Tulsa Dental Research Articles

A Novel Protein Testing Model to Assay the Efficacy of Multiple Irrigation Activation Techniques for Removal ofEx VivoBiomolecular Film

This study aimed to compare the debris removal efficacies of irrigation activation techniques using ex vivo biomolecular film. Root canals of 50 human mandibular premolars were prepared, and freshly prepared collagen solutions were applied into the root canals using a peristaltic pump. Specimens were randomly divided into the five groups and irrigated with 3 mL of 5.25% sodium hypochlorite (NaOCl): G1 (needle irrigation and control group): a 27-gauge notched-tip irrigation needle (Endo-Eze; Ultradent, South Jordan, UT); G2, Vibringe sonic irrigation system (VSS) (Vibringe B.V. Corp., Amsterdam, Netherlands); G3, EndoActivator sonic irrigation system (EA) (Dentsply Tulsa Dental Specialties, Tulsa, OK); G4, passive ultrasonic irrigation (PUI) (EMS, Nyon, Sweden); and G5, photon-induced photoacoustic streaming (PIPS) (Fotona, Ljubljana, Slovenia). Postirrigation solution was collected in beakers containing 3% sodium thiosulfate by which NaOCl solution was neutralized. Residual protein levels in NaOCl solution were evaluated by the Bradford method. Data were analyzed using ANOVA with Duncan post hoc tests (α = 0.05). PIPS (laser-activated irrigation) method removed more artificial collagen than other experimental groups (EA, PUI, VSS) or the control group (p ≤ 0.05). There were no statistical differences among the EA, PUI, and VSS groups. The PIPS, PUI, and EA groups were superior compared with the conventional irrigation (p ≤ 0.05); however, there were no significant differences between VSS and the conventional irrigation groups. Although all the methods and techniques examined in this study were suitable in extruding the ex vivo biomolecular film, the PIPS method was found significantly more effective than all the other tested groups (p ≤ 0.05).

Rotary Versus Reciprocation Root Canal Preparation: Initial Clinical Quality Assessment in a Novice Clinician Cohort

IntroductionReports comparing clinical outcomes using nickel-titanium (NiTi) reciprocating instruments with other instrumentation modalities are scarce. This study examined initial shaping outcomes after an instrumentation change of root canal instrumentation technique in a doctor of dental surgery educational program. Student characteristics, faculty/student ratio, facility, and overall endodontic treatment guidelines remained unchanged. MethodsA total of 200 nonsurgical initial molar root canal treatments completed by third-year dental students were evaluated. The cases were examined regarding the number of treatment appointments, access cavity preparation, canal taper, canal transportation, perforations, missed canals, presence of ledges, fractured instruments, obturation length, obturation quality, and sealer extrusion. Two independent evaluators determined the number of appointments per case; 4 independent and blinded evaluators analyzed radiographs at 4 treatment stages: preoperative situation, working length, cone fit, and obturation. ResultsThe following factors were significantly different between the 2 cohorts: the number of appointments, preparation length, taper, and occurrence of ledges. The WaveOne (Dentsply Sirona, York, PA) cohort had a significantly reduced treatment time compared with hand/GT rotary instrumentation (Dentsply Tulsa Dental, Tulsa, OK) (average of 3.3 vs 4.3 appointments). Appropriate length control and adequate taper were significantly more frequent in the WaveOne group. The frequency of ledges was significantly larger in the hybrid group. Other variables, such as access cavity preparation, canal transportation, perforations, missed canals, fractured instruments, obturation quality, and sealer extrusion, were statistically similar between the 2 groups. ConclusionsNiTi reciprocation instrumentation was superior to hybrid hand/NiTi rotary instrumentation in reducing both patient appointments and the incidence of ledging and in improving obturation length and taper in a dental student clinic setting.

