Or, "to rinse or not to rinse".
Towards the end of last term, it was health week at my younger son's school. Parents were invited in to take part in a lesson about oral health, with the teacher and pupils talking about different types of teeth and doing some tasks. One was to use dental disclosing tablets to show how clean your teeth really were. Sadly I could not stay for this bit, but I did watch the video about cleaning your teeth. This included the advice not to rinse your mouth after you had brushed. I had never thought of this, but the idea was not to wash the toothpaste away, leaving the flouride to remain working.
And then some weeks later, Dr Ranj on the very good Get Well Soon (CBeebies) had a programme about teeth, in which he was observed by my son rinsing.
So, who was right?
I asked my lad about this. Who was right? Dr Ranj, he thought, was a grown up and a lot of grown ups did not know not to rinse. His teacher had said she did not know, and so of course had I. So, I asked, how did he know not to rinse? The video had said so, he said. How did he know the video was right, I asked. Because the person in the video was a woman, he said.
I am not sure which of Isaacs' Alternatives to evidence based medicine this is, although it occurs to me that since my lad is actually called Isaac, this may well be Isaac's Alternative! Anyway, is there another explanation? What is the evidence?
NICE have a guideline on oral health, and there are recommendations relating to action that schools can take. But nothing about rinsing (that I can see).
A search of NICE Evidence Search led me to a record in Central, about toothbrushing education, but not quite on the right topic. It did however tell me there was a MeSH term Toothbrushing/, so I tried that in PubMed combined with the word rinsing. This was on the right lines, and some of the related citations were useful looking. One of those was indexed also with the MeSH term Water/Administration and Dosage (some of the other references were about mouthwash, not water). Trying the two MeSH terms together finds five items, some rather old. In this one, some children rinsed with water and some did not, and there was little difference in flouride retention (the abstract does mention that previous studies did indicate that there was). This one compared rinsing methods (one involved mouthwash, and two water), but with a smaller number of people, and found there was a difference.
Then, I tried a search of PubMed using toothbrushing (water OR rins*), filtered to systematic reviews, and found this (which actually appears to be a report of a consensus meeting, thus being an example of the problem of using a preset limit!). An examination of the full text is needed to see what the recommendations are. The abstract suggests that studies come to various results and that the evidence is of varying quality, although international guidelines, interestingly, come to the same conclusion (the abstract does not say what this is). The full text seems to be freely available, and says "The consistent message emerging from the guidelines in Table 2 is to spit and avoid excessive rinsing with water" (in the section headed "Clinical guidelines"), based on four referenced clinical studies, although it does say that the evidence levels and the methods used to grade the evidence vary.