Stress and strain analyses of removable partial denture abutment tooth in relation to the position of the minor connector

Abstract

Introduction/objective: For optimum loading distribution, the angle formed by the occlusal rest and the vertical minor connector from which it originates should be less than 90°. The objective of the article was to visualize the optimum angle between the occlusal rest and the minor connector in terms of intensity and distribution of occlusal loads using finite element analysis. It was the intention, concerning biomechanical behavior, to document that the optimum angle between the occlusal rest and the minor connector should be less than 90°. Methods: Three different virtual models of partial edentulous Kennedy III class were created using the CATIA design computer program with different angles between the occlusal rest and the minor connector. Stress distribution after simulated occlusal loading was analyzed using the finite element method. Results: Comparing the results obtained for three models, the highest stress values were seen in model 3 (the angle between the occlusal rest and the small connector is greater than 90°) whether the load is applied in the middle or at the end of the saddle. Conclusion: Within limitations and on the basis of the study results, the minimum compressive stress was seen in model 1, where the angle between the occlusal rest and the minor connector was less than 90° whether the load is applied in the middle or at the end of the saddle. It is recommended that obtuse angle between the rest and the minor connector should be avoided due to potential hazardous stress concentration on abutment teeth.

Uvod/Cilj: Okluzalni naslon i mala spojnica treba da zaklapaju međusobni ugao manji od 90 stepeni, kako bi se obezbedilo najpovoljnije prenošenje opterećenja. Cilj rada je bio da se metodom konačnih elemenata prikaže ugao između okluzalnog naslona i male spojnice koji je najpovoljniji za prenošenje okluzalnog opterećenja. Namera je bila da se, posmatrano sa biomehaničkog aspekta, dokumentuje da je ugao manji od 90 stepeni između okluzalnog naslona i male spojnice najpovoljniji. Metod: Izrađena su tri različita virtuelna modela krezube vilice klase krezubosti Kenedi III u programu CATIA sa modelovanim različitim uglovima između okluzalnog naslona i male spojnice. Analiza distribucije napona i deformacija nakon simuliranog okluzalnog opterećenja izvršene su metodom konačnih elemenata. Rezultati: Posle simuliranog okluzalnog opterećenja sva tri modela najveći napon je uočen kod modela 3 (ugao između okluzalnog naslona i male spojnice veći od 90 ste- peni), bez obzira na to da li je opterećenje aplikovano na sredini ili na kraju sedla. Zaključak: U okviru ograničenja u istraživanju, najmanji kompresioni napon uočen je u modelu 1 (ugao između oklu- zalnog naslona i male spojnice manji od 90 stepeni) bez obzira na to da li je opterećenje aplikovano na sredini ili na kraju sedla. Preporučuje se da se tup ugao između okluzalnog naslona i male spojnice izbegava zbog mogućih štetnih koncentracija napona na retencionom zubu.