The Effect of Different Drying Protocols on the Bond Strength of AH Plus Sealer Using Vertical Condensation Technique. (A Comparative in Vitro Study)

Objectives The purpose of this in vitro study was to evaluate the effects of isopropanol alcohol, ethanol alcohol when used for final irrigation and the paper points as drying protocols, on the bond strength of AH Plus sealer using the warm vertical condensation technique. Materials and Methods Thirty single-rooted human permanent teeth were decoronated to a length of 15 mm. The roots were randomly divided into three groups (n = 10 for each group) according to the drying protocol: (G1: Paper points, G2: 70% Isopropanol, and G3: 95%Ethanol). Thirty roots were prepared by using Pro Taper universal rotary instruments. G1: the canals were blot dried with paper points until the last one appeared dry, G2: the canals were dried with paper points followed by dehydration with 70% isopropanol, and G3: the canals were dried with paper points followed by dehydration with 95% ethanol. After drying, the canals were obturated with AH Plus sealer and gutta-percha (AH/GP) using the vertical condensation technique. Then, each root was sectioned into three slices with 2-mm-thick (coronal, middle, apical thirds) using a diamond disc. The push-out strength was tested for each slice between the sealer and dentin wall using a universal testing machine at a crosshead speed of 1 mm/min, and failure modes were examined under a stereomicroscope at a (40X) magnification. The data were statistically analysed using a One-way ANOVA test, this was followed by a pair-wise comparison using the Bonferroni test, and all data were analysed at a 95% confidence interval (P-value ≤ 0.05). Results Results showed that there were statistically significant differences for the studied three groups (P < 0.05), where G2 exhibited significantly higher bond strength values compared to G3 (P < 0.05), while the lowest push-out strength was observed in G1. For the failure modes, there were statistically significant differences in the failure mode between the three groups (P < 0.05). For different levels of root, there were statistically significant differences (P < 0.05): the majority were cohesive failures 80%) in the coronal thirds of G2 and G3, while in G1, mixed failure was common, followed by adhesive failure to a lesser extent. Conclusions Within the limitations of this in vitro study, drying with (70% Isopropanol, 95% Ethanol) enhanced the bond strength between AH Plus sealer and dentinal tubules more effectively than the conventional paper point drying method when using the warm vertical condensation technique, with 70% isopropanol superior to the rest of the studied groups.