Ultrashort-pulse laser as a surface treatment for bonding between zirconia and resin cement

Abstract Objectives To evaluate ultrashort-pulse laser (UPL) as a surface treatment for improved bond strength to Yttria-tetragonal zirconia polycrystalline (Y-TZP). Methods Fully-sintered Y-TZP samples received either no treatment (CTL), or were treated by alumina blasting (ALB), tribochemical silica coating (SIL), or one of two UPL patterns: multiple pulses laser surface dots with 2.5 μm spacing (8 mJ, 10 kHz)(LSD); or single pulse laser surface lines with 2.5 μm spacing (4 mJ, 6.7 kHz)(LSL). Surface roughness, wettability (contact angle), and quantification of crystalline phases were evaluated for each group (n = 3/group). Y-TZP treated slabs were cemented to resin composite slabs using silane and 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing adhesive. Beams from the Y-TZP/resin blocks were microtensile tested (n = 5/group) after 48 h water incubation (37 °C) with or without subsequent thermocycling (5–55 °C, 5000 cycles). Results All surface treatments increased surface roughness values versus control (P   LSL: 31.84 ± 8.46 MPa > SIL: 19.95 ± 3.99 MPa = ALB: 19.51 ± 2.55 MPa > CTL: 14.51 ± 2.23 MPa). Thermocycling significantly reduced bond strength for all treatments in a surface treatment-dependent manner. Significance The ability of UPL to alter Y-TZP surface morphology, increase wettability and μTBS without increasing the monoclinic content suggests its potential to improve bonding to the underlying resin cement and tooth without compromising the strength of the restoration.