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Aim: To compare the accuracy of four different electronic apex locators (EALs) in detecting a position 0.5 mm short of the major foramen. Materials and methods: The actual working length of thirty-five extracted human teeth was determined visually as 0.5 mm short of the apical foramen. After actual working length measurements, electronic working length was measured with four different EALs (Apex Pointer+, Raypex 5, Apex ID, and Raypex 6). Measurements were repeated three times by different operators. The data were analyzed using the intraclass correlation coefficient (ICC), the repeated measure analysis of variance (rANOVA) and Bonferroni post hoc tests. The significance level was set at p = 0.05. Results: The mean differences between electronic and actual working length were-0.305 mm, 0.098 mm, 0.037, and 0.144 mm for the Apex Pointer+, the Raypex 5, the Apex ID, and the Raypex 6, respectively. Multiple paired comparisons (Bonferroni test) also showed the Apex Pointer+ is significantly different from the Raypex 5, Apex ID and Raypex 6 (p = 0.000, p = 0.001, and p = 0.001 respectively). Conclusion: All EALs showed an acceptable determination of the working length between the ranges of ± 0.5mm except for the Apex Pointer+ device, which had the lowest accuracy. Further studies may be beneficial especially to better evaluate the accuracy of the Apex Pointer+. Clinical significance: This article shows that Apex ID, which has only recently been introduced into the market, showed an acceptable determination of the working length. Its accuracy was similar to that of Raypex 5 and 6.

Objective: We aimed here to evaluate the enlargement characteristics of two nickel-titanium rotary instrument systems that use two different preparation techniques, in simulated root canals under "operator-related variables" standardized conditions. Materials and Methods: A total of 40 simulated canals in resin blocks were divided into two groups as the Mtwo group for use with a single-length technique and the ProTaper instrument system group for use with crown down technique. To standardize the operator-related variables, all preparations were carried out with a computer controlled device that was developed and used previously as described in a published study. The pre- and post-operative digital images of the canals were superimposed and measured at 11 levels from the apical tip. The distances between the pre- and post-operative outer lines of the root canals were measured at both the inner and outer sides of the curve. The amount of removed material and the symmetry of the preparations were evaluated. Statistical analyses were performed with Mann-Whitney test. Results: Significantly more material was removed by Mtwo at 9 levels and by ProTaper at 2 levels (P < 0.05) while no significant difference was determined at 11 levels. The preparations made with ProTaper were more symmetrical at 4 levels while no significant difference was determined at 7 levels. Conclusions: Mtwo removed significantly more material than ProTaper at different levels of the curved root canals. Mtwo and ProTaper made symmetrical preparations and maintained the original shape of the root canal at different levels under controlled operator-related variables.

Aim. To assess and compare the water sorption, solubility and apical sealing ability of iRoot SP and three other widely used root canal sealers. Materials and methods. Solubility was assessed by immersing standardized samples of calcium silicate( iRoot SP), calcium hydroxide-(Sealapex), methacrylate resin- (EndoREZ) and epoxy resin-(AH Plus) based sealers in distilled water and measuring weight gain and weight loss at 6 h, 24 h and daily for 14 days. Roots of extracted mandibular premolars (n = 80) were prepared with 0.04-taper nickel-titanium rotary files to a final size 40. Roots were then randomly divided into four experimental groups (n = 18) and two control groups (n = 4), root canal sealers were applied and apical leakage was assessed using the fluid filtration method. Data was analyzed using Kruskal Wallis analysis of variance and Mann-Whitney U-tests, with the level of significance set at p

