A comparative study of Acid and Laser Etching on Micro Shear Bond Strength of Enamel

With the increase of laser application in different fields of dentistry, further research is required to evaluate it's efficiency in dental therapy. This study evaluated the effect of Er,Cr:YSGG laser conditioning of enamel on micro shear bond strength of composite ressin to human enamel following two different tooth preparation tools (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 groops were: A= 23.14 ± 6.53 MPa,B= 23.77 ± 5.56 MPa,C= 23.51 ± 4.89 MPa,D= 19.30 ± 5.56 MPa 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 the laser used for tooth preparation or etching.