Structural changes of acid etched enamel examined under confocal laser scanning microscope

The aim of the present investigation was to elucidate structural alternations in enamel subjected to acid etch technique and treatment under remineralizing conditions by means of a new microscopy technique known as confocal laser scanning microscopy (CLSM). Blocks of enamel were treated with 37% phosphoric acid and exposed for 3 weeks to an oral environment. Tomographic CLSM images were subsequently obtained and compared with controls. CLSM proved to be a reliable, highly reproducible and simple method of qualitative assessment of structural changes occurring on the surface of enamel and in areas below the surface as deep as 100 microns or more. Structural alterations associated with acid application were observed to occur up to 100 microns below the surface; these largely remained after exposure to an oral environment. Changes manifested as differential light reflection were detected in experimental samples in the form of a hyper-reflexible zone extending as a 10 to 15 microns wide band below the etched surface. This finding indicates that deposition of salivary material occurs on and below the surface of etched enamel exposed to an oral environment. Once qualitative results of CLSM are correlated with quantitative measurements, this technique may facilitate large scale remineralization studies.