ZEYNEP ÖZKURT KAYAHAN | Yeditepe University (original) (raw)

Papers by ZEYNEP ÖZKURT KAYAHAN

Biomedical Research-tokyo, 2016

Veneer cracking or chipping is the major complication of the zirconia based restorations. Monolit... more Veneer cracking or chipping is the major complication of the zirconia based restorations. Monolithic zirconia has been introduced to overcome this problem, as well as to use in patients with limited interocclusal space. Many research articles on monolithic zirconia crowns have been published in the last years. The aim of this review article was to present data about the wear, surface roughness, fracture strength, optical properties, and marginal fit of monolithic zirconia. A PubMed search was conducted with the terms of “zirconia” with “monolithic”, “full-contour”, “solid”, “translucent”, “anatomiccontoured”, “un-veneered”, “non-veneered”, “full-coverage”. Based on the results of these studies, monolithic zirconia crowns with polished surfaces have been shown to cause the lowest wear on the antagonists compared to glazed zirconia. The fracture strength of monolithic zirconia has been found higher than veneered zirconia. Monolithic zirconia may be a promising future and long-term fol...

Journal of Prosthodontics, 2010

The application of ceramic materials for the fabrication of dental restorations is a focus of int... more The application of ceramic materials for the fabrication of dental restorations is a focus of interest in esthetic dentistry. The ceramic materials of choice are glass ceramics, spinel, alumina, and zirconia. Zirconia was introduced into dentistry in the 1990s because of its good mechanical and chemical properties and is currently being used as a material for frameworks, dowels, implants, abutments, and orthodontic brackets. Many in vitro studies about zirconia use have been published, but clinical long-term studies are very important. This article presents data regarding the incidence of clinical success and complications of zirconia in these dental applications. Clinical studies published to date seem to indicate that zirconia is well tolerated and sufficiently resistant.

7tepe klinik, 2020

Bu çalışmanın amacı, farklı parametrelerdeki fiber lazer ile yüzey pürüzlendirme işlemlerinin, ti... more Bu çalışmanın amacı, farklı parametrelerdeki fiber lazer ile yüzey pürüzlendirme işlemlerinin, titanyum ve rezin siman arasındaki bağlanma dayanımı üzerindeki etkisini araştırmaktır. Gereç ve Yöntem: Döküm, CAD/CAM ve lazer sinterleme yöntemleriyle 3 farklı şekilde üretilmiş, 90 adet titanyum örneği hazırlandı (n=30). Tüm bağlanma yüzeyleri standardizasyonu sağlamak amacıyla, sırasıyla 600-1000-1200 partiküllü silikon karbid kağıtlarla cilalama yapıldı ve her örneğin yüzey pürüzlülüğü ölçüldü. Her grup 3 alt gruba ayrıldı (n=10): grup (1) 110 mµ Al 2 O 3 partikülleri ile kumlama, grup (2) fiber lazer 10 W, grup (3) fiber lazer 20 W. Yüzey işlemleri tamamlanan örneklerin bağlanma yüzeylerine metal primer ve dual-cure self adeziv rezin siman uygulandı. Polimerizasyonu tamamlanan örnekler kalıptan çıkartıldı ve tesviyesi yapıldı. Örneklerin kırılma işlemi üniversal test cihazında 1 mm kalınlığındaki kesme bıçağı ile yapıldı. Verilerin istatistiksel analizinde titanyum tipi ve pürüzlendirme şeklinin bağlanma dayanımı üzerindeki ortak etkisinin değerlendirilmesinde Two way Anova testi kullanıldı. Devam testi olarak One way Anova Test kullanıldı. Anlamlılık p<0,05 düzeyinde değerlendirildi. Bulgular: Tüm titanyum tiplerinde kumlama işleminin, 20 W gücündeki fiber lazer uygulamasına kıyasla daha yüksek bağlanma dayanımı oluşturduğu görüldü (p<0,05). 10 W gücündeki fiber lazer uygulaması ile kumlamaya yakın bağlanma dayanımı değerleri elde edildi. Kumlama işlemi uygulanan gruplarda, CAD/CAM grubunun ortalama bağlanma dayanımı (6,42 MPa), Döküm (12,61 MPa) ve Lazer Sinter (11,27 MPa) gruplarından anlamlı derecede düşük bulundu (p<0,05). Sonuç(lar): Titanyum-rezin siman bağlanmasında en etkili yüzey pürüzlendirme yönteminin kumlama olduğu, düşük güçte (10W) fiber lazer uygulaması ile yüksek güce kıyasla (20W) daha başarılı bir bağlanma elde edildiği sonucuna varıldı.

