Visible-Light Sensitive Reworkable Resins for Dental Application: Improved Stability

A reworkable resin, which is degradable after use, was developed for application as a dental resin with an enhanced stability. A dimethacrylate monomer containing a ketal linkage in the molecule was used as a reworkable monomer. The reworkable monomer was successfully cured by blue light irradiation (470-nm light) using the camphorquinone/amine photoinitiating system. The cured reworkable resins were degraded in the presence of a UV- and violet-light sensitive photoacid generator by subsequent irradiation of UV light (365-nm light) at room temperature. The degradation was due to the acid-catalyzed decomposition of the ketal linkages in the cured reworkable monomers. Selection of the evaluated photoacid generators is very important in order to improve the stability of the cured resin. The result suggested the possibility of application of the reworkable monomer as a dental resin.