I'm always amazed at the fact that when a baby is born, their jaw bones already house not only an entire set of baby teeth but also the very beginnings of all their adult teeth – so much crammed into such a tiny space.
Our two upper adult front teeth erupt around 7 years old. Teeth love erupting in pairs, with left and right dropping down into position almost simultaneously. They are engaged in an imperceptibly slow, silent dance of astonishing biological engineering, egged on by numerous chemical helpers and fuelled by the power of the facial muscles.
With the trillions of interactions that need to occur in a particular order, it's no wonder that sometimes things go astray with obvious manifestations. Sometimes only one of the big front teeth erupt into position leaving a lonely gap stage centre of a child's smile.
This can be worrisome to parents, who rightly wonder where the other tooth is. A partner tooth is only considered late if it's more than six months delayed, because there's such a wide range of normal development.
So where is this missing tooth? The most common cause is that there simply isn't enough room for the tooth to come in – the jaws have failed to grow to their full size and the adult tooth is jammed high up.
Other times it's down to things that happened many years before, like if a toddler suffers a bang to a baby tooth which can damage the adult tooth above.
A developing tooth has what's called a tooth sac around its crown. It's like an astronaut's helmet protecting the tooth on its journey through the jawbone. If a baby tooth is forced inwards by a knock, the tooth sac can be pierced, and this can put a halt to the chemical eruption fox-trot.
The body can also, for unknown reasons, decide to make an extra oddly shaped tooth. This typically, unhelpfully develops in the path of the big front tooth, blocking its way to the mouth.
In any case the dentist takes an X-ray to determine the exact problem. With superfluous teeth removed, often this allows the big tooth to recommence its journey and if not, braces are called upon to lend an extra hand to get the ball over the touchline.