Apically Extruded Debris in Curved Root Canals Using the WaveOne Gold Reciprocating and Twisted File Adaptive Systems

IntroductionThe purpose of this study was to evaluate apical debris extrusion associated with different kinematics in curved root canals. MethodsForty-five extracted mandibular molars with root curvature angles ranging between 20° and 40° and curvature radii <10 mm were randomly assigned to 3 groups (n = 15) according to the kinematics used for root canal preparation: reciprocating motion with the WaveOne Gold system (Dentsply Tulsa Dental, Tulsa, OK), rotary/reciprocating motion with the Twisted File Adaptive system (SybronEndo, Orange, CA), and the manual technique. The debris apically extruded during preparation was collected into preweighed Eppendorf tubes. The tubes were then stored in an incubator at 70°C for 5 days. The extruded debris was quantified by subtracting the preinstrumentation from the postinstrumentation weight of the Eppendorf tubes. The time required for each instrumentation procedure was recorded. Data were analyzed using 1-way analysis of variance Tukey post hoc tests (∝ = 0.05). ResultsThe WaveOne Gold reciprocating single-file system was associated with less extrusion of debris compared with hand files (P < .05) and the Twisted File Adaptive system (P > .05). The preparation time required by hand files was significantly longer than that required by the other techniques (P < .05). ConclusionsUnder the conditions of this study, all of the instrumentation systems caused apical debris extrusion to some degree. The WaveOne Gold reciprocating system was associated with less debris extrusion in curved root canals compared with the manual technique and the Twisted File Adaptive system although the difference between the WaveOne Gold and Twisted File Adaptive systems was not significant.

Biomechanical Effects of Bonding Pericervical Dentin in Maxillary Premolars

IntroductionPericervical dentin (PCD) loss may increase root fracture propensity in root-filled teeth. This study evaluated the impacts of bonding PCD with composite resin (CR) on radicular microstrain distribution and load at failure of root-filled maxillary premolars. MethodsTen single-canal maxillary premolars decoronated 2 mm coronal to the cementoenamel junction (CEJ) had canals enlarged with ProTaper Universal instruments (Dentsply Tulsa Dental Specialties, Tulsa, OK) to F3. They were root filled with gutta-percha (GP) to the CEJ and restored with Cavit (3M Deutschland GmbH, Neuss, Germany) (GP group, n = 5) or 6 mm apical to the CEJ and restored with bonded CR to simulate bonding of PCD (bonded PCD group, n = 5). Digital moiré interferometry was used to evaluate pre- and postoperative whole-field microstrain distribution in the root dentin under physiologically relevant loads (10–50 N). Another 30 premolars, similarly treated as groups 1 and 2 or left untreated as controls (n = 10/group), were subjected to cyclic loads (1.2 million cycles, 45 N, 4 Hz) followed by uniaxial compressive load to failure. Mechanical data were analyzed with 1-way analysis of variance and the post hoc Tukey test at a 5% level of significance. ResultsMicrostrain distribution showed bending and compressive patterns at the coronal and apical root dentin, respectively. In the GP group, microstrain distribution was unaltered. In the bonded-PCD group, different microstrain distribution suggested stiffening at the PCD. The load at failure did not differ significantly for the GP, bonded PCD, and control groups (P > .05). ConclusionsCR bonding of PCD might impact the biomechanical responses in maxillary premolar roots at low-level continuous loads. The effect of this impact on root fracture loads when subjected to cyclic load warrants further investigation.

Effect of 3 Bioceramic Materials on Stem Cells of the Apical Papilla Proliferation and Differentiation Using a Dentin Disk Model

IntroductionThere is a complex interaction between biomaterials placed as a coronal barrier with stem cells and dentin in regenerative procedures. In this study, the effect of Biodentine (BD; Septodont, Saint-Maurdes-Fossés, France), Endosequence BC Root Repair Material-Putty (ES; Brasseler, Savannah, GA), Endosequence BC Root Repair Material-Putty Fast set (ES-fast, Brasseler), and ProRoot (Dentsply Tulsa Dental Specialties, Johnson City, TN) mineral trioxide aggregate (MTA) on the viability and differentiation of stem cells of the apical papilla (SCAP) was evaluated using an ex vivo dentin disk model. MethodsStandardized human dentin disks were treated using an established protocol. Disk lumens were filled with BD, ES, ES-fast, or MTA, and SCAP were cultured directly onto the samples. Cell viability was measured at 7 days, whereas differentiation into a mineralizing phenotype was evaluated by real-time reverse-transcription polymerase chain reaction and alizarin red staining at 21 days in culture. Results were analyzed using 1-way analysis of variance with the Bonferroni post hoc test or the Mann-Whitney U test (P ≤ .05). ResultsAll materials promoted SCAP viability and proliferation with a greater response in the BD and ES groups. Also, a greater expression of alkaline phosphatase messenger RNA and dentin sialophosphoprotein was noted in the BD and ES groups, whereas MTA promoted a greater expression of the osteoblastic marker IBSP. Interestingly, no difference in alizarin red staining was observed with MTA, BD, or ES, which were significantly greater than ES-fast. ConclusionsThese data suggest that BD and ES promoted greater survival and differentiation of SCAP and the increase of the odontoblastic marker DSPP, whereas MTA appeared to promote greater osteoblastic differentiation. Thus, BD and ES can be considered for regenerative and vital pulp therapies.

