Low-Shrinkage Resin Matrices in Restorative Dentistry-Narrative Review

Abstract

Dimethacrylate-based resin composites restorations have become widely-used intraoral materials in daily dental practice. The increasing use of composites has greatly enhanced modern preventive and conservative dentistry. They have many superior features, especially esthetic properties, bondability, and elimination of mercury and galvanic currents. However, polymeric materials are highly susceptible to polymerization shrinkage and stresses that lead to microleakage, biofilm formation, secondary caries, and restoration loss. Several techniques have been investigated to minimize the side effects of these shrinkage stresses. The primary approach is through fabrications and modification of the resin matrices. Therefore, this review article focuses on the methods for testing the shrinkage, as well as formulations of resinous matrices available to reduce polymerization shrinkage and its associated stress. Furthermore, this article reviews recent cutting-edge developments on bioactive low-shrinkage-stress nanocomposites to effectively inhibit the growth and activities of cariogenic pathogens and enhance the remineralization process.

Thermo-Responsive Shape Memory Vanillin-Based Photopolymers for Microtransfer Molding

“…For example, the shrinkage increased from 1 to 10% as a result of the reduction of the amount of thiol from 1 to 0.25 mol in the resins C9-C12. This can be explained by the dominant reaction mechanism, as it is well known that acrylates have a high shrinkage rate during free radical polymerization [33], while thiol-ene photopolymerization results in a lower shrinkage volume [34]. That is because long-distance connections via weak Van der Waals force are replaced by short, strong covalent bonds between carbon atoms in monomer units during free radical acrylate polymerization, which results in shrinkage of the polymers [33].…”

“…This behaviour can be explained by the long carbon chain of tridecyl methacrylate. As a result, the polymer can stretch more, and is softer and more flexible [34].…”

Anticariogenic and Mechanical Characteristics of Resin-Modified Glass Ionomer Cement Containing Lignin-Decorated Zinc Oxide Nanoparticles

“…This becomes more imperative if the added agent is organic. 19 Lignin is an organic biologic polymer with a chemically diversified structure. It has many functional groups such as thiols (containing in kraft lignin) and hydroxyl which have the potential of capping/reducing metal ions for providing stability and degradability.…”

“…However, the challenging part of such modifications is to achieve adequate bonding between the cement and the supporting agent. This becomes more imperative if the added agent is organic …”

Nanomaterials for Periodontal Tissue Regeneration: Progress, Challenges and Future Perspectives

“…Furthermore, traditional dental materials such as composites and cement in macro and micro sizes are also widely applied in clinics. Despite their low cost, easy application and good biocompatibility, these materials also present several complications, such as degradation [ 5 ], cure shrinkage [ 6 ], stress fatigue [ 7 ], marginal microleakage [ 8 ] and high susceptibility to microbial adhesion. Thus, there is a critical need for alternative techniques and materials.…”