Effect of sandblasting, etching and resin bonding on the flexural strength/bonding of novel glass-ceramics.

Highlights • New patented formulation of leucite glass-ceramics (OLG-C), with high BFS and SBS. • Novel leucite G-C with reduced flaw size and similar sandblasted BFS to IPS e.max®. • Resin bonding increased BFS for all G-Cs, with 24.6% increase for IPS e.max®. • OLG-C useful for minimally invasive, aesthetic and fracture resistant restorations. Abstract Objectives To process novel leucite glass-ceramics and test the effects of surface treatment and resin bonding on the biaxial flexural strength (BFS) and shear bond strength (SBS). Methods Alumino–silicate glasses were ball-milled, and heat treated to form leucite glass-ceramics (LG-C, OLG-C), then sintered into ingots. Ingots were heat extruded into a refractory mould to form disc specimens (1.3 × 14 mm diameter). IPS e.max® was used as a commercial comparison. Glass-ceramic test groups were sandblasted (Groups. 1, 4, 6), sandblasted, etched and adhesively bonded (Groups. 2, 5, 7) or lapped, etched and adhesively bonded (Groups. 3, 8). Specimens were adhesively bonded with Monobond S, followed by the application of Variolink II® cement and light curing. BFS testing was at 1 mm/min and SBS testing at 0.5 mm/min. Samples were characterised using XRD, SEM and profilometry. Results XRD confirmed tetragonal leucite in LG-C/OLG-C and lithium disilicate/lithium orthophosphate in IPS e.max®. Mean BFS (MPa (SD)) were: Gp1 LG-C; 193.1 (13.9), Gp2 LG-C; 217.7 (23.0), Gp3 LG-C; 273.6 (26.7), Gp4 OLG-C; 255.9 (31); Gp5 OLG-C; 288.6 (37.4), Gp6 IPS e.max®; 258.6 (20.7), Gp7 IPS e.max®; 322.3 (23.4) and Gp8 IPS e.max®; 416.4 (52.6). The Median SBS (MPa) were Gp1 LG-C; 14.2, Gp2 LG-C (10 s etch); 10.6 and Gp3 IPS e.max®; 10.8. Mean surface roughness was 5–5.1 μm (IPS e.max®) and 2.6 μm (LG-C). Significance Novel leucite glass-ceramics with reduced flaw size and fine microstructures produced enhanced BFS and SBS by resin bonding. These properties may be useful for the fabrication of minimally invasive aesthetic and fracture resistant restorations. [ABSTRACT FROM AUTHOR]