lowshrinkage

Lowshrinkage, often written as low-shrinkage, describes materials that exhibit reduced volume change during processes such as curing, drying, or solvent evaporation. The term is applied in several fields, notably dentistry, where polymerization shrinkage of resin-based composites and cements can affect restoration integrity, and in construction, where shrinkage affects coatings and cementitious systems.

Shrinkage occurs from polymerization, solvent loss, or moisture loss; measurement is typically reported as volumetric shrinkage percentage or shrinkage stress, using methods such as dilatometry, micro-CT, or bonded-disk tests. Lowshrinkage materials employ chemical and physical strategies to minimize these changes, such as using monomers with reduced molar volume change, higher filler loading, or ring-opening chemistries.

In dentistry, low-shrinkage composites include silorane-based systems that shrink less due to ring-opening reactions, as well as advanced methacrylate formulations with optimized monomer structures and inorganic fillers. In construction, shrinkage-reducing admixtures and expansive cements help manage drying and hydration shrinkage, improving crack resistance and durability.

Advantages of lowshrinkage materials include improved marginal integrity, reduced residual stress, and better long-term durability. Trade-offs can include higher material cost, altered handling properties, and potential changes in mechanical performance or esthetics that require balancing against shrinkage gains.

Research continues to optimize polymer chemistry, filler technologies, and processing protocols to achieve lower shrinkage without compromising other properties. Standards and testing protocols exist to quantify volumetric shrinkage and shrinkage stress for specific material classes, enabling comparison and quality control.