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Background. This study aimed to assess the accuracy of three electronic apex locators (EALs) (Dentaport ZX [J Morita, Tokyo, Japan], Propex Pixi [Dentsply Maillefer, Ballaigues, Switzerland], and iPex II [NSK, Tokyo, Japan]) during root canal retreatment. Methods. The root canal lengths of 90 extracted single-rooted human teeth were determined under a dental operating microscope at X 10 magnification. The actual working length (AWL) was 0.5 mm less than the root length. Electronic measurements were performed with the three EALs. The root canals were instrumented and filled to the actual working length using the lateral compaction technique. After seven days, the teeth were retreated until the retreatment file was applied to the root canal at the working length determined by EALs, and then, the three EALs were used for determining the retreatment working length. Data were analyzed using chi-squared and Kruskal--Wallis tests. Results. In the retreatment, the accuracy of EALs was reported at %83.3 for Dentaport ZX, %83.4 for Propex Pixi, and %80 for iPex II within a tolerance of 0.5± mm of the AWL. Conclusion. Under the limitations of this study, Dentaport ZX, Propex Pixi, and iPex II can be a useful adjunct during retreatment. Clinicians should be aware that residual materials in the root canal during retreatment can affect the accuracy of EALs. [ABSTRACT FROM AUTHOR]

Background. The aim of this study was to compare the postoperative pain intensity following the root canal preparation carried out with XP-endo Shaper (XPS; FKG Dentaire SA, La Chauxde-Fonds, Switzerland), iRace (iRC; FKG Dentaire SA) and Reciproc Blue (REC Blue; VDW, Munich, Germany) files. Methods. Mandibular molar teeth with asymtomatic necrotic pulps in 69 patients were randomly divided into three groups (n=23). The root canals were prepared using XPS, iRC or REC Blue instruments and obturated using the lateral condensation technique. The patients were asked to record their pain intensity at 24-, 48- and 72-hour and 1-week postoperative intervals on VAS. For intolerable pain after the procedure, ibuprofen (400 mg) was prescribed. Data were analyzed using chi-squared, Friedman, Kruskal-Wallis, and Mann-Whitney U tests. Results. The postoperative pain gradually decreased during the study period in all the groups (P<0.05). No statistically significant difference was found between iRC system and the two other systems at 12-, 24- 48-hour and 1-week intervals (P>0.05). When compared to XPS system, a higher level of postoperative pain was observed with REC Blue system at 24- and 48-hour intervals (P<0.05). Conclusion. The XPS group exhibited less postoperative pain than the REC Blue group at 24- and 48-hour intervals. iRC, XPS and REC Blue systems were found to be similar in terms of postoperative pain severity. [ABSTRACT FROM AUTHOR]

This study used micro-CT to compare three obturation techniques with respect to void occurrence in canals filled with bioceramic sealer. Thirty extracted first mandibular premolars were prepared with a ProTaper Universal system and randomly allocated to three groups. Canals were obturated with gutta-percha and bioceramic root canal sealer, using either single-cone, lateral compaction, or Thermafil filling technique. Each tooth was then scanned with micro-CT. Voids in 2D cross-sectional images and void volumes in 3D images of all root thirds were assessed in relation to obturation technique. There was no significant difference between obturation techniques in the proportion of sections with voids (P > 0.05). However, the results of the obturation techniques significantly differed in relation to root region (P < 0.05). In conclusion, no root filling technique resulted in void-free specimens. Void volumes were highest for the single-cone technique and lowest for Thermafil, in all regions (P < 0.05). [ABSTRACT FROM AUTHOR]