WOS: 000310719500011 Background/purpose: The manufacturer claims that Twisted Files (TFs) are superior to file systems made by the traditional grinding method due to their cyclic fatigue resistance, flexibility, and better cutting efficiency. The aim of this study was to compare the shaping ability of TFs with instruments produced by a traditional NiTi grinding process (RevoS and ProTaper). Materials and methods: A total of 60 simulated resin blocks were divided into three experimental groups, each comprised of 20 resin blocks that were prepared with TFs, RevoS, and ProTaper using a crown-down technique. The preparation shape was assessed with a computer image analysis program on superimposed pre- and postoperative images. Material removal was measured at 10 points beginning 1 mm from the end-point of the canal. Mean total widths and outer and inner width measurements were determined on each central canal path, and the data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U-tests. Results: The Revo-S and ProTaper instruments removed more material from the inner side of the curvature compared with the IF instruments. Differences among the three rotary NiTi systems were statistically significant (P < 0.05) except for the first 3 mm and the last 2 mm. On the outer side of the canal, both the ProTaper and Revo-S instruments removed more material than the TF instruments in the apical third (P < 0.05). Conclusion: According to the results of this study, TFs respected the original canal curvature better than did ProTaper and RevoS rotary NiTi instruments. IF instruments also provided a more-centered apical preparation of the simulated canals at the apical third. Copyright (c) 2012, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.

The fracture of nickel-titanium rotary instruments is a serious problem that can jeopardise the outcome of root canal treatment. The aim of this study was to compare the cyclic fatigue resistance of new and used Mtwo rotary nickel-titanium instruments in artificial canals with two different radii of curvature. Four hundred and twenty Mtwo instruments were used in the present study. Thirty new and 30 used instruments of each size were tested for cyclic fatigue in artificial canals with radii of curvature of 5 or 10 mm. Each instrument was rotated until fracture occurred and the number of cycles to fracture was calculated by multiplying time to fracture and rotational speed. Data were analysed using a t-test. According to the results of the study, radius of curvature was an important factor on cyclic fatigue resistance and clinical use significantly reduced the instrument lifespan.

Seyrek M, Vural IM, Tunca YM, Aydin C, Ulku C, Demirkaya K, Inal A, Yildiz O. The vasodilatory effect of a synthetic polymer-based root canal material on thoracic aorta. International Endodontic Journal 43, 590–599, 2010. Abstract Aim To test the hypothesis that, Epiphany, either in its mixed form or as separate components, can alter the vascular reactivity of isolated rat thoracic aorta. The possible mechanism of its vascular action was also investigated. Methodology The relaxant effect of the base, the catalyst and mixed Epiphany on isolated rat aortic rings pre-contracted with phenylephrine (PE) was tested. The aortic rings were then incubated with either nitric oxide synthase (NOS) inhibitor, cyclooxygenase (COX) inhibitor or K+ channel inhibitors; after pre-contraction with PE, relaxations to the various compounds of Epiphany were examined. In another set of experiments, to investigate the Ca2+channel antagonistic effect of the Epiphany, the effect of these compounds in Ca2+-free solution on extracellular Ca2+(CaCl2)-induced contraction in high-K+ pre-challenged rings (in K+-depolarized rings) was examined to determine whether the direct inhibition of [Ca2+] influx increase accounted for the vasodilatory effects of these compounds. For comparison, L-type Ca2+channel blocker nifedipine (1 μmol L−1), instead of Epiphany compounds, was assayed in adjacent rat aortic rings in parallel. Results The catalyst and the mixture of Epiphany induced concentration-dependent relaxations. However, the base of Epiphany did not cause relaxation in rat aorta. The relaxation responses were not significantly altered by incubation of aorta with NOS, COX and potassium channel inhibitors. Whilst nifedipine, the catalyst and the mixture of Epiphany inhibited CaCl2-induced contractions (P 0.05). Conclusion Epiphany induced relaxation of rat aorta via a calcium antagonistic effect. Provided that the vasodilatory effect elicited by Epiphany can be reversed by the circulation, its haemorrhagic potential by virtue of permanent vascular dilatation can be ignored.

WOS: 000253603600042 PubMed: 18280956 Objective. This study compared the shaping ability of Hero Shaper and RaCe instruments in simulated curved canals. Study design. Forty simulated canals in resin blocks were divided into 2 experimental groups, each comprising 20 resin blocks, and prepared with Hero Shaper and RaCe using the crown-down technique. Preoperative and postoperative photographs, recorded using a digital camera, were superimposed and aberrations were recorded. Material removal was measured at 10 points beginning 1 mm from the end point of the canal. Mean total widths, outer and inner width measurements, were determined on each central canal path and differences were statistically analyzed using Student t test. Results. The Hero Shaper and RaCe instruments removed almost the same amount of material from the inner side of the simulated canals. On the outer canal wall, the RaCe instruments removed significantly more material from the first 3 mm (P < .05). However, Hero Shaper removed more material from the middle and coronal aspects of the canal and the differences were statistically significant (P < .01). Conclusion. RaCe instruments removed more resin from the outside of the curvature at the apical thirds, while Hero Shaper removed more material from the middle and coronal thirds on the outer canal wall. Hero Shaper instruments showed better centering ability and fewer aberrations. No instrument fractures but some deformations were observed for both systems.

