30 Short answers
Questions people ask that do not need a chapter each. The format is the same throughout: what the claim is, what supports it, and how confident anyone should be.
Two general warnings before starting. Almost none of these correspond to a recommendation in Delivering Better Oral Health, so there is nothing to audit in the sense the rest of the book means. And I have not systematically reviewed the literature for any of them. These are considered answers, not audits, and where that distinction matters I say so.
Should I use mouthwash?
Probably not routinely, and if you do, not straight after brushing.
The second half of that is the firmer claim and comes from Chapter 7: rinsing after brushing washes away the fluoride you have just applied, and a mouthwash is a rinse. If you want to use one, use it at a different time of day, which is exactly what DBOH says about fluoride mouth rinses in Chapter 12.
Antibacterial mouthwashes containing chlorhexidine do reduce plaque and gingivitis, and are genuinely useful short-term after oral surgery or during acute gum problems. Long-term daily use causes staining and taste disturbance and is not recommended. Cosmetic mouthwashes mask smell without addressing its cause; see Chapter 27.
Does oil pulling work?
Not something I would trade brushing time for, and I have not searched the literature.
Oil pulling means swishing coconut or sesame oil around the mouth for ten to twenty minutes. I ran no search for this chapter, so I am not going to characterize the size, length or comparators of the trials that exist, which an earlier draft did without having read them.
What I can say is about opportunity cost. Twenty minutes of oil swishing is twenty minutes not spent doing the thing with 55 randomized trials behind it. There are also case reports of lipoid pneumonia from aspiration, which is rare but real.
Should I scrape my tongue?
Reasonable if you have bad breath, pointless otherwise.
See Chapter 27. The mechanism is direct, most of the responsible bacteria are on the back of the tongue, and the evidence is thin and measured mostly on volatile sulphur compounds rather than on whether anyone noticed.
Does chewing gum help?
A little, and the mechanism is well understood.
Sugar-free gum stimulates salivary flow, and saliva buffers acid, clears debris and carries calcium and phosphate for remineralization. Chewing after a meal is a reasonable thing to do when you cannot brush.
Xylitol gum is often claimed to do more, on the basis that Streptococcus mutans cannot metabolise xylitol. The trial evidence for a caries benefit specifically from xylitol, as opposed to from chewing anything sugar-free, is weaker than the marketing implies. Chew it if you like it; the saliva is doing most of the work.
Should my wisdom teeth come out?
Not unless there is a reason.
Prophylactic removal of pathology-free impacted wisdom teeth was routine for decades and is no longer recommended in the UK: NICE TA1 says the practice “should be discontinued in the NHS.” Extraction is for teeth with actual pathology, such as unrestorable decay, abscess, cysts or damage to the neighboring tooth. Note one detail people get wrong in both directions: NICE treats a first episode of pericoronitis, unless particularly severe, as not an indication for surgery, while second or subsequent episodes are.
This is another case, like Chapter 19 and Chapter 28, where guidance moved away from a routine intervention and practice took a long time to follow. The harms of surgery are real and immediate; the benefits of removing a tooth that is not causing trouble are speculative.
Are water flossers as good as floss?
Genuinely unclear, and I overstated this in an earlier draft by saying they were worse than floss.
Chapter 17 has the numbers. Added to toothbrushing, oral irrigators may reduce the gingival index at one month (SMD −0.48, 95% CI −0.89 to −0.06, 4 trials, 380 participants, very low certainty) but not at three or six months, and did not reduce bleeding sites or plaque. Head to head against floss, the same review found some evidence that irrigation may be better for gingivitis, not worse, at very low certainty. There is no comparison of irrigators against interdental brushes at all (1).
I had also set the irrigator SMD beside an interdental-brush mean difference on a 0-to-3 index and called the second better. Those are different scales and the comparison was meaningless.
If you cannot manage floss or interdental brushes because of dexterity, arthritis or orthodontic appliances, an irrigator is a reasonable option. What the evidence does not support is a claim that it adds much to brushing beyond one month.
Do I need to replace my toothbrush every three months?
Nobody has established the interval.
The evidence on worn brushes and plaque removal is mixed, and SIGN 138 reviewed the question without arriving at a recommendation. Replace it when the bristles splay, which for most people is somewhere in the region of three months and is a judgment you can make by looking at it.
Is an interdental brush better than floss?
For most people with spaces that will take one, yes, on low-certainty evidence.
This is DBOH’s own ordering and it changed relatively recently. See Chapter 17.
Does whitening damage teeth?
Professionally supervised whitening with peroxide is generally safe. Sensitivity during treatment is common and usually temporary.
The concerns are with unregulated high-concentration products bought online, and with anything applied by someone who is not a registered dental professional. In the UK, tooth whitening is legally restricted to dental professionals for good reason: the agents are caustic at high concentration and gum burns are the predictable result of poor technique.
Should I worry about mercury in amalgam fillings?
No, on current evidence, and the question is becoming moot.
Amalgam has been studied extensively for mercury release and no convincing evidence of harm from ordinary fillings has emerged. Its use is being phased down internationally for environmental reasons rather than patient-safety ones, under the Minamata Convention. The UK restriction is narrower than “children”: it covers deciduous teeth, patients under 15, and pregnant or breastfeeding women, except where the dentist judges it strictly necessary for that patient.
Removing sound amalgam fillings to eliminate mercury exposure exposes you to more mercury during the removal than leaving them alone, and destroys tooth structure. Do not do it on health grounds.
Is it true that you inherit bad teeth?
Partly, and much less than people think.
Tooth shape, enamel thickness, saliva composition and flow, and the shape of the grooves in your molars all have a heritable component and all influence caries risk. Some genuine enamel defects are inherited.
But so are diet, oral hygiene habits, dental attendance and socioeconomic position, none of which are genetic and all of which run in families. “Bad teeth run in my family” describes a real observation with mostly non-genetic causes, and it is a belief that predicts giving up, which is the actual harm.
No systematic searches were run for this chapter.
These are considered answers drawing on the mechanisms and evidence established in earlier chapters, on UK guidance where it exists (NICE for wisdom teeth, GDC regulation for whitening, the Minamata Convention for amalgam), and on general professional knowledge.
Where a claim traces to a review I read in detail for another chapter, it is cited and the numbers are given. Where it does not, I have kept the claim correspondingly vague and said what kind of thing supports it.
This chapter would not survive the standard applied in Part II, and it is not meant to. It is here because these are the questions people actually ask, and declining to answer them would leave the field to sources with no standards at all.
Full record in appraisals/searches/ch30-short-answers.md.