Development and Dental Applications of Spiro Expanding Monomers as Antishrinkage Additives

Abstract Volumetric shrinkage is one of the main reasons cited for the failures and shortening the clinically useful life span of contemporary dental restorations. Owing to the compact and relatively more flexible cyclic structures, expanding monomers (EMs) have demonstrated essentially zero shrinkage or expansion upon polymerization. This article reviews recent studies on the new low shrinkage dental resin with spiro EMs as antishrinkage additives. This includes the most prominent classes of EMs, namely, spiroorthoesters, spiroorthocarbonates and bicycloorthoesters, along with the mechanism of expansion polymerization. A brief introduction of the development of copolymerization mechanism between EMs and dental resin is given, followed by an introduction to the cutting‐edge development and application of EMs with different side chain groups in dental materials. Furthermore, the effect of low‐shrinkage resin modified by EMs on the mechanical and biological properties was found to be within an acceptable range. The dental resins modified by spiro EMs can avoid adverse impact from the volumetric shrinkage of polymers during curing. They are materials with great potential for a variety of biomedical and clinical applications and provide guidance for the synthesis of new low shrinkage dental resin materials with good mechanical properties.