Yazar "Yondem, I." seçeneğine göre listele

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    Efficiency of different light sources to polymerise composite material
    (MANEY PUBLISHING, 2011) Yondem, I.; Usumez, A.; Gunduz, B.; Inan, O.
    The aim of this in vitro study is to examine the polymerisation efficacy of three different polymerisation units through simulated three different ceramic restorations (5 mm in diameter and 2 mm in height) by determining the degree of monomer conversion of a composite luting material. The curing efficiency was observed with Fourier transform infrared micromultiple internal reflectance spectroscopy after 24 h of polymerisation. The degree of conversion was calculated as a percentage of experimentally polymerised versus maximally polymerised composite. The degree of conversion values varied with the light source (light emitting diode, high intensity halogen and conventional halogen) (p<0.05) and the ceramic system (Cercon, IPS Empress 2 and Cerec) (p<0.05).
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    Influence of the Supporting Die Structures on the Fracture Strength of All-Ceramic Materials
    (Springer Heidelberg, 2012) Yucel, M. T.; Yondem, I.; Aykent, F.; Eraslan, O.
    This study investigated the influence of the elastic modulus of supporting dies on the fracture strengths of all-ceramic materials used in dental crowns. Four different types of supporting die materials (dentin, epoxy resin, brass, and stainless steel) (24 per group) were prepared using a milling machine to simulate a mandibular molar all-ceramic core preparation. A total number of 96 zirconia cores were fabricated using a CAD/CAM system. The specimens were divided into two groups. In the first group, cores were cemented to substructures using a dual-cure resin cement. In the second group, cores were not cemented to the supporting dies. The specimens were loaded using a universal testing machine at a crosshead speed of 0.5 mm/min until fracture occurred. Data were statistically analyzed using two-way analysis of variance and Tukey HSD tests (alpha = 0.05). The geometric models of cores and supporting die materials were developed using finite element method to obtain the stress distribution of the forces. Cemented groups showed statistically higher fracture strength values than non-cemented groups. While ceramic cores on stainless steel dies showed the highest fracture strength values, ceramic cores on dentin dies showed the lowest fracture strength values among the groups. The elastic modulus of the supporting die structure is a significant factor in determining the fracture resistance of all-ceramic crowns. Using supporting die structures that have a low elastic modulus may be suitable for fracture strength tests, in order to accurately reflect clinical conditions.