Original Article

The Effect of Ferrule/Crown Ratio and Post Length on the Applied Stress and Strain Distribution to the Endodontically Treated Maxillary Central Teeth: A Finite Element Analysis

Ferrule/Crown Ratio and Maxillary Central Teeth


Objectives: One of the most common methods used for the reconstruction of endodontically treated teeth is post and core and crown. Various factors such as the remaining tissue above the cutting margin (ferrule) affect the fracture resistance of teeth restored with post and core and crown. This study aimed to investigate the effect of ferrule/crown ratio (FCR) on the strength of maxillary anterior central teeth using finite element analysis.

Materials and Methods: A 3D scan of a central incisor was obtained, and the data were transferred to Mimics software. Then, a 3D model of the tooth was designed. Next, 300N load was applied at a 135° angle to the tooth model. Force was applied to the model both horizontally and vertically. Ferrule height was considered to be 5%, 10%, 15%, 20%, and 25% in the palatal surface and 50% in the buccal surface. The length of post in the model was 11, 13, and 15mm.

Results: By increasing the FCR, stress and strain distribution increased in the dental model and decreased in the post itself. As the horizontal angle of load application increased, the level of stress and strain created in the dental model increased as well. The closer the force application site to the incisal area, the higher the stress and strain would be.

Conclusion: Maximum stress was inversely correlated with FCR and post length. In ratios of 20% and higher, insignificant changes occurred in stress and strain patterns in the dental model.

