White spot lesions after orthodontic fixed appliance treatment:The effectiveness of MI Paste Plus® as a remineralising agent: A randomised controlled trial

In this thesis, research is being described that aims at secondary prevention of white spot lesions (WSL), i.e., the remineralisation of these lesions. Also methods to monitor existing WSL in time and methods to predict risk of the formation of WSL are analysed. As described in this thesis, the monitoring of WSL severity by visual comparison of clinical oral photographs taken over time provides discriminatory power in assessing changes in WSL severity. ICDAS assessment on clinical oral photographs did not have enough discriminatory power to reveal changes in WSL. The risk for formation of WSL cannot be predicted by DGGE, nor by conventional microbiological parameters. MI Paste Plus®, a remineralisation agent, does not show its intended effect in patients who have WSL after orthodontic treatment with full fixed appliance. The intended effect was not seen in a 12 weeks period nor a 12 months period after appliance removal. Further research on the secondary prevention of WSL, should focus on the transport of calium an phosphate ions in to the deeper layer of the lesion and prevent hypermineralisation of the lesions. The primary prevention of WSL is considered crucial. Despite available scientific evidence in the prevention of WSL with fluoride, clinical guidelines have not been formulated until now.