M Beerens

12 CHAPTER 1 various stages being either reversible or irreversible. If the demineralization process is not being stopped, an intact enamel surface eventually collapses and cavitates. WSL are considered the precursor of enamel caries but can, in principle, be reversed (Sudjalim et al. , 2006; Chambers et al. , 2013). WSL developed during orthodontic treatment, however, have limited ability to regress after appliance removal and in many cases these lesions will therefore remain visible as permanent scars of the enamel (Mattousch et al. , 2007). Management of white spot lesions (WSL) Modern management of dental caries associated with orthodontic fixed appliance treatment has three major components: prevention, control and atraumatic care of existing WSL after orthodontic treatment with fixed appliances (Willmot, 2004; Ekstrand et al. , 2009). The majority of research addresses the primary prevention of WSL, showing that there is scientific evidence that fluoride has a positive effect on the primary prevention of WSL adjacent to fixed orthodontic appliances. A Cochrane review concluded that there is evidence that daily mouth rinses with 0.05 % NaF with can reduce the occurrence and severity of WSL during orthodontic treatment (Benson et al. , 2004). Despite the clinical effect of daily home use of mouth rinses, compliance can be a problem, as only up to 50% of the studied participants was compliant (Geiger et al. , 1988; Geiger et al. , 1992). A treatment not requiring patient compliance is the application of high concentration (36 000 ppm) fluoride varnishes. It reduces the formation and decreases enamel lesion depth adjacent to bonded brackets during treatment with fixed appliances (Stecksen-Blicks et al. , 2007; Farhadian et al. , 2008; Shafi, 2008) Secondary prevention of existing WSL after orthodontic treatment can be divided into three different approaches. The strategy using fluorides (Zero, 2006; Reynolds et al. , 2008; Huang et al. , 2013) and phosphate-based remineralizing agents (Reynolds et al. , 2008; Yengopal andMickenautsch, 2009; Robertson et al. , 2011; Chen et al. , 2013; Li et al. , 2014) addresses the biologic repair process, aiming to reverse the carious process. A strategy focusing on cosmetic improvement of the lesions is infiltration by resins (Kielbassa et al. , 2009; Kugel et al. , 2009; Senestraro et al. , 2013). Other options can be categorized as invasive strategies such as micro abrasion (Murphy et al. , 2007),