Discussion
incisors, lateral incisors
The number of patients with an increase of ≥1 DL during orthodontic treatment was significantly higher in the CTR group compared to the HFT group and the FMR group when only central incisors, lateral incisors, and canines were included in the analysis. Therefore, in the aesthetic zone, patients benefitted from using fluoride mouth rinse and high-fluoride toothpaste compared to ordinary fluoride toothpaste. The positive effect of high-fluoride toothpaste and fluoride rinse on the development of DL are in line with the findings of previous clinical studies [DLs can persist and create aesthetic concerns for the patient even 12 years after treatment [This study showed a higher baseline prevalence of DL (proportion of patients with at least one white spot lesion) compared to studies with a similar study design [A weakness of the present study is that the randomization was performed manually with sealed envelopes. It would have been preferable to randomize the patients using computer-generated sequence numbers. Another study limitation is that the present study did not use a double-blinded design. The protocol was not published before trial commencement, which must be seen as a weakness. The study was planned 15 years ago, and at that time, trial registration was not a requirement as it is today. Furthermore, patients could have been prescribed additional fluoride products from their general dentist at their home clinics, which could have affected the patient’s DL status during treatment. However, there are several strengths of the study. The study had a randomized controlled trial design ensuring high scientific value. Furthermore, the assessor of the DL score was blinded to the patient’s group affiliation and not involved in the clinical procedure, which minimized the risk for bias. The large material size, sufficient power, and the fact that all the patients were provided with the same toothbrush and fluoride products are strengths of the present study. Furthermore, the good intra- and inter-rater agreement also strengthened the findings of this study.