clinical significance because for better adaptation to oral tissues, denture base material must have dimensional accuracy during and after its processing. However, inaccuracies tend to occur due to unavoidable changes during fabrication such as thermal expansion on heating, contraction on cooling and polymerization shrinkage. The purported significance of this study is to find out the most suitable cooling procedure for achieving maximum dimensional accuracy following a standard heating cycle. This will lead to the fabrication of a denture which will have better retention, support, stability.