Tooth Morphology – Primary (Part B)
Primary Dentition
There are 20 primary teeth: 10 in the maxillary arch and 10 in the mandibular arch. These teeth include incisors, canines and molars.
The primary teeth are smaller overall and have whiter enamel than permanent ones. This is due to the increased opacity of the enamel that covers the underlying dentin.
The crown of any primary tooth is short in relation to its total length. The crowns are narrower at the cementoenamel junction (CEJ). The roots are narrower and longer than the crowns.
The pulp chambers and pulp horns in primary teeth are relatively large compared with those of the permanent teeth. A thick dentin layer exists between the pulp chambers and the enamel, especially in the primary mandibular second molar. The enamel layer is relatively thin.
Clinical Considerations with Primary Teeth
Often, parents do not understand the importance of the primary teeth. Primary teeth hold the eruption space for the permanent teeth, and if lost prematurely, problems with tooth alignment, spacing, and occlusion may result later.
Primary teeth assist with chewing, enhance appearance, and assist with speech. They also support the cheeks and lips. Because the enamel and dentin are thinner in primary teeth, decay can travel quickly through the enamel to the pulp, possibly causing tooth loss. Early dental health education and dental care are essential for the primary dentition.
Primary Teeth
View the slides below to learn more about the primary teeth.
Primary Molars
The primary dentition consists of a total of eight primary molars. Each quadrant includes a first primary molar and a second primary molar. Each molar crown is wider than it is tall. The permanent premolars replace the primary molars when they are exfoliated.
View the slides below to learn more about the primary molars.
Primary Dentition in Order of Eruption
Here is a table showing the order of eruptions for primary dentition.
| Dentition | Date of Eruption | Date of Exfoliation |
| Maxillary Teeth | ||
| Central Incisor | 6-10 months | 6-7 years |
| Lateral Incisor | 9-12 months | 7-8 years |
| First Molar | 12-18 months | 9-11 years |
| Canine | 16-22 months | 10-12 years |
| Second Molar | 24-32 months | 10-12 years |
| Mandibular Teeth | ||
| Central Incisor | 6-10 months | 6-7 years |
| Lateral Incisor | 7-10 months | 7-8 years |
| First Molar | 12-18 months | 9-11 years |
| Canine | 16-22 months | 9-12 years |
| Second Molar | 20-32 months | 10-12 years |
You have completed Module 8B. Please return to Blackboard for the next steps.
Media Attributions
- Images from: Modern Dental Assisting, 13th and 14th Edition
