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Online ISSN 1827-174X
Caroline COTES 1, 2, Lucas ZOGHEIB 3, Vanessa MACEDO 1, Rodrigo CARVALHO 1, Carolina MARTINELLI 1, Estevão KIMPARA 1
1 Department of Dental Materials and Prosthodontics São José dos Campos Dental School UNESP, Universidade Estadual Paulista São José dos Campos, São Paulo, Brasil; 2 Department of Dentistry Centro de Ensino Superior de Valença Valença, Rio de Janeiro, Brasil; 3 Department of Prosthodontics, School of Dentistry, University of Fortaleza, Fortaleza, Brazil
BACKGROUNG: The aim of this study was to evaluate fracture strength of lithium disilicate-based ceramic crowns submitted to neutralization of hydrofluoric acid (HF) precipitates associated with ultrasonic bath and to thermo-mechanical cycling.
METHODS: Eighty human molars received conventional full crown preparation after being included in polyurethane standard to simulate periodontal ligament. After scanning, the ceramic blocks were machined using CAD/CAM system to obtain the crowns. The crowns were distributed according to surface treatment: S and S-C; HF and silane; SNU and SNU-C; HF neutralization of HF precipitates, ultrasonic bath and silane. The crowns were cemented with dual cure resin cement and the specimens in Groups S-C and SNU-C were submitted to thermo-mechanical cycling (5/55 °C/60 s while 1.2 million mechanical cycles of 4 Hz/100 N). The samples were submitted to compressive test. Analysis of fractures was performed macroscopically (Burke method) and using Scanning Electron Microscope. The data of fracture strength were analyzed using the two-way ANOVA.
RESULTS: No statistical difference among the groups was found (p-value = 0,799). Most failures were associated with the remaining tooth fracture and the fracture origin was located on the cementation surface.
CONCLUSIONS: Postetching cleaning protocols do not improve the fracture strength of ceramics crowns. Thermo-mechanical aging did not weakened the ceramic crown.