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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14411/22

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Citation - WoS: 1
Citation - Scopus: 1
Adaptive Stimulus Design for Dynamic Recurrent Neural Network Models
(Frontiers Media Sa, 2019) Doruk, R. Ozgur; Zhang, Kechen; Electrical-Electronics Engineering; 06. School Of Engineering; 01. Atılım University
We present an adaptive stimulus design method for efficiently estimating the parameters of a dynamic recurrent network model with interacting excitatory and inhibitory neuronal populations. Although stimuli that are optimized for model parameter estimation should, in theory, have advantages over nonadaptive random stimuli, in practice it remains unclear in what way and to what extent an optimal design of time-varying stimuli may actually improve parameter estimation for this common type of recurrent network models. Here we specified the time course of each stimulus by a Fourier series whose amplitudes and phases were determined by maximizing a utility function based on the Fisher information matrix. To facilitate the optimization process, we have derived differential equations that govern the time evolution of the gradients of the utility function with respect to the stimulus parameters. The network parameters were estimated by maximum likelihood from the spike train data generated by an inhomogeneous Poisson process from the continuous network state. The adaptive design process was repeated in a closed loop, alternating between optimal stimulus design and parameter estimation from the updated stimulus-response data. Our results confirmed that, compared with random stimuli, optimally designed stimuli elicited responses with significantly better likelihood values for parameter estimation. Furthermore, all individual parameters, including the time constants and the connection weights, were recovered more accurately by the optimal design method. We also examined how the errors of different parameter estimates were correlated, and proposed heuristic formulas to account for the correlation patterns by an approximate parameter-confounding theory. Our results suggest that although adaptive optimal stimulus design incurs considerable computational cost even for the simplest excitatory-inhibitory recurrent network model, it may potentially help save time in experiments by reducing the number of stimuli needed for network parameter estimation.
Citation - WoS: 80
Citation - Scopus: 82
Amine Grafted Silica Supported Craupd Alloy Nanoparticles: Superb Heterogeneous Catalysts for the Room Temperature Dehydrogenation of Formic Acid
(Royal Soc Chemistry, 2015) Yurderi, Mehmet; Bulut, Ahmet; Caner, Nurdan; Celebi, Metin; Kaya, Murat; Zahmakiran, Mehmet; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
Herein we show that a previously unappreciated combination of CrAuPd alloy nanoparticles and amine-grafted silica support facilitates the liberation of CO-free H-2 from dehydrogenation of formic acid with record activity in the absence of any additives at room temperature. Furthermore, their excellent catalytic stability makes them isolable and reusable heterogeneous catalysts in the formic acid dehydrogenation.
Citation - WoS: 9
Citation - Scopus: 11
Analysis of Publications on Health Information Management Using the Science Mapping Method: a Holistic Perspective
(Mdpi, 2024) Tengilimoglu, Dilaver; Orhan, Fatih; Tekin, Perihan Senel; Younis, Mustafa; Business; 05. School of Business; 01. Atılım University
Objective: In the age of digital transformation, there is a need for a sustainable information management vision in health. Understanding the accumulation of health information management (HIM) knowledge from the past to the present and building a new vision to meet this need reveals the importance of understanding the available scientific knowledge. With this research, it is aimed to examine the scientific documents of the last 40 years of HIM literature with a holistic approach using science mapping techniques and to guide future research. Methods: This study used a bibliometric analysis method for science mapping. Co-citation and co-occurrence document analyses were performed on 630 academic publications selected from the Web of Science core collection (WoSCC) database using the keyword "Health Information Management" and inclusion criteria. The analyses were performed using the R-based software Bibliometrix (Version 4.0; K-Synth Srl), Python (Version 3.12.1; The Python Software Foundation), and Microsoft (R) Excel (R) 2016. Results: Co-occurrence analyses revealed the themes of personal health records, clinical coding and data quality, and health information management. The HIM theme consisted of five subthemes: "electronic records", "medical informatics", "e-health and telemedicine", "health education and awareness", and "health information systems (HISs)". As a result of the co-citation analysis, the prominent themes were technology acceptance, standardized clinical coding, the success of HISs, types of electronic records, people with HIM, health informatics used by consumers, e-health, e-mobile health technologies, and countries' frameworks and standards for HISs. Conclusions: This comprehensive bibliometric study shows that structured information can be helpful in understanding research trends in HIM. This study identified critical issues in HIM, identified meaningful themes, and explained the topic from a holistic perspective for all health system actors and stakeholders who want to work in the field of HIM.
