Does Al₂O₃ airborne particle abrasion improve repair bond strength of universal adhesives to aged and non-aged nanocomposites?

Effect of Different Surface Treatments and Repair Materials on Shear Bond Strength of Bulk-Fill Resin Composite

“…In reparative dentistry, the most critical aspect of effective RC repair treatments is ensuring reliable adherence to the RC restoration. 6 Several techniques are used to improve the adhesion between old and new RC but there is no agreement on the procedure or materials that should be used for the repair process. Thus, it was essential to estimate the effect of different surface treatments and different RC repair materials on the repair of aged bulk-fill RC restorations.…”

“…For group 3, the blocks were sandblasted using an air abrasion device (Bio-art Micro Jato, Bio-art Equipamentos Odontologicos LTDA, Brazil) that uses a 50 µm sized aluminum oxide particles stream (Al2O3). 6 It was applied perpendicular to the surface for 10 sec under 2 bar pressure for each block. 6 The nozzle tip was placed 10 mm far from the block surface in slow motions.…”

“…6 It was applied perpendicular to the surface for 10 sec under 2 bar pressure for each block. 6 The nozzle tip was placed 10 mm far from the block surface in slow motions. 23 After that, the block was cleaned with etching gel (Scotchbond™ Universal Etchant, 3M ESPE), which was applied to the surfaces of block for 15 sec, rinsed with water for another 15 sec, and dried with compressed air.…”

“…This layer includes unreacted monomers, which can copolymerize with the newly added RC. 5,6 The absence of this layer is the most difficult aspect of RC repair process. So, the aged RC needs to be activated mechanically and chemically to improve the adhesion of repaired RC, however, there is no agreement on the technique or materials that should be applied for the repair process.…”

“…12 In addition, in vitro bond strength tests are important for evaluating the performance of an adhesive system and can be correlated to the clinical situation. 13,6 It was reported that loading of the specimens under shear may be considered clinically more significant than tensile or flexural loading as it produces elements of shear, tensile and compressive stresses that commonly occur during chewing . 14 Conventional tooth restoration with RCs is generally done with layering or incremental technique.…”