Sealing capability and marginal fit of titanium versus zirconia abutments with different connection designs

Nazmiye Sen,Ibrahim Bülent Sermet,Nezahat Gürler 대한치과보철학회 2019 The Journal of Advanced Prosthodontics Vol.11 No.2

PURPOSE. Limited data is available regarding the differences for possible microleakage problems and fitting accuracy of zirconia versus titanium abutments with various connection designs. The purpose of this in vitro study was to investigate the effect of connection design and abutment material on the sealing capability and fitting accuracy of abutments. MATERIALS AND METHODS. A total of 42 abutments with different connection designs [internal conical (IC), internal tri-channel (IT), and external hexagonal (EH)] and abutment materials [titanium (Ti) and zirconia (Zr)] were evaluated. The inner parts of implants were inoculated with 0.7 μL of polymicrobial culture (P. gingivalis, T. forsythia, T. denticola and F. nucleatum) and connected with their respective abutments under sterile conditions. The penetration of bacteria into the surrounding media was assessed by the visual evaluation of turbidity at each time point and the number of colony forming units (CFUs) was counted. The marginal gap at the implant- abutment interface (IAI) was measured by scanning electron microscope. The data sets were statistically analyzed using Kruskal-Wallis followed by Mann-Whitney U tests with the Bonferroni-Holm correction (α=.05). RESULTS. Statistically significant difference was found among the groups based on the results of leaked colonies (P<.05). The EH-Ti group characterized by an external hexagonal connection were less resistant to bacterial leakage than the groups EH-Zr, IT-Zr, IT-Ti, IC-Zr, and IC-Ti (P<.05). The marginal misfit (in μm) of the groups were in the range of 2.7-4.0 (IC-Zr), 1.8-5.3 (IC-Ti), 6.5-17.1 (IT-Zr), 5.4-12.0 (IT-Ti), 16.8-22.7 (EH-Zr), and 10.3-15.4 (EH-Ti). CONCLUSION. The sealing capability and marginal fit of abutments were affected by the type of abutment material and connection design.

Surface deterioration of monolithic CAD/CAM restorative materials after artificial abrasive toothbrushing

Nazmiye Şen,Betül Tuncelli,Gültekin Göller 대한치과보철학회 2018 The Journal of Advanced Prosthodontics Vol.10 No.4

PURPOSE. The purpose of this in vitro study was to evaluate the effect of abrasive toothbrushing on the surface properties of monolithic computer-assisted design and computer-assisted manufacturing (CAD/CAM) materials stored in food-simulating liquids (FSLs). MATERIALS AND METHODS. Fourty-eight disk-shaped test specimens of each material (Paradigm MZ100/PMZ, Lava Ultimate/LU, Vita Enamic/VE, and Vita Mark II/VMII) with a diameter of 10.0 mm and a thickness of 3.0 ± 0.05 mm were prepared. Specimens were divided into 4 subgroups (n=12) and stored in air, distilled water, 0.02 M citric acid, or 75% ethanol/water solution for 7 days at 36.5 ℃. Then, the specimens were brushed in a multi-station brushing machine under a vertical load of 2.0 N for 3 hours. Surface gloss (GU), roughness (Ra), and hardness (Vickers [VHN]) were measured after storage and brushing simulation. The data sets were statistically analyzed with 2 and 3-way ANOVAs followed by the Tukey's post-hoc comparisons (α=.05). RESULTS. Statistically significant difference was found among the materials concerning the results of surface properties. VMII showed the highest VHN, while PMZ produced the lowest. Storage in FSLs significantly affected the VHN of PMZ and LU. VMII showed the lowest Ra and highest GU irrespective of FSLs and of abrasive toothbrushing. VE, LU, and PMZ produced significant decrease in GU and increase in Ra after toothbrushing. CONCLUSION. Surface properties of monolithic CAD/CAM restorative materials were differently affected by the storage media and abrasive toothbrushing.