Citation - WoS: 7
Citation - Scopus: 7
Antibiotic administration in targeted nanoparticles protects the faecal microbiota of mice
(Royal Soc Chemistry, 2021) Borsa, Baris A.; Sudagidan, Mert; Aldag, Mehmet E.; Baris, Isik I.; Acar, Elif E.; Acuner, Cagatay; Ozalp, Veli C.; Basic Sciences; 08. Medical School; 01. Atılım University
Antibiotic therapy comes with disturbances on human microbiota, resulting in changes of bacterial communities and thus leading to well-established health problems. In this study, we demonstrated that targeted teicoplanin administration maintains the faecal microbiota composition undisturbed in a mouse model while reaching therapeutic improvements for S. aureus infection.
Citation - WoS: 6
Citation - Scopus: 8
Applying Emmert's Law To the Poggendorff Illusion
(Frontiers Research Foundation, 2015) Talasli, Umur; Inan, Asli Bahar; Department of Psychology; 02. School of Arts and Sciences; 01. Atılım University
The Poggendorff illusion was approached with a novel perspective, that of applying Emmert's Law to the situation. The extensities between the verticals and the transversals happen to be absolutely equal in retinal image size, whereas the registered distance for the verticals must be smaller than that of the transversals due to the fact that the former is assumed to occlude the latter. This combination of facts calls for the operation of Emmert's Law, which results in the shrinkage of the occluding space between the verticals. Since the retinal image shows the transversals to be in contact with the verticals, the shrinkage must drag the transversals inwards in the cortical representation in order to eliminate the gaps. Such dragging of the transversals produces the illusory misalignment, which is a dictation of geometry. Some of the consequences of this new explanation were tested in four different experiments. In Experiment 1, a new illusion, the tilting of an occluded continuation of an oblique line, was predicted and achieved. In Experiments 2 and 3, perceived nearness of the occluding entity was manipulated via texture density variations and the predicted misalignment variations were confirmed by using a between-subjects and within-subjects designs, respectively. In Experiment 4, tilting of the occluded segment of the transversal was found to vary in the predicted direction as a result of being accompanied by the same texture cues used in Experiments 2 and 3.
Citation - WoS: 1
Citation - Scopus: 1
Assessment of Anticancer Effects of Aloe Vera on 3D Liver Tumor Spheroids in a Microfluidic Platform
(Wiley, 2025) Tevlek, Atakan; Kibar, Gunes; Cetin, Barbaros; Basic Sciences; 08. Medical School; 01. Atılım University
The search for effective anticancer therapies has increasingly focused on natural compounds like Aloe vera, renowned for its therapeutic properties. This study investigates the anticancer properties of Aloe vera on 3D liver tumor spheroids via a PDMS-based microfluidic device, providing a more physiologically realistic model compared to traditional 2D cultures. HepG2 cells were cultivated to generate 3D spheroids on-chip, thereafter subjected to different concentrations of Aloe vera and the chemotherapeutic drug Doxorubicin to evaluate cytotoxic effects. The microfluidic system, validated by COMSOL simulations, facilitated continuous perfusion and real-time assessment of cell viability over a duration of 10 days. The results indicated that Aloe vera markedly diminished cell viability by triggering apoptosis at concentrations over 12.5 mg/mL. IC50 values were determined at 72 h: 25 +/- 0.10 mg/mL for Aloe vera and 5.47 +/- 0.03 mu g/mL for Doxorubicin in 2D cultures, but in 3D cultures, the IC50 values were 31.25 +/- 0.14 mg/mL for Aloe vera and 8.33 +/- 0.05 mu g/mL for Doxorubicin. This study underscores the promise of Aloe vera as a natural anticancer agent and illustrates the efficacy of microfluidic platforms for enhanced drug screening and customized medicine applications.
