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This study aimed to analyze the proximity of maxillary molar roots to their overlying cortical bone surfaces and the maxillary sinus.Cone-beam computed tomographic images of 151 patients with completely erupted upper molars that had 3 separate roots were studied. The following distances were measured: from the root apex to the cortical plate and maxillary sinus floor, and from the apical 3-mm level of the root to the cortical plate. Differences between groups were analyzed with 1-way analysis of variance and the SchefféThe mesiobuccal and distobuccal root apexes of maxillary second molars were more distant from the buccal cortical plate than the maxillary first molars (Awareness of the anatomical profile of maxillary molar apices in relation to the cortical bones and maxillary sinus will be beneficial for apical surgery.

This study compared the torsional resistance of heat-treated nickel-titanium (NiTi) instruments under different temperature conditions. Four thermomechanically treated single-use NiTi rotary instruments were selected for this study: OneShape (OS), OneCurve (OC), WaveOne Gold (WOG) and HyFlex EDM (HFE). Each instrument was further subdivided by temperature into 2 subgroups. Maximum torque and the distortion angle until fracture occurred were evaluated. Differential scanning calorimetry analysis was performed to measure the phase transformation temperature. Statistical analysis was performed using a two-way ANOVA and t-test (p &lt, 0.05). Fractured fragments were observed using scanning electron microscopy (SEM). The two-way ANOVA showed no significant differences for different temperature conditions. At both room (RT) and body temperature (BT), OS was predominantly austenite while HFE was martensite. OC and WOG were predominantly martensite at RT and mixed phase at BT. At BT, more than half of WOG was martensite, while half of OC was austenite. SEM examination showed no topographical differences between instruments in different temperature groups. In relation to a limitation of this study, there was no difference in torsional resistance of NiTi rotary instruments between the BT and RT conditions. This implies that clinicians do not need to consider a decrease of torsional resistance of heat-treated NiTi instruments at BT.

Introduction The purpose of this study was to evaluate differences in torsional resistance using up-regulated speed of rotational spindle. Methods Three NiTi rotary instrument systems were selected in this study: K3XF (SybronEndo, Glendora, CA), BLX (B&L Biotech, Ansan, Korea), and OneShape (MicroMega, Besancon, France). The tip size and taper for all files were #25 and 0.06. Experimental groups ( n = 10/group) were assigned to 2-, 60-, 350-, and 600-rpm groups by the rotational speed of spindle. Forty new files were used for each test. The file tip of 5-mm length was secured between brass plates. While keeping the file straight, it was rotated clockwise at a constant rotational speed until fracture occurred. The parameters of torsional resistance, torsional load (Ncm), and distortion angle (°) were measured using an AEndoS- k (DMJ System, Busan, Korea), and the toughness until fracture was computed from these data. The 1-way analysis of variance test was used to analyze the torsional resistance at a significance level of 95%. All fractured fragments were observed under a scanning electron microscope to evaluate the topographic features of the fractured surfaces. Results No significant difference in torsional resistance was found among groups when they were compared for ultimate strength at the maximum torque, fracture angle, and toughness. Scanning electron microscopic examination of the fractured cross-sectional surfaces revealed typical features of torsional fractures, concentric abrasion marks, and fibrous dimples from the torsional center. Conclusions Under the conditions of the study, the torsional resistances of the rotary instruments were not affected by the rotational speed.

The spontaneous mutant circling mouse (cir/cir) is deaf and displays abnormal behavior, particularly circling and head tossing. To rescue the circling mouse phenotype, we produced transgenic mice with hair cell-specific expression of the transmembrane inner ear (tmie) gene, using the Myo7a promoter, and generated cir/cir homozygous mice carrying the transgene (cir/cir-tgMyo7a) by breeding with circling mice. The cir/cir-tgMyo7a mice still exhibited circling behavior and were unable to swim in water unlike cir/cir-tgCMV mice and wild-type mice. An auditory brainstem response (ABR) test demonstrated that the cir/cir-tgMyo7a mice could not respond to sound. Immunohistochemical analysis showed enhanced green fluorescent protein, a marker of tmie expression, in the inner and outer hair cells of the cir/cir-tgMyo7a mice. Hair cells and spiral ganglion neurons in the cir/cir-tgMyo7a mice were recovered, but not completely. This study demonstrates that tmie transgene expression in hair cells alone could not restore wild-type hearing and behavior in circling mice.

Objectives The purpose of this study was to evaluate the void of root canal filling over time when a calcium silicate sealer was used in the single gutta-percha cone technique. Materials and Methods Twenty-four J-shaped simulated root canals and twenty-four palatal root canals from extracted human maxillary molars were instrumented with ProFile Ni-Ti rotary instruments up to size 35/0.06 or size 40/0.06, respectively. Half of the canals were filled with Endoseal MTA and the other half were with AH Plus Jet using the single gutta-percha cone technique. Immediately after and 4 weeks after the root canal filling, the samples were scanned using micro-computed tomography at a resolution of 12.8 μm. The scanned images were reconstructed using the NRecon software and the void percentages were calculated using the CTan software, and statistically analyzed by 1-way analysis of variance, paired t-test and Tukey post hoc test. Results After 4 weeks, there were no significant changes in the void percentages at all levels in both material groups (p > 0.05), except at the apical level of the AH Plus Jet group (p < 0.05) in the simulated root canal showing more void percentage compared to other groups. Immediately after filling the extracted human root canals, the Endoseal MTA group showed significantly less void percentage compared to the AH Plus Jet group (p < 0.05). Conclusions Under the limitations of this study, the Endoseal MTA does not seem to reduce the voids over time.

