Changes in white spot lesions following post-orthodontic weekly application of 1.25 per cent fluoride gel over 6 months-a randomized placebo-controlled clinical trial. Part I: photographic data evaluation

Background: White spot lesions (WSLs) are a frequent side-effect of multibracket appliance treatment. The effect of local fluoridation on post-orthodontic WSL is however inconclusive.

Objective: Assessment of WSL changes in response to weekly 1.25 per cent fluoride gel application after multibracket appliance treatment.

Trial design: Randomized, single-centre, double-blind, parallel-group, placebo-controlled study.

Participants: Patients with not less than 1 WSL (modified score 1 or 2) on not less than 1 upper front teeth after debonding.

Interventions: Professional fluoride/placebo gel application during weeks 1-2; self-administered home application (weeks 3-24).

Outcomes: Photographic WSL assessment (dimension and luminance) of the upper front teeth (T0-T5).

Randomization: Random assignment to test (n = 23) or placebo group (n = 23) using a sequentially numbered list (random allocation sequence generated for 50 subjects in 25 blocks of 2 subjects each).

Recruitment: The clinical study duration lasted from March 2011 to September 2013.

Blinding: Unblinding was performed after complete data evaluation.

Numbers analysed: Intent-to-treat analysis set comprising 39 participants (test: n = 21, placebo: n = 18).

Outcome: Dimensional WSL quantification showed limited reliability. Luminance improvement (%) of WSL, however, was seen after 6 months (test/placebo: tooth 12, 24.8/18.0; tooth 11, 38.4/35.4; tooth 21, 39.6/38.3; and tooth 22, 15.2/25.0). No statistically significant group difference existed. Data suggest that WSLs are difficult to measure with respect to reliability and repeatability and methods for monitoring WSLs in clinical trials require improvement/validation.

Harms: Similar adverse events occurred in both groups; none was classified as possibly related to the study product.

Limitations: The number of dropouts was higher than expected and the socio-economic status was not assessed. Furthermore, the unknown level of compliance during the home application phase must be considered as limitation.

Conclusion: Based on the results of this study, no difference could be detected with respect to the development of WSL under post-orthodontic high-dose fluoride treatment.

Registration: The study was registered with ClinicalTrials.gov (Identifier: NCT01329731).

Protocol: The protocol wasn't published before trial commencement.