Citation - WoS: 19
Citation - Scopus: 20
Assessment of Depression, Anxiety, and Social Support in the Context of Therapeutic Abortion
(Wiley, 2019) Topal, Cansu Akdag; Terzioglu, Fusun; Nursing; 07. School of Health Sciences; 01. Atılım University
Purpose The purpose of this study is to determine the levels of anxiety, depression, social support, and nursing care needed by women undergoing therapeutic abortion. Designs and Methods Sixty women were administered a sociodemographic form, the Hospital Anxiety Depression Scale and the Multidimensional Perceived Social Support Scale. Results More than half of the women experienced anxiety (61.7%). Anxiety scores were high (10.8 +/- 3.7), and most of the women had depression (85.0%). Social support from family and friends of the women decreased the women's anxiety and depression levels significantly; social support from their partners also decreased the women's anxiety levels (P < 0.05). Practice Implications Support from family and friends after therapeutic abortion is a fundamental affective variable on anxiety scores.
Citation - WoS: 5
Citation - Scopus: 5
Assessment of Nitrogen Excess in an Agricultural Area Using a Nitrogen Balance Approach
(I W A Publishing, 2005) Muhammetoglu, H; Muhammetoglu, A; Soyupak, S; 01. Atılım University
A pilot study has been initiated to develop an approach for quantification of nitrogen excesses from agricultural activities that involve greenhouse farming in Kumluca Plain, Turkey. Detailed calculations utilizing the nitrogen balance method (NBM) were carried out at nine different locations within the plain over a time period of one year. The major contributing factors and governing operative mechanisms taken into consideration were nitrogen application rates both as organic and chemical fertilizers, irrigation water to application practices, and nitrogen uptake by plants. The adopted approach yielded valuable information such as plant nitrogen uptake efficiencies, excess nitrogen, leaching rates and leachate nitrogen concentrations. Further, a site specific multiple linear regression model has been developed to estimate the ratio (N-leachate/N-groundwater) as a function of independent variables: farming age, excess nitrogen application and SEEPAGE Index Number. The negative sign of the model parameters implies that the ratio (N-leachate/N-groundwater) decreases as values of the independent variables increase. The adopted approach and the obtained results can beneficially be applied to similar sites to establish basic parameters of irrigation and fertilizer application operations.
The Association Between Digital Device Usage Behaviors and the Incidence of De Quervain’s Tenosynovitis Among University Students
(Taylor and Francis Ltd., 2025) Jamil, Y.; Öktem, H.; Sever, S.N.; Basic Sciences; 08. Medical School; 01. Atılım University
Background: The extensive use of mobile and digital devices has been implicated in various musculoskeletal disorders, including de Quervain’s tenosynovitis (dQD), a condition affecting the thumb. Purpose: The present study investigates the relationship between digital device usage patterns and the prevalence of dQD among university students. Methods: A cross-sectional study was conducted with 508 participants (255 females and 253 males), collecting data on daily device use time, wrist positions, hand dominance, and stretching practices via a questionnaire. Data collection was carried out through a supervised, face-to-face survey. Diagnosis of dQD was determined using Finkelstein’s test, all data were analyzed using SPSS software. Results: Out of 508 participants, 187 (36.8%) tested positive for dQD, with 152 (95.6)% occurring in the dominant hand (p =.006, Cramér’s (Formula presented.) = 0.121). 250 participants used their devices with wrists in ulnar deviation (49.2%), which was strongly linked to a positive Finkelstein test result (p =.004, Cramér’s (Formula presented.) = 0.175). Finkelstein’s test showed increasing positivity with device use, ranging from 12.5% for < 2 hours to 46.2% for ≥ 8 hours, with a statistically significant association (p <.001, Cramér’s (Formula presented.) = 0.234). Device usage varied, with the highest test positivity rates among those using devices 6–8 hours per day suggesting a significant association with dQD (p =.001). No significant relationship was found between dQD and the practice of stretching or relieving movements (p =.146). Conclusion: The findings indicate that prolonged digital device usage, specific wrist positions such as ulnar deviation, and dominant-hand use are significantly associated with an increased risk of de Quervain’s tenosynovitis among college students. © 2025 Taylor & Francis Group, LLC.