Evaluation of Quality and Preparation Time of Retrograde Cavities in Root Canals Filled with GuttaCore and Cold Lateral Condensation Technique

IntroductionThe aim of this study was to measure the time consumed preparing retrograde cavities in root canals of maxillary molars filled using the GuttaCore (Dentsply Tulsa Dental Specialties, Tulsa, OK) technique and the cold lateral condensation technique (CLC) and to examine the quality of the root-end cavity preparation by ultrasonic tips using micro–computed tomographic (micro-CT) scanning. MethodsA total of 24 maxillary molars were included; distobuccal and palatal canals were instrumented to size #40 and size #50, respectively. Teeth were randomly distributed into 2 experimental groups; half of the samples were filled with CLC, and half were filled with the GuttaCore technique. After 2 months, the apical 3 mm of each root apex was resected. A retrograde cavity was then prepared 3 mm deep into the root-end–filled canals using ultrasonic tips. The quality of the preparation was first confirmed by a surgical stereomicroscope, and the time required for the root-end preparation was recorded. After root-end cavity preparation, all samples were scanned by micro-CT scanning. ResultsThere was no significant difference between the palatal and distobuccal canals in the time required to prepare a retrograde cavity. Less time was required in the GuttaCore group to remove all root filling material and finish the cavity preparation than in the CLC group (P < .05), especially in the palatal canals. Micro-CT results confirmed that all material was removed from the root-end cavities and the absence of microcracks. ConclusionsGuttaCore was removed in less time from root-end cavities than root filling performed with the CLC technique. No damage to the surrounding dentin was detected by micro-CT scanning in the 2 groups.

Correlation between Temperature-dependent Fatigue Resistance and Differential Scanning Calorimetry Analysis for 2 Contemporary Rotary Instruments

IntroductionThe aim of this study was to assess differences in cyclic fatigue (CF) life of contemporary heat-treated nickel-titanium rotary instruments at room and body temperatures and to document corresponding phase transformations. MethodsForty Hyflex EDM (H-EDM) files (Coltene, Cuyahoga Falls, OH [#25/.08, manufactured by electrical discharge machining]) and 40 TRUShape (TS) files (Dentsply Tulsa Dental Specialties, Tulsa, OK [#25/.06v, manufactured by grinding and shape setting]) were divided into 2 groups (n = 20) for CF resistance tests in a water bath either at room (22°C ± 0.5°C) or body temperature (37°C ± 0.5°C). Instruments were rotated in a simulated canal (angle = 60°, radius = 3 mm, and center of the curvature 5 mm from the tip) until fracture occurred. The motor was controlled by an electric circuit that was interrupted after instrument fracture. The mean half-life and beta and eta Weibull parameters were determined and compared. Two instruments of each brand were subjected to differential scanning calorimetry (DSC). ResultsWhile TS instruments lasted significantly longer at room temperature (mean life = 234.7 seconds; 95% confidence interval [CI], 209–263.6) than at body temperature (mean life = 83.2 seconds; 95% CI, 76–91.1), temperature did not affect H-EDM behavior (room temperature mean life = 725.4 seconds; 95% CI, 658.8–798.8 and body temperature mean life = 717.9 seconds; 95% CI, 636.8–809.3). H-EDM instruments significantly outlasted TS instruments at both temperatures. At body temperature, TS was predominantly austenitic, whereas H-EDM was martensitic or in R-phase. TS was in a mixed austenitic/martensitic phase at 22°C, whereas H-EDM was in the same state as at 37°C. ConclusionsH-EDM had a longer fatigue life than TS, which showed a marked decrease in fatigue life at body temperature; neither the life span nor the state of the microstructure in the DSC differed for H-EDM between room or body temperature.

