Inorganic Fillers for Dental Resin Composites: Present and Future

Abstract

Dental resins represent an important family of biomaterials that have been evolving in response to the needs in biocompatibility and mechanical properties. They are composite materials consisting of mostly inorganic fillers and additives bound together with a polymer matrix. A large number of fillers in a variety of forms (spheroidal, fibrous, porous, etc.) along with other additives have been studied to enhance the performance of the composites. Silane derivatives are attached as coupling agents to the fillers to improve their interfacial properties. A review of the literature on dental composite fillers seems to suggest that each of the fillers tested presents its own strengths and weaknesses, and often combinations of these yield resin composites with the desired balance of properties. Additives such as nanotubes, whiskers, fibers, and nanoclusters have been shown to enhance the properties of these hybrid materials, and their use in small fractions may enhance the overall performance of the dental resin materials.

Polymer-Based Direct Filling Materials

“…Excellent, in depth reviews focusing specifically on the filler technology can be found in the literature [12–14], and a summary is provided here. Microfill composites contain colloidal silica particles with average size of 50 nm.…”

Biodegradable polymers for dental tissue engineering and regeneration

“…Inorganic fillers, such as silicon dioxide, quartz in its crystalline state, aluminium oxide (Al2O3), titanium dioxide (TiO 2 ), zinc oxide (ZnO), and zirconium oxide (ZrO 2 ), that are easy to handle but not immune from marginal degradation during time and the consequent gap formation between the tissue/material interface [46].…”

Kinetics and mechanics of photo-polymerized triazole-containing thermosetting composites via the copper(I)-catalyzed azide-alkyne cycloaddition

“…The roles of the filler involve enhanced mechanical performance including properties such as hardness, strength, and wear resistance, along with improved biocompatibility and moisture resistance [3,5] as well as reduced thermal expansion coefficient and polymerization-induced volumetric shrinkage that leads to significant stress [6]. However, extensive filler loading in resin-based composites can hinder photopolymerization kinetics due to light scattering and also influence handling properties due to the substantial increase in initial viscosity of the uncured composite paste as compared to the unfilled resin [7]. Therefore, the influence of filler types, shapes, sizes, concentrations, and functionalization on kinetics, mechanics, rheology, biocompatibility, and handling properties of resin-based composites has been investigated widely in the search for a more durable and practical dental restorative composite material [1,8–12].…”

“…Different classifications of inorganic fillers include metal oxides (eg: silica, aluminum oxide, titanium dioxide), alkaline silicate glass, bioactive or biomimetic fillers (eg: hydroxyapatite), and organic-inorganic hybrids [7]. Silicon dioxides are often utilized in resin-based dental composites [11] due to their mechanical performance along with reduced water-sorption and solubility [7].…”