Changes in properties of polyacid‐modified composite resins (compomers) following storage in acidic solutions

Abstract

The interaction of three polyacid-modified composite resins (compomers) with various acidic storage solutions, and also water, over periods of time up to 6 months has been studied and compared with those of a glass-ionomer and a composite resin. This interaction has been shown to vary in a complex way with length of storage and nature of the acid, and citric acid was found to be the most aggressive storage medium for glass-ionomer cement, and also for the compomers. The pure composite resin, by contrast, was relatively unaffected by all of the acid solutions examined. In all acids, the compomers showed a distinct buffering effect, i.e. they increased the pH towards neutral, as did the glass-ionomer. The extent of this also varied with duration of storage and nature of the acid. The biaxial flexure strength was determined and found to be essentially unaffected by the complex chemical interactions with acidic storage solutions. Values obtained for the compomers were lower than those of the composite resin, but above those of the glass-ionomer. Fourier-transform infrared (FT-IR) spectroscopy was employed to study the changes in the compomers following storage in the aqueous media, but bands were broad and no detailed assignments could be made. There were changes in the region of the spectra associated with metal carboxylates however, and this indicates that the secondary acid-base reaction had occurred following water uptake.

Surface hardness of different restorative materials after long-term immersion in sports and energy drinks

“…The sports and energy drinks tested in this study had pH levels ranging between 2.67 and 3.79. Immersion therein for 1 week resulted in lower surface hardness of all the restorative materials than at baseline, suggesting a susceptibility of the composite resins to erode under acidic conditions 27,28) . In particular, Compoglass F showed significantly lower surface hardness than the other restorative materials after 1 week of immersion, and this was true for all sports and energy drinks.…”

“…Deterioration of resin materials probably occurred because of water absorption, such that the presence of water softened the resin by swelling the polymer network and reducing the frictional forces between the polymer chains 31,32) . Moreover, composite resins have high solubility in low-pH solutions, leading to surface erosion and dissolution, matrix softening, and loss of structural ions 27,28,33,34) . After 6 months of immersion, further softening of all the restorative materials was observed.…”

“…Citric acid has been shown to be the most aggressive storage medium for dental hard tissues and resin-based restorative materials 28,30,39) . Compared to compomers, pure composite resins were found to be less affected by low-pH beverages 17) or acidic solutions 28) . Therefore, Filtek Z250, Filtek Supreme, and Premise exhibited less surface hardness change with no significant differences among them than did Compoglass F at each immersion period.…”

A Study of the Effect of Hydrogen Sulfide on Conventional and Resin-Modified Glass-Ionomer Dental Cements

“…The pH value recorded compares closely with those of acids previously used in studies of the interaction of dental restoratives with low pH media. These acids include substances such as lactic [3], citric and malic [20,22]. Results have also been obtained for amino acids [22].…”

Neutralizing effect by resin-based materials containing silane-coated glass fillers

“…It is reported that many fluoride-releasing materials and zinc phosphate cements have an ability to neutralize acid solutions [8][9][10][11][12][13][14][15] and the neutralizing ability of materials, which can change the pH of the surrounding aqueous media, may contribute to the inhibition of secondary caries arising from the formation of an acid by bacteria. It is reported that a resin composite with pH stabilizing properties was able to counter the acidic pH of saliva and maintain it at levels where demineralization would not occur in vivo 16,17) .…”