Abstract
Objective: Although the effects of Er:YAG (erbium:yttrium aluminium garnet) laser on cavity preparation as well as on dentin bonding to composite have been described in the literature, the longevity of this bond is still unknown. So, this study evaluated the short-term microtensile bond strength to dentin samples after different protocols of surface treatment. Materials and Methods: 60 bovine incisors were cleaned, worn to expose a dentin area and subdivided into groups according to treatment conditions: surface treatment (no irradiation – control group; dentin irradiation with Er:YAG laser 250 mJ/4 Hz; 160 mJ/10 Hz), adhesive system (Clearfil SE Bond - Kuraray; Adper Single Bond 2 - 3M/ESPE), and storage time (24 h; 90 days). After adhesive procedures, a block of Z250 composite resin (3M/ESPE) was built-up on each tooth. The teeth were sectioned to obtain samples for the microtensile bond strength test. Half of the samples were tested 24 h after cutting, and the other half were stored in distilled water for 90 days before testing. Intergroup analysis was also performed considering the same variables using ANOVA for multiple comparisons with Tukey test with a significance level of 5%. Data showed weaker bond strength for groups previously treated with laser (p < 0.05) compared with control groups, and these were not influenced by adhesive system used, nor by storage period. Stereoscopic microscope observations showed that fractures occurred predominantly at the adhesive interface in the groups irradiated with the Er:YAG laser. Conclusion: Within the parameters and variables used in this study, the Er:YAG laser could not provide an additional improvement in dentin-resin bond strength, irrespective of the type of adhesive system used or the storage period evaluated. KEYWORDSAdhesive systems; Er:YAG laser; Microtensile bond strength.
Highlights
The modern concepts of adhesion in Dentistry are based on minimally invasive and conservative procedures to restore teeth due to carious lesions or trauma [1]
The effects of Er:YAG laser on cavity preparation have been widely described in the literature, as well as the bond strength of irradiated substrate to composite resin [5,12]; its longevity and stability have not yet been well-established
The microtensile bond strength test and fracture pattern analysis were carried out at the interface between dentin prepared with Er:YAG laser at different time intervals, 24 h or 90 days after bonding of composite with different adhesive systems
Summary
The modern concepts of adhesion in Dentistry are based on minimally invasive and conservative procedures to restore teeth due to carious lesions or trauma [1]. When used with the correct parameters, this laser can be safely used for conservative restorative dentistry promoting enamel surface etching or even selectively removal of dental tissue by the process called ablation [4,5,6,7] In enamel, this ablation can create a micro retentive pattern, which would favor adhesive procedures. The microtensile bond strength test and fracture pattern analysis were carried out at the interface between dentin prepared with Er:YAG laser at different time intervals, 24 h or 90 days after bonding of composite with different adhesive systems.
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