Mirelle Maria Ruggiero1, Rafael Soares Gomes1, Edmara Tatiely Pedroso Bergamo2, Mariana Itaborai Moreira Freitas1, Estevam Augusto Bonfante2, Altair Antoninha Del Bel Cury3. 1. Department of Prosthodontics and Periodontology, University of Campinas - Piracicaba Dental School, Limeira Avenue, 901, Piracicaba, SP, 13414-903, Brazil. 2. Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Dr. Octávio Pinheiro Brisolla Avenue, 9-75, Bauru, SP, 17012-901, Brazil. 3. Department of Prosthodontics and Periodontology, University of Campinas - Piracicaba Dental School, Limeira Avenue, 901, Piracicaba, SP, 13414-903, Brazil. Electronic address: delbelcury@gmail.com.
Abstract
OBJECTIVE: To evaluate the influence of resin-matrix ceramic material and thickness on reliability and stress distribution of occlusal veneers (OV). METHODS: One hundred and twenty-six OV of a mandibular first molar were milled using a CAD/CAM system and allocated according to materials (resin nanoceramic (RNC) or polymer-infiltrated ceramic network (PICN)) and thicknesses (0.5, 1.0 and 1.5 mm), totaling six groups (RNC0.5, RNC1, RNC1.5, PICN0.5, PICN1, and PICN1.5). Step-stress accelerated-life testing was performed (n = 21/group) with the load applied at the distobuccal cusp tip of the occlusal veneer until failure or suspension. The use level probability Weibull curves and reliability were calculated and plotted (90% CI). Finite element analysis evaluated the stress distribution according to maximum principal stress (σmax) on the restoration and maximum shear stress (τmax) on the cement layer. RESULTS: There was no difference in the probability of survival for the estimated missions among the groups, except at 600 N in which the results were significantly lower to PICN1.5 (6%) compared to RNC1 (55%) and RNC1.5 (60%). The σmax values were higher for PICN (31.85-48.63 MPa) than RNC (30.78-33.09 MPa) in the same thicknesses. In addition, 0.5 mm groups concentrated more stress in the restoration (33.09-48.63 MPa) than 1.0 mm (31.11-35.36 MPa) and 1.5 mm (30.78-31.85 MPa) groups in the same material. SIGNIFICANCE: Both resin-matrix ceramic materials seem up-and-coming restorative systems for occlusal veneers irrespective of the thicknesses as a consequence of the high reliability.
OBJECTIVE: To evaluate the influence of resin-matrix ceramic material and thickness on reliability and stress distribution of occlusal veneers (OV). METHODS: One hundred and twenty-six OV of a mandibular first molar were milled using a CAD/CAM system and allocated according to materials (resin nanoceramic (RNC) or polymer-infiltrated ceramic network (PICN)) and thicknesses (0.5, 1.0 and 1.5 mm), totaling six groups (RNC0.5, RNC1, RNC1.5, PICN0.5, PICN1, and PICN1.5). Step-stress accelerated-life testing was performed (n = 21/group) with the load applied at the distobuccal cusp tip of the occlusal veneer until failure or suspension. The use level probability Weibull curves and reliability were calculated and plotted (90% CI). Finite element analysis evaluated the stress distribution according to maximum principal stress (σmax) on the restoration and maximum shear stress (τmax) on the cement layer. RESULTS: There was no difference in the probability of survival for the estimated missions among the groups, except at 600 N in which the results were significantly lower to PICN1.5 (6%) compared to RNC1 (55%) and RNC1.5 (60%). The σmax values were higher for PICN (31.85-48.63 MPa) than RNC (30.78-33.09 MPa) in the same thicknesses. In addition, 0.5 mm groups concentrated more stress in the restoration (33.09-48.63 MPa) than 1.0 mm (31.11-35.36 MPa) and 1.5 mm (30.78-31.85 MPa) groups in the same material. SIGNIFICANCE: Both resin-matrix ceramic materials seem up-and-coming restorative systems for occlusal veneers irrespective of the thicknesses as a consequence of the high reliability.