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Öğe Comparison of the effects of different loading locations on stresses transferred to straight and angled implant-supported zirconia frameworks: a finite element method study(Taylor & Francis Ltd, 2015) Guven, Sedat; Atalay, Yusuf; Asutay, Fatih; Ucan, Musa Can; Dundar, Serkan; Karaman, Tahir; Gunes, NedimThe paper presents three-dimensional (3D) finite element models of straight and angled implants and their zirconium-based superstructures. The key objective was to compare the influence of different loading conditions on the stress distribution of straight and angled implants and the zirconia frameworks. 3D finite element straight- and angled-implant models of a mandibular section of bone with missing second molars and their zirconium-based superstructures were used. The straight and angled implants were 4.7 x 13-mm screw-type dental implant systems. Total loads of 300 N were applied in a vertical direction and in an oblique (30 degrees to the vertical) direction buccolingually. Maximum and minimum von Mises stress values of the titanium structures (abutment and implant body) and zirconia frameworks were calculated. When the two groups were examined, the highest stress value was in the zirconia framework of the angled implant-supported model with an oblique loading force (731.46 MPa). The lowest stress values were concentrated in the straight implant-supported model. Thus, the stress values in the angled implant-supported crown were higher than those in the straight implant-supported model. Stress values with oblique loading forces were higher than the values with vertical loading forces. The highest stress value in the zirconia framework was similar to the ultimate strength of the zirconia.Öğe Comparison of the Effects of Local and Systemic Zoledronic Acid Application on Mandibular Distraction Osteogenesis(Lippincott Williams & Wilkins, 2017) Dundar, Serkan; Artas, Gokhan; Acikan, Izzet; Yaman, Ferhan; Kirtay, Mustafa; Ozupek, Muhammed Fatih; Asutay, FatihBisphosphonates are antibone resorptive drugs that are used to prevent bone tissue resorption in several skeletal diseases. The aim of this study was to examine the effects of systemic and local applications of zoledronic acid (ZA) on newly regenerated bone in a model of experimental distraction osteogenesis (DO). To do this mandibular DO was applied to 30 adult female Sprague Dawley rats, which were randomly divided into 3 groups: control, DO only, systemic zoledronic acid (SZA), and local zoledronic acid (LZA). In the LZA group, the gap between the bone fragments was filled with a gelatin sponge soaked in 2mg of ZA and 0.1 mL of sterile saline. In the SZA group, a single dose of 0.1 mg/kg ZA was administered systemically. After the surgery, there was a 5-day latent waiting period and 10-day distraction phase. Following a 28-day consolidation period, the rats were euthanized and theirmandibles were collected. The distracted bone area was seen to be filled with newly regenerated bone tissue in all 3 groups, both histologically and histomorphometrically. In addition, amounts of new bone formation, osteoblast cella, osteoclast (OC) cells, osteopontin, and vascular endothelial growth factor in the SZA and LZA groups were found to be higher when compared with the controls. Furthermore, in the SZA group, new bone formation, osteoblast, OC, osteopontin, and vascular endothelial growth factor were detected in significant amounts compared with the LZA group. Osteoclast numbers did not differ in a statistically significant manner in the SZA group with respect to the LZA group. Based on the results of this study, systemic and local applications of ZA could increase the formation of new bone in patients of DO, and systemic application is a more effective method compared with local application.Öğe The effects of high-fat diet on implant osseointegration: an experimental study(Korean Acad Oral & Maxillofacial Surgery, 2016) Dundar, Serkan; Yaman, Ferhan; Ozupek, Muhammed Fatih; Saybak, Arif; Gul, Mehmet; Asutay, Fatih; Kirtay, MustafaObjectives: In this study, we investigated whether a high-fat diet (HFD) affected the bone implant connection (BIC) in peri-implant bone. Materials and Methods: Four male rabbits were used in this study. Dental implant surgery was introduced into each tibia, and four implants were integrated into each animal. In both the normal diet (ND) group (n=2) and HFD group (n=2), 8 implants were integrated, for a total of 16 integrated implants. The animals continued with their respective diets for 12 weeks post-surgery. Afterward, the rabbits were sacrificed, and the BIC was assessed histomorphometrically. Results: Histologic and histomorphometric analyses demonstrated that BIC was not impaired in the HFD group compared to the ND group. Conclusion: Within the limitations of this study, we found that HFD did not decrease the BIC in rabbit tibias.Öğe Evaluation of calcified carotid atheroma on panoramic radiographs and Doppler ultrasonography in an older population(Dove Medical Press Ltd, 2015) Atalay, Yusuf; Asutay, Fatih; Agacayak, Kamil Serkan; Koparal, Mahmut; Adali, Fahri; Gulsun, BelginAim: The aim of this study is to determine the reliability of panoramic radiograph (PR) as a screening tool for the detection of calcified carotid atheroma (CCA) by comparing it with Doppler ultrasonography (DU) examination. A second aim was to evaluate the relationship among CCA, systemic diseases, smoking, and body mass index in an older population. Materials and methods: A total of 1,650 PRs of patients aged over 45 years (736 males and 914 females) were randomly selected. All the patients had been referred to the Faculty of Dentistry, Afyon Kocatepe University, Afyonkarahisar, Turkey, during 2013-2014 for routine PR screening. Medical data were