Comparison of postoperative pain after the use of different nickel titanium instrumentation systems: a randomized clinical trial.

Purpose: Postoperative pain is a common complication in endodontics contributed by multiple etiological factors, which consist canal preparation instruments and kinematics. The aim of this randomized clinical trial compare the postoperative pain in terms of intensity and incidence after the use of different nickel titanium (NiTi) file systems. Patients and methods: In this randomized clinical trial (NCT03791762), a total of 150 patients were root canal treated by 2 experienced endodontists according to a standardised protocol. The subjects were randomly assigned to 1 of the 3 groups according to preparation instrument used: ProTaper Next (Dentsply Sirona, Ballaigues, Switzerland), Reciproc Blue (VDW, Munich, Germany) and WaveOne Gold (Dentsply Sirona). Following preparation the teeth underwent standardized root canal treatment procedures in a single visit. The patients were contacted to gather information about the incidence of pain and intensity at 6th, 12th, 18th, 24th, 48th, and 72nd hours postoperatively. The data were analysed using chi-square, one-way analysis of variance and post hoc Tukey tests and logistic regression analysis with 5% significance threshold. Results: No significant difference was found among preparation groups in relation to the intensity of postoperative pain. The incidence of postoperative pain was significantly linked with the preoperative pain presence with odds ratio values ranging between 2.06 and 4.08 irrespective of the preparation technique (P<0.05). Conclusion: The effects of reciprocating and the continuous rotary systems on the intensity and incidence of postoperative pain were found to be similar.

Metallurgical characterisation and torsional resistance of blue thermomechanically treated nickel titanium instruments after simulated ex vivo retreatment procedure.

To compare used and unused Reciproc Blue and Reciproc after retreatment, the instruments were used in the mesiobuccal canals of maxillary molars with curvature. The torsional resistances were tested and then unused instruments were subjected to XRD, DSC and microhardness tests. Student's t, ANOVA and Tukey's tests were performed (α-level 0.05). The torsional strength of used Reciproc Blue was not significantly different than unused ones (P > .05), while torsional strength of Reciproc decreased significantly (P < .05). DSC and XRD indicated that Reciproc Blue exhibited prominent transformation peaks corresponding austenite to R-phase. Microhardness of Reciproc was significantly higher (P < .05). A second reuse of Reciproc Blue for retreatment could be considered safe in terms of torsional strength. Blue treatment also decreased surface microhardness of the instrument and changed phase composition by increasing the R-phase.

Diagnostic accuracy of endoscopy for the detection of isthmuses of mandibular molar teeth using micro-CT as reference.

PURPOSE: The aim of this study was to evaluate the efficacy of endoscopic visualisation to detect the presence and type of isthmuses within the mesial root canals of mandibular first molar teeth compared with micro-computed tomography (micro- CT) images as reference. MATERIALS AND METHODS: Thirty-two mesial roots of mandibular first molars presenting isthmuses were selected based on micro-CT scans. In all, 12 type I and 20 band-shaped isthmuses were collected. The specimens were mounted in the posterior socket of dental phantom manikin for endoscopic visualisation. The ability of endoscopes to visualize the presence of isthmuses and distinguish the type of isthmuses was compared. Micro-CT images of the specimens were used as references. Data were analyzed using Fisher's exact tests. RESULTS: Sensitivity of endoscope to detect isthmuses were also calculated for each isthmus type. In 37.5% of the samples, isthmus presence was correctly diagnosed via orthograde endoscopic visualization. Type I istmuses were significantly more detected than band-shaped isthmuses (P<0.05). Endoscope showed higher sensitivity to detect type I isthmus than band-shaped isthmus. CONCLUSION: The endodontic endoscope could detect type I isthmuses more accurately than band- shaped isthmuses.

Comparison of the Torsional Resistance of 4 Different Glide Path Instruments.

