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    The effect of blue thermal treatment on endodontic instruments and apical debris extrusion during retreatment procedures
    (Wiley, 2019) Yildiz, E. Doganay; Arslan, H.
    Aim To determine the effect of blue thermal treatment on Reciproc (VDW, Munich, Germany) endodontic instruments and the amount of apically extruded debris during retreatment procedures. Methodology Thirty extracted mandibular molar teeth having mesial roots with a degree of curvature less than 20 degrees and having an initial apical size equivalent to a size 10 K-file were selected. The mesial roots of the teeth were removed from the cementoenamel junction to obtain a 15-mm root length. The mesiobuccal canals were prepared to size F2 using the ProTaper Universal system (Dentsply Sirona, Ballaigues, Switzerland), filled with gutta-percha and 2Seal (VDW) using the lateral compaction technique and then randomly divided into two groups (n = 15). The root fillings were removed with one of the following instruments using a crown-down preparation technique: M-Wire Reciproc or Reciproc Blue (both VDW). Apically extruded debris was collected in pre-weighed Eppendorf tubes. The Eppendorf tubes were then stored in an incubator at 70 degrees C for five days to evaporate the distilled water. The data were analysed using the Mann-Whitney U test (P = 0.05). Results Reciproc Blue (1.42 +/- 0.4491 mg) extruded significantly less debris apically than M-Wire Reciproc (2.56 +/- 1.0232 mg) (P < 0.05). Conclusions Blue thermal treatment of Reciproc instruments was associated with less debris extrusion during retreatment procedures.
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    An investigation of rolling element vibrations caused by local defects
    (Asme-Amer Soc Mechanical Eng, 2008) Arslan, H.; Aktürk, N.
    In this paper, a shaft-bearing model is developed in order to investigate the rolling element vibrations for an angular contact ball bearing with and without defects. The shaft-bearing assembly is considered as a mass-spring system. The system shows a nonlinear characteristic under dynamic conditions. The equations of motion in radial and axial directions were obtained for shaft and rolling elements, and they were solved simultaneously with a computer simulation program. Additionally, the effect of localized defects on running surfaces (i.e., inner ring, outer ring, and ball) on the vibration of the balls is investigated. Vibration of rolling elements in the radial direction is analyzed in time and frequency domains. Characteristic defect frequencies and their components can be seen in the frequency spectra of rolling element vibrations. Comparison of the obtained results with similar studies available in literature showed reasonable qualitative agreement.
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    Micro-tensile bond strength of adhesives to pulp chamber dentin after irrigation with Ethylenediaminetetraacetic acid
    (2012) Barutcigil, C.; Arslan, H.; Özcan, E.; Harorlı, O. T.
    Aim: The aim of this study was to evaluate the influence of different concentrations of Ethylenediaminetetraacetic acid (EDTA) solution on adhesion, that is, the bond strength of the different adhesive systems, to the pulp chamber dentin. Materials and Methods: Recently extracted, sound, human, third molars were cut horizontally to expose the pulp horn. The roof of the pulp chamber and pulp tissue was removed. The teeth were then divided into five main groups. The teeth in each group were treated as follows: group 1, irrigated with saline; group 2, with 5% EDTA for 5 minutes; group 3, with 15% EDTA for 5 minutes; group 4, with 17% EDTA for 5 minutes and group 5, with 19% EDTA for 5 minutes. Treated specimens were dried and divided into 2 subgroups for adhesives; bonded with a total-etching adhesive (Adper Scotchbond Multi-purpose -ASB) or a one bottle of self-etch adhesive system (Clearfil S3 Bond -CS3). After the bonding procedure and composite restoration, teeth were sectioned and dentin sticks were obtained from each group for micro tensile testing (n = 10). Micro tensile testing was performed and scanning electron microscope (SEM) photographs were taken for each irrigated group. Results: In the ASB group, saline showed statistically higher bond strength values at the different concentrations of EDTA, while the micro-tensile bond strengths of the different concentrations of EDTA were not statistically different. In the CS3 group, saline and 5% EDTA showed statistically higher bond strength values than 17% and 19% EDTA, while the micro-tensile bond strengths of 15% EDTA compared to saline and 5% EDTA and 15% EDTA compared to 17% EDTA and 19% EDTA, were not statistically different. Conclusion: This study showed that EDTA irrigation can affect the bond strength of adhesive systems on pulp chamber lateral walls. Clinically, low EDTA concentrations can be recommended if self-etch adhesives have been selected.