Evaluation of Biocompatibility and Osteogenic Potential of Tricalcium Silicate–based Cements Using Human Bone Marrow–derived Mesenchymal Stem Cells

IntroductionThe success of endodontic regeneration lies in the appropriate combination of stem cells and bioactive materials. Several novel dental materials are available on the market in this regard. Hence, the current study aimed to evaluate the proliferation, differentiation, and osteogenic potential of human bone marrow–derived mesenchymal stem cells (hBMSCs) onto biomaterials like ProRoot MTA (MTA; Dentsply Tulsa Dental, Tulsa, OK), Biodentine (BD; Septodont, Saint Maur de Fosses, France), and EndoSequence Root Repair Material (ERRM; Brasseler USA, Savannah, GA). MethodsDental cements were formulated into discs and assessed for their biocompatibility. hBMSCs were used to study biocompatitibility and the proliferative and osteogenic potential of these dental cements. A live dead assay was performed using confocal microscopy to study the biocompatibility, proliferation, and cell attachment property of the cements. An 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was also performed on days 1, 3, 5, and 7 to study growth kinetics. The osteogenic potential of these cements was studied by inducing hBMSCs over them using osteogenic differentiation medium (assessed by alkaline phosphatase assay). ResultsERRM and MTA have shown the best biocompatibility among the tricalcium silicate materials used with no significant difference between them. Both have shown significantly higher osteogenic bioactivity than BD. All 3 tricalcium silicate cements support good adherence of hBMSCs. ConclusionsAll of the dental cements used in this study are biocompatible with the potential to induce proliferation and osteogenic differentiation of hBMSCs. Therefore, the newly introduced ERRM can be the material of choice in various endodontic applications.

Comparison of Gap Volume after Retrofilling Using 4 Different Filling Materials: Evaluation by Micro–computed Tomography

IntroductionThe purpose of this study was to evaluate the gap volume between dentin and root-end filling materials. MethodsFour root-end filling materials were compared in the present study: ProRoot MTA (PRM; Dentsply Tulsa Dental, Tulsa, OK), MTA Angelus (MAG; Angelus, Londrina, Brazil), EndoCem MTA (ECM; Maruchi, Wonju, Korea), and RetroMTA (RTM; BioMTA, Seoul, Korea). Forty-eight single-rooted, extracted human teeth were instrumented with nickel-titanium instruments and oburated with gutta-percha. The apical 3 mm of the root tip was resected, and root-end preparation was performed with a diamond bur. The root-end cavity was filled with the experimental filling materials for the 4 designated groups (n = 10). Then, the samples were scanned with micro–computed tomographic (micro-CT) imaging. Three-dimensional images of the samples were reconstructed, and the volume of the gap between the tooth surface (dentinal wall) and the root-end filling materials was measured. The percentage volume of the gap between the tooth structure and the root-end filling material (VG%) was calculated. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests at a significance level of 95%. ResultsThe median VG% values for the PRM, MAG, ECM, and RTM groups were 0.00472, 0.00134, 0.00014, and 0.00071, respectively. The ProRoot MTA group showed the greatest gap volume percentage among the experimental groups with a significant statistical difference (P < .05). ConclusionsFrom the micro-CT analysis, ProRoot MTA had a greater gap volume percentage than other root-end filling materials.

