I CE article _ restoration of 2.0mm of ferrule, which is more critical in maxil- lary anterior teeth due to the direction of loading dur- ing mastication. Additionally, how we restore the re- maining tooth plays a role in potential issues in the long term. Metal posts are being used less frequently due to vertical root fractures that can occur when the tooth is overloaded, and the direction has increas- ingly moved to the use of fiber posts, which mimic the roots modulus of elasticity. When teeth restored with a fiber post are overloaded, fracture typically occurs in the coronal (supragingival) portion, leaving suffi- cient tooth remaining to re-restore the tooth. Teeth rarely fail when they are over-engineered, but many fail due to under-engineering._ _References 1. Barkhodar RA, Radke R, Abbasi J: Effect of metal collars on resistance of endodontically treated teeth to root fracture. J Prosthet Dent 61:676, 1989. 2. Galen WW, Muella K.: Restoration of the Endodontically Treated Tooth. In Cohen, S. Burns, RC., editors: Pathways of the Pulp, 10th Edition. 3. Stankiewicz NR, Wilson PR. The ferrule effect: a literature re- view. Int Endod J, 35:575–581, 2002. 4. Galen WW, Mueller KI: Restoration of the Endodontically Treated Tooth. In Cohen, S. Burns, RC, editors: Pathways of the Pulp, 8th Edition. St. Louis: Mosby, Inc. 2002, page 771. 5. 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):443–452. 6. Nicholls JI. An engineering approach to the rebuilding of en- dodontically treated teeth, J Clin Dent, 1:41–44, 1995. 7. Libman WJ, Nicholls JI: Load fatigue of teeth restored with cast posts and cores and complete crowns. Int J Prosthodontics 8:155–161, 1995. 8. Freeman MA, Nicholls JI, Kydd WL, Harrington GW: Leakage associated with load fatigue-induced preliminary failure of full crowns placed over three different post and core systems. J Endod 24:26–32, 1998. _about the author roots Dr Gregori M. Kurtzman is in private general practice in Silver Spring, Md., and a former assistant clinical professor at University of Maryland. He has lectured internationally on the topics of restorative dentistry, endodontics and implant surgery and prosthetics, removable and fixed prosthetics, and periodontics and has over 350 published articles. He has earned fellowship in the AGD, AAIP, ACD, ICOI, Pierre Fauchard, ADI, mastership in the AGD and ICOI and diplomat status in the ICOI and American Dental Implant Association (ADIA). Kurtzman has been honored to be included in the “Top Leaders in Continuing Education” by Dentistry Today annually since 2006 and was featured on their June 2012 cover. He can be reached at dr_kurtzman@maryland-implants.com 12 I roots 3_ 2014 9. Ricucci D, Siqueira JF Jr.: Recurrent apical periodontitis and late endodontic treatment failure related to coronal leakage: a case report. J Endod. 2011 Aug;37(8):1171–5. doi: 10.1016/ j.joen.2011.05.025. 10. De Moor R1, Hommez G.: [The importance of apical and coronal leakage in the success or failure of endodontic treat- ment]. Rev Belge Med Dent (1984). 2000;55(4):334–344. 11. Sritharan A.: Discuss that the coronal seal is more important than the apical seal for endodontic success. Aust Endod J. 2002 Dec;28(3):112–115. 12. Jimenez MP, et al. Fracture resistance of endodontically treated teeth with fiber composite posts. IADR abstract no. 323, March, 2002. 13. Bitter K Kielbassa AM: Post-endodontic restorations with adhesively luted fiber-reinforced composite post systems: a review. Am J Dent. 2007 Dec;20(6):353–360. 14. Martinez-Insua A, et al. Comparison of the fracture resistances of pulpless teeth restored with a cast post and core or fiber post with a composite core. J Prosthet Dent 80(5), 1998. 15. Al-Ansari A.: Which type of post and core system should you use? Evid Based Dent. 2007;8(2):42. 16. Plotino G, Grande NM, Bedini R, Pameijer CH, Somma F.: Flex- ural properties of endodontic posts and human root dentin. Dent Mater. 2007 Sep;23(9):1129–35. Epub 2006 Nov 20. 17. Stewardson DA1, Shortall AC, Marquis PM, Lumley PJ.: The flexural properties of endodontic post materials. Dent Mater. 2010 Aug;26(8):730-6. doi: 10.1016/j.dental.2010.03.017. Epub 2010 Apr 21. 18. Pierrisnard L, Bohin F, Renault P, Barquins M.: Corono-radi - cular reconstruction of pulpless teeth: a mechanical study using finite element analysis. J Prosthet Dent. 2002 Oct; 88(4):442–448. 19. King PA, Setchell DJ. An in vitro evaluation of a prototype Carbon fiber reinforced prefabricated post developed for the restoration of pulpless teeth. J Oral Rehabil 1990;17: 599–609. 20. Purton DG, Chandler NP. Rigidity and retention of root canal posts. Br Dent J 1998;184:294–296. 21. Cormier CJ, Burns DR, Moon P. In vitro comparison of the fracture resistance and failure mode of fiber, ceramic and conventional post system at various stages of restoration. J Prosthodont 2001;10:26–36. 22. Martínez-Insua A, da Silva L, Rilo B, Santana U. Comparison of the fracture strength of pulpless teeth restored with a cast post and core or carbon fiber post with a composite core. J Prosthet Dent 1998;80:527–532. 23. Chieruzzi M, Pagano S, Pennacchi M, Lombardo G, D'Errico P, Kenny JM.: Compressive and flexural behaviour of fibre rein- forced endodontic posts. J Dent. 2012 Nov;40(11):968–78. doi: 10.1016/j.jdent.2012.08.003. Epub 2012 Aug 21. 24. Padmanabhan P. A comparative evaluation of the fracture resistance of three different pre-fabricated posts in endo - dontically treated teeth: An in vitro study. J conserve Dent 2010;13:124–128. 25. 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