Effect of gender of the operator and application mode of adhesives on dentin hydraulic conductance in an in vitro model

ABSTRACT: Aim: To compare the hydraulic conductance of human dentin disks which have been treated with an adhesive by operators of different genders and by active or passive modes of application. 60 third molars of healthy adults were included in resin blocks. These were cut to obtain 60 dentin disks of 1mm +/- 0.1 mm thick. Group 1 and 2, the adhesive was applied by 15 male operators passively (group 1) and vigorously (group 2). Groups 3 and 4, the adhesive was applied by 15 female operators passively (group 3) and vigorously (group 4). The flow rate was measured with a diffusion chamber and the hydraulic conductance of the disks was determined. Results: Mean for hydraulic conductance of each group was: 1 (0.01752), 2 (0.00355), 3 (0.01215), 4 (0.00877) in μl/minxcm2. There was statistically significant difference in the hydraulic conductance between experimental and control groups. There was no difference in dentin hydraulic conductance between genders. There was statistically significant difference in hydraulic conductance between the different modes of application. There was a moderate association between the pressure exerted when applying the adhesive and the values of dentin hydraulic conductance in vitro.

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% ortho-phosphoric 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.