Title Cast Posts Provide Higher Fracture Resistance Than Fiber Posts, but Greater Risk of a Non-Restorable Outcome
Clinical Question For a tooth with inadequate remaining tooth structure to retain a crown and requiring a post, does a cast post resist fracture better than a fiber post?
Clinical Bottom Line Based on in vitro studies, it appears that cast post and cores resist fracture loads better than fiber post and composite cores. At failure, however, cast post treated teeth are often non-restorable while fiber post and composite core treated teeth generally are.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
23228250Zhou/201313 studiesMeta-analysis
Key resultsCast post and cores provide greater resistance to fracture than fiber post and composite cores for obliquely loaded crowns. At failure, fiber posts are associated with restorable fracture patterns while cast posts are not. EBD Review: Ben Balevi reviewed this Meta-analysis in EBD 2013; 14:84. He noted the meta-analysis only assessed in vitro studies, not randomized clinical trials as implied in the original publication. He also questioned the exclusion of two studies from evaluation of the standardized mean difference (SMD) between the two treatment alternatives and suggested that the analysis used is heavily biased in favor of fiber posts. His opinion is that if the excluded studies had been included and, if the two extreme studies were removed, the adjusted SMD would be small, suggesting minimal clinical significance.
24836285Pereira/201440 canine teethIn vitro study
Key resultsConsistent with those of the Zhou review above except that it serves to remind us that “fiber posts” are a heterogeneous group of treatment modalities, not a single entity. Carbon fiber posts were significantly stronger than glass fiber posts in this study, although still significantly weaker than cast posts in load to failure.
17341377Qing/200712 matched pairsIn vitro study
Key resultsAlthough an older study, Qing minimized the variability that extracted teeth introduce to sample uniformity in bench studies by using matched contralateral teeth from a single cadaver. That presumably creates a close anatomic and structural pairing of specimens for testing. Qing’s findings clearly demonstrate that cast posts (in this case NiCr) are stronger than glass fiber and Zircon posts when loaded to failure.
23228250Bolla/200813 studiesSystematic Review
Key resultsThis Cochrane Review concluded that in 2008 there was an insufficient number of RCTs on the question of post selection to allow meaningful clinical recommendations. Only two studies met the criteria for inclusion, and only one of those addressed the comparison of cast gold posts versus fiber posts (Ferrari 2000).
Evidence Search dental[All Fields] AND cast[All Fields] AND posts[All Fields] AND ("dietary fiber"[MeSH Terms] OR ("dietary"[All Fields] AND "fiber"[All Fields]) OR "dietary fiber"[All Fields] OR "fiber"[All Fields]) AND posts[All Fields] AND ("fractures, bone"[MeSH Terms] OR ("fractures"[All Fields] AND "bone"[All Fields]) OR "bone fractures"[All Fields] OR "fracture"[All Fields])
Comments on
The Evidence
Validity: While there is good consensus regarding the higher fracture resistance of cast posts with in vitro load to failure, the strength of in vitro evidence is relatively low compared to prospective, randomized, clinical trials. Few clinical studies have been published on the question. The most robust of those was that of Ferrari in 2000 that retrospectively evaluated 200 teeth/posts. The 2008 Cochrane Review by Bolla suggested the Ferrari study to be at a “high risk of bias” due to an unclear method of randomization and poor definition of tooth selection criteria.
Applicability While the available evidence clearly asserts the superior strength of cast posts compared to fiber posts when loaded to failure, that conclusion forms only a small part of a treatment planning decision between the two methods of restoration. Related research by Creugers in 2005 (evaluating cast posts and composite cores) suggests that the remaining tooth volume and geometry are the dominating variables in defining clinical resistance to fracture. In addition, virtually all of the in vitro studies observed that cast posts are likely to create non-restorable fractures in restored roots when loaded to failure. In contrast, roots restored with fiber posts and composite cores are generally restorable when loaded to failure. That contrast in failure modes may trump the value of cast post fracture strength in some cases. Finally, it is important to note that the in vitro studies do not compare post strengths alone, but include the strength of the composite core for the fiber post option. It may be that when tooth volume is severely compromised, anticipated failure of a composite core might lead to the use of a higher risk/higher strength cast post and core option.
Specialty (Endodontics) (General Dentistry) (Prosthodontics) (Restorative Dentistry)
Keywords Root canal treated, Cast post, Fiber Post, Fracture
ID# 2742
Date of submission 06/25/2014
E-mail mhd-aljameel@hotmail.com
Author Mohammad M. AlJameel
Co-author(s) Adel S. AlQarni, Luke Tibbitts
Co-author(s) e-mail adel.qarni@hotmail.com, Tibbitts@livemail.uthscsa.edu
Faculty mentor Stephan J. Haney, DDS
Faculty mentor e-mail haneys2@uthscsa.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
None available
Comments and Evidence-Based Updates on the CAT
None available