Background: We evaluated and compared the effects of different NiTi rotary systems -- ProTaper Next and New One Shape -- on the volume of dentin removed, canal transportation, and canal curvature in extracted human teeth using CBCT scanning with different voxel sizes. Methods: Fifty extracted human maxillary first molars with mesiobuccal canal curvature (25-35°) were used. Specimens were instrumented with the ProTaper Next or New One Shape. Pre- and post-instrumentation scans were performed to compare transportation at the levels of 2, 5, and 8 mm and volumes with two different voxel sizes (0.125-and 0.100-mm³) using 3D CBCT images. This study evaluated and compare the volume of dentin removed, canal transportation, and canal curvature. Differences according to instrumentation and voxel sizes were assessed using the Mann--Whitney U-test and the Wilcoxon signed-rank test. Results: Significant differences were found between apical and coronal levels for both systems (p < 0.05) in canal transportation. In comparing the systems, similar values were found at each level, without significant difference (p > 0.05) in terms of canal curvature and volume. Voxel sizes did not affect the measurements on canal volume, curvature or transportation; no significant difference was found between the 0.100- and 0.125-mm³ voxel sizes (p > 0.05). Conclusions: Both instrumentation systems produced similar canal transportation and volume changes. The two voxel resolutions also showed similar results, however a 0.125-mm³ voxel size can be recommend for a flat panel CBCT scanner with lower exposure dose. [ABSTRACT FROM AUTHOR]

Objectives: This micro-computed tomographic (CT) study aimed to compare the shaping abilities of ProTaper Next (PTN), One Shape (OS), and One Curve (OC) files in 3-dimensionally (3D)-printed mandibular molars., Materials and Methods: In order to ensure standardization, 3D-printed mandibular molars with a consistent mesiobuccal canal curvature (45°) were used in the present study ( n = 18). Specimens were instrumented with the OC, OS, or PTN files. The teeth were scanned pre- and post-instrumentation using micro-CT to detect changes of the canal volume and surface area, as well as to quantify transportation of the canals after instrumentation. Two-way analysis of variance was used for statistical comparisons., Results: No statistically significant differences were found between the OC and OS groups in the changes of the canal volume and surface area before and after instrumentation ( p > 0.05). The OC files showed significantly less transportation than the OS or PTN systems for the apical section ( p < 0.05). In a comparison of the systems, similar values were found at the coronal and middle levels, without any significant differences ( p > 0.05)., Conclusions: These 3 instrumentation systems showed similar shaping abilities, although the OC file achieved a lesser extent of transportation in the apical zone than the OS and PTN files. All 3 file systems were confirmed to be safe for use in mandibular mesial canals., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported., (Copyright © 2020. The Korean Academy of Conservative Dentistry.)

Objectives: The purpose of the present study was to compare the mean preparation times and frequency with which Reciproc and Reciproc Blue instruments reached the full working length in mandibular molars, with or without glide path preparation., Materials and Methods: Previously untreated mesiobuccal and mesiolingual canals with completely formed apices were randomly divided into 6 groups ( n = 50) depending on the usage of Reciproc (RC; VDW), Reciproc Blue (RC Blue; VDW), C-Pilot (CP; VDW), and R-Pilot (RP; VDW) files: RC, RC Blue, RC + C-Pilot (RC-CP), RC-Blue + C-Pilot (RC Blue-CP), RC+R-Pilot (RC-RP), and RC Blue + R-Pilot (RC Blue-RP). A glide path was prepared using the hand-operated C-Pilot or the machine-operated R-Pilot instruments, respectively. The χ 2 test, analysis of variance, and the Tukey post hoc test were used for statistical comparisons., Results: No statistically significant differences were observed in the distribution of the frequency of reaching the full working length in the RC (94%), RC Blue (88%), RC-CP (94%), RC Blue-CP (90%), RC-RP (96%), and RC Blue-RP (92%) groups ( p > 0.05)., Conclusions: Preparation of a glide path did not have a significant effect on reaching the full working length using these systems., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported.