This study compared the maximum screw-in forces of various instruments during their movements. Forty simulated canals in resin blocks were randomly divided into four groups (n = 10): ProTaper Universal F2, ProTaper Gold F2, WaveOne Primary, and WaveOne Gold Primary. To standardize a lumen size, all artificial canals were prepared with ProTaper Universal F1. The rotation speed was set at 350 rpm with an automated 4 mm pecking motion at a speed of 1 mm/s. The pecking depth was increased by 1 mm for each pecking motion until the file reached the working length. During instrumentation, screw-in forces were automatically recorded by customized software. Maximum screw-in forces were analyzed by one-way ANOVA and Tukey&rsquo, s post hoc comparison with the significance level at 0.05. WaveOne Gold files generated the lowest maximum screw-in forces, followed by ProTaper Gold, WaveOne, and ProTaper Universal (p &lt, 0.05). Under the condition of this study, heat-treated nickel&ndash, titanium (NiTi) files with smaller cross-sectional area, fewer contact points, and reciprocating movements resulted in a lower screw-in effect.

Objectives The purpose of this study was to investigate the involvement of TRPA1 in the cinnamaldehyde-induced pulpal blood flow (PBF) change in the feline dental pulp. Materials and Methods Mandibles of eight cats were immobilized and PBF was monitored with a laser Doppler flowmetry at the mandibular canine tooth. To evaluate the effect of cinnamaldehyde on PBF, cinnamaldehyde was injected into the pulp through the lingual artery at a constant rate for 60 seconds. As a control, a mixture of 70% ethanol and 30% dimethyl sulfoxide (DMSO, vehicle) was used. To evaluate the involvement of transient receptor potential ankyrin 1 (TRPA1) in PBF change, AP18, a specific TRPA1 antagonist, was applied into the pulp through the Class V dentinal cavity followed by cinnamaldehyde-administration 3 minutes later. The paired variables of experimental data were statistically analyzed using paired t-test. A p value of less than 0.05 was considered as statistically significant. Results Administration of cinnamaldehyde (0.5 mg/kg, intra-arterial [i.a.]) induced significant increases in PBF (p < 0.05). While administration of a TRPA1 antagonist, AP18 (2.5 - 3.0 mM, into the dentinal cavity [i.c.]) caused insignificant change of PBF (p > 0.05), administration of cinnamaldehyde (0.5 mg/kg, i.a.) following the application of AP18 (2.5 - 3.0 mM, i.c.) resulted in an attenuation of PBF increase from the control level (p < 0.05). As a result, a TRPA1 antagonist, AP18 effectively inhibited the vasodilative effect of cinnamaldehyde (p < 0.05). Conclusions The result of the present study provided a functional evidence that TRPA1 is involved in the mechanism of cinnamaldehyde-induced vasodilation in the feline dental pulp.

Objectives This study aimed to compare two nickel-titanium systems (rotary vs. reciprocating) for their acceptance by undergraduate students who experienced nickel-titanium (NiTi) instruments for the first time. Materials and Methods Eighty-one sophomore dental students were first taught on manual root canal preparation with stainless-steel files. After that, they were instructed on the use of ProTaper Universal system (PTU, Dentsply Maillefer), then the WaveOne (WO, Dentsply Maillefer). They practiced with each system on 2 extracted molars, before using those files to shape the buccal or mesial canals of additional first molars. A questionnaire was completed after using each file system, seeking students' perception about 'Ease of use', 'Flexibility', 'Cutting-efficiency', 'Screwing-effect', 'Feeling-safety', and 'Instrumentation-time' of the NiTi files, relative to stainless-steel instrumentation, on a 5-point Likert-type scale. They were also requested to indicate their preference between the two systems. Data was compared between groups using t-test, and with Chi-square test for correlation of each perception value with the preferred choice (p = 0.05). Results Among the 81 students, 55 indicated their preferred file system as WO and 22 as PTU. All scores were greater than 4 (better) for both systems, compared with stainless-steel files, except for 'Screwing-effect' for PTU. The scores for WO in the categories of 'Flexibility', 'Screwing-effect', and 'Feeling-safety' were significantly higher scores than those of PTU. A significant association between the 'Screwing-effect' and students' preference for WO was observed. Conclusions Novice operators preferred nickel-titanium instruments to stainless-steel, and majority of them opted for reciprocating file instead of continuous rotating system.

Exposing sound structure of a subgingivally fractured tooth using orthodontic extrusion is considered to be a conservative way to re-establish biologic width without sacrificing esthetics or jeopardizing periodontal support of neighboring teeth. When a misaligned tooth is traumatically involved, a more comprehensive approach combining tooth extrusion and re-alignment may be necessary for a successful restorative outcome. This case report describes a successful esthetic management of a patient with complicated crown-root fracture on the maxillary right central incisor and pre-existing malocclusion in the maxillary anterior region. Forced eruption along with re-alignment of teeth by orthodontic movement seems to allow re-positioning of the fracture line to a favorable position and correction of crowding, providing a better esthetic result.