Citation - Scopus: 1
Association Between Fragmented Qrs and Postprocedural Rhythm Disturbances in Patients Who Underwent Transcatheter Aortic Valve Implantation
(Assoc Medica Brasileira, 2021) Duran, Mustafa; Ziyrek, Murat; Alsancak, Yakup; Ayhan, Huseyin; 01. Atılım University
INTRODUCTION: According to recent studies, the rate of atrioventricular block requiring permanent pacing in patients following transcatheter aortic valve implantation varied between 5.7% and 42.5%. Fragmented QRS is a useful marker of myocardial scar and can predict adverse cardiac events. In this study, we examined association between fragmented QRS and postprocedural rhythm disturbances and the need for permanent pacing in patients who underwent transcatheter aortic valve implantation. OBJECTIVE: In this study, we examined association between fragmented QRS and postprocedural rhythm disturbances and the need for permanent pacing in patients who underwent transcatheter aortic valve implantation' sentence is enough for it. METHODS: We retrospectively analyzed standard 12-lead electrocardiographic recordings of 124 consecutive patients in whom a CoreValve prosthesis was implanted. We examined 12-lead electrocardiogram before and after procedure along with one- and six-month follow-up. We documented QRS fragmentation and postprocedural rhythm disturbances. RESULTS: There was a significant increase in the frequency of left bundle branch block, (21.1 versus 0%, p<0.05) and the incidence of atrioventricular blocks requiring permanent pacing (21.1 versus 0%, p<0.05) following transcatheter aortic valve implantation in patients whose preprocedural electrocardiogram recordings revealed fragmented QRS compared to those without fragmented QRS. Based our collected data, the presence of QRS fragmentation in anterior derivations was the only independent factor associated with postprocedural rhythm disturbances (B-value 0.217; OR 0.805; 95%CI 0.136-4.78; p=0.004). CONCLUSION: Our data showed an increased risk for the development of new-onset left bundle branch block and atrioventricular blocks following transcatheter aortic valve implantation in patients whose baseline electrocardiogram recordings demonstrated QRS fragmentation.
Citation - WoS: 1
Citation - Scopus: 1
The Association Between Respiratory Functions, Pain Tolerance and Body Awareness in Obstructive Lung Diseases
(Elsevier Science Inc, 2025) Vardar-Yagli, Naciye; Saglam, Melda; Firat, Merve; Inal-Ince, Deniz; Calik-Kutukcu, Ebru; Kilic, Kubra; Coplu, Lutfi; 01. Atılım University
Purpose: There are only a limited number of studies in the literature evaluating body awareness, pain perception, and the relationship between clinical parameters and respiratory functions in patients with obstructive lung disease (OLD) and compared with healthy individuals. Therefore, this study aimed to evaluate respiratory functions, pain tolerance, and body awareness in patients with OLD and compare these findings with those of healthy individuals. Methods: The study included 33 patients and 30 healthy individuals. The respiratory function (spirometer), respiratory muscle strength (mouth pressure device), endurance (threshold loading device), pain level and tolerance (short-form McGill Pain Questionnaire and algometer), posture, and body awareness (Body Awareness Questionnaire-BAQ) were evaluated. Results: The pain threshold and tolerance of the biceps, triceps, trapezius, and quadriceps muscles were significantly lower and BAQ scores were higher in patients with OLD compared with healthy individuals (p < .05). There was a significant relationship between FEV1 (%) and pain tolerance of the triceps (r = 0.371, p = .047) and gastrocnemius muscles (r = 0.419, p = .024); FVC (%) and pain threshold of the gastrocnemius (r = 0.413, p = .023), triceps muscles (r = 0.394, p = .034), and pain tolerance of the gastrocnemius muscle (r = 0.549, p = .002). Conclusions: Patients with OLD have a marked increase in pain perception and body awareness levels and a decrease in pain threshold and tolerance compared with healthy controls. Future studies should assess the effectiveness of pain management interventions as a part of pulmonary rehabilitation for patients with chronic respiratory diseases. Clinical Implications: Pain management is important for planning pulmonary rehabilitation programmes. (c) 2024 American Society for Pain Management Nursing. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Citation - WoS: 2
