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Öğe Biomechanical evaluation of different fixation systems after Le Fort I osteotomy in polyurethane models of unilateral clefts(CHURCHILL LIVINGSTONE, 2016) Esen, Alparslan; Isik, Kubilay; Saglam, Haci; Ozdemir, Yusuf Bugra; Dolanmaz, DoganWe compared the stability of three different titanium plate-and-screw fixation systems after Le Fort I osteotomy in polyurethane models of unilateral clefts. Thirty-six models were divided into 3 groups. In the first group, we adapted standard Plates 1 mm thick with 2.0 mm screws and placed them bilaterally on the zygomatic buttress and the piriform rim. In the second group, we did the same and added Plates 0.6 mm thick with 1.6 mm screws between the standard 2 mm miniplates on both sides. In the last group, we placed Plates 1.4 mm thick with 2.0 mm screws bilaterally on the maxillary zygomatic buttress and piriform rim. Each group was tested in the inferosuperior (IS) and anteroposterior (AP) directions with a servo-hydraulic testing unit. In the IS direction, displacement values were not significantly different up to 80 N, but between 80 and 210 N, those in the 2 x 1.4 mm group were better. In the AP direction, displacement values were not significantly different up to 40 N, but between 40 and 180 N, they were better in the standard with 1.6 x 0.6 mm group and the 2 x 1.4 mm group. When normal biting forces (90- 260 N) in the postoperative period are considered, the greatest resistance to occlusal loads was seen in the 2 x 1.4 mm group. In the others, the biomechanical properties were better in the AP direction. (C) 2016 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.Öğe Comparison of stability of 2.0 mm standard and 2.0 mm locking miniplate/screws for the fixation of sagittal split ramus osteotomy on sheep mandibles(CHURCHILL LIVINGSTONE, 2011) Oguz, Yener; Saglam, Haci; Dolanmaz, Dogan; Uckan, SinaTen unembalmed adult sheep mandibles were used. The mandibles were sectioned in the midline, followed by sagittal split ramus osteotomies to obtain 20 hemimandibles. Each distal segment was advanced 5 mm on each hemimandible. Ten of the specimens were fixed with 4-hole extended 2.0 mm titanium miniplates and screws and the other 10 were fixed with 4-hole extended 2.0 min locking miniplates/screws. Each fixed specimen was mounted on a servo-hydraulic testing unit with the fixation device, and was tested to a range of forces of 0-140N. The displacement values (mm) under 20, 60, 120, and 140N were compared with the help of the Mann Whitney U-test, and there were no significant differences between them at any force tested. Locking miniplate/screws and standard miniplate/screws showed similar displacement values at the range of forces tested. (C) 2010 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.Öğe Design and applications of a pneumatic accelerator for high speed punching(ELSEVIER SCI LTD, 2007) Yaldiz, Suleyman; Saglam, Haci; Unsacar, Faruk; Isik, HakanHigh speed forming is an important production method that requires specially designed HERF (high energy rate forming) machines. Most of the HERF machines are devices that consist of a system in which energy is stored and a differential piston mechanism is used to release the energy at high rate. In order to eliminate the usage of specially designed HERF machines and to obtain the high speed forming benefits, the accelerator which can be adapted easily onto conventional presses has been designed and manufactured in this study. The designed energy accelerator can be incorporated into mechanical press to convert the low speed operation into high-speed operation of a hammer. Expectations from this work are reduced distortion rates, increased surface quality and precise dimensions in metal forming operations. From the performance test, the accelerator is able to achieve high speed and energy which require for high speed blanking of thick sheet metals. (c) 2005 Elsevier Ltd. All rights reserved.Öğe Design, development and testing of a four-component milling dynamometer for the measurement of cutting force and torque(ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD, 2007) Yaldiz, Suleyman; Unsacar, Faruk; Saglam, Haci; Isik, HakanThe cutting forces generated in metal cutting have a direct influence on generation heat, tool wear or failure, quality of machined surface and accuracy of the work piece. In this study, a milling dynamometer that can measure static and dynamic cutting forces, and torque by using strain gauge and piezo-clectric accelerometer has been designed and constructed. The orientation of octagonal rings and strain gauge locations has been determined to maximise sensitivity and to minimise cross-sensitivity. The force and torque signals were captured and processed using proper data acquisition system. The dynamometer has been subjected to a series of tests to determine its static and dynamic characteristics. The results obtained showed that the dynamometer could be used reliably to measure static and dynamic cutting forces and torque. (c) 2006 Elsevier Ltd. All rights reserved.