Kumar S, Tadakamadla J, Johnson NW. Effect of Toothbrushing Frequency on Incidence and Increment of Dental Caries: A Systematic Review and Meta-Analysis. J Dent Res. 2016 Oct;95(11):1230-6. doi: 10.1177/0022034516655315. Epub 2016 Jun 22. PMID: 27334438.