• Restorative Dentistry and Endodontics
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• v.32 no.6
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• pp.530-541
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• 2007

Currently, various Nickel-Titanium rotary files are used in endodontic treatment, but there is no one perfect system that can be applied to any clinical situation. Therefore, the combined uses of various file systems which can emphasize the advantages of each system are introduced as hybrid instrumentation. The ProTaper system is efficient in body shaping and apical pre-enlargement but is reported to have more possibility of transportation and produce more aberrations and deformation in more or less severe curved canals. Recently, new ProTaper system(ProTaper Universal) with different configuration and cross-sectional design to overcome the week points of ProTaper have been marketed. The purpose of this study was to compare and evaluate the shaping abilities of ProTaper, ProTaper Universal system, and two hybrid methods using S-series of ProTaper Universal and Hero Shaper or ProFile. The time lapses for instrumentation were measured and the used files were inspected for distortion. The pre- and post-instrumented root canals were scanned and superimposed to evaluate the aberrations and reduction of root canal curvature and change of radius of canal curvature. The increased canal width and apical centering ratio were calculated at 1, 2, 3, 4 and 5 mm levels from apical foramen. Under the conditions of this study, the ProTaper Universal seems to have better shaping ability than ProTaper in terms of instrumented width and instrumentation time. It may be suggested that the ProTaper Universal system is efficient as much as hybrid instrumentation using ProTaper and other constant-tapered NiTi file systems in highly experienced operators.

• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.335-343
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• 2010

Objectives: To compared the effect of different levels of moisture of root canal on the sealing ability after filling with four different types of sealer. Materials and Methods: Single-rooted teeth (n = 90) instrumented to and apical size of 0.06 / 45 were randomly assigned to 12 experimental groups (n = 7 per group), positive/negative control groups (n = 3 per group). The teeth of the experimental groups (a. DRY; b. PAPER POINT DRY; c. WET) were obturated with sealer (Group 1-3: Sealapex; Group 4-6: AH plus; Group 7-9: Tubuli-seal; Group 10-12: EndoRez) and warm vertical compaction method. After 7 days in $37^{\circ}C$, 100% humidity, the coronal-to-apical microleakage was evaluated quantitatively using a glucose leakage model. The leaked glucose concentration was measured with spectrophotometer at 1, 3, 7, 14, 21, and 30 days. Data were recorded ad mmol/L and statistically analysed with the two-way ANOVA and Duncan test (p = 0.05). Results: Throughout the experimental period Tubuli-seal/WET (Group 9) showed the highest mean cumulative glucose penetration (178.75 mmol/L), whereas AH plus/DRY (Group 4) had the least (20.78 mmol/L). Conclusions: The results of this study demonstrated that the moisture condition of root canals at the time of obturation and the type of sealer that was used had a significant effect on leakage and sealing ability. Thus drying procedure according to sealer types is a critical step and should not be missed in endodontic treatment.

• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.515-525
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• 2009

Clinical suggestion for the limitation of application time of NaOCl solution is needed to avoid large reductions in resin-dentin bond strength. The aim of this study was to measure the change of ${\mu}$-tensile bond strength after the various application time of 5.25% NaOCl solution to pulp chamber dentin in endodontic access cavity, and to evaluate the effect of 10% sodium ascorbate application for 10 min on bond strength after the treatment of 5.25% NaOCl solution. In this experiment, there were no statistical differences(p > 0.05) in bond strengths between upper chamber dentin and lower chamber dentin. NaOCl-treated group for 20 min did not show any significant decrease(p > 0.05) in bond strength than non-treated control group. In contrast to that, bond strengths of NaOCl-treated groups for 40 & 80 min were significantly lower(p < 0.05) than that of non-treated control group. 10% sodium ascorbate retreated group for 10 min after 5.25% NaOCl application for 40 min to chamber dentin showed the recovery of bond strength significantly. However, the bond strength of sodium ascorbate retreated group after 5.25% NaOCl application for 80 min was still significantly lower(p < 0.05) compared to the non-treated control group, which means the reductions in resin-dentin bond strength were not fully reversed. On the contrary, sodium ascorbate retreated group after 5.25% NaOCl application for 5 min showed significantly higher(p < 0.05) bond strength compared to the control group, which demonstrates its superior recovery effect. In SEM exminations of specimens retreated with 10% sodium ascorbate after NaOCl application for 40 & 80 min showed that resin tags were formed clearly and densely, but weakly in density and homogeneity of individual resin tag compared to the control specimen.