INTRODUCTION: The present study aimed to compare the torsional strength of the initial files of the Mtwo (VDW, Munich, Germany) and novel Rotate systems (VDW, Munich, Germany) with the ProGlider (Dentsply Sirona, Ballaigues, Switzerland) and R-Pilot (VDW) glide path instruments. METHODS: The Mtwo (10/.04), ProGlider (16/.02), R-Pilot (12.5/.04), and Rotate (15/.04) glide path files were compared regarding their torsional strength, which was tested using a specially designed test device (N = 20). The data obtained were statistically analyzed at 5% significance level using 1-way analysis of variance and the post hoc Tukey test. The fragment surfaces and separated instruments were examined with ×50, ×100, and ×1000 magnification under a scanning electron microscope. RESULTS: The R-Pilot group showed the highest torsional strength value among all groups (P < .05), whereas there was no significant difference between the torsional strength values of the Mtwo and ProGlider groups (P > .05). The Rotate group had the lowest torsional strength among all groups (P < .05). The Mtwo group showed the lowest angle of rotation among all groups (P < .05). CONCLUSIONS: Although the R-Pilot glide path file exhibited the highest torsional strength in all groups, Rotate showed the highest angle of rotation. Differences in torsional resistance of the instruments may be associated with their manufacturing methods and design features.

Visualization and characterization of Enterococcus faecalis biofilm structure in bovine dentin using 2D and 3D microscopic techniques.

Bacterial biofilms are related to various dental and periodontal infectious diseases, and the characterization of this biological structure with micro-computed tomography (micro-CT) may offer valuable information for clinical and research applications. In this study, we aimed to develop a model to visualize three-dimensionally the biofilm structure on dentin using micro-CT. Dentin blocks were prepared and incubated in tryptic soy broth with Enterococcus faecalis (ATCC 29212). The control group did not receive any staining procedure, while groups 1 and 2 were stained with 100% and 50% barium sulfate, respectively. Transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM) were used to detect biofilm formation, barium sulfate penetration, and microbial cell density in the biofilm. Micro-computed tomography (micro-CT) (SkyScan 1172, Bruker Co., Belgium) was used to visualize biofilm formation on the dentin blocks. Biofilm thicknesses were measured from 10 different locations on the specimen surfaces, using CTAn v.1.14.4 software. Obtained data were statistically analyzed using Kruskal-Wallis and Dunn's tests. TEM photomicrographs showed that barium sulfate could penetrate the biofilm structure. CLSM analysis showed that viable and total cell densities were similar between the control and barium sulfate-treated groups (P > 0.05), indicating barium sulfate had no significant influence on cell density. In barium sulfate-treated blocks, biofilm could be discriminated from the dentin, and its thickness could be measured with micro-CT. This study showed that bacterial biofilm on dentin could be characterized by micro-CT after barium sulfate staining without causing any significant side effect on viable and total cell densities.

Accuracy of an endoscope to detect root canal anastomoses in mandibular molar teeth: a comparative study with micro-computed tomography.

Objective: The aim of this study was to investigate the accuracy of endoscopic visualization to detect root canal anastomoses at the coronal half of the mesial root canals of mandibular molars using micro-computed tomographic (micro-CT) images as reference.Material and methods: Seventy-four mesial roots of mandibular first molars with (n = 47) or without (n = 27) intercanal anastomosis were selected based on the micro-CT scans of 269 mandibular first molars at a pixel size of 10 µm. The specimens were mounted on the mannequins and their root canals were evaluated using dental operating microscope (DOM) and endoscope. The endoscopic probe was inserted into the main mesial root canals and 2 blinded observers evaluated the presence of a divergence point of anastomosis (where the branching occurs) as 'present' or 'absent'. The scorings were compared with the three-dimensional reconstructed images of the specimens and recorded as 'correct' or 'incorrect' evaluation. Degree of agreement between evaluators was assessed with Kappa test and the accuracy of endoscopic visualization according to the presence and location of anastomosis was compared using Fisher exact tests with a significance threshold at 5%.Results: High inter-examiner reliability was reported (0.91). None of the divergence points were identified using DOM whereas 11 divergence points were detected using endoscope, corresponding the 23.4% of the intercanal anastomoses. The endoscope also showed the absence of an intercanal anastomosis correctly in all of the specimens without an anastomosis. Detectability of a divergence point using endoscope was not affected by its location within the coronal half of root canal (p > .05).Conclusions: The endoscopes were able to visualize the divergence points of 23.4% of the intercanal anastomoses located at the coronal halves of root canals.