Background/purpose: Glide-path preparation is an important step during initial endodontic procedure to reduce shaping-instrument fracture. The aim of this study was to evaluate the amount of apically extruded debris produced by glide-path preparation instruments with different geometric designs. Materials and methods: Forty teeth extracted for periodontal reasons were randomly divided into four groups (n = 10). The working length was standardized at 17 mm from the apical foramen by a flattening reference point. The glide-path was created using repetitive up-and-down movement three times with one of following four selected instruments: One G, ProGlider, a size 15 ScoutRace, and a size 15 stainless-steel K-file. To collect the apically extruded debris, the customized apparatus was used, and the collected debris was stored in an incubator. The weight of the debris was measured using an analytical balance with an accuracy of 0.00001 g. The data were analyzed by one-way analysis of variance and Duncan's multiple comparison test at a significance level of 95%. Results: The ProGlider group produced significantly less debris extrusion relative to the other groups (P < 0.05). The One G and ScoutRace groups showed no significant difference, but debris production was lower than that observed for the stainless-steel group (P < 0.05). Conclusion: Creating the glide-path using nickel-titanium rotary files produced lower amounts of debris extrusion than using manual stainless-steel files. The progressive taper design of ProGlider, the center-off cross-section of One G, and the alternative-pitch design of ScoutRace may have increased the efficiencies of debris removal with minimal extrusion during glide-path preparation. Glide-path preparation using NiTi rotary files have better clinical efficiency than the manual stainless-steel file. Copyright (C) 2016, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. This is an open access article under

Introduction The purpose of this in vitro study was to compare the torque generated by continuous and adaptive movements of 2 nickel-titanium rotary file systems. Methods Forty-five simulated resin blocks with an S-shaped canal were randomly divided into 3 groups (n = 15) according to the file system and kinematics: the K3XF rotary system (Kerr Endodontics, Orange, CA) with continuous rotary movement, the K3XF with adaptive movement, and the Twisted File (Kerr Endodontics) adaptive file with adaptive movement. After creating a glide path, the canal was instrumented to the same size (.04/#20 for K3XF or SM1 for the Twisted File with adaptive movement) before torque measurement. During the final instrumentation procedure with the .06/25 sized file (K3XF or SM2), the generated torque and the preparation time were recorded. The total torque experienced and the maximum torque value were calculated. The data were statistically analyzed using 1-way analysis of variance and the Tukey post hoc comparison test at a significance level of 95%. Results The K3XF file system used with adaptive motion group showed significantly lower total and maximum torque values compared with the K3XF with continuous rotary movement group. The Twisted File adaptive file with adaptive motion showed significantly lower torque generation and shorter preparation time than the K3XF groups with adaptive or continuous rotation (P Conclusions Under the conditions of this study, adaptive movement for nickel-titanium files may reduce torque generation without increasing preparation time. Nickel-titanium files with a smaller cross-sectional area using adaptive movement may be helpful to reduce the potential risk of root dentin damage.

Summary This study was aimed to evaluate the effect of torsional preloads on the cyclic fatigue life of nickel-titanium (NiTi) instruments with different history of heat treatments by manufacturers. WaveOne (Primary) made of M-wire, K3XF (#30/0.06) of R-phase, and ProTaper (F2) of conventional NiTi alloy was used. Each file was preloaded at four conditions (nil, 25, 50, and 75% of their mean ultimate torsional strength) before fatigue testing. The torsional preloads 10-, 30-, or 50-times were applied by securing 5 mm of the file tip, rotating it until the preset torque was attained before returning to the origin. Then, the number of cycles to failure (NCF) was evaluated by rotational bending in a simulated canal. Data were analyzed using multiple linear regression analysis and two-way ANOVA. Fractured instruments were examined under scanning electron microscope (SEM). SEM showed that most WaveOne after 75% preloading, regardless of repetitions, showed some longitudinal cracks parallel to the long axis of the file, which were rare for K3XF. Regression analysis revealed that the brand of instrument was the most critical factor. At up to 75% preloading, ProTaper and K3XF did not show any significant decline in NCF. For 30-repetition groups of WaveOne, the 50 and 25% torsion preloaded groups showed a significantly higher NCF than the 0 and 75% groups. Within the limitations of this study, the alloy type of NiTi instrument have a significant effect on the phenomenon that a certain amount of torsional preload may improve the cyclic fatigue resistance of NiTi rotary instruments. SCANNING 37:172–178, 2015. © 2015 Wiley Periodicals, Inc.

The aim of this study was to evaluate the root canal shaping effect of 2 nickel-titanium rotary instruments with offset mass of rotation compared with an instrument with a conventional centered mass of rotation.Thirty-six extracted human mandibular first molars with 2 independent mesial canals and 1 oval distal canal were selected and divided equally into 3 groups for instrumentation with ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), Revo-S (RS; Micro-Mega, Besançon, France), and ProTaper Universal (PTU, Dentsply Maillefer) systems (n = 12). For apical preparation, PTN X2 (#25/0.06), RS SU (#25/0.06), and PTU F2 (#25/0.08) were used in the mesial canals and PTN X3 (#30/0.07), RS AS30 (#30/0.06), and PTU F3 (#30/0.09) were used in the distal canals. Specimens were scanned before and after instrumentation using a SkyScan 1272 scanner (Bruker micro-CT, Kontich, Belgium) at 10-μm isotropic resolution. Changes in the canal area, volume, structure model index (SMI), and untouched canal area were evaluated. Canal transportation and centering ratio were measured at 1, 3, 5, and 7 mm from the apical foramen. Data were statistically analyzed using 1-way analysis of variance with the Tukey post hoc test.The PTN and RS systems showed significantly less transportation and better centering ability compared with the PTU system at 1 mm from the apical foramen (P .05). All instrumentation increased the canal area, volume, and SMI values without significant differences among the 3 groups (P .05).Regardless of the differences in the cross-sectional design, alloy type, and taper variation, instruments with offset mass of rotation showed better root canal shaping ability compared with an instrument with a centered mass of rotation.

