BACKGROUND This study compared the quality of marginal sealing in the gingival wall of class II preparations of two low-shirinkage resins of the bulk fill type with a conventional resin isolated or associated with a glass ionomer cement (GIC). METHODS 40 human molars were divided into 4 groups and 80 occlusal-mesial and occlusal-distal restorations were performed with the following materials: SureFil SDR flow, Filtek Bulk Fill Posterior, Z250 resins and Riva Light Cure GIC. 40 restorations were evaluated in Scanning Electron Microscopy (SEM) with Elemental Microanalysis Spectrometry (EDS) initially and the remainder after a period of 6 months of aging in a 37 ± 5°C oven. An average of the silver penetration at each restoration was obtained in the two evaluations and the results were statistically analyzed in a descriptive and inferential way, through the paired t-Student and one-way ANOVA F-test. RESULTS There were no significant statistical differences between the materials with respect to silver nanoinfiltration, except for the Bulk Fill Posterior/3M ESPE resin compared to the GIC and conventional resin in the final evaluation. CONCLUSIONS The low shrinkage resins showed a similar behavior in relation to the marginal sealing quality observed in the GIC or composite resin with the incremental technique, also presenting the advantage of simplicity in the technique of confection of the restorations and reduction of the time of work. Key words:Resin composites, Bulk fill, dental restorations, marginal quality, adhesion.