Methods: Enamel and dentin were irradiated with USLP by varying laser wavelength (355, 532, 1,045, and 1,064 nm), pulse duration (pico and femtoseconds) and irradiation protocols (scanning speed, cooling, pulse repetition rate). Temperature increase, ablation rate and surface morphology were evaluated. The most favorable laser parameters were used for the microtensile bond strength of resin composite to irradiated dentin by using etch-and-rinse and self-etch adhesive systems with different bonding protocols (Clearfil SE Bond with and without Primer, Adper Single Bond with and without acid etching).
Results: Dentin and enamel irradiated with infrared pico- and femtosecond lasers presented rough surface without carbonization. Irradiation was better conducted with higher scanning speed and no additional cooling. When adequate parameters are used, temperature increase is not higher than 6.1ºC for enamel and 4.6ºC for dentin, when temperature increase was measured at the back side of 1-mm thick samples without cooling during irradiation. Bond strength values varied according to laser parameters and adhesive systems used, and showed either similar or significantly higher values for irradiated dentin than control groups, for all laser parameters analyzed (p < 0.05).
Conclusion: USPL are considered a promising technique for the promotion of laser-supported minimally invasive approach.