Appendix 1. MEDLINE Ovid search strategy

1. exp Orthodontics/
2. (orthodontic$ or bracket$ or brace$ or wire$ or archwire$).mp.
3. (fix$ adj5 appliance$).mp.
4. or/1‐3
5. exp Oral hygiene/
6. toothbrush$.mp.
7. ((interdental or interspace or inter‐dental or inter‐space or orthodontic or "single tufted" or specialised or spiral or bottle) adj3 brush$).mp.
8. ("Water Pik" or "Flosser FL‐110" or "water jet" or "jet clean$" or "jet tip$").mp.
9. (oral adj hygiene).mp.
10. ((teeth or tooth) and (interproximal or clean$ or cleans$)).mp.
11. or/5‐10
12. 4 and 11

The above subject search will be linked with the highly sensitive search strategy designed by Cochrane for identifying randomised controlled trials and controlled clinical trials (as described in the Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0, Box 6.4.b. (Lefebvre 2011)).

1. randomized controlled trial.pt.
2. controlled clinical trial.pt.
3. randomized.ab.
4. placebo.ab.
5. drug therapy.fs.
6. randomly.ab.
7. trial.ab.
8. groups.ab.
9. or/1‐8
10. exp animals/ not humans.sh.
11. 9 not 10