Dental Composites/Glass Ionomers: the Materials

Abstract

Most commercial dental composites contain liquid dimethacrylate monomers (including BIS-GMA or variations of it) and silica-containing compositions as inorganic reinforcing filler particles coated with methacrylate-functional silane coupling agents to bond the resin to the filler. They also contain initiators, accelerators, photo-initiators, photosensitizers, polymerization inhibitors, and UV absorbers. Durability is a major problem with posterior composites. The typical life-span of posterior composites is from three to 10 years, with large fillings usually fewer than five years. Polymerization shrinkage and inadequate adhesion to cavity walls are remaining problems. Some pulp irritation can occur if deep restorations are not placed over a protective film. Some have advocated the use of glass-ionomer cement as a lining under resin composite restorations in dentin. The concept of glass-ionomer cements (GICs) was introduced to the dental profession in the early 1970's. Current GICs may contain poly(acrylic acid) or a copolymer. Higher-molecular-weight copolymers may also be used to improve the physical properties of some GICs. Stronger and less-brittle hybrid materials have been produced by the addition of water-soluble compatible polymers to form light-curing GIC formulations. The ion-leachable aluminosilicate glass powder, in an aqueous solution of a polymer or copolymer of acrylic acid, is attacked by the hydrated protons of the acid, causing the release of aluminum and calcium ions. Salt bridges are formed, and a gel matrix surrounds the unreacted glass particles. The matrix is adhesive to mineralized tissues. Provisions must be made for maintenance of the water balance of restorations for the first 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental Novel Silane System in Adhesion Promotion Between Dental Resin and Pretreated Titanium

“…Our hypothesis was that any of these five functional silane primers in a blend with a cross-linking silane produces superior bonding of a bis-GMA resin onto silica-coated Ti, when compared with a standard, pre-activated 3-methacryloxypropyltrimethoxysilane [4] product. A non-filled resin system based on the experimental bis-phenol-Adiglycidyldimethacrylate (bis-GMA) was used in the assay because most modern dental resin-composite cements are chemically based on this system [18]. Similarly, Ti was studied because it is a widely used biomaterial-for example, in crown implants and bridge substructures [14,[19][20][21].…”

Experimental Novel Silane System in Adhesion Promotion between Dental Resin and Pretreated Titanium. Part II: Effect of Long-Term Water Storage

“…1): 3-acryloxypropyltrimethoxysilane [8], 3-methacryloxypropyltrimethoxysilane [9], 3-glycidoxypropyltrimethoxysilane, tetrakis-(2-methacryloxyethoxy)silane and bis- [3-(triethoxysilyl)propyl]tetrasulfide. A non-filled resin system based on the experimental resin bisphenol-A-diglycidyldimethacrylate (bis-GMA) was used in the shear bond strength assay and examination of failure mode [10]. Ti was used as the substrate because it is the biomaterial of choice for crown implants and bridge substructures and its bonding properties have been widely studied [11][12][13].…”

Influence of Curing Light Type and Staining Medium on the Discoloring Stability of Dental Restorative Composite

“…This composite belongs to the class of the glass ionomers that are used for their fluoride release in the oral cavity (Zafar, 2013;Zafar and Ahmed, 2015). Based on the fact that GC Fuji II LC materials are more prone to colour changes upon curing and aging, they should not be considered as the best choice for aesthetic restorations (Bowen and Marjenhoff, 1992).…”

“…The spectrophotometer returned a precise quantitative measurement of surface colours by recording the spectral reflectance/transmittance curve of the specimen. A prism disperses tungsten-filament bulb light into a spectrum of wavelength (5 and 20 nm) bands (Bowen and Marjenhoff, 1992;Kim-Pusateri et al, 2007;Dozić et al, 2007;Al-Dharrab, 2013;Eldiwany et al, 1995;Ruchi et al, 2010). The colour changes (∆E) of each specimen were calculated by analysing the coordinate values before and after beverage ageing.…”