The purpose of this study was to compare in vitro torque generation during instrumentation with or without glide path establishment.Endo-training resin blocks with J-shaped canals were randomly divided into 2 groups according to glide path establishment (with or without) and subdivided into 2 subgroups with shaping instruments (WaveOne [Dentsply Maillefer, Ballaigues, Switzerland] or WaveOne Gold [Dentsply Maillefer]) (n = 15). For the glide path-established group, the glide path was prepared using ProGlider (Dentsply Maillefer). During the instrumentation with WaveOne or WaveOne Gold, in vitro torque was measured. The acquired data were analyzed with software. The maximum torque and total torque (the sum of the generated torque) were calculated. The data were statistically evaluated using 2-way analysis of variance and the Duncan post hoc comparison to examine any correlation of torque generation with glide path establishment and nickel-titanium instruments. The significance level was set at 95%.The generated total torque by WaveOne Gold was significantly reduced by glide path establishment (P .05), whereas glide path establishment did not induce significant changes in the maximum torque for both file systems. WaveOne Gold with a glide path showed the lowest total torque generation among all groups (P .05). WaveOne generated a higher maximum torque than WaveOne Gold regardless of the establishment of a glide path (P .05).Under the limitations of this study, glide path establishment and the mechanical property of instruments have a significant influence on torque generation. It is recommended to create the glide path and use a flexible file to reduce torque generation and, consequently, the risk of file fracture and root dentin damage.

Introduction The aim of this study was to evaluate the effect of different pecking depth on the stress generated by the screw-in forces of a rotating endodontic file in simulated canals. Methods Twenty simulated resin blocks with a J-shaped curvature were used. Twenty OneG files (MicroMega, Besancon, France) were assigned for a screw-in test depending on the pecking depth in 2 groups (n = 10). The files were operated at 300 rpm, and the up and down speed was controlled at 1 mm/s stroke velocity and a 10-millisecond dwell time using a customized device. The distances (pecking depth) for the pecking motion were 2 mm or 4 mm for each group; “6 mm forward and 4 mm backward” and “6 mm forward and 2 mm backward” movements were applied, respectively, for the 2 pecking groups. During the operation, the positive and negative apical loads were recorded at a rate of 50 Hz using customized software attached to the device. The maximum negative apical load (screw-in force [SF]) was recorded, and the total energy during pecking motion until the file reached the working length (cumulative screw-in forces [CSFs]) was computed. The data were analyzed using an independent t test at a significance level of 95%. Results No significant difference in SF was found between the 2 groups of pecking depths. However, the longer pecking depth (4-mm group) showed a significantly larger CSF compared with the shorter pecking depth group (P Conclusions The shorter pecking depth may generate lower overall stresses for the root dentin as well as the instrument.

The purpose of this study was to investigate whether the resistance to torsional stress and cyclic fatigue would be improved by the novel R-phase heat treatment by using instruments with identical geometric characteristics.K3XF and K3 files with sizes of #30/.04 and #30/.06 were selected for the study (n = 10 per group). To evaluate the torsional resistance, the torsional load and distortion angle at yield, ultimate, and fracture points were recorded. The toughness until fracture was calculated as well. The number of cycles to failure for each instrument was determined to evaluate the cyclic fatigue resistance. Statistical analysis was performed by using the nonparametric Mann-Whitney U test (for torsional resistance) and independent t test (for cyclic fatigue). After torsional and cyclic fatigue tests, all fractured fragments were observed under a scanning electron microscope to evaluate the topographic features of the fractured surfaces.Although K3XF showed superior cyclic fatigue resistance to K3 (P.000), there was no significant difference in torsional resistance in terms of ultimate strength, fracture angle, and toughness between the 2 brands of K3XF and K3 regardless of the instruments' taper. The fractured cross-sectional surfaces showed typical features of cyclic fatigue and torsional fractures. K3XF had a distinctive surface with numerous irregular micropores.The heat-treated K3XF instruments that used R-phase heat treatment technology showed improved cyclic fatigue resistance without decline of torsional strength.

The objective of this article was to present two nonodontogenic conditions that may mimic odontogenic toothache: trigeminal neuralgia and burning mouth syndrome. Two cases are presented in which one is related to the upper left second premolar and the other is related to the upper left first molar. Both showed pain when chewing. These two cases highlight the complexities involved in diagnosing nonodontogenic toothache. This article demonstrates the importance of having a thorough knowledge of both odontogenic and nonodontogenic toothache, as well as the need for careful evaluation of the nature of the pain and history, clinical and radiographic examinations.

Closure of interdental spaces using proximal build-ups with resin composite is considered to be practical and conservative. However, a comprehensive approach combining two or more treatment modalities may be needed to improve esthetics. This case report describes the management of a patient with multiple diastemas, a peg-shaped lateral incisor and midline deviation in the maxillary anterior area. Direct resin bonding along with orthodontic movement of teeth allows space closure and midline correction, consequently, creating a better esthetic result.

Introduction Four generations of methacrylate resin–based sealers have been available commercially. Three of these were introduced during the last 5 years when the concept of simultaneous bonding of root canal sealers to root filling materials and dentin was popularized. Methods This article presents an overview of methacrylate resin–based sealers, with the objectives of clarifying the behavior of these materials and delineating their limitations in clinical application. Results The first generation sealer was introduced in the mid-1970s. The initial enthusiasm associated with its use eventually diminished as a result of its suboptimal physical, biologic, and clinical properties. With advances in self-etching adhesive technology acquired from adhesive dentistry, methacrylate resin–based sealers were reintroduced in the beginning of the 21st century to support the introduction of bondable root canal filling materials. Three different generations of these sealers have since been available commercially. Although some in vitro studies on the sealing ability, self-etching potential, biocompatibility, and removability of the sealers showed better potential over conventional nonbonding sealers, accomplishing the ideal goal of a monoblock in the root canal space with these materials is still regarded as a major challenge. Conclusions On the basis of the in vitro and in vivo data available to date, there appears to be no clear benefit with the use of methacrylate resin–based sealers in conjunction with adhesive root filling materials at this point in their development.

