A reshapable retention device for insertion at a dental site and contact with adjacent dental surfaces, for the controlled delivery to the dental site of at least one material having a predetermined intraoral activity. The retention device comprises at least one matrix containing the material. The retention device is adapted for physically affixing at the dental site for at least a predetermined time period correlated to the delivery of a predetermined portion of the at least one matrix to the dental site in a controlled single, bi or multiphase pattern. The retention device comprises a first configuration in which the overall dimensions of the retention device are larger than at least one dimension of the dental site. The first configuration is reshapable to a second configuration in which at least one dimension of the retention device is reduced to enable physically affixing the retention device at the dental site. In the second configuration the retention device comprises a predetermined shape having contours for affixing at the dental surfaces.