Elif Kalyoncuoğlu

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.

A comparative scanning electron microscopy evaluation of smear layer removal from teeth with different irrigation solutions and lasers.

The aim of this study was to evaluate the efficacy of smear layer removal from teeth following root canals using lasers (Er:YAG and Nd:YAG), NaOCl, 17% EDTA, and MTAD by scanning electron microscopy (SEM). Root canals were irrigated with 3 mL of 5.25% NaOCl after each file. Teeth were randomly divided into five groups. In the final irrigation, canals were irrigated with 5.25% NaOCl (Group 1, control), 17% EDTA (Group 2), or BioPure MTAD (Group 3). Laser groups were irradiated with Er:YAG laser (1.8 W, 120 mJ, 15 Hz) (Group 4) or Nd:YAG laser (1 W, 100 mJ, 15 Hz) (Group 5). The smear layer at the apical, middle, and coronal thirds of each root canal was imaged using SEM. Smear layer removal by EDTA was the most effective in all regions. The difference between EDTA and MTAD was statistically significant in the coronal and middle (p < 0.05), but not the apical (p > 0.05), regions. The difference between the control and laser groups was not statistically significant (p > 0.05). In all regions, the difference between 17% EDTA-MTAD and the control-laser groups was statistically significant (p < 0.05). Although improvement was observed in removal of the smear layer using alternative materials and techniques, application of a combination of EDTA and NaOCl remains an effective technique.

Evaluation of goat milk as storage media to preserve viability of human periodontal ligament cells in vitro

BACKGROUND AND AIM The purpose of this study was to evaluate the effectiveness of goat milk as a storage media for maintenance of periodontal ligament (PDL) cell viability of avulsed teeth and compare it with commonly used and/or investigated storage media. MATERIALS AND METHODS PDL cells were obtained from the root surface of healthy premolars and were cultured in Eagles maintenance medium (EMM). Cell cultures were treated with the following storage media: tap water (negative control); EMM (positive control); Hanks balanced salt solution; ultra high temperature (UHT) long-shelf-life lactose-free cow milk; UHT long-shelf-life whole cow milk; UHT long-shelf-life skimmed cow milk; UHT long-shelf-life soy milk; UHT long-shelf-life goat milk, UHT long-shelf-life follow on milk with probiotic, 20% propolis, and egg white. Culture plates were incubated with experimental media at 20°C for 1, 3, 6, 12, and 24 h. PDL cell viability was assessed by tetrazolium salt-based colorimetric (MTT) assay at each test period. One-way anova was used to evaluate the effects of storage solutions at each time point, followed by post hoc Duncans multiple comparison test (P = 0.05). A dendrogram was constructed to show the arrangement of hierarchical clustering. RESULTS Goat milk displayed the highest capacity to maintain cell viability at all test intervals (P < 0.001). Between 3 and 24 h, milk with the probiotic showed the lowest time-dependent PDL cell viability among all test media (P < 0.001). Compared with all milks, HBSS performed significantly less effectively in maintaining PDL cell viability during the entire test period (P < 0.001). CONCLUSION Based on PDL viability, goat milk can be recommended as a suitable storage medium for avulsed teeth.

Cyclic Fatigue Resistance of XP-Endo Shaper, K3XF, and ProTaper Gold Nickel-titanium Instruments

Introduction: The aim of this study was to compare the cyclic fatigue resistance of the ProTaper Gold (PTG; Dentsply Maillefer, Ballaigues, Switzerland), K3XF (SybronEndo, Orange, CA), and XP‐endo Shaper (FKG Dentaire, La Chaux‐de‐Fond, Switzerland) nickel‐titanium rotary instruments at intracanal temperatures. Methods: Eighteen XP‐endo Shaper (30.01), 18 K3XF (30.04), and 18 PTG F3 (30.09v) instruments were used to test the cyclic fatigue resistance at an intracanal temperature of 35° ± 2°C. The instruments were tested in a metal block that simulated a canal curvature angle of 60° and a curvature or radius of 5 mm. All instruments were operated until fracture occurred, and then the number of cycles to failure was calculated. The lengths of fractured fragments were measured with a digital caliper. The data were analyzed statistically using 1‐way analysis of variance and the Tukey post hoc test with significance set at P < .05. Results: The XP‐endo Shaper instruments showed a significantly higher number of cycles to fracture than the K3XF and PTG instruments (P < .05). There was no difference between the PTG and K3XF instruments (P > .05). Conclusions: The XP‐endo Shaper instruments exhibited greater cyclic fatigue resistance compared with the other instruments at the intracanal temperature. Highlights:The cyclic fatigue (CF) resistance of the novel XP‐endo Shaper instrument was compared with the ProTaper Gold F3 and K3XF instruments.The XP‐endo Shaper (30.01) exhibited the highest CF resistance.There was no significant difference between ProTaper Gold (30.09v) and K3XF (30.04) regarding CF resistance.

