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    Factors Affecting Resorption Following Cranioplasty with an Autologous Bone Graft
    (Turkish Neurosurgical Soc, 2024) Yuruk, Burak; Tekiner, Ayhan; Erdem, Yavuz; Celik, Haydar; Yildirim, Mehmet Emre; Kurtulus, Adem; Sahin, Omer
    AIM: To evaluate the relationship between the surgical techniques, the waiting time for surgery, postoperative distance between the graft-bone margin and the percentage of bone resorption, we analyzed patients who underwent cranioplasty. Cranioplasty is a necessary surgery to preserve brain tissue and provide an appropriate microenvironment. MATERIAL and METHODS: In this study, patients who underwent autologous bone grafting after decompressive craniectomy by the Neurosurgery Clinic of University of Health Sciences Ankara Training and Research Hospital between 2018 and 2021 were examined. RESULTS: Thirty-nine patients who underwent autologous cranioplasty following decompressive craniectomy were included in the study. The average expected time for cranioplasty surgery following decompressive craniectomy was 16.97 +/- 13.478 weeks (min:2 max:62 weeks). The expected time between decompressive craniectomy and cranioplasty surgeries and resorption rates were compared. The resorption rate was above 30% in 7 of 10 patients with 24 weeks or more between craniectomy and cranioplasty, and less than 30% in 17 of 25 patients in surgeries less than 24 weeks (p=0.04). Following cranioplasty surgery, the distance between the graft-bone margin and the resorption rates were also compared. In this analysis, statistically significant differences were detected between the distance between the graft-bone border and the resorption rates. Resorption rates increased in 15 of 19 patients with a postcranioplasty distance of 1 mm or more (p<0.00001). CONCLUSION: Early cranioplasty surgery is important in order to reduce complications that may occur after craniectomy. In addition, it is important to keep the defect area small in size during craniectomy surgery and to keep the cutting edge thinner when the bone graft is taken, in order to reduce the development of bone graft resorption.
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    Flux cored arc welding on 30MnB5 steels used in agricultural mechanisation: microstructure evolutions and mechanical properties
    (Springer India, 2021) Cevik, Bekir; Sahin, Omer; Gulenc, Behcet
    30MnB5 steel has taken its rightful place among the materials used in agricultural mechanisation industry due to its excellent mechanical properties. 30MnB5 steel is widely used especially in structural parts requiring hardness, strength and wear resistance. The increasing importance of economic factors in today's industry requires the production of long-lasting agricultural machineries in agricultural mechanisation. Agricultural machinery systems are set-up by assembling the materials used in agricultural mechanisation industry with each other. Therefore, it is important to apply welding process to this steel used in agricultural mechanisation. The number of studies on the use of various welding methods and consumables (electrode, welding wire, shielding gas, etc.) in welding of steels used in agricultural mechanisation continues increasingly today. Flux-cored arc welding technology is one of welding methods that have been mostly studied in recent years and are applied on various metals. In this study, 30MnB5 steel sheets were flux-cored arc welded using rutile and basic flux-cored wires in 100% CO2 atmosphere. Bending, impact, and hardness tests and metallographic examinations were carried out in order to determine the mechanical and microstructural properties of the welded samples. As a result of the microstructure studies, structures such as grain boundary ferrite, widmanstatten ferrite, acicular ferrite, bainite, and martensite were determined in the weld metal and HAZ. As a result of the hardness test, hardness distribution in the form of M was determined in the weld zones. The bending and impact tests indicated that the highest mechanical properties were obtained from the weld seams welded with basic flux-cored wire.