collected from the archival records of the dental school. The patients were divided into two groups: Group A (study group), CCA findings were confirmed by DU (n=59); and Group B (control group), CCA findings were not confirmed by DU (n=34). Results: Of the 1,650 individuals, 93 (5.63%) were detected to have CCA on PR. The population consisted of 43 males and 50 females with mean age of 59.84 +/- 10.92 years. No difference was determined in respect of CCA between the sexes (P=0.745). There was a significant difference between Group A and Group B in respect of hypertension (P=0.004). But there was no difference between Group A and Group B in respect of age (P=0.495), BMI (P=0.756), diabetes (P=0.168), and smoking (P=0.482) distribution. Conclusion: Although PR cannot be used as an initial diagnostic method when searching for CCA, dentists should be aware of CCA on a routine PR, particularly in older patients who may also have the risk factors of obesity, diabetes mellitus, hypertension, and smoking. Recognizing of CCA especially in hypertensive patients could potentially increase the length and quality of life for individuals.Öğe Examination of stress distribution and fracture resistance in five-unit tooth- nd implant-supported partial fixed zirconia prosthesis(Taylor & Francis Ltd, 2015) Guven, Sedat; Aguloglu, Suleyman; Beydemir, Koksal; Dundar, Serkan; Atalay, Yusuf; Ucan, Musa Can; Asutay, FatihIn this study, stress distribution and fracture strength values of zirconia frameworks were compared in five-unit tooth- and implant-supported fixed zirconia prosthesis. Three-dimensional finite element stress analysis and static non-linear analysis were used. Because of the boundary conditions determined for these methods, the tooth- and implant-supported models only included the regions of tooth numbers 43-47. The highest stress value (901.845 MPa) was measured in Model 1 (five-unit tooth-supported fixed zirconia bridge) at the mesial gingival neck area of restoration number 45. This stress value was within the ultimate strength of zirconia (900-1200 MPa). Stress values for connector regions were not in the ultimate strength value of zirconia. Stress values in the tooth-supported fixed zirconia bridge were more than the values in the implant-supported fixed zirconia bridge. The highest stresses in Model 2 (five-unit implant-supported fixed zirconia bridge) occurred in the restoration that the model was installed on. The obtained results showed that five-unit tooth-supported posterior zirconia fixed bridge prostheses are not recommended and that the second premolar region is most seriously affected in terms of stress.Öğe Finite element analysis of the stress distributions in peri-implant bone in modified and standard-threaded dental implants(Taylor & Francis Ltd, 2016) Dundar, Serkan; Topkaya, Tolga; Solmaz, Murat Yavuz; Yaman, Ferhan; Atalay, Yusuf; Saybak, Arif; Asutay, FatihThe aim of this study was to examine the stress distributions with three different loads in two different geometric and threaded types of dental implants by finite element analysis. For this purpose, two different implant models, Nobel Replace and Nobel Active (Nobel Biocare, Zurich, Switzerland), which are currently used in clinical cases, were constructed by using ANSYS Workbench 12.1. The stress distributions on components of the implant system under three different static loadings were analysed for the two models. The maximum stress values that occurred in all components were observed in F-III (300 N). The maximum stress values occurred in F-III (300 N) when the Nobel Replace implant is used, whereas the lowest ones, in the case of F-I (150 N) loading in the Nobel Active implant. In all models, the maximum tensions were observed to be in the neck region of the implants. Increasing the connection between the implant and the bone surface may allow more uniform distribution of the forces of the dental implant and may protect the bone around the implant. Thus, the implant could remain in the mouth for longer periods. Variable-thread tapered implants can increase the implant and bone contact.Öğe Three-dimensional finite-element analysis of a single implant-supported zirconia framework and its effect on stress distribution in D4 (maxilla) and D2 (mandible) bone quality(Taylor & Francis Ltd, 2015) Guven, Sedat; Demirci, Fatih; Yavuz, Izzet; Atalay, Yusuf; Ucan, Musa Can; Asutay, Fatih; Altintas, EyyupThe aim of this in-silico study was to compare stress distributions in implants and zirconia frameworks of mandibular and maxillary implant-supported crowns. For comparison, vertical and oblique loading forces were used. Three-dimensional finite-element implant models of a mandibular section of bone (D2) and a maxillary section of bone (D4) with missing second molars and their zirconium-based superstructures were used. Zimmer dental implants of 13 mm in length and 4.7 mm in diameter were modelled. A load of 200 N was applied toward vertical and oblique (30 degrees to the vertical) directions. Maximum and minimum von Mises stress values of the implants and the zirconia framework were calculated. The highest stress value was concentrated in the zirconia framework of the maxillary implant-supported model with the oblique loading force (301.17 MPa). The lowest stress value was concentrated in the mandibular implant-supported model. And the stress values in the maxilla were higher than in the mandible. The maxilla (D4) showed higher stress values than in the mandible (D2), because the trabecular bone is weaker and less resistant to deformation than the cortical bone. Stress values with oblique loading forces were higher than with vertical loading forces. Because of the high Young's modulus of zirconia (low elastic properties), zirconia frameworks showed higher stress values than the implants.