Öğe Distracted mandible does not reach the same strength as normal mandible in rabbits(ELSEVIER SCIENCE INC, 2012) Bulut, Turker; Durmus, Ercan; Mihmanli, Ahmet; Dolanmaz, Dogan; Kalayci, Abdullah; Saglam, HaciObjective. The aim of this study was to determine the resistance and fracture strength values of the bone with the use of biomechanical tests in different consolidation periods of mandibular distraction osteogenesis. Study Design. In this study, 21 mature male New Zeland rabbits were used. After distraction, rabbits were separated into 3 groups to experience 4, 8, and 12 weeks' consolidation periods. Nonoperated hemimandibles of 6 rabbits were used as a control group. After 5 days' latency period, 0.5-mm distraction was applied twice a day, i.e., 1 mm/d lengthening. After the 5-mm lengthening application, we left the animals for 1, 2, or 3 months of consolidation period. Bending stress and strength values of the bone at fracture point were measured with the use of a 3-point bending test. Results. There were significant differences between the control and 3 study groups regarding bending stress and strength values. In addition, each study group was significantly different from each other. Conclusions. Bending stress and fracture strength of the bone may not reach that of normal bone after completion of 3 months' consolidation. It should be considered to keep in place extraoral appliances or comfortable intraoral distractors for a long period. (Oral Surg Oral Med Oral Pathol Oral Radiol 2012;114(suppl 5): S140-S145)Öğe The effect of tool geometry and cutting speed on main cutting force and tool tip temperature(ELSEVIER SCI LTD, 2007) Saglam, Haci; Yaldiz, Suleyman; Unsacar, FarukIn this paper, the effects of rake angle and entering angle in tool geometry and cutting speed on cutting force components and the temperature generated on the tool tip in turning were investigated. The data used for the investigation derived from experiments conducted on a CNC lathe according to the full factorial design to observe the effect of each factor level on the process performance. As the experiments were designed using an orthogonal arrays, the estimates of the average effects will not be biased. During the tests, the depth of cut and feedrate were kept constant and each test was conducted with a sharp uncoated tool insert. For a comparison, the main cutting force and the temperature generated in secondary shear zone for different cutting parameters and tool geometries were calculated by Kienzle approach and with based on orthogonal cutting mechanism, respectively. The average deviation between measured and calculated force results were found as 0.26%. For statistical analyze the orthogonal arrays as L-16 was used with a total of 16 tests. Finally, it was found that rake angle was effective on all the cutting force components, while cutting speed was effective on the tool tip temperature. The cutting force signals and temperature values provided extensive data to analyse the orthogonal cutting process. (c) 2005 Elsevier Ltd. All rights reserved.Öğe The Effects of Cutting Speed and Depth of Cut on Machinability Characteristics of Austempered Ductile Iron(ASME-AMER SOC MECHANICAL ENG, 2012) Akdemir, Ahmet; Yazman, Sakir; Saglam, Haci; Uyaner, MesutDuctile iron can acquire enhanced thermal and mechanical properties from austempering heat treatment. The present study aims to identify the function of different cutting parameters affecting machinability and to quantify its effects. Turning was performed to test machinability according to the ISO3685-1993 (E) standard. After austenitizing at 900 degrees C for 90 min, austempered ductile iron (ADI) specimens were quenched in a salt bath at 380 degrees C for 90 min. The cutting force signals along three directions were measured in real time, whereas flank wear and surface roughness were measured offline. For the cutting parameters, the cutting speed and depth of cut were varied, but the feed rate was kept constant. In the flank wear tests, machining length was corresponded to tool life. In addition, in order to find out the effect of cutting parameters on surface roughness (R-a), tangential force (F-t), and flank wear (VB) during turning, response surface methodology (RSM) was utilized by using experimental data. The effect of the depth of cut on the surface roughness was negligible but considerable in the cutting forces. The increased cutting speed produced a positive effect on surface roughness. It is found that the