Shrinkage reduction of dental composites by addition of expandable zirconia filler

Abstract

A problem with dental resin composites is the polymerization shrinkage, which makes the filling loosen from the tooth or induces crack formation. We have developed an expandable metastable tetragonal zirconia filler, which upon reaction with water, is able to counter the polymer shrinkage. The shrinkage of the composite was calculated from density measurements using Archimedes method. The rate of the phase transformation in resin was measured by determining the volume fraction of monoclinic zirconia (v m ). The composite had a v m of 0.5 after 8 h of water storage. The overall shrinkage of the composites was reduced from 3.2% (initially) to 1.7%.

Light activated phase transformation of metastable tetragonal nanocrystalline zirconia

“…Thus, the zirconia particles phase transform to a higher degree when exposed to humidity in the atmosphere or water in solvents such as methanol than in the more hydrophobic dimethacrylate matrix. 11,17,18 Light activated phase transformation Molecules, which generate acid upon exposure to radiation, are called PAGs. A large number of PAGs are known because of their wide applications, especially in the field of photolithography.…”

Hybrid denture acrylic composites with nanozirconia and electrospun polystyrene fibers

“…Although ceramic materials can offer improvements in mechanical and thermal properties, their incompatibilities with polymers sometimes lead to agglomeration, diminishing the reinforcing potential of the nanoparticles. Improved ceramic/polymer adhesion can be achieved by coupling agents and nanoparticles coatings [19–23] Interface properties between nanoparticles and polymer matrix are modified by attaching the nanoparticles to the matrix. All these actions result in the improved mechanical and other functional properties of nanocomposites.…”

Relief of Shrinkage of UV-cured Materials by Exchange Reactions of Disulfide Bonds

“…To overcome this problem, some kinds of inorganic fillers were added to the organic bulk [6,7]. When using such fillers, miscibility and optical transparency of them would be concerned, to fabricate thick and homogeneous UV-cured materials.…”