Data for: Distribution of Adhesive Layer in Class II Composite Resin Restorations Before/After Interproximal Matrix Application

Objectives: This study aimed to morphologically investigate the distribution of the adhesive layer when placed prior, or subsequent, to matrix positioning in direct-bonded Class II RBC restorations. An additional aim was to evaluate possible differences when using two-step (CSE, Clearfil SE Bond2) or one-step adhesive system (CU, Clearfil Universal Bond Quick). Methods: Standardized mesio-occlusal and disto-occlusal cavities were prepared on 20 human molars. Teeth were randomly allocated to two protocols according to the positioning of contoured sectional metal matrices before (M->A, n=10), or after adhesive application (A->M, n=10). Both adhesive systems were additioned with crystal violet dye (CV, 10 vol%). Specimen sections were evaluated using optical and scanning electron microscopy (SEM). Microshear bond strength test (μ-SBS) of CV-additioned adhesives was performed on enamel and dentin of 12 additional molars. Rods of CV-additioned adhesives were subjected to three-point bend test (3PB). Results: M->A produced a layer of adhesive both on tooth-restoration interface and on external restoration surfaces in contact with the matrix. A->M produced a thin layer of adhesive on external tooth surfaces, well beyond cavity and RBC restoration margins. In all restorations, excess RBC material with uneven margins was observed protruding over the cervical margin. μ-SBS: CV addition showed a 10-fold reduction in adhesion forces when CU+CV was used on dentine. 3PB: CSE yielded higher flexural strength values than CU. CV addition reduced flexural strength of CSE.