Should we rinse with water after brushing our teeth?

Question

I've heard that rinsing with water after teeth brushing lowers or negates the benefits that fluoride provides to our teeth, but I've also heard everything in between; from there's no problem with it, to rinse with as little water as possible, to mix water with toothpaste and rinse with it.

Example from http://www.theguardian.com/lifeandstyle/2011/feb/08/how-to-brush-your-teeth:

So, should you rinse your mouth out with water when you have finished brushing or leave some toothpaste in your mouth? "For children, I would say wash out, because if they still have adult teeth that have yet to come through, they may end up with too much fluoride in their body, which can damage their teeth. For adults, it's good to leave a film, but in moderation – you don't want a mouthful of toothpaste. I have a semi-rinse: I put a tiny bit of water in my mouth to brush away the toothpaste on my tongue."

and from http://lifehacker.com/5978107/dont-rinse-your-mouth-out-after-brushing-your-teeth:

I know this this is not common practice, but it is actually quite important! Fluoride, one of the active ingredients in toothpaste, doesn't spend much time in contact when your teeth when you are brushing. Thus, it is crucial to let it work after you have already brushed your teeth. According to dentist Dr. Phil Stemmer, from The Fresh Breath Centre in London, "Rinsing washes away the protective flouride coating left by the toothpaste, which would otherwise add hours of protection." If you are thirsty drink a glass of water before brushing your teeth!

In contrast, this article quotes http://www.oralanswers.com/rinse-after-brushing:

Previous studies have indicated that rinsing the mouth with a beaker of water after toothbrushing may compromise the caries reducing effect of fluoride toothpaste. It is concluded that post-brushing rinsing with water, under the conditions of this study, does not significantly affect the caries reducing effect of a fluoride toothpaste.

and

I think the reason that there is some disagreement on this subject is because not rinsing after brushing appears to be only beneficial if you are at a high risk of getting cavities.

And as two commenters said below, not rinsing feels kind of counter intuitive, but seems to be the way to go. Is it?

Assuming normal and healthy teeth, what's actually better? Which one carries the most benefits? Should we rinse with water or not? Are there studies about this? Is there a consensus yet?

Answer 1

The previous answer does not refer to clinical studies so I thought I would have a look.

TLDR; the clinical studies I've seen suggest not to rinse with water after brushing.

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According to Doméjean, et al. (2018), you should not rinse after brushing.

For maximizing the topical effect of the fluoride toothpaste, patients should be encouraged to spit out excess toothpaste and not rinse with water after brushing (Doméjean, et al. 2018).

Ashley, et al. (1999) looked at the DMFT (Decayed, Missing or Filled Teeth) levels for rinsing with water and no rinsing, and the DMFT levels were lower amongst those who rinsed by other methods or did not rinse after brushing. However, those who claimed not to rinse had a lower mean DMFT than the other subjects, which was "on the borderline of significance".

The mean DMFT of the 1,137 subjects who rinsed with a cup or beaker of water after brushing was significantly higher (mean 3.97, SD 3.74) than those who rinsed by other methods or did not rinse (mean 3.61, SD 3.79, p= 0.012, table 1). This represents a 9% difference in DMFT when compared with those who did not use a beaker. The 69 (2%) who claimed not to rinse had a lower mean DMFT (2.91, SD 3.24) than the other subjects, which was on the borderline of significance (p= 0.063) (Ashley, et al. 1999)

So to answer your question

Should we rinse with water after brushing our teeth?

Looking at the DMFT levels after rinsing with water compared to not, and looking at Doméjean, et al. (2018), the clinical studies suggest not to rinse with water after brushing

References

Ashley, P. F., Attrill, D. C., Ellwood, R. P., Worthington, H. V., & Davies, R. M. (1999). Toothbrushing habits and caries experience. Caries research, 33(5), 401-402. doi: 10.1159/000016540

Doméjean, S., Muller-Bolla, M., & Featherstone, J. D. (2018). Caries preventive therapy. Clinical Dentistry Reviewed, 2(1), 14. doi: 10.1007/s41894-018-0025-5

Answer 2

Summary:

• Not rinsing after tooth brushing may somewhat increase the effectiveness of fluoridated toothpaste, but the evidence is inconsistent and the effect can vary greatly among individuals.
• One possible explanation for inconsistent effect: not rinsing after brushing appears to be only beneficial if you are at a high risk of getting cavities.
• Researchers and dental experts usually do not mention any time to wait before rinsing.
• Some authors recommend a single brief slurry rinse. This can remove the toothpaste from the tongue and cheeks and greatly reduce the unpleasant aftertaste of the toothpaste, while still keeping the fluoride on the teeth.

