Dentin

Primary dentin makes the largest part of the dentin in one tooth. It is the substance that is located both in the crown and roots. It is surrounded by enamel and cementum on the outside and with the pulp chamber on the inside. The primary type is the one created during the eruption of the tooth. Once the tooth is in the mouth and starts its function, that is the moment when secondary dentin is created. The outer layer of primary dentin is the most important one. Known also as mantle dentin, it has a significant role in the creation of secondary and tertiary one. This layer includes cells called odontoblasts that are capable to produce new dentin tissue.

Secondary dentin is the one created after the tooth has erupted. It appears only after the root is completely formed. It is created by the odontoblast cells and contains fewer minerals compared to the primary one. The newly created layers are irregular. As the years pass by, this dentin makes the pulp chamber smaller, which is why elderly people are more tolerant of pain. Young kids have large pulp chambers which have to be considered during treatment.

Tertiary dentin is produced when the tooth has to protect itself from a bacterial attack. It is also known as reparative dentin. The stimuli can be of different type, but the most common one is dental caries. So if caries has reached the dentin, but it is a chronic process and the patient has a strong immune system that can fight the infection, there will be tertiary dentin. The process can be fast or slow, which completely depends on the type of stimulus. The new layer of tertiary dentin creates a barrier between caries and the dental pulp. It has a protective function.