The purpose of this ex vivo study was to compare the antifungal activity of a synthetic peptide consisting of 15 amino acids at the C-terminus of human β-defensin 3 (HBD3-C15) with calcium hydroxide (CH) and Nystatin (Nys) against Candida albicans (C. albicans) biofilm.

C. albicans were grown on cover glass bottom dishes or human dentin disks for 48 hr, and then treated with HBD3-C15 (0, 12.5, 25, 50, 100, 150, 200, and 300 µg/mL), CH (100 µg/mL), and Nys (20 µg/mL) for 7 days at 37℃. On cover glass, live and dead cells in the biomass were measured by the FilmTracer Biofilm viability assay, and observed by confocal laser scanning microscopy (CLSM). On dentin, normal, diminished and ruptured cells were observed by field-emission scanning electron microscopy (FE-SEM). The results were subjected to a two-tailed t-test, a one way analysis variance and a post hoc test at a significance level of p = 0.05.

C. albicans survival on dentin was inhibited by HBD3-C15 in a dose-dependent manner. There were fewer aggregations of C. albicans in the groups of Nys and HBD3-C15 (≥ 100 µg/mL). CLSM showed C. albicans survival was reduced by HBD3-C15 in a dose dependent manner. Nys and HBD3-C15 (≥ 100 µg/mL) showed significant fungicidal activity compared to CH group (p < 0.05).

Synthetic HBD3-C15 peptide (≥ 100 µg/mL) and Nys exhibited significantly higher antifungal activity than CH against C. albicans by inhibiting cell survival and biofilm.

To evaluate the effects of three acids on the microhardness of set mineral trioxide aggregate (MTA) and root dentin, and cytotoxicity on murine macrophage.

OrthoMTA (BioMTA) was mixed and packed into the human root dentin blocks of 1.5 mm diameter and 5 mm height. Four groups, each of ten roots, were exposed to 10% citric acid (CA), 5% glycolic acid (GA), 17% ethylenediaminetetraacetic acid (EDTA), and saline for five minutes after setting of the OrthoMTA. Vickers surface microhardness of set MTA and dentin was measured before and after exposure to solutions, and compared between groups using one-way ANOVA with Tukey test. The microhardness value of each group was analyzed using student t test. Acid-treated OrthoMTA and dentin was examined by scanning electron microscope (SEM). Cell viability of tested solutions was assessed using WST-8 assay and murine macrophage.

Three test solutions reduced microhardness of dentin. 17% EDTA demonstrated severe dentinal erosion, significantly reduced the dentinal microhardness compared to 10% CA (p = 0.034) or 5% GA (p = 0.006). 10% CA or 5% GA significantly reduced the surface microhardness of set MTA compared to 17% EDTA and saline (p < 0.001). Acid-treated OrthoMTA demonstrated microporous structure with destruction of globular crystal. EDTA exhibited significantly more cellular toxicity than the other acidic solutions at diluted concentrations (0.2, 0.5, 1.0%).

Tested acidic solutions reduced microhardness of root dentin. Five minute's application of 10% CA and 5% GA significantly reduced the microhardness of set OrthoMTA with lower cellular cytotoxicity compared to 17% EDTA.

This study compared the mechanical properties of various instruments for canal exploration and glide-path preparations.

The buckling resistance, bending stiffness, ultimate torsional strength, and fracture angle under torsional load were compared for C+ file (CP, Dentsply Maillefer), M access K-file (MA, Dentsply Maillefer), Mani K-file (MN, Mani), and NiTiFlex K-file (NT, Dentsply Maillefer). The files of ISO size #15 and a shaft length of 25 mm were selected. For measuring buckling resistance (n = 10), the files were loaded in the axial direction of the shaft, and the maximum load was measured during the files' deflection. The files (n = 10) were fixed at 3-mm from the tip and then bent 45° with respect to their long axis, while the bending force was recorded by a load cell. For measuring the torsional properties, the files (n = 10) were also fixed at 3-mm, and clockwise rotations (2-rpm) were applied to the files in a straight state. The torsional load and the distortion angle were recorded until the files succumbed to the torque.

The CP was shown to require the highest load to buckle and bend the files, and the NT showed the least. While MA and MN showed similar buckling resistances, MN showed higher bending stiffness than MA. The NT had the lowest bending stiffness and ultimate torsional strength (p < 0.05).

The tested instruments showed different mechanical properties depending on the evaluated parameters. CP and NT files were revealed to be the stiffest and the most flexible instruments, respectively.

The purpose of this study was to compare the cutting efficiency of a newly developed microprojection tip and a diamond-coated tip under two different engine powers.

The apical 3-mm of each root was resected, and root-end preparation was performed with upward and downward pressure using one of the ultrasonic tips, KIS-1D (Obtura Spartan) or JT-5B (B&L Biotech Ltd.). The ultrasonic engine was set to power-1 or -4. Forty teeth were randomly divided into four groups: K1 (KIS-1D / Power-1), J1 (JT-5B / Power-1), K4 (KIS-1D / Power-4), and J4 (JT-5B / Power-4). The total time required for root-end preparation was recorded. All teeth were resected and the apical parts were evaluated for the number and length of cracks using a confocal scanning micrscope. The size of the root-end cavity and the width of the remaining dentin were recorded. The data were statistically analyzed using two-way analysis of variance and a Mann-Whitney test.

There was no significant difference in the time required between the instrument groups, but the power-4 groups showed reduced preparation time for both instrument groups (p < 0.05). The K4 and J4 groups with a power-4 showed a significantly higher crack formation and a longer crack irrespective of the instruments. There was no significant difference in the remaining dentin thickness or any of the parameters after preparation.