Biomedical Research-tokyo, 2016

Objectives: The aim of this study was to evaluate the fracture resistance of prepared maxillary i... more Objectives: The aim of this study was to evaluate the fracture resistance of prepared maxillary incisors with incisal access cavities and to compare it with conventional lingual access cavities. Materials and Methods: Freshly extracted maxillary central incisor teeth (n:45) were selected and prepared for full crown restorations. Then, they were divided into 3 groups: group 1, teeth with lingual access cavities (n: 15); group 2, teeth with incisal access cavities (n:15); and group 3, teeth without access cavities (n:15). Endodontic treatments were completed for group 1 and 2. All teeth were embedded in the self-curing acrylic resin. Specimens were subjected to fracture test and the maximum loads were recorded. Oneway ANOVA and Tukey’s HSD test were used for statistical analysis. Results: The mean fracture values of the group 3 (806.87 ± 174.80 N) were significantly higher than the group 1 (607.13 ± 131.14 N) and the group 2 (590.20 ± 237.29 N) (p 0.05). Conclusion: The location of th...

Biomedical Research-tokyo, 2017

Purpose: The aim of this study was to determine the depression levels of dental students in Yedit... more Purpose: The aim of this study was to determine the depression levels of dental students in Yeditepe University and to examine the effect of demographic factors on depression levels. Methods: All students enrolled in Yeditepe University Faculty of Dentistry in 2015-2016 educational period were included in the study. A Zung Self-Rating Depression Scale consists of 20 items for depression level measurement was used. Only age and gender were asked in order to protect the confidentiality, and students filled out the form voluntarily. In the scale, each item was evaluated according to the 4-point Likert-type scale; never or rarely, sometimes, often, always; and depression scores were recorded. One-way ANOVA with Tukey HSD test were used to analyse the data. Demographic factors were analysed using Chi-square test. Results: The response rate was 87.4%. There were 235 students, 72 (30.6%) were male and 163 (69.4%) were female, with the mean age of 21.58 ± 2.02 years. Of the participants, 30...

Hareketli bölümlü protezlerin doğru planlanması hasta memnuniyetini ve diş hekiminin başarısını a... more Hareketli bölümlü protezlerin doğru planlanması hasta memnuniyetini ve diş hekiminin başarısını arttırmaktadır. Bu çalışmanın amacı, kısmi dişsizlik tiplerinin yaygınlığını belirlemek, dişhekimleri tarafından en yaygın olarak planlanan hareketli bölümlü protezleri saptamak ve planlama ile ilgili diş hekimlerinin bakış açılarını incelemektir. Gereç ve Yöntem: Bu çalışmada İstanbul'un en büyük ilçelerinde görev yapan çeşitli diş hekimliği laboratuvarlarında yapılan ve randomize olarak seçilen 100 hareketli bölümlü protez değerlendirildi. Kennedy sınıflaması, tedavi planlama seçenekleri ve protez komponentleri gözlemlendi. Dişsiz bölgelerin sayısı ve yeri, ana bağlayıcılar, kroşe ve tırnak türleri kaydedildi. Hareketli bölümlü protez planlamasının doğruluğunu değerlendirmek için bir planlama rehberi kullanıldı. Bulgular: Kennedy I en fazla görülen dişsizlik sınıflamasıdır (49%). Bölümlü protez komponentleri incelendiğinde, ana bağlayıcıların %27'si, kroşelerin %20'si ve tırnak seçiminin %59'unda yanlış seçim yapıldığı saptanmıştır. Kroşeler için doğru planlama Kennedy I ve Kennedy II'te daha yüksektir (p<0.05). Kennedy sınıflaması ile ana bağlayıcı ve tırnak planlama doğruluğu arasında anlamlı bir fark saptanmamıştır (p>0.05). Sonuçlar: Bu çalışmanın sınırlamaları dahilinde, hareketli bölümlü protezlerde tasarım hatalarının oranı yüksektir. Tırnakların yanlış konumlandırılması sonucu protezlerin başarısı olumsuz etkilenebilir. Diş hekimleri, başarılı sonuçlar elde edebilmek için hareketli bölümlü protez tasarımının doğru yapılması gerektiğinin farkında olmalıdırlar.