Causal Attributions, Social Support and Psychological Morbidity in Patients Undergoing Thyroid Surgery

Nazmiye Kocaman Yıldırım,Beyza Özçınar,Selim Doğan,Nihat Aksakal,Nuri Alper Sahbaz,Fırat Tutal,Bahar Canday Torun,Mine Özkan,Yeşim Erbil 대한갑상선-내분비외과학회 2018 The Koreran journal of Endocrine Surgery Vol.18 No.4

Purpose: The primary objective of the present study was to investigate the course of anxiety and depression in thyroidectomy. The second objective was to investigate the association between somatic symptoms and psychological symptoms, and the final objective was to identify the sociodemographic, clinical, and psychosocial factors that affect psychiatric morbidity. Methods: This prospective study, 101 patients who were admitted to the Endocrine Surgery Clinic of the Department of General Surgery, Istanbul Faculty of Medicine, University of Istanbul, with thyroid pathology were included in the study. Data were collected before surgery, and in the early, and late periods after surgery. Data were collected using a semi-structured interview form, a visual analogue scale, and the Hospital Anxiety and Depression Scale. Results: The average scores of anxiety and depression before surgery were statistically significantly higher compared with the early and late periods after surgery (P<0.001). Psychological morbidity was identified about 10% of patients before surgery and remained after thyroidectomy. A poor positive correlation founded between somatic symptoms and psychological condition in period surgery (P<0.05). Various sociodemographic features and psychosocial parameters affected anxiety and depression level (P<0.05). Conclusion: Anxiety and depression level in thyroid diseases decreased after thyroidectomy. These patients may express psychologic distress through somatic symptoms. Screening of psychological morbidity is suggested in patients planned thyroid surgery, especially in women, low-educated, inadequate social support, attributed to psychological causes.

Half-metallic properties of the CuHg2Ti-type Mn2ZnSi full-Heusler compound

Selçuk Kervan,Nazmiye Kervan 한국물리학회 2013 Current Applied Physics Vol.13 No.1

The half-metallic properties of novel CuHg2Ti-type Mn2ZnSi full-Heusler compound were examined by density functional theory (DFT) calculations. The electronic band structures and density of states of the Mn2ZnSi compound show that spin-up electrons are metallic, but the spin-down bands are semiconductor with a gap of 0.48 eV, and the spin-flip gap is of 0.28 eV. The Mn2ZnSi Heusler compound has a magnetic moment of 2 mB at the equilibrium lattice constant a ¼ 5.80 Å. The Mn2ZnSi full-Heusler compound is ferrimagnetic and maintains the half-metallic character having 100% polarization for lattice constants ranging between 5.62 and 6.91 Å.

Buckling delamination of the PZT/Metal/PZT sandwich circular plate-disc with penny-shaped interface cracks

Fazile I. Cafarova,Surkay D. Akbarov,Nazmiye Yahnioglu 국제구조공학회 2017 Smart Structures and Systems, An International Jou Vol.19 No.2

The axisymmetric buckling delamination of the Piezoelectric/Metal/Piezoelectric (PZT/Metal/PZT) sandwich circular plate with interface penny-shaped cracks is investigated. The case is considered where open-circuit conditions with respect to the electrical displacement on the upper and lower surfaces, and short-circuit conditions with respect to the electrical potential on the lateral surface of the face layers are satisfied. It is assumed that the edge surfaces of the cracks have an infinitesimal rotationally symmetric initial imperfection and the development of this imperfection with rotationally symmetric compressive forces acting on the lateral surface of the plate is studied by employing the exact geometrically non-linear field equations and relations of electro-elasticity for piezoelectric materials. The sought values are presented in the power series form with respect to the small parameter which characterizes the degree of the initial imperfection. The zeroth and first approximations are used for investigation of stability loss and buckling delamination problems. It is established that the equations and relations related to the first approximation coincide with the corresponding ones of the three-dimensional linearized theory of stability of electro-elasticity for piezoelectric materials. The quantities related to the zeroth approximation are determined analytically, however the quantities related to the first approximation are determined numerically by employing Finite Element Method (FEM). Numerical results on the critical radial stresses acting in the layers of the plate are presented and discussed. In particular, it is established that the piezoelectricity of the face layer material causes an increase (a decrease) in the values of the critical compressive stress acting in the face (core) layer.