Citation - Scopus: 1
Association Between the Degree of Nonalcoholic Fatty Liver Disease and Nocturnal Hypertension
(Lippincott Williams & Wilkins, 2025) Astan, Ramazan; Kacmaz, Fehmi; Saricam, Ersin; Ozyer, Esref Umut; Ilkay, Erdogan; 01. Atılım University
Nighttime blood pressure (BP) decreases have prognostic significance owing to circadian patterns. The prevalence of nonalcoholic fatty liver disease (NAFLD) has rapidly increased in recent years. We aimed to investigate circadian blood pressure changes in patients with NAFLD. The present study included 114 patients diagnosed with nonalcoholic fatty liver disease and no previous hypertension diagnosis. Thirty patients comprised the control group (no hepatosteatosis and no hypertension). The patients were divided into 3 groups based on nocturnal BP dipping. Blood pressure patterns using night-day ratios were classified as dipper (ratio <= 0, 9), nondipper (0, 9 < ratio <= 1, 0), or nocturnal hypertension (ratio > 1, 0). There were no significant differences in sex, age, presence of diabetes, or biochemical test results between the groups. According to the blood pressure pattern, the nondipper rate in the hepatosteatosis group was significantly higher than that in the control group. Patients were compared in terms of the presence and severity of hepatosteatosis according to night blood pressure patterns. A significant difference was observed between the groups (P < .001 and P = .001, respectively). We found an association between hepatosteatosis severity and night blood pressure patterns. Patients with nonalcoholic fatty liver disease have a higher incidence of nocturnal hypertension. We observed impaired circadian blood pressure changes in patients with nonalcoholic fatty liver disease.
Citation - WoS: 58
Citation - Scopus: 70
Atmospheric Pressure Plasma Surface Treatment of Polymers and Influence on Cell Cultivation
(Mdpi, 2021) Sasmazel, Hilal Turkoglu; Alazzawi, Marwa; Alsahib, Nabeel Kadim Abid; Metallurgical and Materials Engineering; 06. School Of Engineering; 01. Atılım University
Atmospheric plasma treatment is an effective and economical surface treatment technique. The main advantage of this technique is that the bulk properties of the material remain unchanged while the surface properties and biocompatibility are enhanced. Polymers are used in many biomedical applications; such as implants, because of their variable bulk properties. On the other hand, their surface properties are inadequate which demands certain surface treatments including atmospheric pressure plasma treatment. In biomedical applications, surface treatment is important to promote good cell adhesion, proliferation, and growth. This article aim is to give an overview of different atmospheric pressure plasma treatments of polymer surface, and their influence on cell-material interaction with different cell lines.
Citation - WoS: 13
Citation - Scopus: 15
Atomistic Engineering of Chemiluminogens: Synthesis, Properties and Polymerization of 2,3-Dihydro Scaffolds
(Springer/plenum Publishers, 2017) Algi, Melek Pamuk; Tirkeş, Seha; Oztas, Zahide; Cihaner, Atilla; Tirkes, Seha; Cihaner, Atilla; Algi, Fatih; Tirkeş, Seha; Cihaner, Atilla; Chemical Engineering; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
Two chemiluminescent compounds containing 2,5-di(thien-2-yl)pyrrole and pyridazine units, namely 5,7-di(thiophen-2-yl)-2,3-dihydro-1H-pyrrolo[3,4-d]pyridazine-1,4(6H)-dione (5) and 6-phenyl-5,7-di(thiophen-2-yl)-2,3-dihydro-1H-pyrrolo[3,4-d]pyridazine-1,4(6H)-dione (6), were successfully synthesized and electrochemically polymerized. The compounds have chemiluminescent properties and glow in the presence of hydrogen peroxide in basic medium. The intensity of the glow can be increased dramatically by using Fe3+ ions, hemin (1.0 ppm) or blood samples (1.0 ppm) as catalyst. The compounds 5 and 6 have one well-defined irreversible oxidation peak at 1.08 V and 1.33 V vs Ag/AgCl, respectively. Electrochemical polymerization of both 5 and 6 were carried out successfully by repeating potential scanning in the presence of BF3. Et2O in an electrolyte solution of 0.1 M LiClO4 dissolved in acetonitrile. The electronic band gaps (E-g) of the polymers P5 and P6 were found to be 2.02 eV and 2.16 eV, respectively. On the other hand, the corresponding polymers are electroactive and exhibited electrochromic features.
