White spot formation associated with sealants used in orthodontics.

Oxygen inhibition of sealant polymerization occurs when substantial tin'cknesses of low viscosity resins are applied to smooth tooth surfaces. Measurements have shown a range of sealant thickness from 0 to 228 micrometers. The objective of tins study was to test whether or not the polymedzed film present on the tooth was sufficient to provide protection against enamel dissolution. Metal brackets were bonded to thirty caries-free teeth using five different commercially available resins. The six teeth in each group were exposed for 96 hours to an adtifical caries environment of lactic acid in hydroxy-ethyl cellulose at pH 4.5. The teeth were then embedded and serially sectioned longitudinally. The sections were examined by polarization microscopy, scanning electron microscopy, and contact microradiography. Results showed that with the exception of Nuva Seal, all other resins frequently failed to prevent the formation of subsurface lesions in enamel where sealant was initially applied.