The effect of different surface treatements of CAD/CAM sub-structures on bond strength and mikroleakage of veneering composite resins

As an alternative to restorations made by conventional methods veneer material that can provide stable bond and aesthetic is currently under investigation.The aim of this study was to evaluate the effect of surface treatments on the mikroleakage and mikrotensile bond strength (μTBS) of hybrid composite to Lava Ultimate and Vita Enamic resin-nanoceramic CAD/CAM blocks. In this in-vitro study for each CAD/CAM block, samples were divided into different surface treatment groups as follows: control, 50 μm Al2O3 airborne-particle, femtosecond laser and femtosecond laser & 50 μm Al2O3 airborne-particle.One additional samples were prepared for each surface treatment for mikroleakage test and - SEM analysis. Filtek Z250 hybrid composite was adhered ontoCAD/CAM blocks after application of universal single bond adhesive.1x1 mm sized and 8 mm. lengthmicrobar specimens were prepared.Mikrotensile bond strength (μTBS) and mikroleakage of each sample was eveluated after1000 thermal aging cycle. New specimenswere prepared for SEM analysis. Bond strengths were analyzed through two-way ANOVA test.Tukey LSD test was used for multiple comparisons of the groups. Two-way ANOVA showed statistically significant difference amongst the block and surface treatment methods (p<0.05). However, there was no significant difference between surface treatment and the block interaction (p > 0.05). For all groups, the control group showed the lowest bond strength values and the difference was statistically different (p<0.05). Combination of sandblasting and laser groups showed highest bond strength values (p<0.05).There is no statistical difference between sandblasting and laser surface treatment (p > 0.05). The SEM images were supported the MBSdata. Dyepenetrationmethod usedto accessmicroleakage revealed that there is no microleakage occurred in any of tested groups. As a result of this study it is recommended that using Femtosecond laser + sandblasting as a surface treatment which is redounds the μTBS.