Objectives The purpose of this study was to evaluate the proximity of the mandibular molar apex to the buccal bone surface in order to provide anatomic information for apical surgery. Materials and Methods Cone-beam computed tomography (CBCT) images of 127 mandibular first molars and 153 mandibular second molars were analyzed from 160 patients' records. The distance was measured from the buccal bone surface to the root apex and the apical 3.0 mm on the cross-sectional view of CBCT. Results The second molar apex and apical 3 mm were located significantly deeper relative to the buccal bone surface compared with the first molar (p < 0.01). For the mandibular second molars, the distance from the buccal bone surface to the root apex was significantly shorter in patients over 70 years of age (p < 0.05). Furthermore, this distance was significantly shorter when the first molar was missing compared to nonmissing cases (p < 0.05). For the mandibular first molars, the distance to the distal root apex of one distal-rooted tooth was significantly greater than the distance to the disto-buccal root apex (p < 0.01). In mandibular second molar, the distance to the apex of C-shaped roots was significantly greater than the distance to the mesial root apex of non-C-shaped roots (p < 0.01). Conclusions For apical surgery in mandibular molars, the distance from the buccal bone surface to the apex and apical 3 mm is significantly affected by the location, patient age, an adjacent missing anterior tooth, and root configuration.

The present study investigated the role of peripheral group I metabotropic glutamate receptors (mGluRs) in MO-induced nociceptive behaviour and inflammation in the masseter muscles of lightly anesthetized rats. Experiments were carried out on male Sprague-Dawley rats weighing 300-400 g. After initial anesthesia with sodium pentobarbital (40 mg/kg, i.p.), one femoral vein was cannulated and connected to an infusion pump for intravenous infusion of sodium pentobarbital. The rate of infusion was adjusted to provide a constant level of anesthesia. Mustard oil (MO, 30 microl) was injected into the mid-region of the left masseter muscle via a 30-gauge needle over 10s. After 30 microl injection of 5, 10, 15, or 20% MO into the masseter muscle, the total number of hindpaw shaking behaviour and extravasated Evans' blue dye concentration in the masseter muscle were significantly higher in the MO-treated group in a dose-dependent manner compared with the vehicle (mineral oil)-treated group. Intramuscular pretreatment with 3 or 5% lidocaine reduced MO-induced hindpaw shaking behaviour and increases in extravasated Evans' blue dye concentration. Intramuscular pretreatment with 5 mM MCPG, non-selective group I/II mGluR antagonist, or MPEP, a selective group I mGluR5 antagonist, produced a significant attenuation of MO-induced hindpaw shaking behaviour and increases in extravasated Evans' blue dye concentration in the masseter muscle while LY367385, a selective group I mGluR1 antagonist, did not affect MO-induced nociceptive behaviour and inflammation in the masseter muscle. These results indicate that peripheral mGluR5 plays important role in mediating MO-induced nociceptive behaviour and inflammation in the craniofacial muscle.

The influence of NK1 receptor antagonists applied iontophoretically on pulpal blood flow (PBF) was investigated. Along with substance P (SP, 0.8 approximately 20.0 ng/kg) administration to the canine pulp through the catheterized lingual artery, two NK1 receptor antagonists, [D-Pro2,D-Trp7,9]-SP and [D-Pro2,D-Phe7,D-Trp9]-SP (0.2 approximately 3.4 mM) were applied iontophoretically (cathodal current, 0.02 approximately 0.1 mA, 1 min) to the prepared class V dentinal cavity of ipsilateral teeth in 11 generally anesthetized cats. A paired t-test showed that SP administration caused significant increases of PBF (p < 0.05) without changing systemic blood pressure, and that SP and SP antagonist administration caused significantly less increase of PBF than in control of SP and 0.9% saline administration (p < 0.05). These data provide evidence that the iontophoretic application of NK1 receptor antagonists effectively attenuates SP-induced vasodilatation and show the possibility of their use in the control of neurogenic inflammation in the dental pulp.

The present study investigated the effects of intracisternal administration of MCP-1, Rantes or IL-8 on pain transmission in the orofacial area. We also investigated mechanisms of hyperalgesic responses produced by intracisternal administration of IL-8. An orofacial formalin test was employed to assess the effects of chemokines on nociceptive processing. For each animal, the number of behavioral responses and the time spent grooming, rubbing and/or scratching the facial region proximal to the formalin injection site was recorded for nine successive 5-min intervals. Intracisternal administration of MCP-1, Rantes or IL-8 significantly increased formalin-induced scratching behavioral responses in the orofacial area. Intracisternal pretreatment with indomethacin, a non-selective cyclooxygenase inhibitor, did not block IL-8-induced hyperalgesia. Pretreatment with 100 microg propranolol, a non-selective beta-adrenergic receptor antagonist and 50 microg atenolol, a selective beta(1)-adrenergic receptor antagonist, inhibited the number of scratches and the duration of scratching produced by 1 ng of IL-8 injected intracisternally. These results indicate that intracisternal administration of chemokines produce a hyperalgesic response with an orofacial inflammatory pain model and that the IL-8-induced hyperalgesia is mediated by central beta(1)-adrenergic receptor.

