Postes

International Scholarly Research Network ISRN Dentistry Volume 2011, Article ID 102329, 8 pages doi:10.5402/2011/102329

Research Article A Comparative Study of the Stress Distribution in Different Endodontic Post-Retained Teeth with and without Ferrule Design—A Finite Element Analysis
Lokanath Garhnayak,1 Hari Parkash,2 D. K. Sehgal,3 Veena Jain,2 and Mirna Garhnayak1
1 Department

ofProsthodontics, Rajasthan Dental College and Hospital, Jaipur 302026, India of Prosthodontics, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi 110029, India 3 Department of Applied Mechanics, Indian Institute of Technology, New Delhi 110029, India
2 Department

Correspondence should be addressed to Lokanath Garhnayak, drloknath@gmail.com Received 17March 2011; Accepted 4 May 2011 Academic Editor: H. S. Cardash Copyright © 2011 Lokanath Garhnayak et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Purpose. To analyze the stress distribution in an endodontically treated maxillarycentral incisor restored with various post-core systems and assess the benefit of ferrule using finite element analysis. Material and Methods. Twelve models with metal ceramic crown were created based on the combination of three types of post-core systems (titanium post-composite resin core, nickelchromium post-core, and fiber reinforced composite resin post-composite resin core), two varieties ofposts (tapered, parallel), and with or without ferrule. 100 N load was applied in three directions and the von Mises stress was compared. Results. Ferrule made no difference in stress distribution for the titanium and nickel-chromium posts, though it showed some stress reduction in fiber-reinforced composite resin posts. Nickel-chromium cast post-core transmitted the least amount of stresses to thedentin despite producing the maximum stress. Conclusion. Incorporation of ferrule offered some degree of stress reduction in nonmetal post, and it increased the stresses within cervical dentin.

1. Introduction
The restoration of endodontically treated teeth has been a concern for prosthodontists for more than 100 years [1]. The increasing effectiveness and predictability of endodontic therapy haveonly made the challenge more evident. If a root canal treated tooth is severely damaged beyond the realms of restoration by conventional means, the clinician is left with no alternative other than a post-core. The predominant function of an endodontic post is to retain the core [2], which subsequently provides a suitable foundation for final restoration. The selection of a particular type ofendodontic post is based on its mechanical properties, ease of fabrication, biocompatibility, availability in the market, and the cost factor. Custom made nickel-chromium (Ni-Cr) cast postcore system is routinely used because of its precision and ease of fabrication in the laboratory. Among the prefabricated posts, titanium (Ti) posts are very popular owing to their

proven biocompatibility. Newerpost materials like ceramics and fiber reinforced composite resin (FRC) [3–5] are also gaining popularity due to their unique esthetic properties. The ability of post-core system to sustain masticatory forces and remain firmly seated in the tooth is essential for the survival of a restoration. One other important design consideration in the restoration of an endodontically treated tooth is theferrule. This has been described as a metal band that encircles the external dimension of the residual tooth [6]. A properly built ferrule significantly reduces the incidence of fracture in the nonvital tooth by reinforcing the tooth at its external surface [7, 8]. It resists the lateral forces from the tapered dowels and the leverage from the crown in function [6]. It also increases the retention and...