• Restorative Dentistry and Endodontics
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• v.40 no.2
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• pp.149-154
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• 2015

Objectives: This study evaluated the penetration depth of 2% chlorhexidine digluconate (CHX) into root dentinal tubules and the influence of passive ultrasonic irrigation (PUI) using a confocal laser scanning microscope (CLSM). Materials and Methods: Twenty freshly extracted anterior teeth were decoronated and instrumented using Mtwo rotary files up to size 40, 4% taper. The samples were randomly divided into two groups (n = 10), that is, conventional syringe irrigation (CSI) and PUI. CHX was mixed with Rhodamine B dye and was used as the final irrigant. The teeth were sectioned at coronal, middle and apical levels and viewed under CLSM to record the penetration depth of CHX. The data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests. Results: The mean penetration depths of 2% CHX in coronal, middle and apical thirds were $138{\mu}m$, $80{\mu}m$ and $44{\mu}m$ in CSI group, respectively, whereas the mean penetration depths were $209{\mu}m$, $138{\mu}m$ and $72{\mu}m$ respectively in PUI group. Statistically significant difference was present between CSI group and PUI group at all three levels (p < 0.01 for coronal third and p < 0.001 for middle and apical thirds). On intragroup analysis, both groups showed statistically significant difference among three levels (p < 0.001). Conclusions: Penetration depth of 2% CHX into root dentinal tubules is deeper in coronal third when compared to middle and apical third. PUI aided in deeper penetration of 2% CHX into dentinal tubules when compared to conventional syringe irrigation at all three levels.

• Restorative Dentistry and Endodontics
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• v.40 no.2
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• pp.143-148
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• 2015

Objectives: This study evaluated the maximum depth and percentage of irrigant penetration into dentinal tubules by passive ultrasonic irrigation (PUI). Materials and Methods: Thirty extracted human teeth were instrumented and divided into three groups. According to final irrigation regimen, 5.25% sodium hypochlorite (Group A, NaOCl), 2% chlorhexidine (Group B, CHX) and saline solution (Group C, control group) were applied with Irrisafe 20 tips (Acteon) and PUI. Irrigant was mixed with 0.1% rhodamine B. Sections at 2 mm, 5 mm, and 8 mm from the apex were examined with confocal laser scanning microscopy (CLSM). The percentage and maximum depth of irrigant penetration were measured. Kruskal-Wallis test and Mann-Whitney test were performed for overall comparison between groups at each level and for pairwise comparison, respectively. Within a group, Wilcoxon test was performed among different levels. p values less than 0.05 were considered significant. Results: In all groups, highest penetration depth and percentage of penetration were observed at the 8 mm level. At 2 mm level, Groups A and B had significantly greater depths and percentages in penetration than Group C (p < 0.05), but there were no significant differences between Groups A and B. At 5 mm level, penetration depths and percentage of penetration was not significantly different among the groups. Conclusions: NaOCl and CHX applied by PUI showed similar depth and percentage of penetration at all evaluated levels.

• Restorative Dentistry and Endodontics
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• v.30 no.4
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• pp.319-326
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• 2005

This study compared the microtensile bond strength $({\mu}TBS)$ of single step adhesives to different dentin depths. Superficial or deep dentin was exposed in 30 molar teeth by sectioning immediately under the DEJ or 1.5mm area from central pit, respectively. After polishing with 600-grit SiC paper, the dentin surfaces were assigned to three groups: AQ group-AQ Bond, L-Pop group-Adper Prompt L-Pop, Xeno group-Xeno III. The bonded specimens were sectioned into sticks and subjected to ${\mu}TBS$ testing with a crosshead speed of 1mm/minute. The results of this study were as follows; The ${\mu}TBS$ to superficial dentin was higher than that to deep dentin in all group. The ${\mu}TBS$ of Xeno group was significantly higher than that of L-Pop group and AQ group in both superficial and deep dentin (p<0.05).

• Restorative Dentistry and Endodontics
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• v.34 no.5
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• pp.406-414
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• 2009

The purpose of this study was to examine the effect of hydrogen peroxide at different application time and concentrations on the microtensile bond strength of resin restorations to the deep and the pulp chamber dentin. A conventional endodontic access cavity was prepared in each tooth, and then the teeth were randomly divided into 1 control group and 4 experimental groups as follows: Group 1, non treated; Group 2, with 20% Hydrogen peroxide ($H_2O_2$); Group 3, with 10% $H_2O_2$; Group 4, with 5% $H_2O_2$; Group 5, with 2.5% $H_2O_2$; the teeth of all groups except group 1 were treated for 20, 10, and 5min. The treated teeth were filled using a Superbond C&B (Sun medical Co., Shiga, Japan). Thereafter, the specimens were stored in distilled water at $37^{\circ}C$ for 24-hours and then sectioned into the deep and the chamber dentin. The microtensile bond strength values of each group were analyzed by 3-way ANOVA and Tukey post hoc test(p < 0.05). In this study, the microtensile bond strength of the deep dentin (D1) was significantly greater than that of the pulp chamber dentin (D2) in the all groups tested. The average of microtensile bond strength was decreased as the concentration and the application time of $H_2O_2$ were increased. Analysis showed significant correlation effect not only between the depth of the dentin and the concentration of $H_2O_2$ but also between the concentration of H202 and the application time(p < 0.05), while no significant difference existed among these three variables(p > 0.05). The higher $H_2O_2$ concentration, the more opened dentinal tubules under a scanning electron microscope(SEM) examination.