Method: we used 30 molars and premolars that had been extracted for orthodontic reasons. 24 of these showed degrees of fluorosis: very-mild, mild and moderate, according to Dean criteria. The 8 remaining teeth were healthy and were used as a control. The teeth were immersed in a solution with the fluorophore-rhodamine-B. The low-viscous commercial resin was then applied (Icon,DMG,Hamburg,Germany). To bleach all red-fluorophore that had not been enclosed by the infiltrant resin, specimens were stored in 10% hydrogen peroxide solution for 12h at 37°C and then washed carefully. Following this, teeth were cut&polished, perpendicular to the surface, in 100micron sections. To visualize non-infiltrated enamel, teeth were immersed in a 50%-ethanol solution of 100µM sodium fluorescein (NaFl;Sigma-Aldrich) for 3min. and were then washed. Specimens were observed using a confocal laser scanning microscope (Olympus-Fluorview, FV1000, Japan) with dual fluorescence mode (RICT: Ex 543nm, NaFl: Ex 488nm). Percentage penetration was calculated as PD (Penetration-Depth)/Fdmax (Fluorosis Depth) x100. Differences between groups were analyzed with ANOVA and post-hoc with Bonferroni, with a significance level of p=0.05.
Result: Homogeneous penetration of the resin was observed in all groups. The average penetration percentage was 55% for control group and 74%, 79% and 54% for the very-mild, mild and moderate groups respectively (p<0.05). The penetration depth, in microns, was 246 for control, 410 very mild, 348 mild and 627 moderate groups respectively. These differences were found to be significant (p<0.05).
Conclusion: Infiltration of fluorotic enamel varies in depth and percentage of infiltrated enamel in relation to the degree of fluorosis.