Effect of Cyclic Fatigue Tests on Aging and Their Translational Implications for Survival of All‐Ceramic Tooth‐Borne Single Crowns and Fixed Dental Prostheses

PURPOSE: The objective of this systematic review was to elaborate the aging effect of cyclic fatigue tests on mechanical durability of all-ceramic single crowns and fixed dental prostheses (FDP). MATERIALS AND METHODS: Original scientific papers published in the MEDLINE (PubMed) database in English between 01/01/1950 and 12/31/2013 on cyclic loading on all-ceramics were included in this systematic review. The following MeSH terms, search terms, and their combinations were used: "in vitro," "stress mechanical," "crowns," "denture, partial, fixed," "dentistry," "fatigue," "all-ceramic," "zirconia," "fixed dental prosthesis," "FDP," "bridges," and "cyclic loading." Two reviewers performed screening and analyzed the data. Only the studies that reported on both static fracture strength and static fracture after fatigue of all-ceramic single crowns and FDPs that allowed comparison of aging effect through cyclic loading were included. RESULTS: The selection process resulted in a final sample of 14 journal articles. In total, 9 articles were identified related to all-ceramic single crowns, 3 of which were on anterior and 6 on posterior crowns, and 5 articles on 3-unit FDPs, all of which were on posterior FDPs. Fatigue cycles varied between minimum of 1000 to maximum 1,200,000 cycles for crowns and 10,000 to 2,000,000 cycles for 3-unit FDPs. The applied force during cyclic loading varied between 20 to 300 N for single crowns and 49 to 200 N for 3-unit FDPs. For the 3-unit FDPs, fracture strength results showed slightly decreased values after cyclic loading (659 ± 182 to 2333 ± 183 N) compared to static loading only (841 ± 244 to 2434 ± 154 N). For crowns similar trends were not observed, but cyclic loading decreased the fracture strength in only some materials after cyclic loading (659 ± 182 to 2333 ± 183 N) compared to static loading only (395 ± 96 to 2726 N). CONCLUSIONS: An inclination for decreased static fracture strength could be observed after cyclic loading of all-ceramic single crowns and FDPs, but this was material specific. Due to the heterogeneity of data such as aging, loading conditions, and fewer experimental groups, statistical analysis could not be performed. Cyclic loading tests require more standardized guidelines for testing and reporting.