[Degree of double conversion in nine pit and fissure sealants]

The purpose of the study was to evaluate quantitatively the degree of double bond conversion in nine commercially available pit and fissure sealants. The materials selected for the study were a) Nuva-Seal and Nuva Coat-UV cured b) Delton, Helioseal, Pentra Seal, Prisma Shield, Visioseal-Visible light cured and c) Delton, Concise White-Chemically cured. Infrared spectroscopy of monomer and polymer films, was used for the quantitative analysis at 37 degrees C. Monomer spectra were obtained from liquid films enclosed between two KBr plates while polymer spectra 24h after storage from 0.2 mm thick cylindrical specimens of 10mm diameter exposed to the activating lights for 1 min or mixed according to manufacturers. The results indicate that UV-cured materials provide the highest degree of double bond conversion followed by visible light cured systems. The clinical failure of UV-cured systems, despite their higher conversion rates is probably attributed to stabilization and shelf life problems of the catalyst besides the harmful side effects of UV-radiation which limited the utilization of these systems.