A direct filling composite resin restorative featuring a CTE that is similar to dentin and an antimicrobial is disclosed. The exemplary anti-microbial compound is zinc oxide. The CTE of the direct filling composite resin restorative is in the range of 12-15 ppm/° C. The low CTE is achieved by high filler loading of a trimodal distribution of low CTE filler. By maintaining a CTE substantially similar to that of dentin, the “Marginal Percolation” phenomenon is minimized, which decreases the incidence of secondary caries.