A Review of Chemical-approach and Ultramorphological Studies on the Development of Fluoride-releasing Dental Adhesives Comprising New Pre-Reacted Glass Ionomer (PRG) Fillers

Abstract

This paper reviews our recent studies on fluoride-releasing adhesives and the related studies in this field based on information from original research papers, reviews, and patent literatures. A revolutionary PRG (pre-reacted glass ionomer) filler technology -where fillers were prepared by the acid-base reaction of a fluoroaluminosilicate glass with polyalkenoic acid in water, was newly developed, and a new category as "Giomer" was introduced into the market. On fluoride release capability, SIMS examination revealed in vitro fluoride ion uptake by dentin substrate from the PRG fillers in dental adhesive. On bonding durability, it was found that the improved durability of resin-dentin bonds might be achieved not only via the strengthened dentin due to fluoride ion uptake from the PRG-Ca fillers, but also due to retention of relatively insoluble 4-AETCa formed around remnant apatite crystallites within the hybrid layer in 4-AET-containing self-etching adhesives. On ultramorphological study of the resin-dentin interface, TEM images of the PRG-Ca fillers revealed that the dehydrated hydrogel was barely distinguishable from normal glass fillers, if not for the concurrent presence of remnant, incompletely reacted glass cores. In conclusion, it was expected that uptake of fluoride ions with cariostatic effect from PRG-Ca fillers would endow dentin substrates with the benefit of secondary caries prevention, together with an effective and durable adhesion to dentin. Key words: Pre-reacted glass ionomer (PRG) technology, Giomer, Fluoride-releasing adhesiveReceived May 30, 2007: Accepted Nov 2, 2007 In 1955, Dr. Michael Buonocore 1) first demonstrated the bonding of acrylic resin to etched enamel. This success has since opened a new vista in the field of adhesive dentistry, and so-called acid-etching technique is ubiquitous in today's dental clinics. The field of adhesive dentistry has made a significant progress over the past decade. A large part of this success is attributed to the major advances in a bonding technology 2) . On dental adhesives, most of the developed products are biologically evaluated by means of in vivo histopathological studies and clinical trial investigations. INTRODUCTIONResults obtained thus far, when measured against stringent clinical demands, point to the need for further research and improvement. The ultimate goal in the design and development of dental adhesives is to render a material that is relatively easy to apply, less technique-sensitive, and which inhibits the formation of secondary caries. To achieve these targets through the development of more advanced adhesives, numerous challenges have been continuously performed by rigorous chemical-approach studies with the aim of tackling research problems and speculations that are regularly encountered in the course of exploration and development. In addition, to understand the mechanism of adhesion to dental hard tissues or its degradation at the resin-dentin interface, numerous ultramorphological studies are undertaken, and made valuable ...

Three-year clinical evaluation of posterior composite restorations placed with a single-step self-etch adhesive

“…This S-PRG filler has a layered structure consisting of a fluoroboroaluminosilicate glass core, reacted layers forming a glass ionomer phase on the surface of the core, and a reinforced layer covering the surface of the prereacted phase (13,14). Resin composites containing S-PRG fillers are used in combination with self-etch adhesives, which partially dissolve the smear layer without demineralizing the dentin as deeply as etch-and-rinse systems.…”

Evaluation of selected properties of a new root repair cement containing surface pre-reacted glass ionomer fillers

“…Multiple S-PRG-based dental materials are commercially available and have been collectively categorized as Giomer (Glass ionomer + polymer) [12]. The S-PRG fillers are prepared by the initiation of an acid-base reaction between fluoroboroaluminosilicate glass and aqueous polyacrylic acid.…”

Is the Ditio-Octonoate Monomer the Ideal for Adhesion to Precious Metals and their Alloys?

“…Likewise, metals can be used on numerous and varied substrates: enamel, dentin, ceramics, resins or other metals [1]. Examples of adhesion of enamel or dentin to metals, orthodontic bands and brackets, or Maryland type adhesive bridges.…”

“…The use of metals in dentistry presupposes the need for mechanisms of retention or adhesion of the same to different substrates; Such as enamel, dentin, ceramics, old resins and other metals [1].…”

“…For bonding to dental porcelain, alumina, zirconia and gold alloy, a ternary combination of silane, acidic adhesive monomers and dithio-octonoate monomers appears promising. The most recent development was a multi-purpose self-etching adhesive containing only acid monomers and dihiooctonoate adhesive monomers, producing strong adhesion to enamel and dentin, zirconium oxide and gold alloys [1]. …”