The main objective of this in vitro study was to evaluate the effects of the operator's experience level and pre-flaring on the accuracy of the results of three different brands of a new generation of root canal measuring devices, as well as the comparison among them. Extracted human teeth were prepared and then actual length and electronic length measurements were made by three different operators according to a double-blind technique. Three different operators performed electronic measurements on each specimen separately with three different electronic root canal measuring devices using in vitro models. Measurements were repeated by all operators after the pre-flaring. Taking the clinical tolerance of ± 0.5 mm into account, there was no statistically significant difference between the accuracy of the instruments (P > 0.01). However, the results obtained from the Bingo electronic apex locator in pre-flared canals by the beginner operator were statistically significant (P < 0.01). All of the instruments had a clinically acceptable result at the tolerance of ± 0.5 mm. If the instruments are used in accordance with the manufacturer's instructions, experience with electronic root canal measurement is not essential. However, the operator has to be more careful when working on pre-flared canals.

Introduction: The aim of this study was to evaluate the push-out bond strength of iRoot SP (Innovative Bioceramix, Vancouver, Canada) and compare it with that of other widely used root canal sealers. Methods: Sixty extracted human maxillary canines were sectioned transversally below the cement-enamel junction to obtain 120 4-mm-thick dentin disks that were randomly divided into four groups (n = 30) for treatment with one of four different root-canal sealers (iRoot SP, AH Plus [Dentsply DeTrey GmbH, Konstanz, Germany], Sealapex [SybronEndo Corporation, Orange, CA], EndoREZ [Ultradent Inc, South Jordan, UT]). Standardized cavities were prepared to simulate root canals, cavities were filled with sealer material, and push-out bond-strength testing was performed using a universal testing machine. Failure modes were assessed quantitatively under a stereomicroscope and morphologically under a scanning electron microscope. Statistical analysis was performed using one-way analysis of variance and the post hoc Tukey test, with the significance level set at 0.05. Results: Bond strengths of iRoot SP and AH Plus were significantly higher than those of Sealapex and EndoREZ. There was no significant difference between the bond strength of iRoot SP and AH Plus (p = 0.274). Conclusions: iRoot SP and AN Plus performed similarly and better than EndoREZ and Sealapex in terms of bond strength. (J Endod 2010;36:2000 -2002)

WOS: 000274956600046 PubMed: 20219578 Objective. The aim of this study was to evaluate cyclic fatigue resistance of used and new RaCe rotary nickel-titanium instruments. Study design. Forty RaCe (FKG Dentaire, La-Chaux-de-Fonds, Switzerland) instruments of sizes 30/.06, 30/.02, 25/.04, and 25/.02 were selected and divided into 2 groups: group A = 20 new instruments; group B = 20 used instruments. In group B, each instrument was used for shaping 5 curved molar root canals. Cyclic fatigue testing of new and used instruments was performed using a device that allowed the instruments to rotate freely inside a stainless steel artificial canal. Data were analyzed using t test to determine any statistical significance between used and new instruments of the same file size. Results. For all sizes, new instruments were more resistant to failure then the used ones (P < .05). A reduction in lifespan was observed ranging from 18% (30/.06) to 51% (25/.02). Conclusion. The results showed that clinical use significantly reduced cyclic fatigue resistance of RaCe rotary instruments compared with new ones. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 109: e131-e134)

WOS: 000255344300020 PubMed: 18329912 Objective. The aim of this study was to investigate the effect of sodium hypochlorite immersion on the surface characteristics of RaCe rotary nickel-titanium instruments using atomic force microscopy (AFM). Study design. Four new RaCe instruments were used in this study (two 30.06 and two 30.02). One 30.06 and one 30.02 instrument were immersed in sodium hypochlorite solution for 5 min. Surface topography of the instruments was evaluated using the AFM. The instruments were analyzed on 11 points along a 3-mm section. Root mean square (RMS) values were used to compare the topographic deviations. The data were analyzed using Student t test. Results. Mean RMS values for NaOCl measurements were higher than the measurements on new files, and the difference was statistically significant (P

