Evaluation of chemical and mechanical properties of dental composites

Abstract

Composite materials were aged in distilled, deionized water and a solution by volume of 50% distilled, deionized water and 50% ethanol for three mon at 37 degrees C. Also investigated was the effect of aging dental glass filler powder in distilled, deionized water for one, three, six, and ten mon at 2 degrees C, 37 degrees C, and 72 degrees C. Atomic absorption analysis was performed on the aqueous media in which the samples were aged in order to determine the extent of leaching of silicon and strontium. From the leaching rates at various aging temperatures, the activation energies for silicon (10.3-16.4 j/mol) and strontium (57.0-58.4 j/mol) were determined. Aging in the 50% distilled, deionized water and 50% ethanol solution greatly increased the leaching rate of both silicon and strontium, as compared to aging in distilled, deionized water. Glass powder leached far more than the composite materials, due to an increase in exposed surface area, as well as a lack of chemical bonding to a resin matrix or a linked glass network. Temperature greatly increased the leaching rate of both silicon and strontium. Only after ten mon did strontium leach substantially more than silicon. For the dental composites investigated after 3 mon aging, Mode I fracture toughness decreased 57-68% in ethanol and 37-43% in water, and mode II fracture toughness decreased 41-49% in ethanol and 6-11% in water.

Investigation of Mechanical Properties of Modern Dental Composites After Artificial Aging for One Year

“…[2][3][20][21][22] Some previous studies found that the release of particular filler particles, such as strontium or barium, were different after aging in ethanol, artificial saliva and distilled water. 4,[23][24] However, as only little correlation has been observed between filler leaching and flexural strength, Drummond and others assumed that the deterioration of dental composites is more closely related to degradation of the resin matrix and the matrix-filler bonds than degradation of the glass fillers, 25 which is in accordance with other reports. 20 Zhang reported that storage of specimens in a mixture of ethanol and water led to a significantly higher decrease in FS than did immersion in distilled water or artificial saliva.…”

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

“…Moreover, improved filler-matrix coupling via silanization 33) is at the expense of surface modification of the glass fillers that results in a delay in the ion leaching process 34) . Deterioration of the filler-resin matrix interface may also occur rapidly following water sorption 35,36) , owing to the formation of siliceous hydrogel layers around the ion-leachable glass fillers.…”

“…Moreover, improved filler-matrix coupling via silanization 33) is at the expense of surface modification of the glass fillers that results in a delay in the ion leaching process 34) . Deterioration of the filler-resin matrix interface may also occur rapidly following water sorption 35,36) , owing to the formation of siliceous hydrogel layers around the ion-leachable glass fillers.Such a scenario probably accounted for the change in flexural properties of compomers after water storage 36) . By contrast, the use of silanized PRG fillers permits better coupling between dehydrated hydrogel and the resin matrix.…”

Filler particles used in dental biomaterials induce production and release of inflammatory mediators in vitro

“…The inorganic particles constitute 70-80 wt % of the composite and glass-ionomer materials. 1 Typical composition of the filler particles is crystalline quartz or barium glass in composites 2 and fluoroaluminosilicate glass in glass-ionomer materials. 3 In dental composite and compomer materials, the inorganic filler particles are embedded in a resin matrix, whereas the glass-ionomer reaction is a partial dissolution of the glass fillers by polyalkenoic acids, forming siliceous hydrogel layer on the surface of the glass particles and a matrix of metal ions bound to the polyacid chains.…”

“…The glass filler leaches out of the composite material, which results primarily from a breakdown in the bond between the filler and the matrix. 1 Material degradation results in exposure of the patient to leachables, including particles, either local close to the restoration or systemic after absorption from the gastrointestinal tract. In evaluating the toxicity of dental biomaterials, emphasis has been put on the resin part 7,8 even though it is known from other application that particles of comparable composition and size have potential for biological effects.…”