A dental appliance has an auxiliary feature bonded to a polymeric surface of a shell body with a compartment for receiving teeth. The auxiliary feature is bonded with a light-curable acrylic adhesive comprising acrylate base material and photoinitiator. Auxiliary features include colored layers and, decals, reinforcing features and auxiliary dental devices. A light-curable acrylic adhesive may include a thiol monomer and/or a pigment. A dental appliance may have a shell body with a bonding surface adapted for attachment of an auxiliary feature, such as prepared by a pretreatment to mar the surface of to impregnate the surface with a reactive adhesion promoter.