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Öğe Comparative study of ProTaper gold, reciproc, and ProTaper universal for root canal preparation in severely curved root canals(Medknow Publications, 2017) Arslan H.; Yildiz E.D.; Gunduz H.A.; Sumbullu M.; Bayrakdar I.S.; Karatas E.; Sumbullu M.A.Aim: The aim of this study is to evaluate the root canal transportation, centering ability, and instrumentation times with the ProTaper Gold (Dentsply Tulsa Dental, Tulsa, OK, USA), Reciproc (VDW, Munich, Germany), and ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) using cone-beam computed tomography (CBCT). Materials and Methods: Thirty mesial root canals of mandibular first molars with curvature angles of 35°-70° and radii of 2-6 mm were included in the study. Root canal instrumentation was performed up to F2 or R25. The instrumentation times were recorded. CBCT scanning was performed both pre-and post-instrumentation. Root canal transportation and the centering ratio were calculated for groups, and the data were analyzed using a one-way ANOVA and least significant difference post hoc tests for the instrumentation time, root canal transportation, and centering ratio at the 95% confidence level (P = 0.05). Results: At 3, 5, and 7 mm levels, there was no significant difference in the root canal transportation and centering ratio among the groups (P > 0.05). There were significant differences between the Reciproc and ProTaper Universal groups in the instrumentation times (P < 0.05). Conclusion: Root canal transportation and the centering ratio with the ProTaper Gold were similar to those obtained with the ProTaper Universal and Reciproc. © 2017 Journal of Conservative Dentistry | Published by Wolters Kluwer-Medknow.Öğe Determination of rolling element bearing defects through vibration analysis(2003) Orhan S.; Arslan H.; Aktürk N.Determination of rolling element bearing defects through the available vibration analysis method is studied in this paper. Rolling element bearing defect vibrations, vibration measurement and their analysis is briefly given. The outer ring rolling surface defect diagnosis of a cylindrical rolling element bearing is investigated as a case study. As stated the literature, it is determined in the waveform graph of the vibration that is formed by a single point defect on the outer ring of rolling element bearing that impact signals occur that its frequency equals to ball passage frequency on the outer ring and, in the spectrum graph the frequency of the impact signals is order of rolling element bearing defect frequencies. It is seen that vibration analysis can be effectively used to determine rolling element bearing defects from the obtained results.Öğe Effect of instrument speed when used in reciprocating motion on root canal transportation and centering ability(Medknow Publications, 2017) Yildiz E.D.; Arslan H.; Sumbullu M.; Bayrakdar I.S.; Sumbullu M.A.; Karatas E.Aim: This study aims to evaluate the root canal transportation, centering ability, and instrumentation times after root canal preparation using reciprocating motion at 300 rotations per minute (rpm) and 600 rpm. Materials and Methods: Twenty mesial root canals of mandibular first molars with curvature angles of 35°-70° and radii of 2-6 mm were included in the study. Root canal instrumentation was performed using R25 according to the manufacturer's instructions at 300 rpm or 600 rpm (n = 10). Cone-beam computed tomography scanning was performed both pre-and post-instrumentation. Root canal transportation and the centering ratio were calculated for both the groups, and the data were analyzed using independent sample t-test for the instrumentation time, root canal transportation, and centering ratio at the 95% confidence level (P = 0.05). Results: At the three levels (3 mm, 5 mm, and 7 mm), there were no significant differences in centering ratio between the groups (P > 0.05). At 3 mm, 600 rpm resulted in more transportation than 300 rpm. However, there were no significant differences in the root canal transportation between the groups at 5 mm and 7 mm levels (P > 0.05). Conclusion: At the 3 mm level, 600 rpm resulted in more transportation than 300 rpm. However, centering ratio was similar at both 600 rpm and 300 rpm. © 2017 Journal of Conservative Dentistry | Published by Wolters Kluwer-Medknow.Öğe Fault diagnosis of shaft- Ball bearing system using one-way analysis of variance(Association for Scientific Research, 2014) Yuzukirmizi M.; Arslan H.Roller bearing is one of the most widely used and critical elements in rotating machinery. In consequence, bearing fault diagnosis in machines, as well as to discriminate the different fault conditions have been a great interest. In this study, firstly, analytical model of a shaft-ball bearing system is developed. The shaft is assumed to be perfectly rigid and uniform, and supported by two radial ball bearings. Then, the effect of localized defects on bearing running surfaces (i.e. surfaces of inner and outer rings and balls) on the shaft vibrations are obtained using the simulation program. Then, vibration signatures are analyzed by one-way analysis of variance (ANOVA) method. Finally, post-hoc tests are applied to differentiate the ball bearing element's localized defects in shaft-ball bearing simulation model.Öğe Investigation of ball vibrations in angular contact ball bearings(2004) Arslan H.; Aktürk N.In this study, a shaft-bearing model is developed in order to investigate ball vibrations in case of defected and undefected ball bearings. In this model, shaft-bearing couple is considered as a mass-spring system and balls are massless. It is well known that the behavior of the system has a nonlinear character under dynamic conditions. In this case, equations of motions in radial direction were obtained for shaft and balls and these equations were solved for different preloads simultaneously by a developed computer program. The results obtained from the simulation program, were analyzed both in the time and the frequency domains. When preload increases, the balls deform more by staying longer in loaded region, and their vibration amplitudes increase. In frequency spectra frequency peaks, cage frequency and its harmonics, natural frequency of shaft in radial direction ball oscillation frequency in radial direction can be observed.