# Minimally Invasive Dentistry for Pre-Eruptive Enamel Lesions--A Case Series
## 4 Discussion
The good esthetic outcomes achieved through the microabrasion technique are due to the fact that the mineralized tissue in the enamel surface is compacted within the organic area, and the outer layer of prism-rich enamel is replaced with a densely compacted prism-free layer, creating a fluorapatite-rich surface layer [6; 7; 10; 15]. This prism-free layer of enamel will refract and reflect the light differently, which translates to a clinically smooth, shiny, and lustrous enamel, and camouflages any mild color imperfections in the underlying enamel--the \"abrosion effect\" [6; 10; 15]. Since the enamel surface becomes smoother, plaque adhesion is reduced, which is also a great advantage [15]. However, there are also some drawbacks when using microabrasion since the dental surface may acquire a yellowish appearance due to the fact that there is a reduction in enamel thickness, and the underlying dentin may become more visible [6; 10], which is noticeable in the final photographs of Case 1 and 3. Nevertheless, if the Opalustre product is correctly used according to manufacturer's instructions, only approximately 10-200 um of the outer enamel layer is removed, which is considered as clinically acceptable [19]. Moreover, [PERSON] et al. [11] showed that even though microabrasion had a favorable outcome initially, this might not be resistant to discoloration by smoking, consumption of tannin-rich foods, and long-term use of cationic agents. The efficacy of the microabrasion procedure is also directly related to the severity and depth of the lesions [7], which can be confirmed by Case 2 where, even though it was not possible to achieve full resolution of the lesions due to the severity of the case, it was still possible to improve esthetics significantly. The microabrasion technique is recommended for stains or defects that are no deeper than a few tenths of a millimeter in enamel [20], which is why proper evaluation with a photopolymerizer's light might be useful to decide between this technique and resin infiltration. By using the photopolymerizer and allowing the light to go through the tooth, it is possible to distinguish between deeper lesions, which appear darker, and more superficial lesions, which appear in a lighter shade. As for contraindications, this technique should not be carried out in uncooperative patients, patients with a history of sensitivity to hot, cold, or acidic foods, and patients with dentinogenesis or amelogenesis imperfeta [15]. When necessary, the microabrasion technique may be combined with other treatment approaches in order to improve the final esthetic result. Treatments such as dental bleaching may be useful to whiten the yellowish part of the tooth when there is a great enamel reduction and reduce contrast with the rest of the surface [6; 10; 18; 21]. If, afterwards, there is still a need to further improve results, a resin-infiltration technique may be attempted and later, if necessary, a direct composite restoration. Some authors suggest the use of macro reduction prior to the microabrasion procedure in cases of advanced fluorosis with pitting [6; 10]. [PERSON] et al. [6; 10] showed how the use of a high-speed tapered fine diamond bur and copious irrigation to remove the superficial layer of the stained enamel was able to drastically improve the final results in severe cases of fluorosis. However, this procedure is more invasive and should therefore be, as much as possible, used only in cases where microabrasion and resin-infiltration techniques were attempted and proved insufficient.