Characterization of lased enamel organic matrix using confocal microscopy

Abstract

In the past decade several studies have demonstrated the increased acid resistance in enamel demineralization after laser irradiation. However, the exact mechanism of action to this effect still remains a speculation. Recently, the role of organic matrix was revealed to be significant in the laser-induced inhibition of enamel demineralisation. The aim of the present study was to characterize the lipid component of organic matrix in mature lased enamel and unlased enamel histochemically using a hydrophobic fluorescent probe with Confocal Laser Scanning Microscope (CLSM). Partial decalcification of thin enamel sections was carried out using 0.5 M of EDTA in a stainless steel grid for 5 hours, following fixation with 3.5% paraformaldehyde. Thereafter the sections were stained with Nile red coupled with CLSM. The intensity of the light reflection was analysed under the same conditions for all specimens, ruling out the autofluorescence in the control sections. Confocal imaging revealed a diffuse and increased fluorescence of the lipid stain in the lased areas suggesting that the swelling and coating of organic matrix on the surface of enamel crystals in the peri and interprismatic spaces is rendering the increased acid resistance. These findings will substantiate the proposed organic blocking theory in partially explaining the laser-induced prevention of enamel demineralisation.