I am looking the answer for this question because most of articles I searched just focus on the concentration, the formula of fluoride or different ways to apply it, but they did not mention how long we should keep the fluoride toothpaste in mouth for hydroxyapatite to transform to fluorapatite, and it is good/bad to rinse water after brushing teeth?
I guess keep it overnight as I often recommend to my patients... Avoid rinsing after using fluoride toothpaste or apply a small amount on your teeth with finger before going to bed for optimum PH control...
the longer the time of application , the more is the effect of the fluoride
Immediately after brushing with F dentifrice the F concentration in saliva increased to an average of 9.03 ppm (450 times higher than the baseline value); this concentration returns to baseline levels within 2 hours [1]. It has been found significantly higher F levels in saliva after tooth brushing with F toothpastes when tooth brushing is not followed by oral cavity rinsing. Some of salivary F is taken up by dental plaque. Children should be encouraged to brush their teeth with F toothpaste twice a day at bedtime and at one other time during the day. An in vitro pH-cycling showed that F dentifrices significantly increased enamel F concentrations and enhanced enamel remineralization by reducing carious lesion depths [2].
1. Zero DT, Fu J, Espeland MA, Featherstone JDB: Comparison of fluoride concentrations in unstimulated whole saliva following the use of a fluoride dentifrice and a fluoride rinse. J Dent Res 1988; 67:1257-62.
2. Hattab FN. Remineralization of carious lesions and fluoride uptake by enamel exposed to
various fluoride dentifrices in vitro. Oral Health Prev Dent 2013;11:281-90.
Regarding the specific time i wouldn't know however for the effectiveness of fluoride to be observed..i will advice its retained in the mouth for about a couple of minutes.... probably half an hour
Article Post-brushing rinsing for the control of dental caries: Expl...
It is not exactly evidence-base dentistry; but this article is useful for the idea that adult patients (and specially for ECC) should not rinse after brushing with a fluoridated toothpaste and, rather, just spit out the excess in the mouth, to maintain fluoride levels, is based on Grade III evidence.
2/The effects of toothpaste amounts and post-brushing rinsing methods on salivary fluoride retention. (https://www.emerald.com/insight/content/doi/10.1108/JHR-11-2018-082/full/pdf?title=the-effects-of-toothpaste-amounts-and-post-brushing-rinsing-methods-on-salivary-fluoride-retention)
