An in vitro evaluation of the effect of sandblasting and laser surface treatment on the shear bond strength of a composite resin to the facial surface of primary anterior stainless steel crowns.

Objectives: The present study was conducted to evaluate the optimal method of enhancing the bond strength of a composite resin to the facial surface of the primary anterior stainless steel crowns using various surface treatments namely Nd: YAG laser surface treatment, sandblasting , alloy primer application and no surface treatment.

Study Design: The study sample consisted of 60 primary anterior stainless steel crowns (UnitekTM size R 4), with 15 samples randomly divided into the 4 study groups, embedded in acrylic blocks. The facial surface of these surface treated crowns was utilized as the bonding surface to which 2.5mm diameter composite resin cylinders were bonded for the evaluation of the shear bond strength. Shear bond strength measurements were made using a universal testing machine utilizing a shearing blade (jig).The mode of failure at composite-metal interface was determined using a Stereomicroscope at 10 X magnification.

Results: The mean bond strength values obtained for surface treatment of Nd: YAG laser surface treated, Sandblasting ,Alloy Primer and No surface treatments were 17.01±.92 , 13.18 ± .73, 7.46 ± .70 and 7.33 ± .77 MPa respectively. The obtained bond strength values were subjected to a one way ANOVA and a Scheffe's post-hoc comparison test. The results of the present study indicated that Laser surface treatment of the facial surface of the crowns enhanced the bond strength of the composite resin significantly compared to the other groups.

Conclusions: Nd: YAG laser surface treatment produced an excellent surface roughness and obtained the highest shear bond strength values suggestive for recommendation as an optimal surface treatment to be used to enhance the resin-metal bond at the interface of the composite resin and the facial surface of primary anterior stainless steel crowns for the purpose of chairside veneering. Key words:Nd: YAG laser treatment, Sandblasting, Primary anterior stainless steel crown, Chairside veneering, Enhancing Resin-Metal Bond, Early childhood caries, Shear bond strength (SBS).