Citation - WoS: 5
Citation - Scopus: 4
Avoiding Contingent Incidents by Quadrotors Due To One or Two Propellers Failure
(Public Library Science, 2023) Altinuc, Kemal Orcun; Khan, Muhammad Umer; Iqbal, Jamshed; Mechatronics Engineering; 15. Graduate School of Natural and Applied Sciences; 06. School Of Engineering; 01. Atılım University
With the increasing impact of drones in our daily lives, safety issues have become a primary concern. In this study, a novel supervisor-based active fault-tolerant (FT) control system is presented for a rotary-wing quadrotor to maintain its pose in 3D space upon losing one or two propellers. Our approach allows the quadrotor to make controlled movements about a primary axis attached to the body-fixed frame. A multi-loop cascaded control architecture is designed to ensure robustness, stability, reference tracking, and safe landing. The altitude control is performed using a proportional-integral-derivative (PID) controller, whereas linear-quadratic-integral (LQI) and model-predictive-control (MPC) have been investigated for reduced attitude control and their performance is compared based on absolute and mean-squared error. The simulation results affirm that the quadrotor remains in a stable region, successfully performs the reference tracking, and ensures a safe landing while counteracting the effects of propeller(s) failures.
Citation - WoS: 10
Citation - Scopus: 7
Beyond expectations: disease duration and psychological burden in psoriatic arthritis
(Springer Heidelberg, 2023) Kilic, Gamze; Kilic, Erkan; Tekeoglu, Ibrahim; Sargin, Betul; Cengiz, Gizem; Balta, Nihan Cuzdan; Nas, Kemal; 01. Atılım University
This study aims to investigate the relationship between disease duration and psychological burden in PsA and to identify the risk factors associated with psychological distress. Patients with PsA who met CASPAR classification criteria enrolled by Turkish League Against Rheumatism (TLAR)-Network. Patients were categorized into three groups based on disease duration: early stage (< 5 years), middle stage (& GE; 5, < 10 years), and late stage (& GE; 10 years). All patients underwent clinical and laboratory assessment using standardized protocol and case report forms. The associations between psychological variables and clinical parameters were assessed by a multivariate analysis. Of the 1113 patients with PsA (63.9% female), 564 (%50.7) had high risk for depression and 263 (%23.6) for anxiety. The risk of psychological burden was similar across all PsA groups, and patients with a higher risk of depression and anxiety also experienced greater disease activity, poorer quality of life, and physical disability. Multivariate logistic regression revealed that female gender (OR = 1.52), PsAQoL (OR = 1.13), HAQ (OR = 1.99), FiRST score (OR = 1.14), unemployment/retired (OR = 1.48) and PASI head score (OR = 1.41) were factors that influenced the risk of depression, whereas the current or past enthesitis (OR = 1.45), PsAQoL (OR = 1.19), and FiRST score (OR = 1.26) were factors that influenced the risk of anxiety. PsA patients can experience a comparable level of psychological burden throughout the course of their disease. Several socio-demographic and disease-related factors may contribute to mental disorders in PsA. In the present era of personalized treatment for PsA, evaluating psychiatric distress can guide tailored interventions that improve overall well-being and reduce disease burden.
Bilateral adrenal haemorrhage after blunt abdominal trauma
(Ma Healthcare Ltd, 2023) Guvendi, Bulent; Koksal, Ali; Gozgec, Elif; Ogul, Hayri; Kantarci, Mecit; Medical Imaging Techniques Program; 12. Department of Medical Services and Techniques; 01. Atılım University
[No Abstract Available]
Citation - WoS: 54
Biomechanical Comparison of Implant Retained Fixed Partial Dentures With Fiber Reinforced Composite Versus Conventional Metal Frameworks: a 3d Fea Study
(Elsevier, 2011) Erkmen, Erkan; Meric, Gokce; Kurt, Ahmet; Tunc, Yahya; Eser, Atilim; 01. Atılım University
Fiber reinforced composite (FRC) materials have been successfully used in a variety of commercial applications. These materials have also been widely used in dentistry. The use of fiber composite technology in implant prostheses has been previously presented, since they may solve many problems associated with metal alloy frameworks such as corrosion, complexity of fabrication and high cost. The hypothesis of this study was that an FRC framework with lower flexural modulus provides more even stress distribution throughout the implant retained fixed partial dentures (FPDs) than a metal framework does. A 3-dimensional finite element analysis was conducted to evaluate the stress distribution in bone, implant-abutment complex and prosthetic structures. Hence, two distinctly different models of implant retained 3-unit fixed partial dentures, composed of Cr-Co and porcelain (M-FPD model) or FRC and particulate composite (FRC-FPD model) were utilized. In separate load cases, 300 N vertical, 150 N oblique and 60 N horizontal forces were simulated. When the FRC-FPD and M-FPD models were compared, it was found that all investigated stress values in the M-FPD model were higher than the values in the FRC-FPD model except for the stress values in the implant-abutment complex. It can be concluded that the implant supported FRC-FPD could eliminate the excessive stresses in the bone-implant interface and maintain normal physiological loading of the surrounding bone, therefore minimizing the risk of peri-implant bone loss due to stress-shielding. (C) 2010 Elsevier Ltd. All rights reserved.
