This study aimed to investigate the endodontic characteristics of mandibular premolars with dens evaginatus (DE) that require endodontic treatment.

Patients who underwent endodontic treatment were enrolled. The inclusion criteria were patients who underwent root canal treatment in the lower permanent teeth with DE and were followed up for at least 1 year. Preoperative clinical and radiographic variables were obtained. The frequency distribution of the preoperative variables was compared using the χ² or Fisher’s exact tests. The significance of the change in periapical health index (PAI) and root development stages before and after treatment was examined using the Wilcoxon signed-rank test.

A total of 150 teeth of 134 patients with an average age of 15.3 years were included. The percentage distribution comparison of the preoperative variables and obturation techniques revealed significant differences in pulpal and periapical diagnosis, and percussion, and especially regarding age, root development stage, and PAI. Age was the only statistically significant preoperative variable associated with root growth (p < 0.05).

Approximately, 60% of DEs requiring endodontic treatment had immature roots. Age being the most significant predisposing factor, early treatment provides the greatest opportunity for full root development.

The present study aims to compare the obturation quality of 2 confluence confirmation techniques in artificial maxillary first premolars showing Vertucci type II root canal configuration.

Thirty artificial maxillary premolars having Vertucci type II root canal configuration were made. They were divided into 3 groups according to the confluence confirmation technique as follows. Gutta-percha indentation (GPI) group (confluence confirmation using a gutta-percha cone and a K file); electronic apex locator (EAL) group (confluence confirmation using K files and EAL); and no confluence detection (NCD) group. In the GPI group and the EAL group, shaping and obturation were performed with the modified working length (WL). In the NCD group, shaping was performed without WL adjustment and obturation was carried out with an adjusted master cone. Micro-computed tomography was used before preparation and after obturation to calculate the percentage of gutta-percha occupied volume (%GPv) and the volume increase in the apical 4 mm. Data were analyzed using 1-way analysis of variance and post hoc Tukey's test.

Statistically significant difference was not found in terms of the %GPv from the apex to apical 4 mm. However, the NCD group showed a statistically significant volume increase compared with the EAL group (p < 0.05).

In terms of gutta-percha occupied volume, no significant difference was observed among the 3 groups. Confluence confirmation using an EAL in teeth with Vertucci type II configuration showed less volume increase during canal shaping compared with no confluence confirmation.

The aim of this study was to compare root canal volume change and canal transportation by Vortex Blue (VB; Dentsply Tulsa Dental Specialties), ProTaper Next (PTN; Dentsply Maillefer), and ProTaper Universal (PTU; Dentsply Maillefer) nickel-titanium rotary files in curved root canals.

Thirty canals with 20°–45° of curvature from extracted human molars were used. Root canal instrumentation was performed with VB, PTN, and PTU files up to #30.06, X3, and F3, respectively. Changes in root canal volume before and after the instrumentation, and the amount and direction of canal transportation at 1, 3, and 5 mm from the root apex were measured by using micro-computed tomography. Data of canal volume change were statistically analyzed using one-way analysis of variance and Tukey test, while data of amount and direction of transportation were analyzed using Kruskal-Wallis and Mann-Whitney U test.

There were no significant differences among 3 groups in terms of canal volume change (p > 0.05). For the amount of transportation, PTN showed significantly less transportation than PTU at 3 mm level (p = 0.005). VB files showed no significant difference in canal transportation at all 3 levels with either PTN or PTU files. Also, VB files showed unique inward transportation tendency in the apical area.

Other than PTN produced less amount of transportation than PTU at 3 mm level, all 3 file systems showed similar level of canal volume change and transportation, and VB file system could prepare the curved canals without significant shaping errors.

The aims of this study were to quantify tug-back by measuring the pulling force and investigate the correlation of clinical tug-back pulling force with in vitro gutta-percha (GP) cone adaptation score using micro-computed tomography (µCT).

