This study presents the synthesis of a cross-linkable dextran as starting material for the development of new hydrogels as drug delivery system in dental applications. 2-Hydroxyethyl methacrylate (HEMA) was coupled to dextran after activation with carbonyldiimidazole as monitored by FTIR and H-1-NMR spectroscopy. The Dex-HEMA was crosslinked by visible light in the presence of camphorquinone (CQ) as photoinitiator and a coinitiator in a proper solvent. Aliphatic or aromatic amines were used as coinitiators and the content of the coinitiator was varied from 0.25 to 3.0 mol Diphenyliodonium chloride was added as a third component to the above photoinitiation system. It was observed that, the degree of swelling decreased upon an increase of Dex-HEMA concentration and the water content in the solvent system due to formation of more crosslinking points, that is, increasing crosslink density (P-x). The type of coinitiator shows a prominent impact on the swelling behavior and crosslinking efficiency of hydrogels. Special cryofixation and cryofracture techniques were used to investigate the surface and interior of swollen Dex-HEMA hydrogel samples by SEM. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 3128-3138, 2010