Citation - WoS: 14
Citation - Scopus: 20
Biomechanical Comparison of Two Different Collar Structured Implants Supporting 3-Unit Fixed Partial Denture: a 3-D Fem Study
(Taylor & Francis Ltd, 2012) Meric, Gokce; Erkmen, Erkan; Kurt, Ahmet; Eser, Atilim; Oezden, Ahmet Utku; 01. Atılım University
Objective. The purpose of the study was to compare the effects of two distinct collar geometries of implants on stress distribution in the bone as well as in the fixture-abutment complex, in the framework and in the veneering material of 3-unit fixed partial denture (FPD). Material and methods. The 3-dimensional finite element analysis method was selected to evaluate the stress distribution in the system composed of 3-unit FPD supported by two different dental implant systems with two distinct collar geometries; microthread collar structure (MCS) and non-microthread collar structure (NMCS). In separate load cases, 300 N vertical, 150 N oblique and 60 N horizontal, forces were utilized to simulate the multidirectional chewing forces. Tensile and compressive stress values in the cortical and cancellous bone and von Mises stresses in the fixture-abutment complex, in the framework and veneering material, were simulated as a body and investigated separately. Results. In the cortical bone lower stress values were found in the MCS model, when compared with NMCS. In the cancellous bone, lower stress values were observed in the NMCS model when compared with MCS. In the implant-abutment complex, highest von Mises stress values were noted in the NMCS model; however, in the framework and veneering material, highest stress values were calculated in MCS model. Conclusions. MCS implants when compared with NMCS implants supporting 3-unit FPDs decrease the stress values in the cortical bone and implant-abutment complex. The results of the present study will be evaluated as a base for our ongoing FEA studies focused on stress distribution around the microthread and non-microthread collar geometries with various prosthesis design.
Citation - WoS: 8
Citation - Scopus: 10
Biomechanical Effects of Two Different Collar Implant Structures on Stress Distribution Under Cantilever Fixed Partial Dentures
(Taylor & Francis Ltd, 2011) Meric, Gokce; Erkmen, Erkan; Kurt, Ahmet; Eser, Atilim; Ozden, Ahmet Utku; 01. Atılım University
Objective. The purpose of the study was to compare the effects of two distinct collar geometries of implants on stress distribution in the bone around the implants supporting cantilever fixed partial dentures (CFPDs) as well as in the implant-abutment complex and superstructures. Materials and methods. The three-dimensional finite element method was selected to evaluate the stress distribution. CFPDs which was supported by microthread collar structured (MCS) and non-microthread collar structured (NMCS) implants was modeled; 300 N vertical, 150 N oblique and 60 N horizontal forces were applied to the models separately. The stress values in the bone, implant-abutment complex and superstructures were calculated. Results. In the MCS model, higher stresses were located in the cortical bone and implant-abutment complex in the case of vertical load while decreased stresses in cortical bone and implant-abutment complex were noted within horizontal and oblique loading. In the case of vertical load, decreased stresses have been noted in cancellous bone and framework. Upon horizontal and oblique loading, a MCS model had higher stress in cancellous bone and framework than the NMCS model. Higher von Mises stresses have been noted in veneering material for NMCS models. Conclusion. It has been concluded that stress distribution in implant-supported CFPDs correlated with the macro design of the implant collar and the direction of applied force.

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