TURKISH JOURNAL OF MATHEMATICS, 2020

Let Ln be the free metabelian Leibniz algebra generated by the set Xn = {x 1 ,. .. , xn} over a f... more Let Ln be the free metabelian Leibniz algebra generated by the set Xn = {x 1 ,. .. , xn} over a field K of characteristic zero. This is the free algebra of rank n in the variety of solvable of class 2 Leibniz algebras. We call an element s(Xn) ∈ Ln symmetric if s(x σ(1) ,. .. , x σ(n)) = s(x 1 ,. .. , xn) for each permutation σ of {1,. .. , n}. The set L Sn n of symmetric polynomials of Ln is the algebra of invariants of the symmetric group Sn. Let K[Xn] be the usual polynomial algebra with indeterminates from Xn. The description of the algebra K[Xn] Sn is well known, and the algebra (L ′ n) Sn in the commutator ideal L ′ n is a right K[Xn] Sn-module. We give explicit forms of elements of the K[Xn] Sn-module (L ′ n) Sn. Additionally, we determine the description of the group Inn(L Sn n) of inner automorphisms of the algebra L Sn n. The findings can be considered as a generalization of the recent results obtained for the free metabelian Lie algebra of rank n.

Clinical Oral Investigations, 2020

Objectives The aim of this study was to evaluate the stress distribution on different thicknesses... more Objectives The aim of this study was to evaluate the stress distribution on different thicknesses of mineral trioxide aggregate (MTA) placed on various widths of pulp perforations during the condensation of the composite resin material. Materials and methods The mandibular molar tooth was modeled by COSMOSWorks program (SolidWorks, Waltham, MA). Three finite elemental analysis models representing 3 different dimensions of pulp perforations, 1, 2, and 3 mm in diameter, were created. The perforation area was assumed as filled with MTA with different thicknesses, 1, 2, and 3 mm for each pulp perforation width, creating a total of 9 different models. Then, a composite resin material was layered on MTA for each model. A 66.7 N load was applied and an engineering simulation program (ANSYS, Canonsburg, US) was used for the analysis. Results were presented considering von Mises stress criteria. Results As MTA thickness increased, the stress values recorded within the area between pulp and MTA decreased. Strain was decreased when the thickness of MTA increased. Conclusions Stresses at MTA-pulp interface and strain on MTA decreased with the increase in MTA thickness. Clinical relevance In clinical practice, when MTA is required for pulp capping, using a thick layer of the material seems to be a better option in order to reduce the stress under forces of hand condensation of overlying restorative materials.

TURKISH JOURNAL OF MATHEMATICS, 2019

In this work, we determine the structure of the automorphism group of the free metabelian Leibniz... more In this work, we determine the structure of the automorphism group of the free metabelian Leibniz algebra of rank three over a field K of characteristic zero.