Evidence:

1) Post-brushing rinsing for the control of dental caries: exploration of the available evidence to establish what advice we should give our patients, British Dental Journal, 2012

The opinion of participants of the 2012 meeting between the authors and other experts in the UK:

Rinsing with water after brushing with fluoride toothpaste can reduce the benefit of fluoride toothpaste.

Post-tooth brushing rinsing behaviours have the potential to either reduce or enhance the effectiveness of fluoride toothpaste and show wide variation in the general population. There is a lack of high-quality evidence to support definitive guidance in this area.

2) The influence of rinsing routines on fluoride retention after toothbrushing (Gerodontology, 2001):

It is suggested that for maximal effect, brushing with fluoride toothpaste should be followed by one brief slurry rinse, at the convenience and comfort of the patient/user.

3) Prospective study of the effect of post-brushing rinsing behaviour on dental caries (Caries Research, 2002)

A 3-year clinical trial of daily supervised brushing with fluoride toothpaste at school was used to test the effect of post-brushing rinsing with water on caries increment. A total of 407 children, mean age 11.8 years, attending three schools in Kaunas, Lithuania were enrolled following informed consent of the children and their parents. Caries was recorded at baseline and annually for 3 years. During the study, children in two schools (A and B) performed daily supervised brushing with a 1,500-ppm fluoride toothpaste. Children in school A rinsed their mouths thoroughly with a beaker of water after toothbrushing whereas children in school B were only permitted to spit out once after brushing. Furthermore, the children in these schools were supplied with toothpaste and toothbrushes for use at home and in school. A third school (C), without daily brushing and without supply of toothpaste, served as control. Compliance with the protocol was consistently better in school B. After 3 years 276 children were available for examination. Three-year DMFS increments, including non-cavitated lesions (mean, 95% CI), were: school A, 6.8 (5.3; 8.3); school B, 6.2 (4.6; 7.8), and school C, 12.4 (10.6; 14.1). Mean increments for schools A and B did not differ significantly but were both significantly lower than those of school C (p< 0.001). It is concluded that post-brushing rinsing with water, under the conditions of this study, does not significantly affect the caries reducing effect of a fluoride toothpaste.

4) Toothbrushing habits and caries experience (Caries Research, 1999)

The mean DMFT of the 1,137 subjects who rinsed with a cup or beaker of water after brushing was significantly higher (mean 3.97, SD 3.74) than those who rinsed by other methods or did not rinse (mean 3.61, SD 3.79, p= 0.012, table 1). This represents a 9% difference in DMFT when compared with those who did not use a beaker. The 69 (2%) who claimed not to rinse had a lower mean DMFT (2.91, SD 3.24) than the other subjects, which was on the borderline of significance (p= 0.063).

Answer 3

Rising removes the material the toothbrush detached. I see no reason NOT to rinse. The main use of tooth paste is actually to provide a suspension where the food and other particles can be incorporated during brushing. If you don't rinse, they will deposit again.

Source: https://www.choice.com.au/health-and-body/dentists-and-dental-care/dental-products/articles/toothpaste-whats-the-difference "Tartar is the build-up of hardened plaque that can lead to gum disease. Although regular brushing can minimise its build-up, tartar can only be properly removed by a dentist. Of the toothpastes we looked at, almost all contain a tartar suspension agent – the most common being pyrophosphates and xanthan gum – designed to suspend tartar particles in saliva and prevent them from clinging to teeth."

Other source: http://www.stab-iitb.org/newton-mirror/askasci/chem03/chem03188.htm