WOS: 000251677300031 PubMed: 17904394 Objective. This study compared the cyclic fatigue resistance of ProTaper rotary nickel-titanium (NiTi) files in artificial canals with 2 different radii of curvature. Study design. One hundred ProTaper rotary instruments were used in this study. Twenty files of each size (S1, S2, F1, F2, and F3) were tested. Cyclic fatigue testing was performed using a device that allowed the instruments to rotate freely inside stainless steel artificial canals with radii of curvature of 5 and 10 mm. The number of cycles to fracture was recorded for each file and the data were analyzed using a t-test. Results. The 5-mm radius group had significantly fewer cycles to fracture than the 10-mm radius group for all file sizes. For sizes F2 and F3, the difference between the 5 and 10-mm radius groups was highly significant (P < .001). For the 10-mm group, the difference between S1 and F3 was significant (P < .05). For the more abrupt 5-mm radius group, the difference between S1-F2, S2-F2, and F1-F2 was statistically significant. The difference between S1-F3, S2-F3, and F1-F3 was highly significant (P < .001). Conclusion. Cyclic fatigue resistance of ProTaper instruments was dependent on both instrument size and radius of curvature. Especially larger-size instruments should be used with great care in curved canals.

Objective. This study aimed to test the hypothesis that aggressive dentin removal through greater-tapered instrumentation reduces the intracanal bacteria more effectively than conservative dimension instrumentation. Material and methods. Twenty extracted human lower premolar teeth were used. After extirpation of the pulps, the teeth were autoclaved and immersed in a broth inoculated with Enterococcus faecalis and incubated for 7 days to allow infection of the dentinal tubules. The teeth were divided into 2 experimental groups, each comprising 10 teeth. The teeth were instrumented either with ProTaper or with Hero Shaper nickel-titanium rotary instrumentation techniques. It was calculated that ProTaper theoretically has the potential to remove at least twice the dentin volume compared with Hero Shaper. The apical preparation was standardized to file size 30. Saline solution was used for irrigation. Bacteriological samples were taken before and after instrumentation and plated onto tryptic soy agar, and the reduction in numbers was calculated. Results. Both instrumentation techniques significantly reduced the number of bacteria in the root canal (p < 0.05). Reduction in absolute bacterial numbers was up to 98%. There was no statistically significant difference between the two techniques. Conclusions. Preparation with an instrumentation technique removing substantial amounts of dentin did not reduce the intracanal bacteria more effectively than a more conservative instrumentation technique.

WOS: 000250764300016 PubMed: 17963958 The purpose of this study was to evaluate the topography of new and used ProTaper rotary nickel-titanium (NiTi) instruments by using atomic force microscope. Four new and four used size S1, S2, F1, and F2 instruments were selected for this study. New and used instruments were analyzed on 11 points along a 3-mm section at the tip of the instrument. Quantitative measurements according to the topographic deviations (root mean square) were recorded. Data were analyzed by paired samples t test. Mean root mean square values for used ProTaper instruments were higher than the new ones, and the difference between them was statistically significant. The results of this study showed that used ProTaper instruments demonstrated more surface deformation and wear.

Mineral trioxide aggregate (MTA) is being advocated for vital pulp therapy. In the case of direct pulp capping, hemorrhage control is an important step on success, but little is known about the effect of MTA on pulpal bleeding. In addition, there has been a lack of information on the effect of MTA on smooth muscle contraction, such as can occur in the blood vessels of dental pulp. The present study assessed the vascular effects of MTA, using the rat aortic ring preparations as a tissue model. MTA (100–500 mg) induced dose–dependent contraction in rat thoracic aorta. The contractile effect of MTA was blocked by calcium channel blocker nifedipine (1 μM). These data suggest that the vasoconstrictor property of MTA is related to calcium influx and it may allow proper control of hemorrhage which is critical for the success of any pulp-capping treatment.