Low Environmental Temperature Influences the Fatigue Resistance of Nickel-titanium Files

IntroductionThe purpose of this study was to evaluate the effect of different temperatures (0°C, 10°C, 22°C, 37°C, and 60°C) on the cyclic fatigue life of nickel-titanium (NiTi) files using a new fatigue test model in zirconium oxide. MethodsThree superelastic NiTi files (EndoSequence [Brasseler USA, Savannah, GA], ProFile [Dentsply Tulsa Dental Specialties, Tulsa, OK], and K3 [SybronEndo, Orange, CA]), and 3 heat-treated (K3XF [SybronEndo], Vortex [Dentsply Tulsa Dental Specialties], and HyFlex CM [Coltene-Whaledent, Allstetten, Switzerland]) NiTi files, all size 25/.04, were subjected to cyclic fatigue tests inside a novel, artificial ceramic canal with a curvature of 60° and a 5-mm radius. The model was immersed in water at 5 different preset temperatures. The number of cycles to failure (NCF) was recorded, and the fracture surface of the fragments was examined by a scanning electron microscope. The data were analyzed using 2-way analysis of variance with the significance level at 0.05. ResultsWhen the temperature was reduced from 60°C to 0°C, the NCF significantly increased from over 2 to 10 times for the NiTi file groups (P < .01). K3XF had the highest fatigue resistance of all files at 0°C (P < .05). Vortex files had the highest NCF at 10°C–60°C. The NCF of heat-treated files was significantly higher than superelastic NiTi files at 10°C and 20°C (P < .05). There was no significant difference in the NCF of HyFlex CM at 0°C and 22°C. There was little difference in the fractographic appearance among different temperatures, except that the fraction area occupied by the dimple region of some instruments at 0°C was slightly smaller than at 60°C. ConclusionsCooling down to low temperatures may be an interesting strategy to improve the fatigue resistance of rotary NiTi files.

Effect of acidic pH on microhardness and microstructure of theraCal LC, endosequence, mineral trioxide aggregate, and biodentine when used as root repair material.

Introduction:The aim of this study was to investigate the microhardness and microstructural features of newer tricalcium silicate materials: TheraCal LC, mineral trioxide aggregate (MTA), biodentine (BD), and Endosequence Root Repair Material (ERRM) putty, after exposure to acidic environments in comparison with distilled water.Materials and Methods:A total of 80 extracted single-rooted premolars were collected. All the selected specimens were sectioned vertically, and cavities were prepared on the root surface. Specimens were divided into four groups of 20 each, i.e., Group 1: (n = 15) MTA (ProRoot, Dentsply Tulsa Dental, Tulsa, OK, USA), Group 2: (n = 15) BD (Septodont, France), Group 3: (n = 15) ERRM putty (Brasseler, USA), and Group 4: (n = 15) TheraCal LC (Bisco Inc Schaumburg). Materials were placed into prepared cavities. About 10 specimens per each group were exposed to butyric acid buffered at a pH level of 5.5 for 7 days at 37c, and 10 specimens from each group were exposed to distilled water serving as a control group. The surface microhardness was measured after exposure to either acid or distilled water. Scanning electron microscope was used to observe the internal microstructure morphology. Two-way analysis of variance was applied to evaluate the Knoop microhardness value (KHN).Results:Results showed that the microhardness values of the materials were significantly higher in the neutral environment of butyric acid at pH 7.4 when compared to those in the acidic condition of pH 5.4 for all groups (P < 0.001). TheraCal LC had higher microhardness values than BD, MTA, ERRM putty at 5.5 pH levels (P < 0.001).Conclusion:The microhardness values of TheraCal LC, BD, ERRM Putty, and MTA were reduced in an acidic environment, which resulted in these materials having more porous and less crystalline microstructures. TheraCal LC seems the most suitable material for application to an area of inflammation where a low pH value may exist.

In Vitro Mechanical Properties of Mineral Trioxide Aggregate in Moist and Dry Intracanal Environments.

