Yazar "Celik M.Y." seçeneğine göre listele

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    Öğe
    The criteria for classification tree methods in clinical researches
    (2010) Akkus Z.; Sanisoglu S.Y.; Ugurlu M.; Celik M.Y.
    This study aimed at evaluating a statistical method, classification tree, which are recently developed parallel to the improvements in computer technology. The advantages over other methods and the criterions developed for classification tree are reported in this study. Classification tree (CT) is a non-parametric statistical method using a tree algorithm for reaching diagnosis by utilizing one or more risk factors. Classifications (discriminative, logistic regression and cluster analysis etc) and regression methods are frequently employed in analysing data acquired from scientific studies. However, hypothesis in these models makes the statistical analysis limited to be performed in wide range of disciplines. As there is no need for hypothesis in analysing these data sets, classification trees are serious alternative for other statistical classification and regression techniques. Classification tree, also known as Decision tree, is a good choice for data mining classifications in respect to both understanding and explaning the some particular rules about estimating the results. These methods are evolved following the improvements in computer technology. Classification tree is becoming more important in practice as it provides reliable measures in building accurate classifications. The advantages of the method over others are the following: simplification of the results, provision of non-parametric and lineer solutions, generalization of the conclusions optained by inductive reasoning. More over the technique can utilize mixed data types and the same variable can be employed in different parts of the tree. The determination of choices, which is crucially important in accurate interpretation of the results, needs time and effort in practicing the method. In field of medicine, classification tree is one of the favorable methods particulary utilized in clinical studies.
  • [ X ]
    Öğe
    Investigation of fracture resistance of different core materials
    (2012) Bahşi E.; Colak M.; Atakul F.; Celik M.Y.
    The aim of this study was comparatively investigation of in vitro fracture resistance of four different restorative core materials in endodontically-treated mandibulary premolar teeth. Eighty caries-free human permanent mandibular premolar teeth, freshly extracted because of periodontal or orthodontic reasons were randomly divided into four groups of 20 teeth each. Core restorations were prepared using these core materials: Group 1: Filtek P60 (3M ESPE, USA), Group 2: Clearfil Photo Core (Kuraray Medical Inc., Japan), Group 3: Miracle Mix (GC Corporation, Japan) and Group 4: Vitremer (3M ESPE, USA). Then were subjected to thermocycling 1.000 times with a dwell time of 30 second at 5 ± 2 °C and 55 ± 2 °C. The teeth were loaded in a Universal Testing Machine (TSTM 02500; Elista Ltd. Şti., Türkiye). All the teeth were loaded until fracture was occured. The fracture force (Newton) was recorded for each specimen. The results obtained were statistically evaluated with ANOVA and Bonferroni corrected Mann Whitney U-tests. Statistically, the mean fracture resistance scores among groups (p<0.001) and values of fracture code between Group 1 and Group 4, were significant. The group of Filtek P60 was found succesfull when the values of fracture resistance were examined.