Objective: To compare the depth of microfiltration in resin restorations in Class I cavities, varying the restoration method and the adhesive system. Material and Methods: an ex vivo experimental study was carried out, in which 128 molars without morphological alterations in the coronary structure were included, in which cavities were carved in the occlusal face in a standardized way (4x4x3mm) and later randomly distributed in two groups according to the adhesive system applied (Group I, acid etching prior to the adhesive; Group II, self-etchingadhesive), each Group being subdivided into two subgroups according to the restoration method, A: composite resin; B: Flowable resin base, composite resin restoration and surface sealer. All trial bodies were sealed at the apex and on the entire external surface with two layers of nail polish up to 1 mm from the tooth-restoration interface, thermo...