Introduction:The purpose of this study was to examine the microhardness and modulus of elasticity (MOE) of White ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK) after setting in moist or dry intracanal conditions. Methods and Materials: To simulate root canal system, 14 polyethylen molds with internal diameter of 1 mm and height of 12 mm were used. These molds were filled with 9-mm thick layers of White ProRoot Mineral Trioxide Aggregate (MTA; Dentsply Tulsa Dental, Tulsa, OK). The experimental group (n=7) had a damp cotton pellet with 1.5 mm height and a 1.5 mm layer of resin composite placed on it. In control group (n=7) the whole 3 mm above MTA were filled with resin composite. The specimens were kept in 37°C and relative humidity of 80% for 4 days in order to simulate physiological conditions. Specimens were longitudinally sectioned and nanoindentation tests were carried out using Berkovich indenter at loading rate of 2 mN/s at 4×5 matrices of indents which were located in the coronal, middle and apical thirds of the specimen’s cross section, to evaluate the microhardness and modulus of elasticity of the specimen to appraise the progression of the setting process. Differences were assessed using nonparametric generalized Friedman rank sum and Wilcoxon Rank-Sum tests. Results:Statistical analysis showed that there was a significant difference in microhardness and MOE between control and experimental groups at coronal (P<0.001), middle (P<0.001) and apical (P<0.001) thirds of the simulated rod from simulated apical foramen. Kruskal-Wallis test showed no significant effect of depth on microhardness of material in experimental or control groups. Conclusion: Within limitations of this in vitro study, it seems that moist intracanal environment improves setting of MTA in various depths.

Root canal volume change and transportation by Vortex Blue, ProTaper Next, and ProTaper Universal in curved root canals.

ObjectivesThe 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.Materials and MethodsThirty 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.ResultsThere 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.ConclusionsOther 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.

CYCLIC FATIGUE RESISTANCE OF PROTAPER GOLD, EDGEFILE, ONESHAPE AND PROTAPER UNIVERSAL

Aim: This study aimed to compare the cyclic fatigue of EdgeFile, ProTaper Gold, OneShape, and ProTaper nickel-titanium rotary instruments. Materials and methods: F2 ProTaper Universal and ProTaper Gold (Dentsply, Tulsa Dental Specialties, Tulsa, OK, USA), C2 EdgeFile (EDGEENDO, Albuquerque, NM, USA), and size 25 OneShape (Micro-Mega, Besancon Cedex, France) (15 instruments each group) were tested for cyclic fatigue in an artificial canal with a 6-mm radius and a 45° curvature. The number of cycles to fatigue (NCF) was recorded, the lateral surface and fractured face of segments were examined using scanning electron microscopy (SEM), and the cross-sectional area was measured. One-way ANOVAs and Games-Howell tests were utilized for data analysis. A significant difference was set at 0.05. Results: The EdgeFile had significantly greater resistance to cyclic fatigue, compared with the ProTaper Gold, OneShape, and ProTaper Universal (p 0.05), and the ProTaper Universal exhibited significantly lower resistance to cyclic fatigue compared to the other systems (p 0.05). No significant differences were found among the groups regarding the length of the fractured segments (p>0.05). Conclusion: EdgeFile rotary files have superior resistance to cyclic fatigue, followed in order by the ProTaper Gold, OneShape, and ProTaper Universal rotary files.

An in vitro cyclic fatigue resistance comparison of conventional and new generation nickel-titanium rotary files.

BackgroundNew designs and processing of Niquel-Titanium (NiTi) have been introduced to increase resistance to cyclic fatigue. The purpose of this study was to compare the cyclic fatigue resistance of 3 NiTi rotary instruments, ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), Profile Vortex Blue (PVB; Dentsply Tulsa Dental, Tulsa, OK, USA) and ProTaper Universal (PTU; Dentsply Maillefer, Ballaigues, Switzerland).Material and MethodsA cyclic fatigue test was conducted operating instruments from ProTaper Next X2, Profile Vortex Blue 25.06 and ProTaper F2. A total of 234 instruments were rotated in 2 simulated stainless steel curved canals with different angles of curvature (45º and 60°) and 5-mm radius of curvature. The number of cycles to fracture (NCF) was calculated. Data were compared using 2-way analysis of variance and post-hoc Bonferroni test in software (SPSS 15.0, Chicago, IL). Statistical significance was set at P<0.05.ResultsProfile Vortex Blue showed higher resistance to cyclic fatigue in both curved canals than ProTaper Next and ProTaper Universal (P<0.001). ProTaper Universal obtained the lowest resistance to cyclic fatigue in both canals (P<0.001).ConclusionsProfile Vortex Blue was the most resistant to cyclic fatigue failure, followed by ProTaper Next and ProTaper Universal. Anatomical complexity (angle of curvature) and manufacturing process of NiTi are important factors for resistance to cyclic fatigue. Key words:Cyclic fatigue, M-Wire, Protaper Next, ProTaper Universal, Profile Vortex Blue.

