M Beerens

14 CHAPTER 1 Screening and monitoring methods The management of WSL relies on methods screening the caries risk, incidence of new caries lesions and monitoring of the severity of existing caries lesions. Given the rapid development of WSL during orthodontic treatment, such methods need to have excellent discriminatory power, such that even small changes in caries risk, caries prevalence and caries severity can be detected. Caries risk assessment is currently based on past caries experience or DMFS scores complemented by current oral hygiene level (Sundell et al. , 2013). Low hygiene levels result in high amount of plaque and especially a high amount of mature plaque (Marsh, 1994). Orthodontic fixed appliance treatment is associated with a rapid increase of dental plaque, lower pH and shift in the composition of the bacterial flora (Chatterjee and Kleinberg, 1979; Marsh, 2010) towards higher levels of acidogenic bacteria, such as Streptococcus mutans and lactobacilli (Lundstrom and Krasse, 1987). Therefore, monitoring changes in the microbial composition may help guide prevention and treatment of caries (Lucchese and Gherlone, 2013). Traditional detection methods, such as visual inspection and intra-oral photography are commonly available in clinical practice. Visual inspection is the first choice to screen for the presence or absence of caries. Visual inspection according to the international caries assessment and detection system (ICDAS) includes the assessment of early WSL and scores the severity of lesions (Ismail et al. , 2007). An advantage that the use of intra-oral photographs has over visual examination methods, is the ability to archive intra-oral photographs, remote scoring, allowing multiple scorers to score images and enabling longitudinal analysis (Wenzel et al. , 1991). Also it is beneficial in studies when examiner blinding is required and in practice based RCTs (Boye et al. , 2013). Quantitative light-induced fluorescence imaging (QLF) has been developed for the longitudinal assessment of early WSL and changes in WSL severity (Hafstrom-Bjorkman et al. , 1992). The technique is based on tooth illumination by a broad beam of blue-violet light (405 nm). The resulting fluorescence of the enamel in the yellow-green region (520 nm) is observed through a yellow high-pass filter, which filters out all reflected and back-scattered light. The difference between the measured values and the reconstructed values gives