Teeth by Numbers


Why Do Dentists Count Teeth?

Have you ever noticed when your dentist or hygienist examines your teeth that a lot of numbers seem to fly around? That’s because Dentists use a variety of numbering systems to identify teeth in our mouth. Today, the F.D.I. (Federation Dentaire International) system is being increasingly adopted worldwide. In this system, the permanent teeth are given two numbers, the first number indicating the quadrant and the second number identifying each tooth in the quadrant.

So, the Patient’s upper right quadrant of the mouth is referred to as 1, then each tooth in this quadrant is numbered from 1 to 8, moving from the incisors back to the molars.



The quadrant numbers are

Upper Right – 1 Upper Left – 2

Lower Right – 4 Lower Left – 3

Remember, it’s the patient’s left or right, not the dentists!


How Many Teeth Does An Adult Have?

Our second set of permanent teeth are often referred to as adult teeth and usually being to appear when a child is six to seven years of age. At five to twelve years of age the maxillary arch and the mandibular arch enlarge and grow.

The permanent teeth begin to exert pressure on the primary teeth and the primary teeth begin to shed or fall out. During this stage, the child has some primary teeth and some permanent teeth. There are 32 permanent teeth in the normal adult mouth. However, not all individuals develop a full complement of 32 teeth and it is not unusual for some teeth to be absent. In many instances, the third molars never appear and there is considerable variation in the age at which they erupt.

Sometimes, extra teeth appear in excess of the normal thirty-two. They often have to be removed to prevent injury to adjacent teeth or to improve the patient’s appearance.

Can Adults Have Baby Teeth?

Baby teeth within adults is actually quite common. Adult baby teeth are also known as retained baby teeth. People who have adult baby teeth will often find the second molar is most likely to stay retained. This is because it often doesn’t have a permanent one growing behind it. Some adult baby teeth do require treatment, however, and leaving them untreated can cause complications with tooth development. It is always best to follow the advice of your dentist in this situation.