Three-dimensional analysis of the natural vibration of the three-layered hollow sphere with middle layer made of FGM

Surkay D. Akbarov,Hatam H. Guliyev,Nazmiye Yahnioglu 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.5

This paper is a continuation of the investigations started in the paper by Akbarov, S.D., Guliyev, H.H and Yahnioglu, N. (2016) "Natural vibration of the three-layered solid sphere with middle layer made of FGM: three-dimensional approach", Structural Engineering and Mechanics, 57(2), 239-263, to the case where the three-layered sphere is a hollow one. Three-dimensional exact field equations of elastodynamics are employed for investigation and the discrete-analytical method is employed for solution of the corresponding eigenvalue problem. The FGM is modelled as inhomogeneous for which the modulus of elasticity, Poison's ratio and density vary continuously through the inward radial direction according to power law distribution. Numerical results on the natural frequencies are presented and discussed. These results are also compared with the corresponding ones obtained in the previous paper by the authors. In particular, it is established that for certain harmonics and for roots of certain order, the values of the natural frequency obtained for the hollow sphere can be greater (or less) than those obtained for the solid sphere.

The influence of initial stresses on energy release rate and total electro-mechanical potential energy for penny-shaped interface cracks in PZT/Elastic/PZT sandwich circular plate-disc

Akbarov, Surkay D.,Cafarova, Fazile I.,Yahnioglu, Nazmiye Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.22 No.3

This paper studies the energies and energy release rate (ERR) for the initially rotationally symmetric compressed (or stretched) in the inward (outward) radial direction of the PZT/Elastic/PZT sandwich circular plate with interface penny-shaped cracks. The investigations are made by utilizing the so-called three-dimensional linearized field equations and relations of electro-elasticity for piezoelectric materials. The quantities related to the initial stress state are determined within the scope of the classical linear theory of piezoelectricity. Mathematical formulation of the corresponding problem and determination of the quantities related to the stress-strain state which appear as a result of the action of the uniformly normal additional opening forces acting on the penny-shaped crack's edges are made within the scope of the aforementioned three-dimensional linearized field equations solution which is obtained with the use of the FEM modelling. Numerical results of the energies and ERR and the influence of the problem parameters on these quantities are presented and discussed for the PZT- 5H/Al/PZT-5H, PZT-4/Al/PZT-4, $BaTiO_3/Al/BaTiO_3$ and PZT-5H/StPZT-5H sandwich plates. In particular, it is established that the magnitude of the influence of the piezoelectricity and initial loading on the ERR increases with crack radius length.

Natural vibration of the three-layered solid sphere with middle layer made of FGM: three-dimensional approach

Surkay D. Akbarov,Hatam H. Guliyev,Nazmiye Yahnioglu 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.2

The paper studies the natural oscillation of the three-layered solid sphere with a middle layer made of Functionally Graded Material (FGM). It is assumed that the materials of the core and outer layer of the sphere are homogeneous and isotropic elastic. The three-dimensional exact equations and relations of linear elastodynamics are employed for the investigations. The discrete-analytical method proposed by the first author in his earlier works is applied for solution of the corresponding eigenvalue problem. It is assumed that the modulus of elasticity, Poisson’s ratio and density of the middle-layer material vary continuously through the inward radial direction according to power law distribution. Numerical results on the natural frequencies related to the torsional and spheroidal oscillation modes are presented and discussed. In particular, it is established that the increase of the modulus of elasticity (mass density) in the inward radial direction causes an increase (a decrease) in the values of the natural frequencies.

