RESUMO
With the increase of laser application in different fields of dentistry, further research is required to evaluate its efficiency in dental therapy. This study evaluated the effect of Er, Cr:YSGG laser conditioning of enamel on micro shear bond strength of composite resin of human enamel following two different tooth preparation methods [Diamond disk versus Er, Cr:YSGG laser]. In this invitro study, 125 human third molars were randomly assigned into 5 groups. Buccal and lingual enamel slices were prepared as below: A] laser-ablated without etching, B] laser-ablated and laser-etched, C] laser-ablated and acid-etched, D] cut by diamond disk and laser-etched and E] cut by diamond disk and acid-etched. Tubs of Z100 composite resin [3M, Dental Product/ USA] were bonded to conditioned enamel surfaces after applying two layers of Single Bond [3M ESPE, Dental product/ USA] Shear bond strength was measured by Micro-Tensile tester [Bisco Inc/USA] at a cross-head speed of 0.5 mm/min. Data were analyzed by one-way ANOVA, and Tukey tests. Mean shear bond strengths in groups were: A=23.14 +/- 6.53 MPa, B=23.77 +/- 5.56MPa, C=23.51 +/- 4.89MPa, D=19.30 +/- 5.56MPa and E=28.99 +/- 6.40 MPa respectively. The differences between [E, A], [E, B], [D, B], [C, D] and [D, E] were significant [P<0.05]. Micro shear bond strength of groups prepared by diamond disk and acid-etched were higher than groups prepared and etched by Er, Cr:YSGG laser. Therefore, re-etching with acid phosphoric is necessary if laser is used for tooth preparation or etching. Etching with acid phosphoric is recommended when laser is to used for tooth preparation or etching