Objective: The purpose of this study was to analyze the ability of multiple compounds to seal the dental tubules using scanning electron microscopy (SEM) and micro-computed tomogra-phy (micro-CT)., Material and Methods: Twenty-four single-root human mandibular premolars were selected and instrumented with nickel-titanium rotary file and the final file size was #40/06. They were then randomly allocated into 2 groups, and all samples were filled with single cone gutta-percha (#40/06) and one of the tested sealers (AH Plus and EndoSequence BC sealers). All specimens were scanned using micro-CT and then three from each group were randomly selected for SEM analysis., Results: According to SEM, both root canal sealers showed sufficient adaptation to dentin along the whole length of the root canal, though the coronal sections presented superior sealing than the apical sections. Micro porosity analyses revealed that the volume of closed pores and the surface of closed pores had the largest values in the coronal sections, followed by the middle and the apical sections for both sealants (p<0.05). However, no significant difference was observed for those two parameters between AH Plus and EndoSequence BC sealers in any of the three sections (p>0.05), whereas they were larger in the apical section when the AH Plus sealer was used., Conclusions: By using the single cone technique, neither EndoSequence or AH Plus pro-vides a porosity-free root canal filling. The EndoSequence BC sealer may have similar sealing abilities regarding the whole root canal as the AH Plus sealer. A better sealing effect could be obtained in the coronal and middle sections of a root canal than the apical part by using the tested sealers.

The aim of this study was to evaluate and compare the presence of voids in oval root canals filled with different root canal sealers (EndoSequence BC Sealer, Smartpaste bio, ActiV GP) and to compare those with root canals filled with AH Plus sealer using micro-CT. In total, 40 freshly extracted human single-root maxillary premolars were used. Specimens instrumented with the EndoSequence NiTi rotary instrument were assigned randomly into four groups. In each group, root canals were filled with single-cone gutta-percha and one of the tested sealers. Each specimen was then scanned using micro-CT at a voxel resolution of 13.47 μm. Proportions of sections with voids in cross-sectional images and void volumes for each sealer were calculated in the apical, middle, and coronal thirds. Differences according to root canal sealers were evaluated statistically using the Kruskal-Wallis test and the Mann-Whitney U-test at a significance level of 5%. The analysis showed a decrease in void formation in the apical third, with a significant difference between the apical and coronal thirds among bioceramic sealers, ActiV GP, and AH Plus (p < 0.05) but no significant difference between the apical and middle thirds or between the middle and coronal thirds was found for the sealers tested (p > 0.05). All root canal sealers tested resulted in voids. The bioceramic sealers (EndoSequence BC Sealer, Smartpaste bio) produced similar voids which had the fewest in the apical third of root canals among the sealers tested which can be related due to root canal anatomy variations., (© Wiley Periodicals, Inc.)

Objectives: Because of economic and political issues, Turkish Cypriots have been emigrating from Cyprus since the 1920s, especially to the United Kingdom, other European countries and Australia. Recently, according to the UK House of Commons, Home Affairs Committee, ~300,000 Cypriot Turks were living in the United Kingdom. However, this ethnic population residing in the United Kingdom has been insufficiently analysed. Although many Turkish Cypriots have been living abroad, little is known about the dental characteristics of this group. Premolar teeth, especially maxillary premolars, pose great challenges in endodontic treatment because of the number of roots and canals, and the variation in the configurations of the pulp cavity. Thus, it was considered valuable to determine the morphological characteristic of premolar teeth in a Turkish Cypriot population to aid clinicians in performing endodontic treatment in this ethnic population., Materials and Methods: The sample for this cross-sectional study consisted of a retrospective evaluation of cone-beam CT scans of 263 adult patients (age range 16-80 years). The number of roots and their morphology, the number of canals per root and the canal configuration were examined. The root canal configurations were also classified according to the scheme of Vertucci in the maxillary and mandibular premolar teeth. Pearson's χ 2 -test was performed among canal configurations, sides and gender ( P ⩽0.05)., Results: In the present study, most root canal configurations were type IV (76.8%) and type I (49.4%) in the maxillary first and second premolars, respectively, whereas most root canal configurations were type I (93%) in both mandibular first and second premolars. In total, four (0.9%) teeth in the maxillary first premolars and two (0.4%) teeth in the maxillary second molar premolars had three roots., Conclusions: This is the first population-based study to focus solely on Turkish Cypriots' root canal anatomy. Our findings will be valuable for dental professionals who treat many Turkish Cypriot patients, in the United Kingdom, Australia and other countries., Competing Interests: The authors declare no conflict of interest.