Er:YAG laser has been studied as a potential tool for restorative dentistry due to its ability to selectively remove oral hard tissue with minimal or no thermal damage to the surrounding tissues. The purpose of this study was to evaluate in vitro the tensile bond strength (TBS) of an adhesive/composite resin system to human enamel surfaces treated with 37% phosphoric acid, Er:YAG laser (lambda=2.94 microm) with a total energy of 16 J (80 mJ/pulse, 2Hz, 200 pulses, 250 ms pulse width), and Er:YAG laser followed by phosphoric acid etching. Analysis of the treated surfaces was performed by scanning electron microscopy (SEM) to assess morphological differences among the groups. TBS means (in MPa) were as follows: Er:YAG laser + acid (11.7 MPa) > acid (8.2 MPa) > Er:YAG laser (6.1 MPa), with the group treated with laser+acid being significantly from the other groups (p=0.0006 and p= 0.00019, respectively). The groups treated with acid alone and laser alone were significantly different from each other (p=0.0003). The SEM analysis revealed morphological changes that corroborate the TBS results, suggesting that the differences in TBS means among the groups are related to the different etching patterns produced by each type of surface treatment. The findings of this study indicate that the association between Er:YAG laser and phosphoric acid can be used as a valuable resource to increase bond strength to laser-prepared enamel.

Infrared lasers have been used for several clinical applications in dentistry, including laser ablation, oral surgeries and dentin hypersensitivity treatment. Despite of dentin low absorption coefficient in the near infrared spectrum, Nd:YAG laser radiation (λ= 1064 nm) is able to melt the human dentin surface resulting in dentin tubules closure that can suppress the symptoms of dentin hypersensitivity pathology. Objectives: This study aims to analyze, through SEM technique, the morphological changes in dentin surface after Nd:YAG laser irradiation using different parameters in energy distribution. Materials and Methods: In this study sixteen human dentin samples were submitted to Nd:YAG laser radiation using a total energy of 900mJ distributed in one, two, three or six laser pulses with energy for each pulse of 900, 450, 300 or 150 mJ respectively. All the samples were irradiated with laser pulse width of 90ms, pulse intervals of 300 ms and spot size area of 0,005 cm 2 . Results: SEM analysis suggests that differences in energy distribution results in morphological differences even though the same energy is used for all the samples.