Please DO take care to brush your tiny child's teeth, even if they do appear to have smooth "self cleansing" surfaces.It really is not sufficient for them just to have the brush in their mouth .Baby teeth are very susceptible to decay, and what's more they have big "pulps" - the soft inner core of the teeth which contains the nerve and blood vessels, and this means it does not take a great depth of decay to reach the sensitive part, i.e. cause pain.
Another thing about baby teeth. While it is correct that they may have less deep pits and fissures than adult teeth there is a lot of variation in tooth morphology and some children do have deep pits and fissures in their deciduous teeth.
Another factor is how close together their teeth are. If their teeth are very close it is easier for decay to develop interproximally ( where two teeth in the same arch meet )and the thing about interproximal decay is it can seem to appear literally overnight. Of course it does not really appear overnight but what happens is the enamel ( The really hard outer shell) in one or both teeth at the contact point develops a tiny "pore" of decay, which spreads very quickly into the underlying and softer dentine. The decay can spread much more quickly in the dentine and not much is visible in the mouth (unless you know what to look for) until the enamel caves in over the softened dentine and a cavity appears seemingly from nowhere.
Although fluoride at the correct concentration is a great strengthener of enamel there is some evidence that fluoride strengthened teeth are at even more risk of decay progressing unnoticed, but only once the decay has started if you get what I mean. In other words this is not an argument against fluoride which definately does protect against decay, but if interproximal decay does get a foothold the dentine can decay to a greater extent before the enamel caves in the problem gets noticed.
Incidentally , interproximal decay shows up earlier in x-rays that by careful oral examination, but few parents are happy to have their child's apparently perfect teeth x-rayed "just in case". Also not too many young kids are very cooperative with the process of obtaining a decent x-ray.
Wendy makes an excellent point about sugars in things like fromage frais and weetabix; think of it this way - the bacteria in plaque which feed on sugars in food and drink to produce acid (which causes decay) are microscopic, tiny bugs. They don't need a huge quantity of sugar to do their damage. Bacteria can metabolise tiny amounts of sugar. And not all mouths are created equal in terms of the type of bacteria they play "host " to! Certain bacteria are far more efficient than others at this process, which is why some very unlucky individuals can take better than average care of their/ their children's teeth and still get decay. while others feed their kids junk and don't brush their teeth carefully yet escape problems. However these are two extremes and not an excuse to think you or your kids are genetically programmed regards the fate of your teeth!
Ahem! Is anyone still awake??!