MTA-esaslı bir kök-kanal dolgu materyalinin radyo-opasitesinin dijital radyografi kullanılarak değerlendirilmesi

Amaç: Bu çalışmanın amacı son zamanlarda kullanıma giren mineral trioksit agregat (MTA) esaslı bir kök-kanal dolgu materyali olan MTA Fillapex’in radyo-opasitesinin dört farklı kök-kanal dolgu materyali ile dijital görüntüleme yöntemi kullanılarak karşılaştırılmasıdır. Yöntemler: Çalışmada kök-kanal dolgu maddesi olarak MTA Fillapex, Adseal, AH Plus, Endomethasone ve güta-perka kon kullanılmıştır. Her bir kök-kanal dolgu materyalinden hazırlanan disk şeklindeki standart numuneler ve alüminyum penetrometre fosfor plaka (size 4; 5.7x7.6 cm) üzerine konarak 70 kVp, 8 mA ve 0.2 sn ışınlama parametreleri ile dijital radyografileri elde edilmiştir. Obje-ışın mesafesi 30 cm olacak şekilde ayarlanmıştır. Test edilen materyallerin grilik değerleri sistemin kendi yazılımı ile dijital olarak ölçülmüş ve eşdeğer alüminyum kalınlığını bulmak amacıyla penetrometre ile karşılaştırılmıştır. Elde edilen bulgular istatistiksel olarak, anlamlılık p<0.05 düzeyinde değerlendirilmiştir. Bulgular: Test edilen materyallerin radyo-opasite değerlerinin milimetre cinsinden alüminyum eşdeğerleri büyükten küçüğe doğru AH Plus (9.70), güta-perka (6.82), MTA Fillapex (5.30), Adseal (3.71) ve Endomethasone (3.67) şeklindedir. Kullanılan kanal dolgu materyallerinin ortalama radyografik dansite değerleri arasında istatistiksel olarak anlamlı farklılık tespit edilmiş (p<0.005) olup en yüksek radyografik dansite değerine sahip olan kanal dolgu materyali AH Plus olmuştur. Sonuç: MTA Fillapex çalışmada test edilen kök-kanal dolgu materyalleri arasında radyo-opasite açısından üçüncü sıradadır. Çalışmada kullanılan tüm materyallerin radyo-opasite değerleri Uluslararası Standartlar Örgütü ve Amerikan Ulusal Standartlar Enstitüsü/Amerikan Dişhekimleri Birliği tarafından tavsiye edilen minimum standart değerlerini karşılamıştır

Amfibi İHA için tekne şeklindeki gövdenin parametrik incelenmesi.

Performance of amphibious unmanned aerial vehicles (UAV’s) that take off from and land on water, like seaplanes, greatly depend on hydrodynamic effects as well as aerodynamic effects, therefore their geometries need to be optimized for both. This study mainly investigates the effect of geometric parameters of a generic, hull-shaped fuselage that are constrained by hydrodynamic drivers, such as the step height needed to reduce hydrodynamic drag, sternpost angle and deadrise angle needed for safe landing; on aerodynamic drag of the fuselage under cruise conditions by using the commercial CFD (Computational Fluid Dynamics) code ANSYS Fluent. Study includes a comparison of the experimental results obtained from literature with numerical results around a hull-shaped fuselage at angles of attack varying between -8° to 16°. M.S. - Master of Scienc

Comparison of ProTaper and Mtwo retreatment systems in the removal of resin-based root canal obturation materials during retreatment

To evaluate the effectiveness of the ProTaper and Mtwo retreatment systems for removal of resin-based obturation techniques during retreatment. A total of 160 maxillary anterior teeth were enlarged to size 30 using ProTaper and Mtwo rotary instruments. Teeth were randomly divided into eight groups. Resilon+Epiphany, gutta-percha+Epiphany, gutta-percha+AH Plus and gutta-percha+Kerr Pulp Canal Sealer (PCS) combinations were used for obturation. ProTaper and Mtwo retreatment files were used for removal of root canal treatments. After clearing the roots, the teeth were split vertically into halves, and the cleanliness of the canal walls was determined by scanning electron microscopy. Specimens obturated with gutta-percha and Kerr PCS displayed significantly more remnant obturation material than did specimens filled with resin-based obturation materials. Teeth prepared with Mtwo instruments contained significantly more remnant filling material than did teeth prepared with ProTaper. ProTaper files were significantly faster than Mtwo instruments in terms of the mean time of retreatment and time required to reach working length. The Resilon+Epiphany and AH Plus+gutta-percha obturation materials were removed more easily than were the Epiphany+gutta-percha and Kerr PCS+gutta-percha obturation materials. Although ProTaper retreatment files worked faster than did Mtwo retreatment files in terms of removing root canal obturation materials, both retreatment systems are effective, reliable and fast

