Resin infiltration of enamel white spot lesions: An ultramorphological analysis

Objective: There is not a clear understanding of the ultramorphology of enamel white spot lesions (WSLs). The purpose of this study is to characterize resin infiltration of enamel WSLs using electron microscopy. Materials and methods: Enamel sections with sound enamel and WSLs were sectioned from extracted teeth and assigned to three groups: (a) left untreated; (b) etched with 15% hydrochloric acid (Icon-Etch); (c) restored with the resin infiltration sequence (Icon-Etch, Icon-Dry, and Icon-Infiltrant). Restored specimens were demineralized to obtain replicas. Observations were carried out under a field-emission scanning electron microscope. Results: Icon-Etch resulted in an array of pits and funneled holes on the WSL. Replicas of WSLs depicted 0.5-6.0-μm-thick shaggy resin tags up to a depth of 465 μm. Enamel crystallites were enveloped with resin at the bottom of the WSL forming a hybrid layer. Conclusions: The resin infiltrant filled the spaces between the crystallites and resulted in an enamel hybrid layer. Clinical significance: In addition to masking enamel WSLs, resin infiltration is able envelop residual enamel crystallites forming an enamel hybrid layer. This hybridization makes resin-embedded enamel more resistant to acid attack than sound enamel.