Journal of Prosthodontics, 2017

Purpose: Apical microleakage between the root canal and periapical tissues is considered a common... more Purpose: Apical microleakage between the root canal and periapical tissues is considered a common cause of endodontic failure. The aim of this study was to evaluate the apical microleakage of various obturation techniques after immediate post space preparations with different drills. Materials and Methods: One hundred twenty human single-rooted teeth were selected for this study. The coronal portions were removed to achieve a uniform length of 15 mm. All root canals were instrumented with ProTaper Next rotary files using crown-down technique. The 120 roots were randomly assigned to 3 experimental groups according to obturation technique (n = 40). The root canals were obturated with lateral condensation in group 1, single-cone technique in group 2, and Calamus 3D obturation system in group 3. Each group was divided into two subgroups (n = 20) according to drill types (Gates Glidden and Peeso drills) leaving 5 mm of apical gutta-percha. The apical microleakage was measured using the computerized fluid filtration meter method. The results were evaluated using Kruskal-Wallis test with Bonferroni Corrected Mann-Whitney U multiple comparison post hoc tests. Results: There was no statistically significant difference between obturation techniques after post space preparation with Peeso drills (p > 0.05). In Gates Glidden drill groups, single-cone technique demonstrated higher leakage (0.0051 ± 0.0037 μl x min −1 × cmH 2 O −1) than Calamus techniques (0.0019 ± 0.0012 μl x min −1 × cmH 2 O −1) (p < 0.017). Conclusions: Gates Glidden drills caused the highest apical leakage in teeth obturated with single-cone technique.

Yeditepe Dental Journal, 2017

The aim of this study was to evalute the prevalence of different prosthetic restoration types of ... more The aim of this study was to evalute the prevalence of different prosthetic restoration types of dental implants in a Turkish subpopulation. Materials and Methods: A retrospective evaluation was conducted by examining the digital patient record system of the faculty. Age, gender, edentulism, implant sites, replaced tooth numbers and restoration types were recorded. Descriptive statistical methods and Chi-square test were used to analyze data. An alpha level of 0.05 was used for all statistical analyses. Results: There were 368 patients with 1143 implants which were placed to maxilla in 116 patients (31.5%), mandible in 179 patients (48.6%), and maxilla and mandible in 73 patients (19.8%). They were in anterior region in 58 patients (15.8%), posterior region in 245 patients (66.6%), and anterior and posterior region in 65 patients (17.7%). Two hundred and nine patients (56.8%) had single-unit fixed partial dentures (S-FPDs), 83 patients (22.6%) had multi-unit fixed partial dentures (M-FPDs), 44 patients (12%) had both S-FPDs and M-FPDs, and 32 patients (8.7%) had overdentures. Conclusions: The great majority of patients treated with dental implants had S-FPDs. Only 8% of patients had overdentures. The most implant treated sites were mandible and posterior regions.

Yeditepe Dental Journal, 2017

The purpose of this study was to determine the prevalence of various types of partial edentulism,... more The purpose of this study was to determine the prevalence of various types of partial edentulism, and type of prosthetic restorations most commonly chosen to treat the patients. Materials and Methods: A retrospective evaluation was conducted in Department of Prosthodontics, Dental School of Yeditepe, Turkey, by examining the digital record system of the faculty. The patients were selected randomized and the inclusion criteria were; patients who had partial edentulism at least on their one jaw, who had panoramic radiographs, whose treatment had been finished, and who had no treatment. Age, gender, Kennedy classification and treatment options were recorded. Descriptive statistical methods and Chisquare test were used to analyze data. An alpha level of 0.05 was used for all statistical analyses. Results: There were 345 patients (147 males, 198 females) with the mean age of 50.88±14.09 years. Kennedy III was the most common in the maxilla (71.1%) and in the mandible (55.9%). Partial edentulism was most frequently managed by fixed partial dentures in the maxilla (57.9%) and in the mandible (41.7%). Implant treatment was applied to 13-14% of the patients. Conclusions: Dental implants were the least common treatment option for partial edentulism. Fixed partial dentures were the most common treatment for Kennedy III and IV, whereas removable partial dentures were the most common for Kennedy I and II.

