“…Saliva can be collected, without medical training, non-invasive and non-stress, by two methods: whole saliva by passive droll, and using a cotton swabs, that promote minimal risk of gingival bleeding [ 4 ], as described by three studies in this review [ 14 , 15 , 24 ], or using a sterilized plastic tube [ 10 , 13 , 16 , 18 , 19 , 21 , 22 , 23 , 25 ]. Major studies described the unstimulated passive droll [ 6 , 13 , 14 , 16 , 22 , 24 , 25 , 26 , 27 , 28 , 29 ], but the time used to collected the saliva were not congruent. Two studies used a sample collection time of one minute [ 13 , 16 ], four used two minutes [ 14 , 20 , 22 , 25 ], one study used five minutes [ 30 ] and four did not describe how long the collection took [ 10 , 17 , 18 , 19 ], and three studies did not use time for collection but the volunteers needed to droll at least 1 mL [ 6 , 31 ] or 0.5 mL [ 21 ].…”