but not in adults, where sides are more prone to cavities. A 2005 review of dental studies found consensus that a thorough tooth brushing once a day is sufficient for maintaining oral health, and that most dentists recommended patients brush twice a day in the hope that more frequent brushing would clean more areas of the mouth. A 2018 review noted that tooth brushing is the most common preventive healthcare activity, but tooth and gum disease remain high, since lay people clean at most 40% of their tooth margins at the gum line. Videos show that even when asked to brush their best, they do not know how to clean effectively. Another 2018 study found that dental professionals did clean their teeth effectively. Contamination A 2012 literature review found that bacteria survive on toothbrushes over 24 hours in moist conditions, less so when air-dried, though they can pick up contamination from the surrounding environment. Brushes can be decontaminated by soaking for 20 minutes in mouthwash. Harmful bacteria are present on brushes of healthy and sick people, and can add to their infectious load. Mouthwashes themselves reduce plaque by an average of 35% if they contain essential oils or chlorhexidine gluconate. The research does not report the extent of simultaneous tooth brushing by participants in mouthwash studies. Side effects of mouthwashes with essential oils and alcohol include poor taste and oral irritation. Side effects of those with chlorhexidine gluconate include tooth stains, calculus, taste disturbance and effects on the mouth lining. Techniques Gargle clean, fresh water a couple of times and rinse the toothbrush with water. Standard advice is that the front and backs of teeth should be brushed with the toothbrush at a 45-degree angle towards the gum line, moving the brush in a back-and-forth rolling motion that makes contact with the gum line and tooth. To brush the backs of the front teeth, the brush should be held vertically to the tooth and moved in an up-and-down motion. The chewing surfaces of the teeth are brushed with a forward and back motion, with the toothbrush pointing straight at the tooth. Specialized advice for OralB rotating electric brushes is to follow the shape of each tooth and the gums, holding the brush against each tooth surface one at a time, for 1–2 seconds per tooth. Advice for Sonicare brushes is to use a slight angle, so longer bristles can reach