HYDROFLUORIC acid, BOND strengths, ETCHING, CAD/CAM systems, and SURFACE preparation
Abstract
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. [ABSTRACT FROM AUTHOR]
SURFACE preparation, BOND strengths, CEMENT, FREE surfaces, and SHEAR strength
Abstract
The aim of this study was to determine the influence of different surface treatments of CAD/CAM composite blocks on bonding effectiveness of resin cements, based on the shear bond strength test and the surface science examination. Specimens were fabricated from two types of CAD/CAM composite blocks (Cerasmart and VITA Enamic), and the specimen surfaces were alumina sandblasted. Specimen surfaces were treated with i) silane, ii) primer, and iii) silane+primer, then two types of cements (Block HC Cem and Super Bond) were bonded. After 24 h storage, bond strengths were measured. Surface free energy measurements were performed of the treated CAD/CAM composite blocks surfaces. The groups ii) and iii) showed significantly higher bond strengths than the group i), apart from VITA Enamic with Block HC Cem. Although the total surface free energy showed different trends in different surface treatments, a similar trend was found in both CAD/CAM composite blocks. [ABSTRACT FROM AUTHOR]
SURFACE preparation, FLEXURAL strength, DENTURES, METHYL methacrylate, and ZIRCONIUM oxide
Abstract
This study assessed the impact of surface treatments and repair resin reinforcement with zirconium oxide nano-particles (nano-ZrO2) on flexural strength (FS) of repaired denture base. A total of 320 heat-polymerized acrylic resin specimens were prepared and sectioned creating 2-mm gap. According to repair surface treatment, specimens were distributed into four groups: I) methyl methacrylate (M); II) alumina-blasted (AB); III) AB+silane coupling agent (SC); and IV) AB+methacrylate based composite bonding agent (MA). Groups were subdivided into 4 (n=20) according to nano-ZrO2 concentration (0, 2.5, 5, 7.5 wt%). Half the specimens were thermo-cycled before testing. FS was determined by three-point bending test. Statistical analysis was done using ANOVA and Tukey-Kramer multiple comparison tests, with α=0.05. Alumina-blasting+(SC) or (MA) significantly increased FS of repaired specimens compared to control (p<0.05). All surface-treated specimens combined with nano-ZrO2 reinforced repair resin significantly increased FS. [ABSTRACT FROM AUTHOR]
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.
