Prevention of white spot lesion formation during treatment with fixed orthodontic appliances: The efficacy of using a fluoride rinse and repeated oral hygiene instructions

The central theme of this thesis is prevention of white spot lesion (WSL) formation during fixed orthodontic appliance treatment. The thesis comprises two RCTs studying the efficacy of a) a fluoride rinse in preventing WSL formation, maintaining gingival health and oral microbial changes and b) repeated oral hygiene instructions with different feedback methods on the level of plaque. WSLs in the studies were assessed using Quantitative Light-induced Fluorescence (QLF), therefore a study was conducted into the influence of tooth rotation on WSL-assessments.
Using a daily fluoride rinse resulted in fewer WSL, while gingival health, assessed as bleeding sites, remained stable. Little effect was seen on the oral microbiome composition in comparison to a placebo rinse. The microbial changes in relation to gingival health, orthodontic treatment and time were more pronounced.
Repeated oral hygiene instructions during treatment can help to lower the level of plaque in patients with inadequate oral hygiene irrespective of the feedback method used, but has no added benefit in subjects with low levels of plaque.
When using QLF to assess WSL during orthodontic treatment, caution must be taken, because fluorescence loss and lesion size are influenced by the angle of rotation under which the WSL is photographed.
Based on these RCTs there are two advises, that can be easily incorporated in daily practice. In the first place daily rinsing with fluoride should be promoted during fixed appliance treatment. Secondly, if oral hygiene is inadequate during treatment, repeated instructions should be given to decrease the level of plaque.