FEN BİLİMLERİ ENSTİTÜSÜ/LİSANSÜSTÜ TEZ PROJESİ

AMFİBİ İNSANSIZ HAVA ARACI TASARIMI VE ÜRETİM

Protaper ve Mtwo retreatment sistemlerinin rezin esaslı kök kanal dolgu materyallerinin retreatment süreleri yönünden karşılaştırmalı olarak incelenmesi

Amaç: Bu çalışmada retreatment amacıyla kullanılan Ni-Ti esaslı döner sistemlerin (ProTaper Retreatment, Mtwo R) kök kanallarından rezin esaslı kanal dolgu materyallerinin sökülme sürelerinde bir etkisinin olup olmayacağının incelenmesi amaçlanmıştır. Yöntem: Çalışmamızda 160 adet çekilmiş maksiller anterior diş kullanılmıştır. Bu dişler ProTaper ve Mtwo döner sistemleri ile genişletilmiştir. Daha sonra dişler rastgele sekiz gruba ayrılmıştır (n=20). Grup 1 ve 5 Resilon-Epiphany kök kanal dolum sistemi, Grup 2 ve 6 güta-perka ve Epiphany, Grup 3 ve 7 güta-perka ve AH Plus, Grup 4 ve 8 ise, kontrol grubu olarak, güta-perka ve öjenol esaslı kanal dolgu patı Pulp Canal Sealer ile dolduruldu. ProTaper ile genişletilen dişlerin kök kanal sökümleri ProTaper Retreatment eğeleri, Mtwo ile genişletilen dişlerin sökümleri ise Mtwo Retreatment eğeleri ile yapıldı. Çalışma boyuna ulaşmak için geçen süre (T1), tekrar şekillendirme için geçen süre (T2) ve retreatment için geçen toplam süre (Tt) kronometre ile ölçüldü. Bulgular: Retreatment çalışma süreleri, kök kanallarının başlangıç şekillendirmesinde kullanılan iki döner sisteme göre değerlendirildi. T1 süreleri arasında istatistiksel olarak anlamlı farklılık bulunmaktadır. Mtwo kullanılan dişlerde T1, T2 ve Tt süreleri, ProTaper kullanılan dişlerden anlamlı şekilde uzundur. Dolum şekline göre T1, T2 ve Tt süreleri arasında istatistiksel olarak anlamlı farklılık bulunmaktadır. Dolum şekli Güta-perka+AH Plus olan dişlerin çalışma süreleri, diğer tekniklerle doldurulan dişlerden anlamlı düzeyde kısadır. Mtwo ile şekillendirilen dişlerin T1, T2 ve Tt süreleri, dolum ve retreatment tekniklerinden bağımsız olarak, ProTaper ile şekillendirilen dişlerden uzun bulundu. Sonuç: Araştırmamızın sonuçlarına göre, ProTaper Retreatment eğelerinin Mtwo Retreatment eğelerine kıyasla, kanal dolum materyallerini kök kanallarından daha çabuk uzaklaştırdıkları sonucuna varılmıştır

Parametric investigation of hull shaped fuselage for an amphibious UAV

Performance of amphibious UAV’s (Unmanned Aerial Vehicles) that take off from and land on water, like seaplanes, greatly depend on hydrodynamic effects as well as aerodynamic effects, therefore their geometries need to be optimized. This study mainly investigates the effect of geometric parameters of a generic, hull-shaped fuselage that are constrained by hydrodynamic drivers, such as the step height needed to reduce hydrodynamic drag, and deadrise and sternpost angles needed for safe landing, on aerodynamic drag of the fuselage under cruise conditions by means of the commercial CFD code ANSYS Fluent. Study includes a comparison of the experimental [1] and numerical results obtained at angles of attack varying between 8° to 16° and with Spalart-Allmaras, k-ω and k-ε turbulence models.Amphibious UA

