Have you ever heard of "supernumerary teeth"?

This is the 4368th article of Da Yi Xiao Hu

A 6-year-old child came to see the dentist. His mother said that the child had replaced his teeth and new teeth had grown on top. Should the baby teeth be extracted? We found that there was a small tooth cusp exposed in the maxillary anterior area, which was cone-shaped and different from the normal shape of the incisors. We initially considered it to be a supernumerary tooth, not a replacement of the child's teeth. The child's mouth is shown in the following figure.

Figure 1

1. What is “supernumerary teeth”?

Supernumerary teeth refer to teeth that occur outside the normal dentition (any extra teeth other than the 20 deciduous teeth and 32 permanent teeth in the normal dentition), also known as extra teeth. Supernumerary teeth can occur in both deciduous and permanent dentitions, but are relatively rare in deciduous dentition, with an incidence of 0.3% to 0.6% in deciduous dentition, with a male-female ratio of 2:1, and an incidence of 1.5% to 3.5% in permanent dentition. Studies have found that if supernumerary teeth occur in the deciduous dentition, the probability of supernumerary teeth occurring in the permanent dentition is 30% to 63%.

2. Common sites of supernumerary teeth

Supernumerary teeth are more common in the maxillary anterior teeth area, and are mostly cone-shaped. The erupted supernumerary teeth are easy to find, and often present small tooth-like changes. It is very easy for clinicians to distinguish them, just like the child above. The premolar area is also prone to supernumerary teeth, and the shape is very similar to normal premolars, so special attention should be paid to distinguish them.

3. Number of supernumerary teeth

Are there usually only one supernumerary tooth? I once saw an adult sister with a supernumerary tooth that had already erupted in her mouth. I suggested to extract it, but she said it couldn't be extracted because it would grow back after extraction. She said she had extracted a supernumerary tooth before and another one grew back afterwards. Are supernumerary teeth going to grow back like mushrooms after a spring rain? The answer is no. The number of supernumerary teeth varies. Some have one (as shown in Figure 2), some have more than one, and it is possible to have more than a dozen. How to find them? Some supernumerary teeth are discovered because abnormally shaped teeth erupt in the mouth, such as the child we saw above, who was discovered because supernumerary teeth grew out. Most supernumerary teeth are impacted in the jawbone and often require imaging examinations to be discovered (as shown in Figure 3). So it can be understood that this sister has multiple supernumerary teeth.

Figure 2

Figure 3

4. Impact of supernumerary teeth

The presence of supernumerary teeth affects the eruption of adjacent teeth, interferes with the normal development of dentition occlusion, and affects the normal development and eruption of surrounding teeth, resulting in delayed eruption, torsion, tooth gaps, abnormal root development, etc. The case shown in Figure 3 shows that supernumerary teeth affected the normal eruption of the right central incisor.

Supernumerary teeth will have adverse effects on the growth and development of the dentition, so timely and correct treatment is needed. Supernumerary teeth and their complications have adverse effects on the normal development of the dentition, so early diagnosis and timely treatment by clinical physicians are urgently needed.

Author: Department of Stomatology, Affiliated Hospital of Guangdong Medical University

Jia Shujuan