Material tissue interactions of a newly developed organically modified ceramic (ormocer)-based dental restorative composite based on a resin containing mixture of alkoxides of silicone and calcium with polymerizable methacrylate end groups are discussed in this study. Admira, a commercially available ormocer was used as control. A solgel process has been used to synthesize organically modified ceramic resins from liquid precursors, which allow one to produce inorganicorganic hybrid polymer materials, which can be functionalized to optimize their physical and chemical properties. Besides, the resulting material properties have been significantly modified by further technological processing such as photochemical curing of the materials by incorporating dimethacrylate groups as organically polymerizable units. Intracutaneous (intradermal) irritation test is found not to elicit any gross signs of tissue reaction. The results of maximization test for delayed hypersensitivity also did not show any adverse skin reaction during the induction or challenge period. Histological analysis after 1, 4, and 12 weeks of subcutaneous implantation of restorative composite resin on the dorsal surface on one side of the spinal column of Wister rats is also found not to reveal any inflammatory response after the implantation. Granuloma and material debris is found to be absent in all three periods of implantation in both test and control. No necrosis was observed around the implanted materials, which were found to be encapsulated by fibrous connective tissue consisting of predominantly fibroblasts and inflammatory cells. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012