Recently the role of free radicals in health has attracted tremendous interest in the fi eld of medicine, dentistry and molecular biology. Hydrogels may be prepared from either natural or synthetic polymers. Generally, natural polymer-based ones present weak mechanical properties, a shortcoming that may be corrected, on the one hand, by their biocompatibility and biodegradability, and on the other, by the fact that they allow the sequence of cellular activity. Over the past three years there has been a strong development towards chitosan-based gels as functional restorative biomaterials and an assessment of their performance in shear bond strength, cytotoxicity and capacity to deliver a therapeutic agent; together with an assessment of the antioxidant capacities of the newly designed materials, as well as free radical defense capabilities, of the chitosan-containing hydrogels. Th is chapter summarizes the important and crucial interaction between oral drug delivery and chitosan-based systems, which are easy to assemble, with multi-component design and fl exible, as well as easy to analyze and modify. Th e fi eld of degradable polymeric biomaterials and its future and applications are only limited by imagination, creativity and multidimensional science linking scientist and health professionals, and will only continue to progress if the recent advances cross the barrier from in vitro to in vivo and beyond.