Title Risk of Failure for Fiber-Reinforced Resin Post and Cores Is Higher With Lack of Coronal Walls than With No Ferrule
Clinical Question For patients with endodontically treated teeth restored with direct fiber-resin post & cores and crowns, what is the risk of failure for teeth with deficient coronal walls compared to teeth with adequate remaining tooth structure?
Clinical Bottom Line While the absence of a 360° ferrule increases the risk of failure for endodontically treated teeth restored with fiber post & cores and crowns (risk ratio = 1.94), the risk posed by the absence of sufficient coronal walls is even greater (risk ratio = 2.73)
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
25965640Yang/20155 studies/880 endodontically treated teethMeta-Analysis
Key resultsMeta-analysis was based on four clinical studies related to the failure risk for fiber-reinforced composite post-core restorations posed by inadequate coronal walls and on two clinical studies focused on the failure risk posed by the presence or absence of a ferrule in the tooth preparation. The importance of coronal walls was validated, while no implications for practice could be drawn from the ferrule studies. The risk ratio for absence of coronal walls was 2.73. The risk ratio for absence of a ferrule was 1.94.
22699672Ferrari/2013345 patients/360 premolarsRandomized Controlled Trial
Key resultsOne of the four clinical studies included in the meta-analysis above, this study at 6 years of service fueled the findings regarding the relative importance of ferrule and coronal walls. "Teeth with one (p = 0.004), two (p < 0.001), and three coronal walls (p < 0.001) had significantly lower failure risks than those without ferrule. Similar failure risks existed for teeth without coronal walls, regardless of the presence/absence of ferrule (p = 0.151). Regardless of the restorative procedure, the preservation of at least one coronal wall significantly reduced failure risk."
16616126Ng/200650 extracted anterior teethLaboratory study
Key resultsA well-designed in vitro study that investigated the relative significance of the location of remaining coronal walls for endodontically treated teeth with an incomplete ferrule restored with fiber posts & cores and crowns versus the presence of a complete ferrule. They concluded that the location of the remaining tooth structure relative to the applied load may be of significance when a complete ferrule is not possible. In particular, the study identified the importance of a 2-mm palatal wall as ferrule for anterior teeth when the facial wall is compromised.
Evidence Search (“crowns”[MeSH Terms] OR “crowns” [All Fields] OR “crown” [All Fields] AND ferrule [All Fields] AND post [All Fields] and core [All Fields] and failure [All Fields]
Comments on
The Evidence
Validity: In the Yang article, over 600 citations were reviewed with only 5 studies included for the meta-analysis: 4 related to the presence of coronal walls and 2 related to the presence of a ferrule. Of the 5 included studies, 3 were cohort studies and 2 were randomized controlled trials. Statistical analysis was thorough and included Forest and funnel plots. Perspective: The inclusion criteria for Yang's systematic review and meta-analysis were appropriate but created a relatively small sample size. Though small in number of studies, the results appear to be consistent, with the consensus of lower level evidence.
Applicability Faced with restoring coronally deficient endodontically treated teeth with fiber posts & composite cores, clinicians can better estimate the risk of fracture for treatment planning consideration. In addition, clinicians can better tailor their prep design to maximize longevity.
Specialty (General Dentistry) (Prosthodontics) (Restorative Dentistry)
Keywords Ferrule, Post & Core, Crown, Height, Fiber-reinforced posts;
ID# 2945
Date of submission 10/22/2015
E-mail slackwe@yahoo.com, slackw@livemail.uthscsa.edu
Author William Slack, DDS
Co-author(s) e-mail
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