Publication: Eğri kök kanallarında şekillendirme sırasında kanal duvarlarında ve aletlerin üzerinde oluşan streslerin üç boyutlu sonlu elemanlar yöntemiyle değerlendirilmesi
Abstract
EĞRİ KÖK KANALLARINDA ŞEKİLLENDİRME SIRASINDA KANAL DUVARLARINDA VE ALETLERİN ÜZERİNDE OLUŞAN STRESLERİN ÜÇ BOYUTLU SONLU ELEMANLAR YÖNTEMİYLE DEĞERLENDİRİLMESİ Bu çalışmanın amacı eğri kök kanallarında ProTaper ve HeroShaper sistemleri ile şekillendirme yapılırken aletler üzerinde ve kanal duvarlarında oluşan streslerin üç boyutlu sonlu elemanlar analizi ile belirlenmesidir. Ni-Ti döner alet sistemlerinin seçiminde farklı kesit şekillerine sahip olmaları esas olmuştur. Her sistem içindeki eğelerin geometrileri üç boyutlu sonlu elemanlar yöntemi ile oluşturulmuştur. Eğri kök kanalına sahip dişin üç boyutlu sonlu elemanlar modeli doğal diş ve yapay kanalın birleştirilmesi ile oluşturulmuştur. Modellerin taranması için mikro-fokus CT kullanılmıştır. Birleştirme ve modifikasyondan sonra düzgün yüzeyli ve kanalı merkezde seyreden üç boyutlu model elde edilmiştir. Kök kanalı şekillendirilirken alet üzerinde oluşan stresler, nikel-titanyum materyalinin doğrusal olmayan mekanik özellikleri dikkate alınarak, üç boyutlu sonlu elemanlar DYNA ile sayısal olarak analiz edilmiştir. Şekillendirme benzetimi sırasında eğeler ve kanal duvarlarında oluşan stresler kayıt edilmiştir. HeroShaper kesitinde ProTaper kesitlerine göre daha fazla stres oluştuğu görülmüştür. ProTaper eğe sistemi ile şekillendirmede kanalın apikal kısmında eğimin dışına doğru stres yoğunluğu oluştuğu ancak HeroShaper ile yapılan şekillendirme benzetiminde orta kısımda ve ProTaper modelinden daha az stres oluştuğu belirlenmiştir. HeroShaper eğelerin pozitif kesme açısına bağlı olarak daha etkin kesme işlemi yaptıkları için kanal duvarlarında ProTaper modelinden daha az stres oluşturmuşlardır. Eğelere ait tüm stres değerleri gerilim- gerinme eğrisinin geçiş fazında bulunmuştur.
Finite Element Analysis of Stress Distribution on Instruments and Canal Walls While Preparation of Curved Canals The aim of this study is to determine stress evaluation of root canal wall and instruments during shaping curved canals with ProTaper and HeroShaper systems by using three-dimensional finite element analysis. Two Ni-Ti rotary instruments selected according to their different cross-sectional geometries. The geometries of the selected files three-dimensional finite element models were created for each system. The three-dimensional FEA model within a curved canal was established by integrating a simulated canal and natural tooth. A micro-focus CT scanner was used to scan the models. After integration and modification a final three-dimensional model with a smooth surface and mostly centered canal was established. The stresses on the instrument during simulated shaping of a root canal were analyzed numerically by using a three-dimensional finite element package, LS-DYNA, taking into account the nonlinear mechanical behavior of the nickel-titanium material. Stress distribution in the instruments and in the canal walls was recorded during simulated shaping. More stress concentrations were determined in the HeroShaper cross-section. With ProTaper file system, stress concentrations were determined towards the outer aspect of the curvature in the apical portion of the canal but in HeroShaper system stress was more concentrated in the middle portion of the canal and were less than ProTaper model. Because of possitive rake angle of HeroShaper files, cut more efficiently and generated less stress on the canal walls than ProTaper files. Stress values of all files were found in the transformation phase of stress-strain diagram.
Finite Element Analysis of Stress Distribution on Instruments and Canal Walls While Preparation of Curved Canals The aim of this study is to determine stress evaluation of root canal wall and instruments during shaping curved canals with ProTaper and HeroShaper systems by using three-dimensional finite element analysis. Two Ni-Ti rotary instruments selected according to their different cross-sectional geometries. The geometries of the selected files three-dimensional finite element models were created for each system. The three-dimensional FEA model within a curved canal was established by integrating a simulated canal and natural tooth. A micro-focus CT scanner was used to scan the models. After integration and modification a final three-dimensional model with a smooth surface and mostly centered canal was established. The stresses on the instrument during simulated shaping of a root canal were analyzed numerically by using a three-dimensional finite element package, LS-DYNA, taking into account the nonlinear mechanical behavior of the nickel-titanium material. Stress distribution in the instruments and in the canal walls was recorded during simulated shaping. More stress concentrations were determined in the HeroShaper cross-section. With ProTaper file system, stress concentrations were determined towards the outer aspect of the curvature in the apical portion of the canal but in HeroShaper system stress was more concentrated in the middle portion of the canal and were less than ProTaper model. Because of possitive rake angle of HeroShaper files, cut more efficiently and generated less stress on the canal walls than ProTaper files. Stress values of all files were found in the transformation phase of stress-strain diagram.