Öğe Investigation of the Using of Shape Memory Alloys to Reduce Vibration in the Cutting Tool in Turning Operations(Institute of Electrical and Electronics Engineers Inc., 2020) Akdeniz E.; Arslan H.Turning is one of the most widely used machining processes in the industry. The main requirement in the turning process is to achieve acceptable roughness for the surface of the workpiece. Since one of the main factors that affect the surface roughness of the workpiece is the vibration of the cutting tool, these vibrations that occurred during the internal and external turning operations have been analyzed analytically and numerically. Laplace transform method was applied to achieve the analytical study. Both 3140 steel and TiNi3 alloy (as a shape memory alloy) were used in this study as a material of the cutting tool. As a result, it has been found that the use of TiNi3 alloy has a significant effect of reducing vibrations in both internal and external turning operations, and therefore to improve the quality of machining surface, where the vibration amplitude was reduced by 62% and 60.2% in external and internal turning operations respectively. © 2020 IEEE.Öğe Micro-tensile bond strength of adhesives to pulp chamber dentin after irrigation with Ethylenediaminetetraacetic acid(2012) Barutcigil C.; Arslan H.; Özcan E.; Harorli O.T.Aim: The aim of this study was to evaluate the influence of different concentrations of Ethylenediaminetetraacetic acid (EDTA) solution on adhesion, that is, the bond strength of the different adhesive systems, to the pulp chamber dentin. Materials and Methods: Recently extracted, sound, human, third molars were cut horizontally to expose the pulp horn. The roof of the pulp chamber and pulp tissue was removed. The teeth were then divided into five main groups. The teeth in each group were treated as follows: group 1, irrigated with saline; group 2, with 5% EDTA for 5 minutes; group 3, with 15% EDTA for 5 minutes; group 4, with 17% EDTA for 5 minutes and group 5, with 19% EDTA for 5 minutes. Treated specimens were dried and divided into 2 subgroups for adhesives; bonded with a total-etching adhesive (Adper Scotchbond Multi-purpose -ASB) or a one bottle of self-etch adhesive system (Clearfil S3 Bond -CS3). After the bonding procedure and composite restoration, teeth were sectioned and dentin sticks were obtained from each group for micro tensile testing (n = 10). Micro tensile testing was performed and scanning electron microscope (SEM) photographs were taken for each irrigated group. Results: In the ASB group, saline showed statistically higher bond strength values at the different concentrations of EDTA, while the micro-tensile bond strengths of the different concentrations of EDTA were not statistically different. In the CS3 group, saline and 5% EDTA showed statistically higher bond strength values than 17% and 19% EDTA, while the micro-tensile bond strengths of 15% EDTA compared to saline and 5% EDTA and 15% EDTA compared to 17% EDTA and 19% EDTA, were not statistically different. Conclusion: This study showed that EDTA irrigation can affect the bond strength of adhesive systems on pulp chamber lateral walls. Clinically, low EDTA concentrations can be recommended if self-etch adhesives have been selected.Öğe Modeling of the vibrations caused by ball bearing defects(2003) Arslan H.; Orhan S.; Aktürk N.In this study a shaft-ball bearing system is modeled in order to investigate the vibrations of ball bearings with running surfaces defects. Shaft and bearing was modeled as mass-spring system and balls were assumed have masses in order to investigate the effects of the balls on the overall vibrations. It is well known that the behaviour of the system has a nonlinear character under dynamic conditions. Equations of motion were obtained and solved with a computer program developed in order to study the radial and axial vibrations. The results obtained from simulation program for shaft and balls were analyzed both time and frequency domains. The ball masses are shown not to have a significant effect on the overall vibration behaviour of the shaft bearing system. The vibrations of shaft and the ball bearing system have been observed to have sensivity for different working conditions. The effects of localized defects on bearing running surfaces (i.e. surfaces of inner and outer rings and balls) on the shaft-ball bearing vibrations were investigated by using the simulation program. When the results obtained from the computer simulation have been compared with previous studies available in the literature, a reasonably good agreement has been observed.Öğe Relapsing polychondritis misdiagnosed and treated as a “soft tissue infection” and a brief review of diagnostic clinical clues(OrtadogŸu Reklam Tanitim Yayincilik Turizm Egitim Insaat Sanayi ve Ticaret A.S., 2017) Gündüz Ö.; Demirkan S.; Samav G.; Arslan H.; Çakartaş R.Relapsing polychondritis (RPC) is a rare immune-mediated disease, which targets particularly the cartilaginous tissue. At the initial stages of RPC, recurring mild-inflammatory attacks targeting the ears, nose, eyes, joints and respiratory tract can be observed but as the disease progresses, aortic and/or mitral valvular regurgitation (AR/MR) or life-threatening tracheobronchomalacia (due to involvement of aortic, mitral valves and/or trachea) may occur, as well as severe destruction of the ear, nose, etc. RPC may coexist with other diseases, such as systemic vasculitides, Graves disease or myelodysplastic syndrome. Establishing an early diagnosis is of utmost importance to prevent the development of AR/MR, or tracheobronchomalacia by preserving the cartilage tissue and also to diagnose a possible coexisting disease. Patients, particularly at the initial stages of the disease may object to a skin biopsy due to concerns for visible scars. Therefore, a good grasp of RPC's clinical symptoms may facilitate to establish an early diagnosis. Copyright © 2017 by Türkiye Klinikleri.
