Fiber-Reinforced Composites: A Breakthrough in Practical Clinical Applications with Advanced Wear Resistance for Dental Materials.

Abstract

Newer dental fiber-reinforced composites can provide service with less wear than enamel. Further, fibers in bulk molding form pack oriented parallel to the occlusal-dentinal floor planes that wear by uniform thinning into micrometer-sized fiber remnants and subsequent flat plate-like particulate bond by compression back into the polymer matrix. The fiber wear-in process is accomplished by creating fine crystalline chemically resistant nanoparticulates that become an exceptional polishing agent. Resulting consolidation by the underlying fiber network squeezes plasticized polymer and partially hydrolyzed polymer chains along with residual monomer, pendant methacrylate groups and nano-sized particulate to the surface that surround larger exposed micrometer-sized particulate and smallest fiber remnants. Eventually consolidation of the polymer matrix overall squeezes up and engulfs the top particulate or fiber remnants forming a smooth polished hard polymer-matrix composite wear surface probably filled with small nanoparticulate. The final hardened polymer surface may show particulate from worn fibers, but displays no signs of the original fibers after an in vitro wear simulator test comparable to 3 years of clinical service. Nanoparticulates formed from the fibers that have broken down generally reconsolidate back in to the top surface for a polished toughened polymer surface or behave as a polishing agent. The underlying fiber-reinforced composite network supports wear loads to greatly reduce wear especially as fibers extend well beyond a critical length that prevents fiber debonding from the matrix. Further, fiber-reinforced composite consolidation can aid in cavity molding placement by applied pressure to squeeze monomer, resin and particulates from the fiber network toward collapsing or filling in voids and removing entrapped air.