Which number refers to which tooth?



You have probably already seen that dentists mark the teeth with a special numbering method in the treatment plans. This method is also used in the dental lab so that misunderstandings can be avoided when it comes to a particular tooth. What do these numbers mean exactly? How can you interpret it? We are now taking a closer look at this issue.



The winning numbering method


The question of tooth numbering was also an issue in the advancement of dentistry. As time passed there were a lot of numbering methods but the most widely spread was the one that was developed by the World Dental Federation (FDI). Most of the dentists work based on this method in the world and it is taught in most of the universities.

 

Left side or right side?


Like in the case of theatres, the left side and the right side numbering is also an interesting question in dentistry. Shall we see it from the patient’s or the doctor’s point of view? In theatres there are the “director right and left” sides so the director who is standing opposite the actors marks the importance of the sides. Director right means the left side of the actors.


The case is similar in dentistry. The injured tooth on the right side of the patient’s mouth is on the left side of the treatment plan so it is the reflection.

 

Tooth numbering - Left side or right side

RIGHT side                    LEFT side

(Image source: PlanMaster 3D) 

 


The teeth on the left side of the treatment plan are on the right side of the patient’s mouth in real life.


 

What do the numbers mean?


The numbers used for identification show whether we are talking about the upper or lower jaw and the exact place of the particular tooth within. All of them are made up of two digits as all the digits are telling more exact information. The numbers should be examined by the digits separately. Let’s see how!

 

The first digits

The first digits shows the quarter of the whole set of teeth that the tooth is: right or left side, upper or lower.

Based on these (counterclockwise):

  • numbers staring with 1:     mark the right upper teeth
  • numbers staring with 2:     mark the left upper teeth
  • numbers staring with 3:     mark the left lower teeth
  • numbers staring with 4:    mark the right lower teeth

 

The second digits


The first digits shows where to find the tooth within a particular the quarter of the whole set of teeth: at the front or at the back.

The front teeth (central incisors) are marked with digit 1, while the very back tooth is marked with digit 8. The various teeth are marked with the following numbers:

  • numbers ending with 1:     mark the central incisors
  • numbers ending with 2:     mark the lateral incisors
  • numbers ending with 3:     mark the canines
  • numbers ending with 4:     mark the first premolars
  • numbers ending with 5:     mark the second premolars
  • numbers ending with 6:     mark the first molars
  • numbers ending with 7:     mark the second molars
  • numbers ending with 8:     mark the third molars

Let’s see and example:

Tooth numbering example
We have selected a tooth from the photo above: tooth no. 14


Regarding tooth no. 14 the first digit is not. 1 which means that the tooth can be found on the right side of the upper jaw. The second digit is not. 4 which means that we are talking about the 4. tooth counting down from the centre (front) so it is one of the premolars. So,


14 = tooth no. 4 on the right side of the upper jaw


It is not that complicated, is it?

A little extra: milk teeth


There is also a numbering in the case of milk teeth but it is a bit different:

 Upper right Upper left
 -  -  -

 55

 54

 53  52  51  61  62  63  64  65  -  -  -
 -  -

 85

 84  83  82  81  71  72   73  74  75   -  -  -
Lower right Lower left

 


Numbers staring with 5 mark the right upper, numbers staring with 6 mark the left upper, numbers staring with 7 mark the left lower and numbers staring with 8 mark the teeth in the right lower quarter.


The numbers are not connected to digits 1-8, only 1-5. Similarly to the teeth of the adults the numbering starts from the front and goes towards the back.

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