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  • Küçük Resim
    Öğe
    Effect of Chloroform On the Cyclic Fatigue Resistance of Nickel-Titanium Retreatment Instruments
    (Selçuk Üniversitesi, 2021) Eren, Selen Küçükkaya; Keleş, Ahmet; Örs, Sevinc Askerbeyli; Aksel, Hacer
    Background: The purpose of this study was to evaluate the cyclic fatigue resistance of 4 different rotary nickel-titanium (NiTi) retreatment instruments after immersion in chloroform solution. Methods: A total of 120 ProTaper D3, R-Endo R3, D-Race DR2 and Mtwo R2 retreatment instruments were used. Thirty instruments of each system were randomly divided into 2 groups (n=15); Group 1: no immersion and Group 2: immersion in chloroform for 5 min. The instruments were operated in a dynamic cyclic fatigue test device until fracture occurred. The number of cycles to fracture and length of the fractured fragment for each instrument were recorded. Representative samples were examined under a scanning electron microscope. Data were analyzed by using 2-way analysis of variance and Bonferroni tests. Results: The ProTaper D3 and R-Endo R3 instruments showed the highest cyclic fatigue resistance whether or not immersed in chloroform (p<0.05). The immersion in chloroform did not affect the cyclic fatigue resistance of the instruments (p>0.05). The Mtwo R2 instruments were more resistant to cyclic fatigue than the DRace DR2 instruments before and after immersed in chloroform (p<0.05). Conclusion: The immersion in chloroform had no effect on the cyclic fatigue resistance of retreatment instruments. The ProTaper D3 and R-Endo R3 instruments were more resistant to cyclic fatigue than other retreatment instruments regardless of chloroform exposure.
  • Küçük Resim
    Öğe
    Effect of tannic acid irrigation on microhardness of root canal dentin and bond strength of epoxy resin based sealer
    (Selçuk Üniversitesi, 2019) Askerbeyli Örs, Sevinc; Aksel, Hacer; Küçükkaya Eren, Selen; Zeybek, Naciye Dilara
    Background: To investigate the effects of final irrigation protocols with tannic acid (TA) on dentin microhardness and push-out bond strength of an epoxy resin based sealer to root canal dentin. Materials and Methods: The 50 root halves were embedded in an acrylic resin for the microhardness measurement. After the initial baseline microhardness measurement the root samples were immersed in 2.5% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA) for 2 min, respectively. Then, the root halves were randomly divided into 5 groups according to the final irrigation protocol used (n=10): distilled water (control), 10% TA for 2 min, 10% TA for 5 min, 20% TA for 2 min, and 20% TA for 5 min. After surface treatment, dentin microhardness values were recorded at close proximity to the initial indentation areas. For push-out bond strength test, the root canals of 75 single-rooted mandibular premolars were instrumented and the irrigation protocols were applied as described above (n = 15). Following root canal obturation with single cone technique using matched-taper gutta percha cones and a epoxy resin based root canal sealer, 1 mm-thick slices were obtained from the middle third of the root canals. Push-out bond strength test was applied. Data were analyzed using one way analysis of variance and Tukey HSD tests (p=0.05). Results: In TA-treated groups, there was a significant increase in the microhardness values compared with the control group (p<0.05) while no significant difference was found among the microhardness values of TA-treated groups (p>0.05). Regarding the push-out bond strength test, there was no significant difference between the bond strength values of 10% TA for 2 min and the control group (p>0.05). The remaining groups presented higher bond strength values than the control group (p<0.05). Conclusion: TA increased dentin microhardness and the bond strength of the epoxy resin based sealer to root canal dentin. The effect on the bond strength was time and concentration dependent.