Influence of ethanol concentration on softening tests for cross-link density evaluation of dental composites

Abstract

This study investigated the influence of ethanol concentration on softening tests for cross-link density evaluation (microhardness) of dental composites. Specimens of Filtek Z100 (3M ESPE) were light-activated by standard or pulse-delay methods. After initial Knoop hardness readings (KHN 1 ), half of specimens (n = 10) for each irradiation method was stored in 100% ethanol, and half in 75% ethanol, during 24 hours, and hardness was determined anew. Hardness deterioration (ΔKHN) was recorded as the difference between pre and post-storage values. KHN 1 data were submitted to one-way ANOVA and Tukey's test (α = 0.05), and hardness deterioration was analyzed by two-way ANOVA and Tukey's test (α = 0.05). For KHN 1 , no significant differences were detected between the activation modes (p = 0.697). Samples light-activated by the pulse-delay method presented significantly higher softening compared to the standard mode when samples were immersed in 100% ethanol. Conversely, no significant differences between curing modes were detected for samples stored in 75% ethanol.

Preliminary Study of the Influence of Post Curing Parameters to the Particle Reinforced Composite's Mechanical and Physical Properties

“…Nevertheless, the cross linked polymers may swell and become soft depending from the cross link density. The swelling and softening effect gets smaller as the cross-link density increases [11,25]. Figure 4 presents how much percentage a sample lost in indentation hardness when samples that were stored in air in 37 °C for 24 h were compared to samples that were placed into 80 % ethanol-water solution at 37 °C for 24 h. The samples that were post cured in elevated temperatures lost less than 20 % in indentation hardness.…”

Properties of alkoxysilane functionalized polycaprolactone/polydimethylsiloxane‐modified epoxy resin composites: Effect of curing temperature and compositions

“…As one method used to determine the crosslink densities of crosslinked thermoset materials, a swelling test was always performed to qualitatively evaluate the crosslinked density 13, 14. Generally, highly crosslinked structures took up less solvent than lightly crosslinked ones,15, 16 as more limited space and pathways were available for solvent molecules to diffuse within the former structure 17. Figure 3 showed the dependence of the swelling value Δ m versus the PCS‐2Si content of the different systems, respectively.…”

Shear Bond Strength of Bisphenol a-Glycidyl Methacrylate Adhesive Resin After Application of Eucalyptus Oil Before Debonding Metallic Orthodontic Bracket

“…Absorption of solvents is directly related to the degree of crosslinking. Therefore, the slightly cross-linked polymer becomes more sensitive to the plasticizing reaction [19]. This indicates that the 4-META/ MMA-TBB adhesive resin was easier to debond when compared with the bis-GMA adhesive resin.…”