Effects of ethanol addition on the water sorption/solubility and percent conversion of comonomers in model dental adhesives

Abstract

Objectives-This study evaluated the kinetics of water uptake and percent conversion in neat versus ethanol-solvated resins that were formulated to be used as dental bonding agents.Methods-Five methacrylate-based resins of known and increasing hydrophilicities (R1, R2, R3, R4 and R5) were used as reference materials. Resins were evaluated as neat bonding agents (100% resin) or they were solvated with absolute ethanol (95% resin/5% ethanol or 85% resin/15% ethanol). Specimens were prepared by dispensing the uncured resin into a circular mold (5.8 mm × 0.8 mm). Photo-activation was performed for 80 s. The water sorption/diffusion/solubility were gravimetrically evaluated, while the degree of conversion (DC) was calculated by Fouriertransform infrared spectroscopy.Results-Water sorption increased with the hydrophilicity of the resin blends. In general, the solvated resins exhibited significantly higher water sorption, solubility and water diffusion coefficients when compared to their corresponding neat versions (p<0.05). The only exception was resin R1, the least hydrophilic resin, in which neat and solvated versions exhibited similar water sorptions (p>0.05). Addition of ethanol increased the DC of all tested resins, especially of the least hydrophilic, R1 and R2 (p<0.05). Despite the increased DC of ethanol-solvated methacrylate-based resins, it occurs at the expense of an increasing in their water sorption/ diffusion and solubility values. Significance-Negative effects of residual ethanol on water sorption/solubility appeared to be greater as the hydrophilicity of the resin blends increased. That is, the use of less hydrophilic resins in dental adhesives may create more reliable and durable bonds to dentin. NIH Public Access

Influence of a heating device and adhesive temperature on bond strength of a simplified ethanol-based adhesive system

“…This discrepancy may be explained by the possibility that the temperature increase promoted by the light-curing unit itself could have been enough to improve the physicochemical reactions and enhance monomeric permeation into the etched dentin 16,[20][21][22] . In addition, the solvent in Adper Single Bond 2 is based on ethanol, which reduces viscosity 23 . Studies of acetone-based adhesives may present different results since the higher vapor pressure of acetone increases solvent evaporation 22,24 .…”

A New Level of Knowledge in the Field of Adhesive Systems – A Real Success in Practical Dentistry

“…Промежуточная часть молекулы мономера разделяет функциональную и полимеризуемую группы между собой, а также влияет на свойства мономера и итогового полимера [19,21].…”

“…Размер промежуточной части влияет на вязкость мономера, его способность к смачиванию и проникновению в микропористую поверхность эмали и дентина. По данным зарубежных исследований объемные промежуточные группы могут препятствовать достижению другими мономерами полимеризуемых групп, тем самым ухудшая полимеризацию [4,19,21]. Функциональные группы в функциональных мономерах обычно проявляют гидрофильные свойства [1,4,16].…”

“…Растворители используются в адгезивных системах для улучшения смачивания поверхности зуба, диффузии мономеров в микропористую структуру эмали и дентина [4][5]21].…”

“…Полярные протонные растворители, такие как вода и этанол, содержат гидроксильную группу [4]. Полярные апротонные имеют большой дипольный момент и, как правило, содержат кетоновую группу, например, ацетон [3,21]. Неполярные растворители имеют низкую диэлектрическую константу и дипольный момент.…”