This study was aimed to evaluate the effect of torsional preloads on the cyclic fatigue life of nickel-titanium (NiTi) instruments with different history of heat treatments by manufacturers. WaveOne (Primary) made of M-wire, K3XF (#30/0.06) of R-phase, and ProTaper (F2) of conventional NiTi alloy was used. Each file was preloaded at four conditions (nil, 25, 50, and 75% of their mean ultimate torsional strength) before fatigue testing. The torsional preloads 10-, 30-, or 50-times were applied by securing 5 mm of the file tip, rotating it until the preset torque was attained before returning to the origin. Then, the number of cycles to failure (NCF) was evaluated by rotational bending in a simulated canal. Data were analyzed using multiple linear regression analysis and two-way ANOVA. Fractured instruments were examined under scanning electron microscope (SEM). SEM showed that most WaveOne after 75% preloading, regardless of repetitions, showed some longitudinal cracks parallel to the long axis of the file, which were rare for K3XF. Regression analysis revealed that the brand of instrument was the most critical factor. At up to 75% preloading, ProTaper and K3XF did not show any significant decline in NCF. For 30-repetition groups of WaveOne, the 50 and 25% torsion preloaded groups showed a significantly higher NCF than the 0 and 75% groups. Within the limitations of this study, the alloy type of NiTi instrument have a significant effect on the phenomenon that a certain amount of torsional preload may improve the cyclic fatigue resistance of NiTi rotary instruments.

Objectives Glide path preparation is recommended to reduce torsional failure of nickel-titanium (NiTi) rotary instruments and to prevent root canal transportation. This study evaluated whether the repetitive insertions of G-files to the working length maintain the apical size as well as provide sufficient lumen as a glide path for subsequent instrumentation. Materials and Methods The G-file system (Micro-Mega) composed of G1 and G2 files for glide path preparation was used with the J-shaped, simulated resin canals. After inserting a G1 file twice, a G2 file was inserted to the working length 1, 4, 7, or 10 times for four each experimental group, respectively (n = 10). Then the canals were cleaned by copious irrigation, and lubricated with a separating gel medium. Canal replicas were made using silicone impression material, and the diameter of the replicas was measured at working length (D0) and 1 mm level (D1) under a scanning electron microscope. Data was analysed by one-way ANOVA and post-hoc tests (p = 0.05). Results The diameter at D0 level did not show any significant difference between the 1, 2, 4, and 10 times of repetitive pecking insertions of G2 files at working length. However, 10 times of pecking motion with G2 file resulted in significantly larger canal diameter at D1 (p < 0.05). Conclusions Under the limitations of this study, the repetitive insertion of a G2 file up to 10 times at working length created an adequate lumen for subsequent apical shaping with other rotary files bigger than International Organization for Standardization (ISO) size 20, without apical transportation at D0 level.

Objectives: This study compared the mechanical properties of various instruments for canal exploration and glide-path preparations. Materials and Methods: 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. Results: 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). Conclusions: 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. (Restor Dent Endod 2014; 39(4):270-275)

Introduction The aim of this study was to evaluate the effect of torsional preload on the cyclic fatigue life of nickel-titanium rotary instruments. Methods ProFile (#25/0.06) (Dentsply Maillefer, Ballaigues, Switzerland) and ProTaper (F1; Dentsply Maillefer) were used. Each file was preloaded at 4 conditions (ie, no preloading and 25%, 50%, and 75% of mean ultimate torsional strength) of torsional prestress before the fatigue test. The torsional preloads were applied by securing 5 mm of the file tip while keeping the file straight, rotating it clockwise until the preset torque, and then returning to the original position. This motion was repeated until a preset number (10, 30, or 50) of repetitions were reached ( n = 12). After torsional preloading, the number of cycles to failure was evaluated in a simulated canal. Data were analyzed using 2-way analysis of variance and the Duncan post hoc comparison. The fractured fragment surfaces were examined under a scanning electron microscope for the topographic features of fractured instruments. Results For both instruments, there was a significant effect because of the extent of torsional preloads. The 50% and 75% torsionally preloaded ProFile and all ProTaper preloading groups had a higher number of cycles to failure than the other group(s). There was little difference in the lateral view appearance between new and torsionally preloaded files. After cyclic fatigue testing, all preloaded instruments showed numerous microcracks adjacent to the fracture site on lateral view examination. The microcracks did not seem to follow the machining grooves on the instrument surface but rather ran irregularly. Conclusions The torsional preloads within the superelastic limit of the material may improve the cyclic fatigue resistance of nickel-titanium rotary instruments.

Introduction This study evaluated the true self-etching potential of RealSeal and RealSeal SE to ensure that they are aggressive enough to etch through endodontic smear layers and demineralize the intact radicular dentin without adjunctive use of ethylenediaminetetraacetic acid (EDTA). Methods Mixed RealSeal and RealSeal SE were applied to (1) instrumented canal wall dentin that was irrigated with water as the final rinse to preserve smear layers, (2) fractured radicular dentin that was devoid of smear layers, and (3) instrumented canal wall dentin that was irrigated with EDTA as the final rinse to remove smear layers. Sealer-bonded specimens were processed for transmission electron microscopy. Results Unlike RealSeal, RealSeal SE could hardly demineralize the fractured dentin and was unable to etch beyond smear layers into the underlying intact dentin. EDTA dissolved smear layers completely and partially demineralized the intact dentin.. Conclusions RealSeal SE might not be aggressive enough to achieve optimal dentin bonding to root canal walls in locations that are not reachable by calcium chelating irrigants. Conversely, RealSeal possesses mild etching ability on the fractured and smear layer–covered radicular dentin.

