**2. White-spot lesions**

One of the most common negative side effects of orthodontic treatment with fixed appliances is the development of incipient caries lesions around brackets and bands, particularly in cases with poor oral hygiene (Fig. 1). Caries lesions typically form around the bracket interface, usually near the gingival margin (Gorelick *et al.,* 1982). Certain bacterial groups such as mutans streoptococci and lactobacilli ferment sugars to create an acidic environment that over time might lead to the development of dental caries. Since orthodontic appliances make plaque removal more difficult, patients are more susceptible to carious lesions. The irregular surfaces of brackets, bands, wires, and other attachments also limit naturally occurring self-cleaning mechanisms, such as movement of the oral musculature and saliva (Rosenbloom and Tinanoff, 1991).

Incipient lesions are characterized by their opacity, mineral loss, and decrease of fluorescence radiance when compared to healthy enamel surfaces. Many incipient enamel lesions have a white appearance due to an optical phenomenon caused by mineral loss in the surface and sub-surface that alters the refractive index and increases the scattering of light in the affected area, all resulting in greater visual enamel opacity.

Studies have shown that white spot lesions can take only one month to develop (Øgaard *et al.,* 1988*;* O'Reilly and Featherstone, 1987; Gorton and Featherstone, 2003). A clinical study reported the prevalence at 50% (Gorelick *et al.,* 1982), while recent investigations put the incidence of white spot lesions in the orthodontic populations studied at 73-95% (Richter *et al*., 2009; Lovrov *et al,* 2007). Orthodontists and patients will notice these lesions after removal of the fixed appliances, especially since the white spots tend to form in the maxillary esthetic zone (Gorelick *et al.,* 1982; Banks and Richmond, 1994). While some studies have reported a decrease in the display of white spot lesions over time postorthodontic treatment, these unesthetic spots tend to remain unless they are resolved with more aggressive treatment, such as minimally invasive or even full restorative dentistry (Øgaard, 1989; Årtun and Thylstrup, 1989).