Yeditepe Dental Journal, 2016

The aim of this study was to obtain information among 2 dental schools in Turkey regarding precli... more The aim of this study was to obtain information among 2 dental schools in Turkey regarding preclinical students' perception, stress levels and preparedness for their future clinical studies. Materials and methods: This study was conducted on the second year students in one foundation and one state dental school in Istanbul. The questionnaire consisted of questions about students' opinions about their stress levels in preclinical exercises of prosthodontics, as well as adequacy of knowledge they received from their preclinical training. Data were analyzed using the chi-square test. Results: The students of the foundation school considered that feedback received from the instructors during laboratory exercises was highly satisfactory with statistically significant differences. In addition they regarded didactic knowledge received for preclinical exercises as highly satisfactory. In general, students of the foundation school felt themselves more prepared for treating patients with statistical significance. Conclusions: Student's perceptions on preclinical prosthodontic educational program were different in foundation and state dental school. Dental school instructors must provide a well-established program for the students and educational curriculum must be regularly evaluated and updated to be beneficial for the dental student who is expected to start serving the public in the near future.

Yeditepe Dental Journal, 2016

The aim of this study was to assess the final year students' experience and confidence in prosthe... more The aim of this study was to assess the final year students' experience and confidence in prosthetic dentistry within a dental school in Turkey. Materials and Methods: A questionnaire was prepared to assess the students' experience of clinical skills in prosthetic procedures (n:44). Twenty questions were multiple-choice; 1 question was open-ended and 3 questions used a Likerttype scale ranging from 1 (very little confident) to 5 (very confident). The data were statistically analyzed. Results: Forty percent of the students thought that prosthodontics was the most difficult field in dentistry. Students rated themselves as being least confident in tooth preparation (2.89), making impression for post-core (2.84), determination of occlusal vertical dimension for complete (2.36) and removable partial dentures (2.21), followed by peripheral sealing for complete (2.50) and removable partial dentures (2.32). Conclusions: There are lots of subjects in which the students reported a lack of confidence that warrants greater emphasis in the undergraduate prosthodontic curriculum.

Cumhuriyet Dental Journal, Feb 16, 2011

Atatürk Üniversitesi Diş Hekimliği Fakültesi Dergisi, 2015

Ağız sağlığını korumak, var olan hastalığı durdurmak, sağlığı yeniden kazanmak ve kazanılan sağlı... more Ağız sağlığını korumak, var olan hastalığı durdurmak, sağlığı yeniden kazanmak ve kazanılan sağlığın devamlılığında en önemli etken, düzenli, yeterli ve doğru bir ağız bakımı gerçekleştirmektir. Ağız bakımı denilince diş fırçası ve diş macununun yanında diş ipi ya da diş arası fırçası gibi arayüz ajanları ve diğer ağız bakım araçlarının da kullanımı akla gelmektedir 1. Ağız bakımı konusunda yapılmış olan çalışmalara bakıldığında düzenli ve yeterli bir ağız bakımı için en azından ABSTRACT Aim: The purpose of the study is to evaluate the oral and dental care attitudes of students enrolled in Yeditepe University, Faculty of Dentistry. Material and Methods: Two hundred and fifty students of the faculty in the 1st until the 5th years of education were included in the study of which 159 were females and 91 were males. The students were asked to fill out a survey form consisting of 15 questions in order to evaluate oral and dental healthcare attitudes. Results: The results indicated that a statistical significance existed between the education level of parents and the age of initiation of tooth brushing. Conclusion: It can be concluded that dental education has a positive impact on oral and dental healthcare attitudes on individuals involved in it. Key words: oral and dental health, dental students günde 2 kez dişlerin fırçalanması ve günde 1 kez diş aralarının diş ipi ile temizlenmesi gerektiği vurgulanmaktadır. 1-3 Ağız sağlığı için doğru, düzenli ve yeterli bir ağız bakımı kadar bunun öncesinde kişinin ağız sağlığı ve bakımı hakkındaki bilgilerinin de doğru olması çok önemlidir 1. Konuyla ilgili yapılan literatür incelemesinde diş çürükleri ve periodontal hastalıkların ne olduğu, primer sebepleri, klinik belirtileri ve hastalıkları önlemenin yolları ile ilgili soruları içeren az sayıda çalışmaya rastlanmakta ve Türkiye'de bu konuda yapılmış olan çalışmanın bulunmaması dikkat