1. Londono J, Ghasemi S, Lawand G, Dashti M. Evaluation of the golden proportion in the natural dentition: A systematic review and meta-analysis. J Prosthet Dent. 2021 Sep 3:S0022-3913(21)00415-7.
2. Dashti M. Maxillary anterior teeth width proportion a literature review. EC Dent Sci. 2017;16:197-206.
3. Shadmehr E, Hashemi S, Hashemi SS, Chung YJ, Goudarzi A, Khademi A. The Effect of Adding Clonidine to Articaine and Epinephrine on Post-treatment Pain: A Randomized Clinical Trial Study. Iran Endod J. 2021 Fall;16(4):210-216.
4. Moaddabi A, Valletta A, Koochek Dezfuli M, Soltani P, Ebrahimikiyasari S, Hosseinnataj A, et al. Does a New Modification of the Two-Step Injection Technique for Inferior Alveolar Nerve Block Reduce Pain Compared to the Conventional Technique? A Randomized Clinical Trial. Int J Dent. 2023 Mar 17;2023:5922663.
5. Dashti M, Zadeh MA. Gingival Recession Classification and Treatment. Innov Perspect Oral Maxillofac Surg. 2021:155-68.
6. Madfa AA, Al-Sanabani FA, Al-Qudaimi NH. Effect of post materials on the biomechanical behaviour of endodontically treated tooth. Sci Publ Group. 2014 Apr 28;2(3):54.
7. Madfa AA, Kadir MR, Kashani J, Saidin S, Sulaiman E, et al. Abu Kasim NH. Stress distributions in maxillary central incisors restored with various types of post materials and designs. Med Eng Phys. 2014 Jul;36(7):962-7.
8. Kazemifard S, Dashti M. Molecular and Cellular Basis of Bone. Innov Perspect Oral Maxillofac Surg. 2021:7-10.
9. Eliyas S, Jalili J, Martin N. Restoration of the root canal treated tooth. Br Dent J. 2015 Jan;218(2):53-62.
10. Fathi A, Atash R, Fardi E, Ahmadabadi MN, Hashemi S. Comparison of the outcomes and complications of three-unit porcelain-fused-to-metal tooth-implant-supported prostheses with implant-supported prostheses: A systematic review and meta-analysis. Dent Res J (Isfahan). 2023 Jan 18;20:3.
11. Ferrari M, Vichi A, Fadda GM, Cagidiaco MC, Tay FR, Breschi L, et al. A randomized controlled trial of endodontically treated and restored premolars. J Dent Res. 2012 Jul;91(7 Suppl):72S-78S.
12. Merdji A, Bouiadjra BB, Chikh BO, Mootanah R, Aminallah L, Serier B, et al. Stress distribution in dental prosthesis under an occlusal combined dynamic loading. Mater Des (1980-2015). 2012 Apr 1;36:705-13.
13. Valletta A, Tavakoli Tafti K, Baghaei K, Moaddabi A, Soltani P, et al. Evaluating the Mandibular Trabecular Structure in Patients with and without Bruxism: A Cross-Sectional Study. Appl Sci. 2023 Apr 4;13(7):4568.
14. Mehdizadeh M, Tavakoli Tafti K, Soltani P. Evaluation of histogram equalization and contrast limited adaptive histogram equalization effect on image quality and fractal dimensions of digital periapical radiographs. Oral Radiol. 2023 Apr;39(2):418-424.
15. Madfa AA, Senan EM, Yue XG. Tensile stress distribution in maxillary central incisors restored with cast-made and prefabricated dental posts. J Oral Res. 2017;6(9):237-44.
16. Yettram AL, Wright KW, Pickard HM. Finite element stress analysis of the crowns of normal and restored teeth. J Dent Res. 1976 Nov-Dec;55(6):1004-11.
17. Gegauff AG. Effect of crown lengthening and ferrule placement on static load failure of cemented cast post-cores and crowns. J Prosthet Dent. 2000 Aug;84(2):169-79.
18. Dikbas I, Tanalp J, Ozel E, Koksal T, Ersoy M. Evaluation of the effect of different ferrule designs on the fracture resistance of endodontically treated maxillary central incisors incorporating fiber posts, composite cores and crown restorations. J Contemp Dent Pract. 2007 Nov 1;8(7):62-9.
19. Schmitter M, Rammelsberg P, Lenz J, Scheuber S, Schweizerhof K, Rues S. Teeth restored using fiber-reinforced posts: in vitro fracture tests and finite element analysis. Acta Biomater. 2010 Sep;6(9):3747-54.
20. Mahdavi Izadi Z, Jalalian E, Eyvaz Ziaee A, Zamani L, Javanshir B. Evaluation of the effect of different ferrule designs on fracture resistance of maxillary incisors restored with bonded posts and cores. J Dent (Tehran). 2010 Summer;7(3):146-55. Epub 2010 Sep 30.
21. Eraslan O, Aykent F, Yücel MT, Akman S. The finite element analysis of the effect of ferrule height on stress distribution at post-and-core-restored all-ceramic anterior crowns. Clin Oral Investig. 2009 Jun;13(2):223-7.
22. Bitter K, Perdigão J, Exner M, Neumann K, Kielbassa A, Sterzenbach G. Reliability of fiber post bonding to root canal dentin after simulated clinical function in vitro. Oper Dent. 2012 Jul-Aug;37(4):397-405.
23. Ichim I, Kuzmanovic DV, Love RM. A finite element analysis of ferrule design on restoration resistance and distribution of stress within a root. Int Endod J. 2006 Jun;39(6):443-52.
24. Lima AF, Spazzin AO, Galafassi D, Correr-Sobrinho L, Carlini-Júnior B. Influence of ferrule preparation with or without glass fiber post on fracture resistance of endodontically treated teeth. J Appl Oral Sci. 2010 Jul-Aug;18(4):360-3.
25. Pereira JR, de Ornelas F, Conti PC, do Valle AL. Effect of a crown ferrule on the fracture resistance of endodontically treated teeth restored with prefabricated posts. J Prosthet Dent. 2006 Jan;95(1):50-4.
26. Tan PL, Aquilino SA, Gratton DG, Stanford CM, Tan SC, Johnson WT, Dawson D. In vitro fracture resistance of endodontically treated central incisors with varying ferrule heights and configurations. J Prosthet Dent. 2005 Apr;93(4):331-6.
27. Al-Omiri MK, Rayyan MR, Abu-Hammad O. Stress analysis of endodontically treated teeth restored with post-retained crowns: A finite element analysis study. J Am Dent Assoc. 2011 Mar;142(3):289-300.
28. Kainose K, Nakajima M, Foxton R, Wakabayashi N, Tagami J. Stress distribution in root filled teeth restored with various post and core techniques: effect of post length and crown height. Int Endod J. 2015 Nov;48(11):1023-32
29. Fathi A, Hashemi S, Tabatabaei SS, Mosharraf R, Atash R. Adhesion to Zirconia: An umbrella review. Int J Adhes Adhes. 2023 Jan 7:103322.
IssueVol 20 (Continuously Published Article-Based) QRcode
SectionOriginal Article
DOI https://doi.org/10.18502/fid.v20i16.12686
Finite Element Analysis Tooth Crown Root Canal Therapy Dental Stress Analysis

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How to Cite
Mosharaf R, Abolhasani M, Fathi A, Rajabi A. The Effect of Ferrule/Crown Ratio and Post Length on the Applied Stress and Strain Distribution to the Endodontically Treated Maxillary Central Teeth: A Finite Element Analysis. Front Dent. 2023;20.