Influence of a Novel Spherical Connection Interface for Angled Abutments in Cantilever-Extended All-on-Four Bar Prostheses on Stress Distribution

Öz

In this study, the biomechanical performance of a newly developed spherical connection interface design for angled abutment systems used in all-on-four implant-supported bar-retained overdenture prostheses in completely edentulous patients was investigated. It is well known that bending moments generated in cantilever-extended prostheses lead to high stress concentrations in the implant, abutment, and surrounding bone tissue. In order to mitigate these adverse effects, novel abutment designs featuring a spherical connection surface were developed as an alternative to conventional 15° and 30° angled abutment models, and were evaluated in combination with two different bar cross-sections (I and UCG). The three-dimensional mandibular model was generated based on CT data, and the mechanical behavior of the prosthesis-implant-bone assembly was analyzed using the finite element method in the ANSYS Workbench environment. The models were assumed to be homogeneous, isotropic, and linearly elastic, and a 100 N occlusal load was applied in a 45° oblique direction. The results obtained according to the von Mises criterion demonstrated that the spherical connection designs provided a significant reduction in stress, particularly in the posterior region, compared with conventional models. In the I-section spherical model with 15° angulation, stress reduction of up to 23.2% was observed in the cortical bone surrounding the posterior implant, whereas the spherical models with UCG section demonstrated an improvement ranging between 24 - 27% in the posterior implant body. The findings indicate that the spherical interface design has the potential to reduce biomechanical risks associated with the cantilever effect and to enhance the service life of implant and superstructure components. This approach offers an innovative and clinically applicable solution for preventing complications related to the use of angled abutments.

Anahtar Kelimeler

• Angled abutment
• Spherical connection
• Finite element analysis
• Cantilever prosthesis
• Bar-retained overdenture
• Dental implant

Kantilever Uzantılı All-on-Four Bar Protezlerde Açılı Abutmentlar için Geliştirilen Küresel Bağlantı Arayüzeyinin Gerilme Dağılımına Etkisi

Öz

Bu çalışmada, tam dişsiz hastalarda uygulanan all-on-four implant destekli bar tutuculu overdenture protezlerde kullanılan açılı abutment sistemleri için geliştirilen yeni nesil küresel bağlantı arayüzey tasarımının biyomekanik performansı incelenmiştir. Kantilever uzantılı protezlerde oluşan eğilme momentlerinin implant, abutment ve implantı çevreleyen kemik dokusunda yüksek gerilmelere yol açtığı bilinmektedir. Bu olumsuz etkileri azaltmak amacıyla 15° ve 30° açılı klasik abutment modellerine alternatif olarak küresel formda bağlantı yüzeyine sahip özgün abutment tasarımları geliştirilmiş ve iki farklı bar kesiti (I ve UCG) ile birlikte değerlendirilmiştir. Alt çeneye ait üç boyutlu model, BT verilerinden yararlanılarak oluşturulmuş; protez-implant-kemik bileşenlerinin mekanik davranışı ANSYS Workbench ortamında sonlu elemanlar analizi yöntemiyle incelenmiştir. Modeller homojen, izotropik ve doğrusal elastik kabul edilmiş; 45° oblik yönde 100 N oklüzal yük uygulanmıştır. Von Mises kriterine göre elde edilen sonuçlar, küresel bağlantılı tasarımların klasik modellere kıyasla özellikle posterior bölgede belirgin gerilme azalması sağladığını göstermiştir. I kesitli ve 15° açılı küresel modelde posterior implant çevresindeki kortikal kemikte %23,2’ye varan iyileşme etkisi olurken, UCG kesitli küresel modellerin posterior implant gövdesinde ise %24-27 aralığında iyileşme olduğu tespit edilmiştir. Elde edilen bulgular, küresel arayüzey tasarımının kantilever etkisinden kaynaklanan biyomekanik riskleri azaltarak implant ve üst yapı bileşenlerinin servis ömrünü artırma potansiyeline sahip olduğunu ortaya koymaktadır. Bu yaklaşım, açılı abutment kullanımına bağlı komplikasyonların önlenmesinde yenilikçi ve uygulanabilir bir çözüm sunmaktadır.

Anahtar Kelimeler

• Açılı abutment
• Küresel bağlantı
• Sonlu elemanlar analizi
• Kantilever protez
• Bar tutuculu overdenture
• Dental implant

Kaynakça

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