Journal of Lie theory

We show how to detect non-tame automorphisms by using a criterion which is based on the Dieudonné... more We show how to detect non-tame automorphisms by using a criterion which is based on the Dieudonné determinant and we construct some specific non-tame automorphisms of free metabelian Lie algebras and free Lie algebras of the form F/γ m (F) .

Journal of dental sciences

Background/purpose: The aim of this study was to compare the frequency of 3 treatment alternative... more Background/purpose: The aim of this study was to compare the frequency of 3 treatment alternatives in a Turkish subpopulation with a single missing tooth: implant retained crowns (IRCs), fixed partial dentures (FPDs), and no replacement. Materials and methods: A study comparing 3 different treatment alternatives for a single missing tooth was conducted. Data were collected by panoramic radiographic examination. Age, gender, and treatment method for a single missing tooth were recorded. Differences between the groups were examined using one-way ANOVA, and multiple comparisons were evaluated by using Tukey's HSD test. A Chi-squared test was used to compare qualitative data. The significance level was set to 5%. Results: Of 1953 examined radiographs, 218 (11.16%) patients were found to have a single missing tooth. Of these 218 patients, 101 (46.3%) had FPD restorations, and 23(10.6%) had IRCs. Ninety-four (43.1%) patients had no restorations. The mean age of patients with FPDs was ...

Australian Dental Journal

Bonding properties of luting cements are important for retention of restorative core materials. T... more Bonding properties of luting cements are important for retention of restorative core materials. The aim of this study was to compare the bonding performance of a resin-modified glass ionomer cement and a self-adhesive resin cement to various fixed prosthodontic core materials. Cylindrical specimens with a thickness of 2 mm and a diameter of 5 mm were fabricated from Au-Pd-Ag, Co-Cr, Ni-Cr-Mo, Ni-Cr-Fe alloys, titanium, zirconia and Empress II (n = 20). Each group was divided into two subgroups to be luted with two different luting agents. Composite resin blocks were cemented onto specimens with RelyXUnicem and FujiCem. A shear bond strength machine with 50 kg load cell and 0.50 mm/min crosshead speed was used. Kruskal Wallis test, Dunn's Multiple Range test and Mann-Whitney-U test were used for statistical analysis. The results were evaluated in a confidence interval of p < 0.05. The highest bond strength was obtained between Ni-Cr-Fe-RelyXUnicem (8.22 +/- 2.15 MPa) and the l...

Biomedical Research-tokyo, 2016

Journal of Prosthodontics, 2010

7tepe klinik, 2020

Biomedical Research-tokyo, 2016

Biomedical Research-tokyo, 2017

TURKISH JOURNAL OF MATHEMATICS, 2020

Clinical Oral Investigations, 2020

TURKISH JOURNAL OF MATHEMATICS, 2019

Journal of Prosthodontics, 2017

Yeditepe Dental Journal, 2017

Yeditepe Dental Journal, 2016

Cumhuriyet Dental Journal, Feb 16, 2011

Atatürk Üniversitesi Diş Hekimliği Fakültesi Dergisi, 2015

Journal of Lie theory

Journal of dental sciences

Australian Dental Journal