The influence of initial stresses on energy release rate and total electro-mechanical potential energy for penny-shaped interface cracks in PZT/Elastic/PZT sandwich circular plate-disc

Surkay D. Akbarov,Fazile I. Cafarova,Nazmiye Yahnioglu 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.3

This paper studies the energies and energy release rate (ERR) for the initially rotationally symmetric compressed (or stretched) in the inward (outward) radial direction of the PZT/Elastic/PZT sandwich circular plate with interface penny-shaped cracks. The investigations are made by utilizing the so-called three-dimensional linearized field equations and relations of electro-elasticity for piezoelectric materials. The quantities related to the initial stress state are determined within the scope of the classical linear theory of piezoelectricity. Mathematical formulation of the corresponding problem and determination of the quantities related to the stress-strain state which appear as a result of the action of the uniformly normal additional opening forces acting on the penny-shaped crack’s edges are made within the scope of the aforementioned three-dimensional linearized field equations solution which is obtained with the use of the FEM modelling. Numerical results of the energies and ERR and the influence of the problem parameters on these quantities are presented and discussed for the PZT- 5H/Al/PZT-5H, PZT-4/Al/PZT-4, BaTiO3/Al/BaTiO3 and PZT-5H/StPZT-5H sandwich plates. In particular, it is established that the magnitude of the influence of the piezoelectricity and initial loading on the ERR increases with crack radius length.

The Relationship between the Breast Arterial Calcification Detected by Mammography and the Hypertensive Retinopathy in Hypertensive Women

Cuneyt Calisir,Ulas Savas Yavas,Nazmiye Erol 대한영상의학회 2008 Korean Journal of Radiology Vol.9 No.4

Objective: The purpose of this study was to investigate the relationship between the breast arterial calcification (BAC) detected by mammograms and the hypertensive retinopathy (HR) in hypertensive women who underwent ophthalmologic examination. Materials and Methods: Screening mammography was performed in 99 hypertensive women and these women also underwent an ophthalmologic examination. The presence of arterial calcification and the number of calcified blood vessels in each breast were evaluated. The grade of HR was determined. The presence of BAC and the number of blood vessels involved was compared according to the presence of HR and the grade of HR. Results: Among the 99 patients, HR was detected in 70 patients, and of these 70 patients, 42 patients had grade I HR and 28 had grade II HR. BAC was detected in 54 cases. Forty-six patients with HR (66%) and eight patients without HR (27%) were diagnosed with BAC after they underwent mammographic examination. The prevalence of BAC in the subjects who had HR was statistically higher than that in those subjects who did not have HR (p < 0.01). The grade of HR was not significantly associated with BAC (p > 0.05). The positive predictive value of the BAC detected on mammography for HR was 0.80 in those subjects who were 60 years old. Conclusion: The detection of BAC by mammography is associated with an increased risk of HR, and particularly for patients after the age of 60. The findings of BAC may be related to hypertensive end-organ damage, and performing mammograms might contribute to predicting the presence of ophthalmologic hypertensive complications in these patients. Objective: The purpose of this study was to investigate the relationship between the breast arterial calcification (BAC) detected by mammograms and the hypertensive retinopathy (HR) in hypertensive women who underwent ophthalmologic examination. Materials and Methods: Screening mammography was performed in 99 hypertensive women and these women also underwent an ophthalmologic examination. The presence of arterial calcification and the number of calcified blood vessels in each breast were evaluated. The grade of HR was determined. The presence of BAC and the number of blood vessels involved was compared according to the presence of HR and the grade of HR. Results: Among the 99 patients, HR was detected in 70 patients, and of these 70 patients, 42 patients had grade I HR and 28 had grade II HR. BAC was detected in 54 cases. Forty-six patients with HR (66%) and eight patients without HR (27%) were diagnosed with BAC after they underwent mammographic examination. The prevalence of BAC in the subjects who had HR was statistically higher than that in those subjects who did not have HR (p < 0.01). The grade of HR was not significantly associated with BAC (p > 0.05). The positive predictive value of the BAC detected on mammography for HR was 0.80 in those subjects who were 60 years old. Conclusion: The detection of BAC by mammography is associated with an increased risk of HR, and particularly for patients after the age of 60. The findings of BAC may be related to hypertensive end-organ damage, and performing mammograms might contribute to predicting the presence of ophthalmologic hypertensive complications in these patients.