Sit in on a smile consultation and you'll hear us use a few words that sound like jargon: lip line, smile arc, buccal corridors. They're simpler than they sound. You can check every one of them in your bathroom mirror.
Lip line: how much shows when you smile
Smile properly, the way you would at a friend's joke, and look at your upper lip. How far does it lift? That's your lip line.
For some people the lip stays low and covers part of the front teeth. For most, the full length of the teeth shows, with little triangles of gum peeking between them. And for some, the lip rises high enough to show a band of gum above the teeth. A couple of millimetres of gum is perfectly normal. When it's a lot more, people tend to call it a gummy smile, and many of them have spent years smiling with their mouth half closed because of it.
Why do we care? Because it tells us where to look. If your lip never lifts above the teeth, nobody sees your gum line and we can concentrate on the teeth. If your lip lifts high, the gums become just as important as the teeth, and an uneven gum line will show in every photograph.
Smile arc: the curve of the edges
Now look at the biting edges of your top front teeth. Do they form a gentle curve, or a straight line? In most young, natural smiles the edges curve slightly, following the line of the lower lip as it rises towards the corners of the mouth.
Over the years that curve often flattens. Grinding at night, a habit of biting thread or nails, or simply decades of chewing wear the front teeth down. A flat smile arc is one of the reasons a smile can look older than the face around it. Bringing back a soft curve, even by a millimetre or two, can make a real difference.
Buccal corridors: the shadows at the corners
This is the one with the strange name. When you smile wide, there's a small dark space at each corner of your mouth, between your back teeth and the inside of your cheeks. Dentists call these buccal corridors (buccal just means "to do with the cheek").
A little shadow there is good. It gives a smile depth. If the shadows are wide, the smile can look narrow, as if the teeth stop too soon. If they disappear completely, the smile can look like a wall of teeth, which is just as odd. When a smile looks narrow, the side teeth are usually tipped inwards or a bit small. Depending on the cause, aligners can widen the arch, or veneers and bonding can bring the side teeth out slightly.
A couple of others
You may also hear us talk about incisal display, which is simply how much of your top teeth shows when your lips are relaxed and slightly apart. In younger adults it's usually a few millimetres, and it shrinks with age as the lip muscles relax. And the midline is the line between your two front teeth. Ideally it sits close to the centre of your face and runs straight up and down rather than at a tilt.
How we record all this
We don't judge these things by eye alone. At the consultation we take photographs and a short video of you talking and smiling, because a posed "say cheese" smile often hides what your everyday smile looks like. Then we measure everything on screen, over pictures of your own face. None of these terms is a rule to force on you. They just give us, and you, a shared way to talk about what you'd like to change.
In the next post we'll get to colour, and why "white" isn't a single shade.