Accumulating evidence indicates that the metabotropic glutamate receptor mGluR5 is involved in the peripheral mechanisms of inflammatory nociception. To investigate whether mGluR5 may mediate the inflammatory pain and thermal hyperalgesia in the dental pulp, we examined the expression of mGluR5 and transient receptor potential vanilloid 1 (TRPV1) in human dental pulp by immunohistochemistry and electron microscopy; mGluR5-immunopositive (+) axons were observed in nerve bundles and branched extensively within the peripheral coronal pulp. Most of the mGluR5+ axons were unmyelinated. A large fraction of these axons (36.5%) were immunostained for TRPV1. Immunoreactivity for mGluR5 and TRPV1 was also observed in odontoblasts. These results support the possibility that the nerve fibers in the dental pulp mediate inflammatory pain and thermal hyperalgesia through coactivation of mGluR5 and TRPV1 and also suggest a possible role for odontoblasts in the transduction of nociceptive signals via mGluR5-mediated mechanism.

In IETFpsilas fast mobile IPv6, the mobile node may switches into the reactive mode of handover operation when the prediction of the movement is wrong. In this case, the mobile node may experience severe service disruption due to large handover latency and packet loss. In order to solve this problem, we propose a fast mobile IP handover with multiple pre-registration. In the proposed approach, the new IP addresses are prepared in advance at multiple locations where the mobile node may probably moves into. If the predictive mode of handover operation by FMIPv6 fails, the mobile node tries to move into the previously prepared locations. Therefore, delay time of generating new care-of-address is saved. We have built a prototype system, and measure the performance of the proposed system. The experimental results show that the proposed approach can reduce greatly the handover latency.

Objectives The purpose of this study was to evaluate the accuracies of 7 different frequency-dependent electronic apex locators (EALs) on using different irrigants in the root canal. Study design Root canal lengths were measured with 7 different EALs in 40 extracted human teeth embedded in an alginate model after canal preparation and compared with the actual canal length measurements taken before embedding the teeth in alginate. The EALs used were Apex Finder 7005, Apit, Bingo-1020, e-Magic Finder, ProPex, Root ZX, and SmarPex. Measurements were taken with the canal dry, and saturated sequentially with 5.25% NaOCl, saline, 0.1% chlorhexidine, and 15% EDTA. Data were analyzed with 1-way ANOVA and Tukey's studentized range test. Results There were some differences in accuracies among EALs; however, some of the differences were not statistically significant. All EALs were less accurate when the apical foramen size was larger. Conclusion Within the limitations of the present study, most of the EALs tested can be considered reliable in the presence of various root canal irrigants and varying sizes of the apical foramen.

Signal substances of axon terminals presynaptic to jaw spindle Ia afferents and their ultrastructural features were examined using a combination of intra-axonal horseradish peroxidase injection and postembedding immunogold-labeling techniques in cats. A total of 35 axon terminals presynaptic to 22 horseradish peroxidase-labeled Ia boutons were examined. Of the 35 presynaptic axon terminals, 14 (40%) were immunoreactive for both gamma-aminobutyric acid and glycine, 9 (26%) for gamma-aminobutyric acid alone and 9 (26%) for glycine alone. The bouton volume, mitochondrial volume, active zone area, and apposed surface area were larger for Ia boutons than for presynaptic axon terminals, while each of the values is similar among the three types of presynaptic axon terminals. These results suggest that gamma-aminobutyric acid and glycine play an important role for modulating the jaw-jerk reflex presynaptically and that the smaller size of presynaptic axon terminals is important to prevent action potential generation from Ia afferents.

Dearest APEC members, Greetings! I am back again to Amman after attending the 16th Biennial Congress of the European Society of Endodontology (ESE) that was held in Lisbon, Portugal, with huge participation exceeding 2000 dentists representing more than 70 countries from all over the world. Our booth in the exhibition venue to launch the Asian Pacific Endodontic Confederation (APEC) Amman 2015 Conference worked during the 3 days of the Congress (Fig. 1). More than 1000 flyers of the first announcement were distributed to the attendees in addition to other advertising material and Jordanian dates provided by the Jordan Tourism Board through their office in Madrid (Fig. 2). I would like to take this opportunity to thank the organising committee of the ESE Lisbon Conference for their support to APEC and congratulate them on this successful event. The esteemed official support to Amman APEC Conference gained by the government, the Jordanian Dental Association and the Jordanian Endodontic Society (JES) reflects the great interest and desire in Jordan to make this event special and different. I was also promised full support by sponsoring companies, pronounced speakers and dentists from well-known and prestigious universities as a result of formal personal contacts to invite them to our upcoming event that will form a Pan Arab and international gathering. Back to Amman, our preparations in JES will speed up to finalise the PDF file of the 4th Jordanian and 18th APEC Conference that will include more detailed information to be distributed to all APEC members and friends in due time. Before and during Amman conference, APEC family members will witness new initiatives that will materialise the goals, vision and decisions of previous Biennial General Meetings and will constitute a turning point to be added to the bright and rich history of our organisation and glory of the event. Aspired by the history and constitution of our organisation and the support of all APEC family members, we will move forward to compete in raising the

This study analyzed quantitatively the ultrastructural features of tooth pulp afferent terminals and their presynaptic axonal endings (p-endings) in the trigeminal principal (Vp), dorsomedial oral (Vdm), and caudal nuclei (Vc). Mitochondrial volume, active zone area, apposed surface area, and vesicle number were highly correlated with afferent bouton volume. The afferent bouton volume varied widely in Vp, compared to that in Vdm and Vc. The values of all parameters of p-endings were within a narrow range, and were smaller than those of afferent boutons. The afferent bouton volume correlated with the number of postsynaptic dendrites and p-endings. These results suggest that pulpal afferent information is regulated in a unique manner in the each trigeminal sensory nucleus.

