White spot lesions (WSLs) are an all too common negative outcome of orthodontic treatment: a disheartening truth in an esthetically driven profession. WSLs are areas of enamel demineralization 100-150-µm deep, with an intact porous surface layer, which can progress until a complete inward collapse of the surface occurs. Their un-esthetic opaque appearance is potentially reversible, but irreversible once cavitated. Clinically detectable WSLs can occur as early as 1 month after fixed appliance placement. It is estimated that 50% of patients develop WSLs in at least one tooth by the end of orthodontic treatment. Although orthodontists have recognized this issue, the problem still persists. An immediate application of fluoride to a white spot lesion will cause a rapid surface remineralization, leaving deeper layers demineralized, so prevention of lesion progression is necessary for an ideal esthetic outcome. Aside from excellent oral hygiene, fluoride varnish, MI Paste, and smooth surface sealants are currently the primary methods of WSL prevention. There is an existing body of research related to the use of topical fluoride and calcium-phosphate pastes to prevent demineralization during orthodontic treatment, including at-home topical treatments. However, the self-reported compliance rate is approximately 50%. Professional fluoride varnish is thought to have the advantages of reducing demineralization without being technique sensitive. Other methods of WSL prevention are available, such as placement of sealants on facial surfaces of teeth, but preliminary research has shown conflicting results on their effectiveness. Regression of WSLs after treatment is attributed to gradual surface abrasion of tooth structure. Research has shown no improvement in WSLs when comparing non-invasive treatment methods such as MI Paste to routine oral hygiene practice. Success has been shown in treating arrested WSLs with a resin infiltration technique, but this is most useful on a small scale.
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