Lithium Disilicate Restorations Fatigue Testing Parameters: A Systematic Review.
OBJECTIVE
To review laboratory studies that investigated fatigue resistance of lithium disilicate (LD) crowns and fixed dental prostheses (FDPs) to elucidate study designs and testing parameters.


METHODS
An electronic search was performed in PubMed, Scopus, and Ovid to identify in vitro studies that investigated fatigue resistance of LD crowns and FDPs. The search included all studies published in English in peer-reviewed journals in the period from 1998 to June 2014. The search followed a specific strategy that included combination of the following keywords: lithium disilicate, e.max, empress, all-ceramic, all ceramic, glass ceramic, fatigue, cyclic loading, dynamic loading, chewing simulator, fracture resistance, thermocycling, laboratory simulation, aging, crown, FDPs, FPDs, fixed partial denture, fixed dental prosthesis, and bridge. Studies were selected if mechanical and thermal loading parameters were clearly identified. Search results with abstracts were transferred into Endnote reference system, and duplicates were deleted. The remaining studies were then reviewed at three levels (title, abstract, full text) to further refine the articles.


RESULTS
The initial search retrieved 1044 eligible studies. After deduplication, 864 records were examined by titles and then abstracts; 826 were excluded, and 38 were assessed by full-text reading. In total, 19 articles met inclusion criteria and were included in this study.


CONCLUSIONS
The studies reviewed showed a level of heterogeneity, as testing parameters were considered through different setups. The current study demonstrated that various setting of the testing parameters and having a lack of testing standardization has likely led to inconsistency in the reported results. The obvious heterogeneity in the setting of testing variables-especially the magnitude of load and number of cycles applied-made it impractical to run direct comparisons between the reviewed studies. Therefore, specific international standardization of fatigue testing of dental restorations is urgently needed to ensure the delivery of consistent, indicative, and comparable data.
School of Dentistry and Oral Health, Griffith University, Queensland, Australia.
Noor
N
Nawafleh
Cranio-Maxillofacial Prosthetics Unit, King's College Hospital NHS Foundation Trust, London, UK.
Muhanad
M
Hatamleh
School of Dentistry and Oral Health, Griffith University, Queensland, Australia.
Shareen
S
Elshiyab
School of Dentistry and Oral Health, Griffith University, Queensland, Australia.
Florian
F
Mack
D003442:Crowns; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D003830:Denture, Partial, Fixed; D006801:Humans
C493120:lithia disilicate; D003776:Dental Porcelain
Cyclic loading; chewing simulator; laboratory simulation; testing parameters; thermocycling