الفهرس 
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Abstract
WSLs are characterized by mineral loss beneath an intact surface layer of enamel giving a whitish appearance. They are thought to be a common problem that may impair aesthetics. These lesions can be the initial signs of enamel caries. They can also result from developmental defects of the enamel, such as molar incisor hypomineralization and dental fluorosis. Post-orthodontic treatment constitutes a major etiological factor.
Treatment of WSLs is challenging. It comprises non-invasive techniques such as remineralizing agents, minimally invasive techniques such as RI, invasive approaches such as microabrasion and resin restorations, or even invasive veneers or crowns.
RI is a minimally invasive treatment modality which was introduced to arrest the progression of initial caries, improve the aesthetic appearance of WSLs restore the natural colour of enamel. RI provides remarkable aesthetic improvement of WSLs over microabrasion and bleaching, however, some WSLs exhibit partial or no response to resin infiltration. The current study aimed to identify the best practice in managing WSLs; either RI alone or in combination with microabrasion or bleaching, in addition to assessment of the colour stability for these treatment approaches.
Thirty sound human premolars were extracted for orthodontic reasons. They were free from caries, microcracks, white spots, or enamel structural defects. The selected premolars went through washing, cleaning with distilled deionized water, for soft tissue debris or blood removal, and then kept in physiologic saline in a closed container for a maximum of one month. Each specimen was immersed in a demineralizing solution for 10 days to induce WSLs on teeth and was randomly assigned to three groups.
All teeth were randomly divided into three groups (10 samples per group):
group (A): 10 teeth treated with (bleaching followed by RI)
group (B): 10 teeth treated with (microabrasion followed by RI)
group (C): 10 teeth treated with (RI alone).
For each specimen, measuring the colour was performed, at baseline, after demineralization, after treatment and after thermocycling, using Vita Easyshade Spectrophotometer (Cary 5000-Agelant, USA). Then, data were collected and the mean and standard deviation values were calculated for each group.
The mean values of (∆E) for the three groups (A, B, and C) after demineralization were (5.22), (5.20), and (5.19). And, after applying treatment the mean values of (∆E) were (1.55), (1.93), and (2.46). However, after applying thermocycling the mean values of (∆E) were (1.87), (2.48), and (3.24). There was a significant difference in colour change (∆E) between the three groups after treatment and after thermocycling (p<0.0001).
Finally, the results found that the WSLs treated with bleaching followed by RI exhibited superior improvement in colour matching immediately after treatment than WSLs treated with microabrasion followed by RI and RI alone.
Conclusions
On the basis of the results of current study, the following can be concluded:
1) White spot lesions treated with bleaching followed by RI exhibited superior improvement in colour matching immediately after treatment than WSLs treated with microabrasion followed by RI and RI alone.
2) After thermocycling, WSLs treated with bleaching followed by RI exhibited superior improvement in colour matching than WSLs treated with microabrasion followed by RI and RI alone.
3) Microabrasion followed by resin infiltration showed significant colour change immediatey after treatment and after thermocycling than resin infiltration only.