A Systematic Review of All-Ceramic Crowns: Clinical Fracture Rates in Relation to Restored Tooth Type

Department of Prosthodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China.
The International journal of prosthodontics (Impact Factor: 1.46). 08/2012; 25(5):441-50.
Source: PubMed


The objective of this systematic review was to evaluate the clinical fracture incidence of tooth-supported all-ceramic crowns according to restored tooth type.
An electronic search of clinical trials published in English and Chinese was performed using four databases (Medline/PubMed, EMBASE, Cochrane Library, and the Chinese Biomedical Literature Database) from 1990 to 2011 and complemented by an additional manual search. The annual core and veneer fracture rates of various tooth types were estimated and compared using Poisson regression. Moreover, the 5-year cumulative incidence was calculated.
Of 5,600 titles and abstracts retrieved, 37 publications were included, with a follow-up period that ranged from 36 to 97 months. Based on the calculated results, all-ceramic crowns demonstrated an acceptable overall 5-year fracture rate of 4.4% irrespective of the materials used. Molar crowns (8.1%) showed a significantly higher 5-year fracture rate than premolar crowns (3.0%), and the difference between anterior (3.0%) and posterior crowns (5.4%) also achieved significance. Fractures were classified as either core or veneer fractures. Core fracture rates were calculated as having a 5-year incidence of 2.5%, and a significantly higher core fracture rate was found in the posterior region (3.9%). The overall 5-year incidence of veneer fracture was 3.0%, and no clear difference was found between restored tooth types, with incidences of 2.0%, 2.5%, 1.0%, and 3.0% for incisor, canine, premolar, and molar crowns, respectively.
Within the limitations of this study, current dental ceramic materials demonstrated acceptable 5-year core and veneer fracture incidences when used for tooth-supported single crowns in both anterior and posterior segments. A higher fracture tendency for posterior crowns was the trend for all-ceramic crowns, while molar crowns showed a significantly higher fracture rate than premolar crowns. Moreover, it is recommended that randomized controlled trials with large sample sizes be undertaken to obtain more definitive results.

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Available from: Ke Zhao, Mar 23, 2014
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    • "A long-term prospective study showed a survival rate of 97.4% for bilayered LDG crowns after 5 years and 94.8% after 8 years (93.8% for anterior crowns; 100% for posterior crowns) of clinical service [3]. The 5-year complication rate of 4.3% for bilayered LDG crowns exhibited a minor chipping rate of 2.1% and no bulk fracture, which are clearly lower than the mean values of 5-year chipping rate (3.0%) and fracture rate (2.5%) of all-ceramic crowns, respectively, irrespective of the materials used, as stated in a recent systematic review [4]. Based on clinical long-term data LDG bilayered single crowns can be considered as a reliable and promising treatment option that can be recommended in the anterior and posterior region [3]. "
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    ABSTRACT: This in vitro study was designed to investigate the influence of the veneer and cyclic loading on the failure behavior of lithium disilicate glass-ceramic (LDG) crowns on maxillary first molar. Sixty-four LDG crowns were divided into 4 groups (n=16). Thirty-two monolithic crowns were fabricated from IPS e.max Press (M), and the remaining bilayered crowns using cut-back technique and conventional manual layering technique from IPS e.max Press/Ceram (B). Monolithic or bilayered crowns were subjected to single-load-to-fracture (SLF) testing using a universal testing machine, before (M1 and B1) and after exposure to sliding-contact fatigue (SCF) testing (M2 and B2), consisting of 1,200,000 mechanical cycles (Fmax=98N). Data were statistically analyzed using two-by-two factorial design ANOVA. Fractographic analysis was performed to determine the fracture modes of the failed specimens. The mean fracture load values (N±S.D.) for M1, B1, M2 and B2 were 2686±628N, 1443±327N, 2133±578N and 1464±419N, respectively. Significant differences were found between the failure loads of all groups (P<0.001), except between groups B1 and B2. Bulk fracture initiating from the occlusal surface is the primary failure mode of monolithic and veneered LDG crowns. Cracking that initiated from core-veneer interfacial defects and ultimately resulted in bulk fracture is another major failure origin of veneered all-ceramic crowns. Veneer application resulted in significantly lower fracture load values compared to monolithic LDG crowns. Cyclic loading is an accelerating factor contributing to fracture for monolithic LDG crowns but not for bilayered ones.
    Full-text · Article · Dec 2013 · Dental materials: official publication of the Academy of Dental Materials
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    • "In vitro studies often present fracture strength values that exceed the loads usually present during mastication, indicating that they should not fracture during normal service [18] [19]. Clinical data, on the other hand, reveal that fractures of allceramic restorations are prevalent [20] [21] [22] [23]. Thus, it is indicated that the commonly used laboratory tests do not adequately mimic the clinical fracture resistance and fracture features of "
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    ABSTRACT: Objectives: Fracture strength measured in vitro indicates that most all-ceramic crowns should be able to withstand mastication forces. Nevertheless, fractures are one of the major clinical problems with all-ceramic restorations. Furthermore, the fracture mode of all-ceramic crowns observed in clinical use differs from that found in conventional fracture strength tests. The aim of the present study was to develop and investigate a method that simulates clinical fracture behavior in vitro. Methods: 30 crowns with alumina cores were made to fit a cylindrical model with a molar-like preparation design. These crowns were randomly allocated to 3 tests groups (n=10). The crowns in group 1 were cemented to abutment models of epoxy and subsequently fractured by occlusal loading without contact damage. The crowns in group 2 were fractured by cementation with expanding cement. The crowns in group 3 were cemented on an abutment model of epoxy split almost in two and fractured by increasing the diameter of the model in the bucco-lingual direction. The fractured crowns were analyzed by fractographic methods and compared to a reference group of 10 crowns fractured in clinical use. Results: The fracture modes of all the in vitro crowns were similar to clinical fracture modes. The fracture modes in group 1 were most closely matched to the clinical fractures. These crowns also fractured at clinically relevant loads. Conclusion: Laboratory tests that induce a distortion of the abutment model during occlusal loading without occlusal contact damage can simulate clinical fractures of all-ceramic crowns.
    Full-text · Article · Jun 2013 · Dental materials: official publication of the Academy of Dental Materials
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