Ultrasonic tips with microprojections would be an option to substitute for the conventional ultrasonic tips with a diamond coating with the same clinical efficiency.

The aim of this study was to compare the cleaning efficacy of different final irrigation regimens in canal and isthmus of mandibular molars, and to evaluate the influence of related variables on cleaning efficacy of the irrigation systems.

Mesial root canals from 60 mandibular molars were prepared and divided into 4 experimental groups according to the final irrigation technique: Group C, syringe irrigation; Group U, ultrasonics activation; Group SC, VPro StreamClean irrigation; Group EV, EndoVac irrigation. Cross-sections at 1, 3 and 5 mm levels from the apex were examined to calculate remaining debris area in the canal and isthmus spaces. Statistical analysis was completed by using Kruskal-Wallis test and Mann-Whitney U test for comparison among groups, and multivariate linear analysis to identify the significant variables (regular replenishment of irrigant, vapor lock management, and ultrasonic activation of irrigant) affecting the cleaning efficacy of the experimental groups.

Group SC and EV showed significantly higher canal cleanliness values than group C and U at 1 mm level (p < 0.05), and higher isthmus cleanliness values than group U at 3 mm and all levels of group C (p < 0.05). Multivariate linear regression analysis demonstrated that all variables had independent positive correlation at 1 mm level of canal and at all levels of isthmus with statistical significances.

Both VPro StreamClean and EndoVac system showed favorable result as final irrigation regimens for cleaning debris in the complicated root canal system having curved canal and/or isthmus. The debridement of the isthmi significantly depends on the variables rather than the canals.

The purpose was to investigate the preference and usage technique of NiTi rotary instruments and to retrieve data on the frequency of re-use and the estimated incidence of file separation in the clinical practice among general dentists.

A survey was disseminated via e-mail and on-site to 673 general dentists. The correlation between the operator's experience or preferred technique and frequency of re-use or incidence of file fracture was assessed.

A total of 348 dentists (51.7%) responded. The most frequently used NiTi instruments was ProFile (39.8%) followed by ProTaper. The most preferred preparation technique was crown-down (44.6%). 54.3% of the respondents re-used NiTi files more than 10 times. There was a significant correlation between experience with NiTi files and the number of reuses (p = 0.0025). 54.6% of the respondents estimated experiencing file separation less than 5 times per year. The frequency of separation was significantly correlated with the instrumentation technique (p = 0.0003).

A large number of general dentists in Korea prefer to re-use NiTi rotary files. As their experience with NiTi files increased, the number of re-uses increased, while the frequency of breakage decreased. Operators who adopt the hybrid technique showed less tendency of separation even with the increased number of re-use.

This study investigated changes in gene expressions concerning of differentiation, proliferation, mineralization and inflammation using Human-8 expression bead arrays when white Mineral Trioxide Aggregate and calcium hydroxide-containing cement were applied in vitro to human dental pulp cells (HDPCs).

wMTA (white ProRoot MTA, Dentsply) and Dycal (Dentsply Caulk) in a Teflon tube (inner diameter 10 mm, height 1 mm) were applied to HDPCs. Empty tube-applied HDPCs were used as negative control. Total RNA was extracted at 3, 6, 9 and 24 hr after wMTA and Dycal application. The results of microarray were confirmed by reverse transcriptase polymerase chain reaction.

Out of the 24,546 genes, 43 genes (e.g., BMP2, FOSB, THBS1, EDN1, IL11, COL10A1, TUFT1, HMOX1) were up-regulated greater than two-fold and 25 genes (e.g., SMAD6, TIMP2, DCN, SOCS2, CEBPD, KIAA1199) were down-regulated below 50% by wMTA. Two hundred thirty nine genes (e.g., BMP2, BMP6, SMAD6, IL11, FOS, VEGFA, PlGF, HMOX1, SOCS2, CEBPD, KIAA1199) were up-regulated greater than two-fold and 358 genes (e.g., EDN1, FGF) were down-regulated below 50% by Dycal.

Both wMTA and Dycal induced changes in gene expressions related with differentiation and proliferation of pulp cells. wMTA induced changes in gene expressions related with mineralization, and Dycal induced those related with angiogenesis. The genes related with inflammation were more expressed by Dycal than by wMTA. It was confirmed that both wMTA and Dycal were able to induce gene expression changes concerned with the pulp repair in different ways.

The aim of this study was to investigate levels of matrix metalloproteinase-8 (MMP-8) and substance P (SP) in root canal exudates during root canal treatment (RCT) of nonvital, painful teeth.

Patients scheduled for nonsurgical RCT were prospectively selected; the study was performed after obtaining informed consent from the patients and was approved by the Institutional Review Board for Clinical Research of Gangnam Severance Hospital, Yonsei University (3-2008-0118). Canal exudates samples were collected using sterilized paper points from teeth scheduled for RCT across three different time periods. MMP-8 and SP levels were measured using enzyme-linked immunosorbent assay (ELISA). Data were analyzed using a mixed model analysis and the Pearson correlation analysis (p < 0.05).

MMP-8 and SP levels in GCF were decreased during RCT (p < 0.0001), and they showed a weak positive correlation to each other (p < 0.05). Patients'subjective pain levels and the response from percussion test were significantly related to SP level.

This study demonstrated that periradicular inflammation endodontic origin can elevate SP and MMP-8 levels in root canal exudates. Interestingly, SP level of canal exudates showed a possibility of being used as an indicator of pain due to periapical pathosis.