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Öğe Determination of optimal EDM machining parameters for machined pure titanium-porcelain adhesion(SPRINGER LONDON LTD, 2009) Secilmis, Asli; Olmez, A. Murat; Dilmec, Murat; Halkaci, H. Selcuk; Inan, OzgurThe objective of this experimental study is to determine electrical discharge machining (EDM) parameters that offer the best adhesion at the interface of a machined titanium-porcelain composite. First of all, with Taguchi method, machining parameters that will be effective in the bonding strength as well as their interactions on each other were determined in the test. Then, multiple level experiments were conducted to determine how the effective parameters varied over a wide area. Slopes of the curves obtained in these tests were studied, and then, final tests were conducted to obtain the best bonding strength possible. In this way, machining parameters that would offer the highest bonding strength of the titanium-porcelain matrix in a stepwise adjustable EDM machine were obtained. By taking into consideration the steps on the EDM machine where the tests were conducted, it is seen that, when a full factorial experiment is undertaken, 5 power x 2 polarity x 2 type of dielectric x 2 sandblasting or non-sandblasting x 2 kind of electrode x 10 pulse-on time, it necessitates 800 different tests to be executed, but, with the applied method, 16 + 18 + 3 yields 37 different tests where the results that include all possible alternatives were obtained. As a result, EDM machining parameters that offer the highest adhesion and are relatively higher, 31.5 N/mm(2), than the acceptable minimum value of 25 N/mm(2) were specified.Öğe Effect of finishing methods on surface roughness and color stability in all-ceramic systems(ELSEVIER SCIENCE BV, 2011) Yondem, Isa; Secilmis, Asli; Inan, OzgurThe objectives of the study were to evaluate the effect of the finishing methods on the surface roughness, and to investigate changes in CIE L*a*b* color coordinates of all-ceramic systems after different finishing methods and accelerated aging. Sixty specimens were prepared, 20 specimens each for Vitadur-N, IPS Empress II, and Cerec Vita Block Mark II. The surface roughness (Ra) following treatment with the different finishing methods was measured using a profilometer. Surface examinations in all groups were made by using a scanning electronic microscope. CIE L*a*b* values of the specimens were determined. After all specimens were subjected to accelerated aging, color measurements were repeated, and the total color differences (Delta E) were calculated. Data were analyzed statistically. Significant differences in surface roughness among all-ceramics were found (P < 0.05). No significant differences were found between the surface roughness of the glazed and polished all-ceramics (P > 0.05). After accelerated aging, all groups had acceptable color changes (Delta E < 2). (c) 2011 Elsevier B.V. All rights reserved.Öğe EFFECT OF PONTIC FRAMEWORK DESIGN ON THE FRACTURE RESISTANCE OF IMPLANT-SUPPORTED ALL-CERAMIC FIXED PARTIAL DENTURES(UNIV SAO PAULO FAC ODONTOLOGIA BAURU, 2009) Inan, Ozgur; Secilmis, Asli; Eraslan, OguzObjective: The purpose of this study was to compare the fracture resistance of implant-supported all-ceramic fixed partial dentures, which have three different pontic designs. Material and Methods: Two implants were placed in a metal model simulating mandibular left second premolar and mandibular left second molar. Thirty standardized 3-unit all-ceramic fixed partial dentures with biconvex, convex or concave pontic designs were fabricated using IPS e.max system (n=10). Afterwards, specimens were centrally loaded on the pontics until failure with a universal testing machine. Results were analyzed by Kruskal-Wallis and Mann-Whitney U tests at 5% significance level. Results: The fracture resistance values of all-ceramic fixed partial dentures designed with biconvex, convex or concave pontics were 349.71, 438.20 and 300.78 N, respectively. There were no statistically significant differences between the fracture resistances of the groups (p>0.05), except for convex and concave groups (p<0.05 and p=0.009, respectively). Conclusions: Convex design showed the best mechanical properties as demonstrated by the high values of fracture resistance.Öğe Effects of storage solutions on mineral contents of dentin(ELSEVIER TAIWAN, 2011) Secilmis, Asli; Dilber, Erhan; Gokmen, Fatma; Ozturk, Nilgun; Telatar, TubaBackground/purpose: It is important to understand how storage conditions affect the tooth structure for in vitro studies. There is little information regarding the selection of an appropriate storage solution. This study was conducted to determine the influence of storage solutions on the mineral contents of dentin. Materials and methods: Ninety dentin specimens were obtained from 30 molar teeth. Specimens were divided into two groups of 45 each (storage for 45 and 90 days). Each of the two groups was further divided into nine storage solution groups (n = 5). For the control group, freezing was used to store the teeth. The mean percentage weights of calcium, potassium, sodium, and phosphorus in each dentin slab were measured by inductively coupled plasma-atomic emission spectrometry. Two-way analysis of variance and Tukey's honest significant difference test were used to analyze the data (P = 0.05). Results: There were significant differences in calcium among groups. The potassium level of slabs stored in artificial saliva and the sodium level of slabs stored in buffered solutions and saline solution increased (P < 0.05). Potassium, sodium, and phosphorus levels were highest when stored for 45 days (P < 0.05). Conclusion: The storage solution and storage time affected the compositional structure of dentin. The results suggest that storage processes may influence outcomes of in vitro dental research. Copyright (C) 2011, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.
