Approach for valuating the significance of laboratory simulation.
OBJECTIVE
The aim of this investigation was to compare the clinical survival rate of all-ceramic FPDs with failures during in vitro simulation.


METHODS
40 anterior FPDs were manufactured from lithiumdisilicate ceramic and alumina-oxide ceramic. The FPDs were adhesively bonded to human teeth and artificially aged to investigate the survival rate during thermal cycling and mechanical loading (TCML(1); 3.6 Mio*50 N ML). Survival rates were compared to available clinical data, and the TCML parameter 'mastication force' was adapted accordingly for a second TCML run (TCML(2); 3.6 Mio*25 N/35 N ML). The fracture resistance of the FPDs that survived TCML was determined. Data were statistically analysed by means of Mann-Whitney U-test, and survival rates were determined by curve fitting/regression analysis.


RESULTS
TCML decreased survival rates by 30-50%, depending on the type of material used. Failures during TCML included cracking, chipping or fracture. Increased masticatory loading during TCML caused a higher decrease in the fracture resistance of FPDs. Fracture results were 403 N (278/453) and 426 N (317/538) for Empress 2 and 325 N (164/584) and 405 N (344/558 N) for Inceram.


CONCLUSIONS
Despite the limitations of this study, the results indicate that TCML with 1,200,000*25/35 N provide a sufficient prognosis of probable clinical failures. Longer TCML-time with higher mastication forces may help to exclude catastrophic clinical failures.
Rosentritt
Martin
M
Department of Prosthetic Dentistry, Regensburg University Medical Center, Franz-Josef Strauss Allee 11, D-93042 Regensburg, Germany. Martin.Rosentritt@klinik.uni-regensburg.de
Siavikis
Georgios
G
Behr
Michael
M
Kolbeck
Carola
C
Handel
Gerhard
G
D000537:Aluminum Oxide / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D001696:Biomechanical Phenomena; D001732:Bite Force; D001840:Dental Bonding; D003776:Dental Porcelain / Q000737:chemistry*; D019232:Dental Restoration Failure; D003830:Denture, Partial, Fixed; D006801:Humans; D018020:Lithium Compounds / Q000737:chemistry; D008422:Materials Testing; D008962:Models, Theoretical; D013314:Stress, Mechanical; D013499:Surface Properties; D016019:Survival Analysis; D013696:Temperature
D000538:Aluminum Silicates; C118557:Empress 2; D018020:Lithium Compounds; C493120:lithia disilicate; D003776:Dental Porcelain; C078519:leucite; C070870:In-Ceram; D000537:Aluminum Oxide