The aim of this study is to evaluate a self-adhesive flowable resin composite, a flowable resin composite with high viscosity and a conventional flowable resin composite in combination with a universal adhesive using two different application modes. All patients will receive at least 4 occlusal restorations. Cavities will be divided into four groups according to restorative systems used: Constic (a self-adhering flowable composite), G-ænial Universal Flo (a highly filled flowable composite), Tetric N-Flow (self-etch) (a conventional flowable composite), Tetrin N-Flow (etch&rinse).

Inclusion Criteria:

• having no medical or behavioral problems preventing then from attending review visits
• absence of previously placed restorations
• having antagonist teeth

Exclusion Criteria:

• poor gingival health
• uncontrolled, rampant caries
• bruxism
• removable partial dentures
• xerostomia