Push-out bond strength of oval versus circular fiber posts irradiated by erbium-doped yttrium aluminum garnet laser.

STATEMENT OF PROBLEM: Fiber posts in conjunction with resin cements are widely used to provide retention in endodontically treated teeth. The bond strength of restorative materials to root canal dentin is an important issue for the long-term success of restorative procedures. The push-out test is widely used to measure the bonding between the post and radicular dentin. PURPOSE: The purpose of this in vitro study was to evaluate the effect of erbium-doped yttrium aluminum garnet (Er-YAG) laser treatment of dentinal walls on the bond strength of circular and oval fiber posts luted in oval root canals. MATERIAL AND METHODS: Forty mandibular premolar teeth were endodontically treated and restored with 2 different intracanal post systems. Push-out tests were performed and data were analyzed by using 2-way analysis of variance and post hoc Bonferroni tests. RESULTS: Laser pretreatment of dentinal walls resulted in higher push-out bond strength than that of the nonlasered groups (P<.05). Oval fiber posts showed significantly higher push-out bond strength values than those of circular fiber posts in the coronal region (P<.05). In the apical region, no statistically significant difference was noted among the groups regarding push-out bond strength (P>.05). CONCLUSIONS: The laser pretreatment with an oval ultrasonic tip of an oval fiber post system improved bonding to root canal dentin when compared with a circular post system with conventional preparation.

Effect of 1-piece post and core fabrication techniques on fracture strength.

PURPOSE: The purpose of this in vitro study was to evaluate and compare the fracture strengths of post and core systems produced with different fabrication techniques and materials. METHODS: Forty extracted human single-root premolars were used in this study. After root canal treatment, the teeth were randomly divided into 4 groups of 10 each as follows: group C: metallic 1-piece posts and cores fabricated by casting, and serving as the control; group CM: metallic posts and cores fabricated with the copy milled technique; group LS: 1-piece posts and cores fabricated with the laser sintering technique; and group ZR: 1-piece zirconia posts and cores fabricated with computer-aided design and computer-aided manufacturing (CAD-CAM). The posts and cores were cemented to the teeth with adhesive resin cement; then, the specimens were mounted to acrylic resin blocks, attached to an Instron Universal Testing Machine, and loaded with a crosshead speed of 1 mm/min, until fracture. Data were statistically analyzed using 1-way analysis of variance (ANOVA), followed by the post hoc Tukey test (α = 0.05). RESULTS: The highest fracture results were found in group ZR (315.4 ± 53.4 N), which showed significant differences from all other groups (p<0.05). The lowest test values were found in group C (230.2 ± 29.8 N). Group LS (250.9 ± 29.0 N), group CM (253.0 ± 22.4 N) and group C did not show any significant differences (p>0.05). CONCLUSIONS: Custom-made zirconia 1-piece posts and cores, fabricated using the CAD-CAM procedure, can be an alternative treatment method when compared with other techniques.

Effect of F-File on removal of the smear layer: a scanning electron microscope study.

The aim of this study was to evaluate the effectiveness of F-File with NaOCl on removal of the smear layer. A total of 48 single-rooted teeth were instrumented using crown-down technique with one of the irrigation agents: distilled water, 5.25% NaOCl, RC-Prep, Glyde, MTAD or F-File with NaOCl. The remaining smear layer was scored at cervical, middle and apical thirds of the roots with SEM. In all the canals of experimental groups the coronal sections were cleaner than the middle and apical sections except with distilled water (P<0.001). In the coronal third, intensive smear layer was observed in distilled water, NaOCl and F-File groups and less smear layer in MTAD (P<0.05) and least in RC-Prep and Glyde groups. In the middle third, RC-Prep and Glyde groups had less smear layer than the other groups (P<0.001). In the apical third, there was intensive smear layer in all specimens and statistical analyses showed no significant difference among the groups (P>0.05). The F-file failed to improve the effect of NaOCl in removing smear layer.

Effect of immediate and delayed post space preparation on the apical seal of root canals obturated with different sealers and techniques.