Effect of blood contamination on the push-out bond strength of four endodontic root perforation repair materials: An in vitro study

Aim: To evaluate the push-out bond strength of four endodontic root perforation repair materials on blood contamination. Materials and Methods: Freshly extracted 80 single-rooted human canine teeth were used. The crowns of all teeth were removed, and the mid-root dentin was sectioned horizontally into slices with a thickness of 1.0mm by using a diamond disk. In 40 samples, a 27-gauge syringe was used to inject blood into the perforated area, which was taken from the patient. Biodentine (Septodont, Pennsylvania, USA) liquid from a single dose container was emptied into a powder-containing capsule and mixed 30 seconds, was mixed in 10 samples; glass ionomer cement (GIC) (GC Fuji IX; GC, Tokyo, Japan) was mixed in 10 samples; ProRoot mineral trioxide aggregate (MTA) (DENTSPLY, Tulsa Dental Specialties, Tulsa, Oklahoma), hand mixed with sterile water at a powder to liquid ratio of 3:1 in accordance with the manufacturer’s instructions, was mixed in 10 samples; and Cavit (ESPE Dental Products, Ohio, USA) was mixed in 10 samples and placed in perforation area. In the remaining 40 samples, normal saline irrigation was performed before restoring 10 samples with Biodentine, 10 samples with GIC, 10 samples with ProRoot MTA, and 10 samples with Cavit. The samples were carried in wet gauze piece and placed in a closed container in an incubator at 370°C and 100% humidity until push-out bond strength was carried out. Results: The result was statistically analyzed using one-way analysis of variance (ANOVA) and Tukey’s post hoc tests. P <0.05 was considered as significant. Conclusion: Push-out bond strength of Biodentine was higher than that of ProRoot MTA, GIC, and Cavit on blood contamination.

Effectiveness of Two Techniques in Removal of Calcium Hydroxide Medicament from Root Canals: An in-vitro Assessment

Introduction: Calcium Hydroxide {Ca(OH)2} is widely used as intracanal medicament. However, complete removal of Ca(OH)2 is very difficult from canal walls resulting in its residues on canal wall which interfere with bonding of sealers and reduce success of root canal treatment.Aim: To compare the effectiveness of two techniques, i.e., wave one and wave one with EndoActivator in removing Ca OH)2 from the root canals.Materials and Methods: This was an in vitro study involving 30 extracted single-rooted mandibular premolar bicuspid teeth. Access opening was done followed by biomechanical preparation with ProTaper universal rotary file system (Dentsply, Tulsa Dental Specialities) till F2. Canals were filled with injectable Ca(OH)2 (UltraCal XS, Ultradent Products, INC). The tooth was stored in saline for one week. Then samples were divided into two main groups T1 and T2 (n=15) according to the method of Ca(OH)2 removal. Group 1 (T1): Ca(OH)2 was removed using wave one file alone. Group 2 (T2): Ca(OH)2 was removed using wave one file followed by EndoActivator.Teeth were sectioned buccolingually. The amount of residual Ca(OH)2 was observed and under a stereo microscope (30X magnification) for coronal, middle and apical third. The data were analysed using Mann-Whitney U test to compare between the two techniques, i.e., T1 and T2, taking into consideration p 0.05). The most efficient Ca(OH)2 removal in apical and middle third was recorded in Group 2 (T2), i.e., Wave one with EndoActivator (p<0.05) as compared to Group 1 (T1) wave one file alone.Conclusion: EndoActivator results in better debridement of root canals when used in combination with different rotary file systems.