cutting speed was the dominant factor on the surface roughness, tangential force, and flank wear. [DOI:10.1115/1.4005805]Öğe Evaluation of strain values of critical anatomic regions for two different pterygomaxillary approaches in Le Fort I osteotomy: An experimental study(MEDICINA ORAL S L, 2017) Ozdemir, Yusuf-Bugra; Dolanmaz, Dogan; Esen, Alparslan; Terzioglu, Hakan; Saglam, HaciBackground: The purpose of this experimental study was to measure stresses both on the pterygoid plates and the skull base following two different pterygomaxillary approaches in Le Fort I osteotomy. Material and Methods: The prepared skull models were randomly divided into 2 groups of 7. In the first group (A), the pterygomaxillary area was left intact. In the second group (B), pterygomaxillary separation was performed with a fine bur. The stresses were measured by using strain gauges. These strain gauges were attached to 6 different anatomical sites. The skull models were mounted on a servo-hydraulic testing unit. Each model was then subjected to a continuous linear tension until a plastic deformation was seen. Results: The statistical analyses showed that there were no significant differences (p>.05) between the 2 groups regarding the strain values. Moreover, no statistical differences (p>.05) were found between the two groups in terms of maximum applied forces. Conclusions: Considering the clinical conditions, the present study shows that when Le Fort I osteotomy performed without pterygomaxillary separation, there is no significant stress on the skull base during the downfracture. Moreover, it is considered that there is no need for an excessive force applied to perform downfracture in Le Fort osteotomies without pterygomaxillary separation.Öğe Immediate mechanical stability of sagittal split ramus osteotomy fixed with resorbable compared with titanium bicortical screws in mandibles of sheep(CHURCHILL LIVINGSTONE, 2006) Cilasun, Ulkem; Uckan, Sina; Dolanmaz, Dogan; Saglam, HaciTen fresh mandibles from adult sheep were stripped of all soft tissues and sectioned in the midline. We did sagittal split osteotomies and 5 mm advancement on all the 20 hemimandibles. Ten hemimandibles were fixed with three 2.0 mm x 13 mm titanium bicortical screws, and the other 10 were fixed with three 2.0 mm x 13 MM poly-L-lactic acid/polyglycolic acid (PLLA/PGA) bicortical screws in an inverted L pattern. All the hemimandibles were then mounted in a servohydraulic testing unit and tested to permanent deformation. Maximum forces that the mandibles resisted before breaking, maximum displacements, and the displacement values under 20, 60, 120, and 150N were compared using the Mann-Whitney U-test. There were no significant differences in stability between the bones fixed with titanium and those fixed with resorbable screws. (C) 2005 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.Öğe Tool wear monitoring in bandsawing using neural networks and Taguchi's design of experiments(SPRINGER LONDON LTD, 2011) Saglam, HaciThe bandsawing as a multi-point cutting operation is the preferred method for cutting off raw materials in industry. Although cutting off with bandsaw is very old process, research efforts are very limited compared to the other cutting process. Appropriate online tool condition monitoring system is essential for sophisticated and automated machine tools to achieve better tool management. Tool wear monitoring models using artificial neural network are developed to predict the tool wear during cutting off the raw materials (American Iron and Steel Institute 1020, 1040 and 4140) by bandsaw. Based on a continuous data acquisition of cutting force signals, it is possible to estimate or to classify certain wear parameters by means of neural networks thanks to reasonably quick data-processing capability. The multi-layered feed forward artificial neural network (ANN) system of a 6 x 9 x 1 structure based on cutting forces was trained using error back-propagation training algorithm to estimate tool wear in bandsawing. The data used for the training and checking of the network were derived from the experiments according to the principles of Taguchi design of experiments planned as L (27). The factors considered as input in the experiment were the feed rate, the cutting speed, the engagement length and material hardness. 3D surface plots are generated using ANN model to study the interaction effects of cutting conditions on sawblade. The analysis shows that cutting length, hardness and cutting speed have significant effect on tooth wear, respectively, while feed rate has less effect. In this study, the details of experimentation and ANN application to predict tooth wear have been presented. The system shows that there is close match between the flank wear estimated and measured directly.
