How do we determine where the teeth should go in a smile?
I am often asked by patients how the teeth should look in a smile when we are restoring wear, poor positioning, or missing teeth. There are three main determinants. The first is related to the lips and how they are positioned and how the lips move when smiling. Some people have a really big smile and show lots of teeth (10%). Others have a very low lip line and show very little tooth (20%). The other 70% have what is considered to be an average lip line where the lip rests at the necks of the top teeth in full smile.
Age also plays a part in tooth display. As we age, less tooth is shown on the top and more on the bottom. So, at age 30 the display is 3.0 to 3.5 mm, at 50 it becomes 1.0 to 1.5 mm, and by 70 less than 1/2mm. This of course is related more to facial changes than tooth changes but can be accentuated with tooth wear. We work through these issue with trial (prototypes) teeth to assure an esthetic outcome.
These are guidelines that are used in combination with other factors that I will discuss in the next Blog.