Influence of the Passive Evaporation of adhesive on the conductance of dentin

Abstract

Aim: Determine the influence of time of passive evaporation of the solvent in a universal adhesive on the hydraulic conductance and permeability of dentin in an ex vivo human model. Henceforth, 60 healthy non-occluding third molars, indicated for therapeutic extraction/removal, of informed and consented patients aged between 18 and 30 years, were used here in. First, extracted teeth were incorporated into epoxy resin blocks and then dentin disks (1mm +/-0.1 mm thick) were prepared. Dentin was acid etched with 35% orthophosphoric acid for 15 seconds in order to remove the smear layer and obtain permeable dentin. Samples were then randomized and divided into 5 groups (n=12). A Single Bond Universal adhesive layer with different time of passive evaporation of the solvent was then applied: GC=10 seconds, G1=30 seconds, G2=60 seconds, G3=300 seconds and G4=50 minutes. Finally, the flow rate was measured using a diffusion chamber, a model previously proposed by Pashley et al. Results: The obtained hydraulic conductance averages were as follows: GC=0.00052, G1=0.00018, G2=0.00006, G3=0.00005, G4=0.00005 expressed in uL•cm-2•min-1cm•H2O-1. For comparisons between groups, ANOVA and post hoc Tukey (ρ<0.05) tests were applied, resulting in a statistically significant difference between the GC group and all experimental groups (ρ <0.05). An influence of solvent passive evaporation thereby reducing hydraulic conductance in the experimental groups, was detected. key wordsPassive evaporation, adhesion, hydraulic conductance.

Effect of alternative solvent evaporation techniques on mechanical properties of primer–adhesive mixtures.

“…The elastic modulus represents the relative stiffness of the material as well as its resistance to plastic deformation, which is directly related to the formation of more crosslinks in the polymer structure. 2 The increase in the modulus as a result of the heated air spray is probably due to the efficient removal of the solvent, leading to a more efficient polymerization process 3,4,14 . This phenomenon may be also explained based on the formulation of the two adhesive systems investigated in this study, in which the primer formulation contains HEMA and water.…”

“…Tensile strength evaluates the cohesion in the polymer layer formed after polymerization. Thus, increasing cohesion indicates a formation of a hybrid layer with lower microporosity, which is consequently less susceptible to infiltration 2 . In this study, there was no statistical difference in tensile strength, indicating that the evaporation obtained was not sufficient to improve material cohesion.…”

“…However, the bond between the dental substrate and the restorative material is affected by the presence of residual water or excess solvent. The residual solvent in these systems may act as a polymeric matrix plasticizer, interfering with the mechanical properties of these materials and consequently with the bonding interface 2,3 .…”