Stress analysis of maxillary central incisors endodontically treated with varying ferrule heights and three different post dowel materials a finite element analysis.
AbstractStatement of problem : fracture of endodontically treated teeth is reduced by the use of a post with ferrule, but the effect of different ferrule configurations and dowel materials is not clear. Purpose: to evaluate the effect of ferrules with different configurations and heights on the stress of endodontically treated teeth restored with three different post and dowel materials. Materials and Methods: fifteen models of maxillary central incisors restored with porcelain fused to metal crowns were obtained using pro engineer software. the models were divided into three groups, each consisting of five models with ferrule heights of 0mm, 2mm, 4mm, 2mm with oblique fracture, 4mm with oblique fracture, the models under group GFR were restored with fiberglass reinforced post (GFR) and composite core build-up, group NiCr with a custom cast post metal alloy (NiCr), and group Zr with zirconia post (Zr) and composite core build-up. an oblique load of 100N and 150N at an angle of 135 degrees was applied to the palatal surface of the tooth, a vertical load of 100N and 150N at an angle of 90 degrees was applied to the incisal tip of the tooth. The maximum principal stress and the von mises stress was calculated for the remaining tooth structure and post apex using the finite element analysis (FEA) software. Results: the maximum von misses stress was observed in the apex of the post (p<0.05). Group Zr showed the highest mean stress (6.39Mpa) followed by group NiCr (5.65Mpa). There was a significant difference between post and between NiCr and Zr post for 2mm and 4mm ferrule height, while for 0mm ferrule there was a significant difference between the GFR and NiCr groups (p<0.05). Under oblique load, the maximum mean stress was observed in remaining tooth structures while for vertical load, it was observed at the apex of the post. Regarding ferrule heights, there were significant differences between 0mm-2mm, and 0mm-4mm uniform ferrule in post apex in the case of NiCr posts (p<0.05). Absence of ferrule resulted in higher stress for the NiCr group. Conclusion: higher loads that led to fracture were observed only at the apex of the post. Zirconia posts (group Zr) had higher fracture loads, whereas absence of ferrule resulted in higher fracture load with custom cast posts (group NiCr). Fracture thresholds were high on the remaining tooth structure for all the dowel systems especially for composite core build up irrespective of ferrule height and configuration. Clinical implications: appropriate selection of post and dowel materials in different configurations of ferrule heights ensures clinical success.
2. Christensen GJ. When to use fillers, build-ups or posts and cores. J Am Dent Assoc. 1996;127(9):1397–8.
3. Stankiewicz NR, Wilson PR. The ferrule effect: a literature review. Int Endod J. 2002;35(7):575–81.
4. Sorensen JA, Engelman MJ. Ferrule design and fracture resistance of endodontically treated teeth. J Prosthet Dent. 1990;63(5):529–36.
5. Libman WJ, Nicholls J. Load fatigue of teeth restored with cast posts and cores and complete crowns. Int J Prosthodont. 1995;8(2):155–61.
6. Torbjörner A, Fransson B. Biomechanical aspects of prosthetic treatment of structurally compromised teeth. Int J Prosthodont. 2004;17(2):135–41.
7. Assif D, Gorfil C. Biomechanical considerations in restoring endodontically treated teeth. J Prosthet Dent. 1994;71(6):565–7.
8. Spazzin AO, Galafassi D, de Meira-Júnior AD, Braz R, Garbin CA. Influence of post and resin cement on stress distribution of maxillary central incisors restored with direct resin composite. Oper Dent. 2009;34(2):223–9.
9. Singh S, Thareja P. Fracture resistance of endodontically treated maxillary central incisors with varying ferrule heights and configurations: In vitro study. J Conserv Dent. 2014;17(2):115–8.
10. Isidor F, Brøndum K, Ravnholt G. The influence of post length and crown ferrule length on the resistance to cyclic loading of bovine teeth with prefabricated titanium posts. Int J Prosthodont. 1999;12(1):78–82.
11. 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;95(1):50–4.
12. Pereira JR, Valle AL, Shiratori FK, Ghizoni JS, Melo MP. Influence of intraradicular post and crown ferrule on the fracture strength of endodontically treated teeth. Braz Dent J. 2009;20(4):297–302.
13. Ma PS, Nicholls J, Junge T, Phillips KM. Load fatigue of teeth with different ferrule lengths, restored with fiber posts, composite resin cores, and all-ceramic crowns. J Prosthet Dent. 2009;102(4):229–34.
14. da Silva NR, Raposo LH, Versluis A, Fernandes-Neto AJ, Soares CJ. The effect of post, core, crown type, and ferrule presence on the biomechanical behavior of endodontically treated bovine anterior teeth. J Prosthet Dent. 2010;104(5):306–17.
15. Meira JB, Espósito CO, Quitero MF, Poiate IA, Pfeifer CS, Tanaka CB, Ballester RY. Elastic modulus of posts and the risk of root fracture. Dent Traumatol. 2009;25(4):394–8.
16. Pegoretti A, Fambri L, Zappini G, Bianchetti M. Finite element analysis of a glass fibre reinforced composite endodontic post. Biomaterials. 2002;23(13):2667–82.
17. Akkayan B, Gülmez T. Resistance to fracture of endodontically treated teeth restored with different post systems. J Prosthet Dent. 2002;87(4):431–7.
18. Shetty PP, Meshramkar R, Patil KN, Nadiger RK. A finite element analysis for a comparative evaluation of stress with two commonly used esthetic posts. Eur J Dent. 2013;7(4):419–22.
19. Dietschi D, Duc O, Krejci I, Sadan A. Biomechanical considerations for the restoration of endodontically treated teeth: a systematic review of the literature--Part 1. Composition and micro- and macrostructure alterations. Quintessence Int. 2007;38(9):733–43.
20. Reeh ES, Messer HH, Douglas WH. Reduction in tooth stiffness as a result of endodontic and restorative procedures. J Endod. 1989;15(11):512–6.
21. Fernandes AS, Shetty S, Coutinho I. Factors determining post selection: a literature review. J Prosthet Dent. 2003;90(6):556–62.
22. Hayashi M, Takahashi Y, Imazato S, Ebisu S. Fracture resistance of pulpless teeth restored with post-cores and crowns. Dent Mater. 2006;22(5):477–85.
23. Fernandes AS, Dessai GS. Factors affecting the fracture resistance of post-core reconstructed teeth: a review. Int J Prosthodont. 2001;14(4):355–63.
24. Ichim I, Kuzmanovic DC, Love RM. A finite element analysis of ferrule design on restoration resistance and distribution of stress within a root. Int Endod J. 2006;39(6):443–52.
25. Sherfudhin H, Hobeich J, Carvalho CA, Aboushelib MN, Sadig W, Salameh Z. Effect of different ferrule designs on the fracture resistance and failure pattern of endodontically treated teeth restored with fiber posts and all-ceramic crowns. J Appl Oral Sci. 2011;19(1):28–33.
26. Saupe WA, Gluskin AH, Radke RA Jr. A comparative study of fracture resistance between morphologic dowel and cores and a resin-reinforced dowel system in the intraradicular restoration of structurally compromised roots. Quintessence Int. 1996;27(7):483–91.
27. Plotino G, Grande NM, Bedini R, Pameijer CH, Somma F. Flexural properties of endodontic posts and human root dentin. Dent Mater. 2007;23(9):1129–35.
28. Rosentritt M, Fürer C, Behr M, Lang R, Handel G. Comparison of in vitro fracture strength of metallic and tooth-coloured posts and cores. J Oral Rehabil. 2000;27(7):595–601.
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