4. Details of funding.

Cronin 1997 and Isaacs 1999 were supported by Braun AG, Germany (Braun Oral‐B Interclean ID2); Yankell 2002 by Dental Concepts, Paramus, USA (oral hygiene devices); Jackson 2006 and Schiff 2006 by the Colgate Palmolive Company (toothbrushes, floss and toothpaste); Meklas 1972 by the General Electric Company (Aqua Pulse Oral Irrigator); Zimmer 2006 and Ishak 2007 by GlaxoSmithKline (manual toothbrush and floss); Finkelstein 1990 by Johnson & Johnson (waxed floss); Cronin 2005 by Oral‐B (manual toothbrush and flosser); Biesbrock 2007; NCT00855933 and Rosema 2008 by Procter and Gamble (sponsorship) (DE International supplied the toothpaste for Rosema 2008); Yost 2006 and Jared 2005 by Sunstar Inc. (GUM, manual toothbrush); Barnes 2005, Goyal 2012 and Rosema 2011 by Waterpik Inc., Fort Collins, USA (oral irrigator); Hague 2007 by William Getgey Company (ultra‐flosser); and NCT01250769 was sponsored by Philips Oral Healthcare. Walsh 1989 was partially funded by Xouth, Inc, Lancaster, PA, USA. In Bauroth 2003, the authors were affiliated to industry, Pfizer; in Frascella 2000, the authors were affiliated to Braun and Procter and Gamble; and in Mwatha 2017, the authors AM, MO, SS, MW and WJ were employees of Philips (Sonicare Toothbrush). The Italian Ministry of Health and Tuscan region provided a grant to Graziani 2017; the State Scholarship Foundation of Greece grant‐aided Christou 1998 (Entra‐Lactona BV provided brushes and interdental brushes); a University of Tennessee College of Dentistry Alumni Grant was given to Lewis 2004.