Little is known about the wear rate of enamel and dentin opposing resin composite following restoration of the occlusal surface in patients with tooth wear. Hence, the aim of this in vitro study was to evaluate the wear of enamel and dentin surfaces when opposing each of three resin composites in a two-body and three-body wear test. The two-body and three-body wear of dentin, enamel, and three resin composites (Clearfil AP-X, Filtek Z250, and Filtek Supreme) opposing four antagonists (stainless steel and three resin composites) were evaluated using the ACTA wear machine. In addition, all the surfaces were evaluated with scanning electron microscopy. The results showed the lowest wear rate in enamel and the highest in dentine, with the composite showing intermediate wear rates. The three-body wear results were not affected by the antagonist and showed pure wear caused by the abrasive food medium. The in vitro enamel/composite wear ratio was 2.5. The results show that tooth wear accelerates as soon as enamel disappears and dentin is exposed to composite resin. Therefore, it is important to protect dentin with a restorative material.