While the aesthetic effect of orthodontic treatment is clear, the knowledge on how it influences the oral microbiota and the consequential effects on oral health are limited. In this randomized controlled clinical trial we investigated the changes introduced in the oral ecosystem, during and after orthodontic treatment with fixed appliances in combination with or without a fluoride mouthwash, of 10–16.8 year old individuals (N = 91). We followed several clinical parameters in time, in combination with microbiome changes using next-generation sequencing of the bacterial 16S rRNA gene. During the course of our study, the oral microbial community displayed remarkable resilience towards the disturbances it was presented with. The effects of the fluoride mouthwash on the microbial composition were trivial. More pronounced microbial changes were related to gingival health status, orthodontic treatment and time. Periodontal pathogens (e.g. Selenomonas and Porphyromonas) were highest in abundance during the orthodontic treatment, while the health associated Streptococcus, Rothia and Haemophilus gained abundance towards the end and after the orthodontic treatment. Only minor compositional changes remained in the oral microbiome after the end of treatment. We conclude that, provided proper oral hygiene is maintained, changes in the oral microbiome composition resulting from orthodontic treatment are minimal and do not negatively affect oral health.

Demineralizations around orthodontic brackets are a main disadvantage of orthodontic treatment. Several methods have been advocated to prevent their development, such as fluoride rinses or varnishes. In this randomized clinical trial, a fluoride rinse (a combination of sodium fluoride and amine fluoride) was compared with a placebo rinse, to be used every evening after toothbrushing. A total of 81 participants (mean age: 13.3 yr) completed the study (mean treatment period: 24.5 months). Demineralizations, measured using quantitative light‐induced fluorescence and the decayed, missing, and filled surfaces (DMFS) index, were assessed before treatment (baseline) and around 6 wk after debonding (post treatment). Bleeding scores were measured at baseline, and during and post treatment. The incidence rate ratio for demineralizations was 2.6 (95% CI: 1.1–6.3) in the placebo group vs. the fluoride group. In the fluoride group, 31% of participants developed at least one demineralization, compared with 47% in the placebo group. Relative to baseline, gingival bleeding increased significantly in the placebo group 1 yr after the start of treatment and onwards. For the fluoride group, bleeding scores during treatment were not different from those at baseline. In conclusion, using a fluoride rinse helps to maintain better oral health during fixed appliance treatment, resulting in fewer demineralizations.

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BackgroundA quantitative light-induced fluorescence digital (QLF-D) camera is able to assess demineralizations adjacent to orthodontic brackets. Rotations of teeth during and the presence of the orthodontic appliances may influence the longitudinal follow-up of such lesions over time.MethodsBrackets were bonded on extracted teeth: 54 incisors and 31 canines. Demineralizations were formed in vitro directly cervical of the bracket. Images were captured using a QLF-D camera mounted on an optical bench, equipped with a goniometer on a turntable. The teeth were placed in the goniometer simulating buccolingual rotation (0°, 10°, 20°), the turn-table was used for mesiodistal rotations (0°, 10°, 20°). Standardized QLF-D images were made before (with and without a wire) and after debonding at combinations of aforementioned angles of rotation. The image after debonding at 0° buccolingual and 0° mesiodistal rotation served as a control.ResultsThe presence of a bracket resulted in a significantly higher fluorescence loss, yet a smaller lesion area (p < 0.05) in comparison to the control. A significant higher fluorescence loss was seen for rotations towards lingual relative to the 0° buccolingual and 0° mesiodistal rotation, while the effect was less explicit towards buccal.ConclusionsFluorescence loss and lesion size are influenced by the angle of rotation under which the demineralization is photographed. The full extent of demineralizations is only apparent after debonding when photographed at rotations of 0° mesiodistal and up to 20° buccal. Precaution must be taken into account assessing demineralizations of patients undergoing treatment with fixed appliances when using a QLF-D camera.Electronic supplementary materialThe online version of this article (10.1186/s12903-018-0667-3) contains supplementary material, which is available to authorized users.