Effect of etching with low concentration hydrofluoric acid on the bond strength of CAD / CAM resin block

• Published in: Dental Materials Journal Vol. 39; no. 6; pp. 1000 - 1008
• Main Authors: Yuiko NIIZUMA, Mikihiro KOBAYASHI, Toshinari TOYAMA, Atsufumi MANABE
• Format: Journal Article
• Language: Japanese
• Published: Japanese Society for Dental Materials and Devices 25.11.2020
• ISSN: 0287-4547; 1881-1361

The effect of etching for 90 s with low concentrations (0.5, 1.0, 2.0, 3.0, 3.5, and 4,0%) of hydrofluoric acid (HF) on the adhesiveness of computer-aided design/computer-aided manufacturing (CAD/CAM) resin blocks [CERASMART (CS), SHOFU BLOCK HC (HC), KATANA AVENCIA Block (KA), and VITA ENAMIC (EN)] was investigated. Energy dispersive spectroscopy revealed that the silicon content of HC, KA, and EN groups remained almost constant with HF etching of<=4%. HF etching increased the surface roughness of all blocks. The HF concentration resulting in the highest shear bond strength in each group was as follows: CS (2.0%), HC (3.0%), KA (3.5%) and EN (0.5%). Scanning electron microscopy revealed that the bonding interface of etched surfaces differed significantly from that of airborne-particle abrasion surfaces. Thus, low concentration HF etching is effective for surface treatment of CAD/CAM resin blocks. The etching effect and optimum HF concentration differ with the block composition and structure.