Twenty-eight roots from human single-rooted teeth were divided into 2 groups. In the ProTaper Next (PTN) group, root canals were prepared with PTN, and in the ProFile (PF) group, root canals were prepared using PF (n = 14). The degree of tug-back was scored after selecting taper-matched GP cones. A novel method using a spring balance was designed to quantify the tug-back by measuring the pulling force. The correlation between tug-back scores, pulling force, and percentage of the gutta-percha occupied area (pGPOA) within apical 3 mm was investigated using µCT. The data were analyzed using Pearson's correlation analysis, one-way analysis of variance (ANOVA) and Tukey's test.

Specimens with a strong tug-back had a mean pulling force of 1.24 N (range, 0.15–1.70 N). This study showed a positive correlation between tug-back score, pulling force, and pGPOA. However, there was no significant difference in these factors between the PTN and PF groups. Regardless of the groups, pGPOA and pulling force were significantly higher in the specimens with a higher tug-back score (p < 0.05).

The degree of subjective tug-back was a definitive determinant for master cone adaptation in the root canal. The use of the tug-back scoring system and pulling force allows the interpretation of subjective tug-back in a more objective and quantitative manner.

This study aimed to evaluate the healing rate of non-surgical endodontic treatment between C-shaped and non-C-shaped mandibular second molars.

Clinical records and radiological images of patients who had undergone endodontic treatment on mandibular second molars between 2007 and 2014 were screened. The periapical index scoring system was applied to compare healing outcomes. Information about preoperative and postoperative factors as well as the demographic data of the patients was acquired and evaluated using chi-square and multinomial logistic regression tests.

The total healing rate was 68.4%. Healing rates for the mandibular second molar were 70.9% in C-shaped canals (n = 79) and 66.6% in non-C-shaped ones (n = 117). The difference was not statistically significant.

The presence of a C-shaped canal in the mandibular second molar did not have a significantly negative effect on healing after treatment. Instead, proper pulpal diagnosis and final restoration were indicated as having significantly greater influence on the healing outcomes of C-shaped and non-C-shaped canals, respectively.

We analyzed gene-expression profiles after 14 day odontogenic induction of human dental pulp cells (DPCs) using a DNA microarray and sought candidate genes possibly associated with mineralization.

Induced human dental pulp cells were obtained by culturing DPCs in odontogenic induction medium (OM) for 14 day. Cells exposed to normal culture medium were used as controls. Total RNA was extracted from cells and analyzed by microarray analysis and the key results were confirmed selectively by reverse-transcriptase polymerase chain reaction (RT-PCR). We also performed a gene set enrichment analysis (GSEA) of the microarray data.

Six hundred and five genes among the 47,320 probes on the BeadChip differed by a factor of more than two-fold in the induced cells. Of these, 217 genes were upregulated, and 388 were down-regulated. GSEA revealed that in the induced cells, genes implicated in Apoptosis and Signaling by wingless MMTV integration (Wnt) were significantly upregulated.

Genes implicated in Apoptosis and Signaling by Wnt are highly connected to the differentiation of dental pulp cells into odontoblast.

The purpose of this study was to determine the optimal master apical file size with minimal transportation and optimal efficiency in removing infected dentin. We evaluated the transportation of the canal center and the change in untouched areas after sequential preparation with a #25 to #40 file using 3 different instruments: stainless steel K-type (SS K-file) hand file, ProFile and LightSpeed using microcomputed tomography (MCT).

Thirty extracted human mandibular molars with separated orifices and apical foramens on mesial canals were used. Teeth were randomly divided into three groups: SS K-file, Profile, LightSpeed and the root canals were instrumented using corresponding instruments from #20 to #40. All teeth were scanned with MCT before and after instrumentation. Cross section images were used to evaluate canal transportation and untouched area at 1- , 2- , 3- , and 5- mm level from the apex. Data were statistically analyzed according to' repeated nested design'and Mann-Whitney test (p = 0.05).

In SS K-file group, canal transportation was significantly increased over #30 instrument. In the ProFile group, canal transportation was significantly increased after preparation with the #40 instrument at the 1- and 2- mm levels. LightSpeed group showed better centering ability than ProFile group after preparation with the #40 instrument at the 1 and 2 mm levels.

SS K-file, Profile, and LightSpeed showed differences in the degree of apical transportation depending on the size of the master apical file.