Percentage of Gutta-percha–filled Areas in Canals Obturated by 3 Different Techniques with and without the Use of Endodontic Sealer

IntroductionThis study had 2 purposes: to compare the Microseal, continuous wave, and Thermafil techniques and to compare the same techniques with and without endodontic sealer. MethodsNinety extracted mandibular premolars were allocated into 6 groups obturated with Microseal (Analytic, Glendora, CA) and sealer (Mseal), Microseal without sealer (Mnoseal), System B (EIE Analytic Technology, Orange, CA) and sealer (SBseal), System B without sealer (SBnoseal), Thermafil (Dentsply, Tulsa Dental, Tulsa, OK) and sealer (Tseal), and (Tnoseal) Thermafil without sealer (Tnoseal). The teeth were sectioned at 1 and 3 mm from the apex. The total area of each canal segment was measured, and the areas were converted to the percentage of gutta-percha–filled areas, sealer-filled areas, and void areas. Data obtained were statistically elaborated using the t test (P ≤ .01). ResultsAt 1 mm, SBseal produced a higher VA than Mseal and Tseal. At 3 mm, Tseal produced a lower VA than Mseal and SBseal, whereas Mseal produced a lower VA than SBseal (P > .01). At 1 mm, Tnoseal produced a significantly higher VA than Mnoseal and SBnoseal (P = .001). At 3 mm, Tnoseal produced a higher VA than Mnoseal and SBnoseal (P = .01). Tnoseal produced a significantly higher VA than Tseal both at 1 mm (P = .001) and 3 mm (P = .001). ConclusionsEndodontic space filling is traditionally provided by sealer and gutta-percha. In this study's conditions, gutta-percha alone showed better filling at both 3 mm and 1 mm in the Microseal and System B techniques. Considering the limits of our study, we can affirm that endodontic techniques using sealer could counteract thermoplasticized gutta-percha progression.

Cyclic and Torsional Fatigue Resistance of XP-endo Shaper and TRUShape Instruments

IntroductionThe purpose of this study was to evaluate the cyclic and torsional fatigue resistance of the XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) and TRUShape (Dentsply Tulsa Dental Specialties, Tulsa, OK) instruments. MethodsTwenty XP-endo Shaper (30/0.01) instruments and 20 TRUShape (30/0.06v) instruments were used. Cyclic fatigue resistance was tested by measuring the number of cycles and time to fracture in an artificial stainless steel canal with a 60° angle and a 5-mm radius of curvature (n = 10). The torque and angle of rotation at failure of new instruments (n = 10) were measured according to ISO 3630-1. The fracture surface of all fragments was examined with a scanning electron microscope. Results were statistically analyzed using the Student t test at a significance level of P < .05. ResultsThe XP-endo Shaper instruments showed a significantly longer number of cycles to fracture and time to failure in seconds than the TRUShape instruments (P < .05). The XP-endo Shaper also presented a lower maximum torque load (P < .05) but a significantly higher angular rotation to fracture than TRUShape (P < .05). ConclusionsThe XP-endo Shaper instruments showed a higher cyclic fatigue resistance and angle of rotation to fracture but lower torque to failure than TRUShape instruments.

Cyclic fatigue resistance of XP-endo Shaper compared with different nickel-titanium alloy instruments.

The aims of this study were to assess and compare the resistance to cyclic fatigue of XP-endo Shaper (XPS; FKG Dentaire, La Chaux-de-Fonds, Switzerland) instruments with TRUShape (TRS; Dentsply Tulsa Dental Specialties, Tulsa, OK, USA), HyFlex CM (HCM; Coltene, Cuyahoga Falls, OH, USA), Vortex Blue (VB; Dentsply Tulsa Dental Specialties), and iRace (iR; FKG Dentaire) nickel-titanium rotary instruments at body temperature. Size 30, 0.01 taper of XPS, size 30, 0.04 taper of HCM, VB, iR, and size 30, 0.06 taper of TRS instruments were immersed in saline at 37±1°C during cyclic fatigue testing. The instruments were tested with 60° angle of curvature and a 3-mm radius of curvature. The number of cycles to failure (NCF) was calculated and the length of the fractured segment was measured. Fractographic examination of the fractured surface was performed using a scanning electron microscope. The data were analyzed statistically using Kruskal-Wallis H test and Mann-Whitney U tests. Statistical significance was set at P<0.05. XPS had a significantly greater NCF compared with the other instruments (P<0.001). The topographic appearance of the fracture surfaces of tested instruments revealed ductile fracture of cyclic fatigue failure. XPS instruments exhibited greater cyclic fatigue resistance compared with the other tested instruments. XP-endo Shaper instruments could be used more safely in curved canals due to their higher fatigue resistance.