Comparison of intracoronal bleaching methods on teeth discolored by different antibiotic pastes

Aim: To compare the bleaching efficacy of sodium perborate with different activation methods on crowns discolored by two different antibiotic pastes. Materials and Methods: Eighty-five extracted human incisors were prepared to size #30 using ProTaper rotary instruments. After chemomechanical preparation and irrigation procedures, the specimens received triple antibiotic paste (TAP, n = 40), minocycline paste (MP, n = 40), or calcium hydroxide (n = 5, control group) and coronally sealed with temporary filling material. Spectrophotometric readings were obtained on day 0uweek 4. Data were analyzed with the MannuWhitney U-test and Wilcoxon sign test (P 0.05). Results: Both groups showed statistically significant coronal discoloration at each time interval (P 0.05). Although the MP subgroups exhibited more bleaching than the TAP subgroups on days 3 and 7, the difference was not significant (P > 0.05). The bleaching results for the sodium perborate activation techniques did not significantly differ among groups (P > 0.05). Conclusions: Both antibiotic pastes induced crown discoloration that was reversible using all sodium perborate bleaching techniques

Effect of Storage Temperature on the Shelf Life of Self-adhesive Resin Cements

Purpose: To compare the bonding performance of three new self-adhesive resin cements to human dentin after storage under two different conditions. Materials and Methods: Buccal, lingual, mesial, and distal dentin surfaces of 36 human molars were abraded to directly below the enamel with #600 SiC papers. The teeth were divided into two main test groups. In the first test group (FT), the cements were kept in a refrigerator (6 +/- 2 degrees C) for three months and then used for the test. The remainder of the cements was kept at a constant room temperature of 19 +/- 2 degrees C for an additional three months, and then used again for the second test group (ST). Each test group comprised 6 teeth and 24 dentin sections. The cements Clearfil SA (CSA), G-Cem (GC), and Bis-Cem (BC) were applied to the surfaces according to the manufacturers' recommendations. After application of the cements to the flat dentin surfaces and light curing, shear bond strengths were determined at a crosshead speed of 0.5 mm/min. Bond strengths were then calculated and expressed in MPa. Data were analyzed with Kruskal-Wallis and Wilcoxon Signed Rank tests. To investigate the cement/dentin interfaces using SEM, the buccal surfaces of three additional teeth were used for each test group. Results: The bond strength values of cement groups were significantly different for the FT and ST groups (p < 0.01). GC showed the highest bond strength values of all materials. There was a difference between the bond strength values of the two testing periods for all materials (p < 0.01). Bond strengths significantly decreased after storage at room temperature. Conclusion: Storage temperatures considerably affect the shelf life of self-adhesive resin cements

Radiologic Assessment of Periapical Health: Comparison of 3 Different Index Systems

Introduction: The aim of this study was to evaluate observer variations and observer reproducibility in the interpretation of periapical health using the Strindberg system, the periapical index (PAI), and the probability index for radiologic assessment of periapical health. Methods: Four observers read digital periapical images to evaluate the periapical health of 200 root-filled teeth. Each observer evaluated a tooth twice by using the Strindberg system, twice by using the PAI, and twice by using the probability index. Each observation session was held at 1-month intervals. Three scores were used for the evaluations conducted by using the Strindberg system. Both the PAI and the probability index were considered on 5-point scales and were also dichotomized. SPSS for Windows 15.0 software (SPSS InC, Chicago, IL) was used for data analysis, and intra- and interobserver agreements were described by using kappa statistics. Results: The average kappa values of intra- and interobserver agreement calculated for the Strindberg system were 0.53 and 0.36, respectively. The corresponding average kappa values were calculated as 0.48 and 0.39 for the PAI and 0.45 and 0.30 for the probability index. The highest mean proportion values of intra- and interobserver agreement were observed for the dichotomization of the PAI (88.9% and 87.0%, respectively) followed by the dichotomization of the probability index (86.8% and 82.9%, respectively). Conclusions: The Strindberg system has lower intraobserver variation compared with the PAI and the probability index, whereas PAI has lower interobserver variation compared with the Strindberg system and the probability index. The dichotomization of the PAI and the probability index provided higher intra- and interobserver agreement values in the radiologic assessment of periapical health