Effect of the region of the CAD/CAM block on the flexural strength and structural reliability of restorative materials

• Published in: Journal of the mechanical behavior of biomedical materials 2023-02, Vol.138, p.105597-105597, Article 105597
• Main Authors: Venturini, Andressa Borin, Dapieve, Kiara Serafini, de Kok, Paul, Pereira, Gabriel Kalil Rocha, Valandro, Luiz Felipe, Kleverlaan, Cornelis Johannes
• Format: Article
• Language: English
• Subjects: Ceramics - chemistry; Composite Resins; Computer-Aided Design; Dental Porcelain; Digital dentistry; Flexural Strength; Glass-ceramics; Materials Testing; Mechanical phenomena; Mechanical reliability; Processing; Reproducibility of Results; Resin composites; Surface Properties
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2022.105597

The aim of the study was to evaluate whether the region (internal or external) of the CAD/CAM block influences the mechanical performance of restorative materials. Blocks of different CAD/CAM materials (Composites: KAV – Katana Avencia; LULT – LULT Ultimate; Ceramics: ENAM – Vita Enamic; NICE - N!CE; EMP – IPS Empress CAD; VMII – Vita Mark II; EMAX – IPS e.max CAD) were selected, and direct resin composite blocks (APX - Clearfil AP-X; FSUP - Filtek Supreme) were built using the incremental technique on a mold from one of the CAD/CAM blocks. All blocks were sectioned into bar-shaped specimens (1 × 1 × 14 mm), which were separated into two groups according to the region of the block (inside or outside). 3-point bending tests were performed following ISO 6872:2015 and flexural strength data were analyzed using one-way ANOVA and Bonferroni post-hoc tests (p  0.05) between the inside and outside regions of each material, except for LULT (inside > outside) and EMAX (outside > inside). Comparing the materials, a similar strength (only discrete variations) was observed for inside, outside or merged (inside and outside data assembled together) regions: EMAX > KAV = LULT > NICE = APX > EMP = ENAM = VMII ≥ FSUP (merged condition). Characteristic strength at 63.2% failure probability and at 5% failure probability generally corroborates such observations. There were no statistical differences for Weibull module data (inside, outside, or merged), except for KAV and NICE (outside > inside). Thus, the region from where the restoration is milled within the CAD/CAM block generally does not influence the mechanical performance hereof (flexural strength, failure probability, risk of premature failures, and mechanical reliability) of the material, except for LULT and EMAX. •The region of CAD-CAM blocks only influenced the mechanical performance for two materials.•Materials composition affected the mechanical properties more than the region of the blocks.•The fractographic features for internal and external regions are similar.