Scanning electron microscopy with energy dispersive X-ray spectrophotometry analysis of reciprocating and continuous rotary nickel-titanium instruments following root canal retreatment

This study aimed to evaluate superficial defects and the composition of Reciproc R25 and ProTaper Retreatment file systems (Dentsply Maillefer, Ballaigues, Switzerland) used for retreatment. A total of 100 maxillary incisor teeth were randomly divided into the following two groups: Reciproc R25 (n = 25) and ProTaper Retreatment instrument (n = 75) groups. The nickel-titanium (Ni-Ti) compositions of the files before and after use were analyzed using energy dispersive X-ray spectrophotometry (EDX). Chi-square, Mann-Whitney U, and Kruskal-Wallis tests were used to analyze the data. ProTaper Retreatment instrument group showed a significantly higher number of defects than the Reciproc group (P < 0.05). No instrument fracture was detected. The presence of debris was observed in both groups before use, although the level was significantly higher in the ProTaper Retreatment group, which consisted of metals (P < 0.05). There was no significant difference between new and used instruments with regard to Ni-Ti composition (P < 0.05). EDX analysis showed that both the Reciproc and ProTaper Retreatment instruments had a Ni-Ti composition that was within the standards specified by the American Society of Testing and Materials. This study confirmed the use of both the Reciproc R25 file and ProTaper Retreatment file system for root canal filling removal in straight root canals as a safe procedure. (J Oral Sci 58, 401-406, 2016).

Effect of propolis as a root canal irrigant on bond strength to dentin

Purpose The purpose of this in vitro study was to evaluate the effect of propolis on bond strength to dentin of a self-etch adhesive when used as a final irrigant. Methods 126 human third molars were sectioned 3 mm below the occlusal level and then randomly divided into 7 groups (n = 18). The exposed dentin surfaces were treated with irrigation solutions as follows: Group 1: 5.25% NaOCl; Group 2: 5.25% NaOCl followed by 17% EDTA; Group 3: 5.25% NaOCl followed by Tubulicid Plus (Temrex, Freeport, NY, USA); Group 4: 5.25% NaOCl followed by MTAD; Group 5: 5.25% NaOCl followed by 20% propolis; Group 6: 5.25% NaOCl followed by 2% CHX; Group 7: distilled water (control). Irrigated specimens were bonded using Clearfil SE Bond (Kuraray, Osaka, Japan) with Tygon (Saint-Gobain, Saint-Gobain Performance Plastics, France), tubes for microshear bond strength testing. Data was analyzed using a one-way ANOVA and Tukey test. Results Among the tested groups, although the lowest bond strength values were detected in Group 1 (11.25 ± 1.97), a significant statistical difference was detected only between this group and Group 4 (18.70 ± 1.82) and Group 5 (16.75 ± 3.70) (p = 0.0012). Conclusions 20% propolis solution as a final irrigant was found to have a favorable effect on the dentin bond strength of the tested self-etch adhesive to coronal dentin when compared with other irrigation solutions.

The Effects of Smoking on the Osmotic Pressure of Human Dental Pulp Tissue.

Objective: We aimed to investigate the effect of smoking on the osmotic pressure (OP) of human dental pulp tissue. Materials and Methods: Sixty male dental patients (smokers and nonsmokers) scheduled for root canal treatment for prosthodontics were included in the study. Fifteen patients (1 premolar tooth/patient) were allocated to each of the following groups according to their smoking habits, i.e. group 1: ≤10 cigarettes/day, group 2: 11-20 cigarettes/day, group 3: >20 cigarettes/day and group 4: nonsmoking controls. Apical pulp tissues were removed via coronal access. Pulp tissue supernatants were obtained to measure the pulpal OP by means of a semimicro digital osmometer. One-way analysis of variance and the post hoc Duncan test were used to analyze the differences in OP between groups. Regression analysis was used to determine the relationship between the number of cigarettes smoked daily and the pulpal OP. Results: The mean (± SD) OP value decreased as cigarette consumption increased: group 4 (268.00 ± 10.09 mosm/kg) > group 1 (259.20 ± 7.16 mosm/kg) > group 2 (248.90 ± 2.23 mosm/kg) > group 3 (239.90 ± 7.40 mosm/kg). The OP differed significantly between groups (p < 0.01), and a significant negative correlation was found between cigarette consumption and pulpal OP (r = -0.809, p < 0.01). Conclusion: In this study, the OP decreased as the number of cigarettes smoked increased. In clinical examination, there may be misdiagnosis of pulpal conditions in smokers (even in healthy pulp tissue) due to the effect of altered OP on pulpal tissue reactions.

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.