The present study was performed to investigate the antinociceptive response to the intracisternal administration of NMDA in the orofacial area. To achieve this purpose, the effects of NMDA injected intracisternally on the orofacial formalin test were monitored in freely moving rats. We also investigated underlying the mechanisms of NMDA-induced antinociceptive response. Experiments were carried out on 80 male SD rats and surgical procedures were performed under pentobarbital sodium (40 mg/kg, i.p.). Fifty microliters of 5% formalin was applied subcutaneously to the vibrissa pad without any restraining of the animals. For each animal, the number of noxious behavioral responses and the time spent grooming, rubbing, and/or scratching the facial region proximal to the injection site were recorded for nine successive 5-min intervals. The orofacial formalin responses showed two distinct phases separated by a time of relative inactivity. Intracisternal administration of NMDA produced intense scratching behavioral responses with dose related manner. NMDA injected intracisternally 30 min prior to formalin injection, however, inhibited noxious behavioral responses produced by a formalin injection significantly. Pretreatment with naloxone 20 min prior to NMDA injection abolished the inhibition of number of scratches and the duration of scratching produced by the intracisternal injection of NMDA in the late phase. Pretreatment with L-NAME, NO synthesis inhibitor, however, did not affect the antinociceptive response produced by NMDA injected intracisternally. These results suggest that NMDA injected intracisternally produces brief pain behavioral responses and also produces delayed antinociceptive effects in the orofacial formalin test. The opioid pathway seems to be involved in the NMDA-induced antinociception in the orofacial area.

Objective. The purpose of this study was to compare the root canal shaping abilities of 4 nickel-titanium rotary instruments. Study design. ProFile, GT Rotary, Quantec, and ProTaper files were used to instrument 48 simulated curved root canals in plastic blocks with the crown-down technique. One operator prepared all the canals until reaching an apical canal size of #30. The instrumentation time, changes of canal dimension and curvature, canal aberration, and instrument deformation were evaluated. Data were analyzed by using one-way analysis of variance followed by the Duncan multiple range test. Results. The ProTaper took significantly less instrumentation time, removed more canal wall (especially at the inner side of the canal curve), lessened the canal curvature, and induced more instrument deformation than did the other instruments. Conclusion. Although ProTaper files cut more canal wall more quickly than the other instruments in the curved canal, they were also the instruments that most frequently became deformed. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;95:228-33)

Screw-in effect is one of the unintended phenomena that occurs during the root canal preparation with nickel-titanium rotary files. The aim of this study was to compare the screw-in effect among various nickel-titanium rotary file systems. Six different nickel-titanium rotary instruments (ISO 20/.06 taper) were used: (SybronEndo, Glendora, CA, USA), (VDW GmbH, Munchen, Germany), NRT with safe-tip and with active tip (Mani Inc., Shioya-gun, Japan), ProFile (Dentsply-Maillefer, Ballaigues, Switzerland) and ProTaper (Dentsply-Maillefer, Ballaigues, Switzerland). For ProTaper, S2 was selected because it has size 20. Root canal instrumentations were done in sixty simulated single-curved resin root canals with a rotational speed of 300 rpm and single pecking motion. A special device was designed to measure the force of screw-in effect. A dynamometer of the device recorded the screw-in force during simulated canal preparation and the recorded data was stored in a computer with designed software (LCV-USE-VS, Lorenz Messtechnik GmbH, Alfdorf, Germany). The data were subjected to one-way ANOVA and Tukey's multiple range test for post-hoc test. P value of less than 0.05 was regarded significant. ProTaper produced significantly more screw-in effects than any other instruments in the study (p produced significantly more screw-in effects than , and ProFile (p , NRT, and ProFile (p > 0.05), and between NRT with active tip and NRT with safe one neither (p > 0.05). From the result of the present study, it was concluded, therefore, that there seems significant differences of screw-in effect among the tested nickel-titanium rotary instruments. The radial lands and rake angle of nickel-titanium rotary instrument might be the cause of the difference.

Objectives: The introduction of nickel-titanium alloy endodontic instruments has greatly simplified shaping the root canal systems. However, these new instruments have several unexpected disadvantages. One of these is tendency to screw into the canal. In this study, the influence of taper on the screw-in effect of the Ni-Ti rotary instrument were evaluated. Materials and Methods: A total of 20 simulated root canals with an S-shaped curvature in clear resin blocks were divided into two groups. ProFile .02, .04, .06 (Dentsply-Maillefer) and GT rotary files .08, .10, .12 (Dentsply) were used in Profile group, and K3 .04, .06, .08, .10, and .12 (SybronEndo, Glendora) were used in K3 group. Files were used with a single pecking motion at a constant speed of 300 rpm. A special device was made to measure the force of screw-in effect. A dynamometer of the device recorded the screwin force during simulated canal preparation and the recorded data was stored in computer with designed software. The data were subjected to one-way ANOVA and Tukey's multiple range test for post-hoc test. p value of less than 0.05 was regarded significant. Results: The more tapered instruments generated more screw-in forces in Profile group (p