UNLABELLED: During mechanical preparation of the post space, the root canal filling may be twisted or vibrated, depending on several factors associated with the preparation technique and quality of filling. OBJECTIVE: The purpose of this study was to investigate the effect of immediate and delayed post space preparation on the integrity of the apical seal. MATERIAL AND METHODS: Sixty-four extracted human incisors were biomechanically prepared using the step-back technique. Sixty roots were randomly assigned to 6 experimental groups of 10 teeth each and the remaining 4 roots served as positive and negative controls (n=2). The root canals in the different groups were obturated with cold lateral and warm vertical condensation of gutta-percha and one of two sealers (Sealapex and Diaket). Post space was prepared either individually or simultaneously. An insulated copper wire was cut into 10-cm-long pieces. In each canal, one piece was inserted to maintain contact with gutta-percha and extended to the outside as one of two working electrodes. A stainless steel wire with the same dimensions of those of the copper wire, used as the other working electrode, was immersed into the background electrolyte from the center of the bottle. The electrical current between standard and experimental electrodes in canals was measured over a period of 10 days applying a conductivity meter. The Kruskal-Wallis test (p=0.05) determined whether there was a significant difference in microleakage among the groups and the Mann-Whitney U test (p=0.01) was used for multiple comparison grouping variables. RESULTS: The results suggest that only the differences between the root canal filling techniques were statistically significant (p<0.01). There were no statistically significant difference in the sealers and the times of filling removal for post space preparation (p>0.01). CONCLUSION: The quality of the root canal filling is important for the integrity of the apical seal.

Effect of immediate and delayed post space preparation on the apical seal of root canals obturated with different sealers and techniques

During mechanical preparation of the post space, the root canal filling may be twisted or vibrated, depending on several factors associated with the preparation technique and quality of filling. OBJECTIVE: The purpose of this study was to investigate the effect of immediate and delayed post space preparation on the integrity of the apical seal. MATERIAL AND METHODS: Sixty-four extracted human incisors were biomechanically prepared using the step-back technique. Sixty roots were randomly assigned to 6 experimental groups of 10 teeth each and the remaining 4 roots served as positive and negative controls (n=2). The root canals in the different groups were obturated with cold lateral and warm vertical condensation of gutta-percha and one of two sealers (Sealapex and Diaket). Post space was prepared either individually or simultaneously. An insulated copper wire was cut into 10-cm-long pieces. In each canal, one piece was inserted to maintain contact with gutta-percha and extended to the outside as one of two working electrodes. A stainless steel wire with the same dimensions of those of the copper wire, used as the other working electrode, was immersed into the background electrolyte from the center of the bottle. The electrical current between standard and experimental electrodes in canals was measured over a period of 10 days applying a conductivity meter. The Kruskal-Wallis test (p=0.05) determined whether there was a significant difference in microleakage among the groups and the Mann-Whitney U test (p=0.01) was used for multiple comparison grouping variables. RESULTS: The results suggest that only the differences between the root canal filling techniques were statistically significant (p<0.01). There were no statistically significant difference in the sealers and the times of filling removal for post space preparation (p>0.01). CONCLUSION: The quality of the root canal filling is important for the integrity of the apical seal.

Leakage evaluation of three different root canal obturation techniques using electrochemical evaluation and dye penetration evaluation methods.

The aim of this study was to compare the apical sealing ability of three different obturation techniques using an electrochemical evaluation and evaluating dye penetration. One hundred and thirty-two maxillary anterior teeth were randomly divided into six groups. There were 20 teeth in each group. The teeth were obturated as follows: Groups 1 and 4 with Thermafil, Groups 2 and 5 with System B, and Groups 3 and 6 with cold lateral condensation (CLC). The apical leakage in these groups was evaluated using an electrochemical method for Groups 1, 2, 3 and a dye penetration method for Groups 4, 5 and 6. In both methods, the lowest mean leakage values were observed for Thermafil and the highest were observed for the CLC groups. The difference between Thermafil and CLC was statistically significant (P < 0.05). In both groups, System B fillings showed moderate leakage and the difference was not significant with Thermafil and CLC groups.