Hydrolytic Degradation of Dental Composites

Abstract

The leakage of filler elements from four composites after storage in water was investigated by use of atomic absorption spectrophotometry. The results confirmed previous findings that leaching of silicon from different composites is strongly dependent on filler composition. Consideration of the total filler surface of each composite material indicated that quartz as well as pyrolytic silica-containing composites leached less silicon than did composites containing fillers of strontium and/or barium glasses. A correlation between leakage and crack formation in the matrix appeared to exist for all composites except for the microfilled resin. These cracks were explained as a result of osmotic pressure built up at the matrix-filler interface due to hydrolytic degradation of the filler. Of the investigated materials, the microfilled resin was found to be the most stable material in a wet environment with respect to crack formation. This finding was explained by filler composition, filler form, and the specific structure of the microfilled resin.

Repair bond strength of microhybrid, nanohybrid and nanofilled resin composites: effect of substrate resin type, surface conditioning and ageing

“…The water absorption has a detrimental effect on the physical and structural integrity of some RBCs, including flexural and bond strength. Decreased cohesive strength of the material due to the hydrolytic degradation through the oxidation process and/or hydrolysis was reported [32]. One recent study showed even more ageing effect of the presence of biofilm [34].…”

“…bis-GMA leads to the formation of a rigid cross-linked network (1.43 GPa) that absorbs less water than TEGDMA but higher than those of UDMA and bis-EMA [31]. TEGDMA is a hydrophilic monomer, meaning that it absorbs greater amounts of water [32,33].…”

“…Ageing of RBCs is often as a consequence of mechanical/physical degradation mechanisms such as wear, abrasion and fatigue or due to chemical degradation mechanisms such as enzymatic, hydrolytic, acidic or temperaturerelated breakdown [32]. One common route of simulating the hydrothermal ageing is exposing the specimens to thermocycling.…”

Analysis of the relationship between the surface hardness and Wear resistance of indirect composites used as veneer materials

“…The decrease of hardness and wear resistance of the tested composites, especially Artglass, might be justified based on the reports of Sölderholm et al (17), according to whom the permeability of resins and their hydrolytic degradation interfere with their wear, and Tarumi et al (10), who found that barium is reactive when immersed in water and, when eliminated, interferes with resin mechanical properties. Such reports justify the good wear resistance of Artglass after 1-day immersion and the high wear rate after 55 days, considering that this composite has barium glass silicate in its composition.…”

Surface Hardness of Resin Composites After Staining and Bleaching

“…13 Following polymerization, the inward movement of water molecules causes mobilization of ions within the matrix and outward movement of unreacted monomers, as well as the leaching out of ions from fillers and activators, which may cause softening of the resin matrix, reduction in stain resistance and leakage of filler elements. [14][15][16] Salivary enzymes, pH fluctuation, organic solvents and the ionic composition of food, beverages or saliva may influence the surface quality of dental resins. 17 One factor affecting the surface quality of resin composites is the finishing and polishing procedure.…”