Eruption of primary and permanent dentitions

Summary

This video provides a detailed overview of the process of tooth eruption, which occurs in three phases: pre-eruptive, eruptive, and post-eruptive. It explains how developing teeth move through jaw bones and mucosa to emerge into the oral cavity. The script covers the stages of tooth eruption, from the formation and movement of tooth germs in the jaw to the eruption of primary and permanent teeth. The process also includes the role of various factors like root formation, dental follicle signals, and the development of the periodontal ligament. The video emphasizes the importance of the eruption phases and how teeth maintain their position through growth and wear.

Takeaways

• 😀 Tooth eruption is the process where developing teeth move through the jaw and mucosa to emerge into the oral cavity.
• 😀 Humans are diphyodonts, meaning we have two sets of teeth during our lifetime: primary (baby) teeth and permanent teeth.
• 😀 Primary teeth start erupting around six months of age and fall out by about six years, replaced by permanent teeth.
• 😀 Tooth eruption occurs in three phases: pre-eruptive, eruptive, and post-eruptive.
• 😀 The driving force behind tooth eruption is still unclear but likely involves factors such as signals from the dental follicle, root formation, and the periodontal ligament.
• 😀 In the pre-eruptive phase, tooth germs grow within the jaw as the bones expand, allowing space for the teeth to spread out.
• 😀 During the eruptive phase, the tooth moves through the bone and connective tissue, coming into contact with the oral epithelium to emerge into the oral cavity.
• 😀 The post-eruptive phase focuses on maintaining the position of teeth after they emerge, compensating for changes due to jaw growth and wear.
• 😀 Permanent molars erupt before primary teeth are lost, with no exfoliation of an overlying primary tooth required for their eruption.
• 😀 The eruption timeline for primary and permanent teeth varies, with wisdom teeth (third molars) typically erupting between the ages of 17 and 25, or not at all.

Q & A

What is tooth eruption?

Tooth eruption is the process by which developing teeth move through the jaw bones and overlying mucosa to emerge in their respective place within the oral cavity.

What does it mean for humans to be diphyodonts?

Humans are diphyodonts, meaning we have two sets of teeth during our lifetime. The first set is the primary (baby) teeth, and the second set is the permanent teeth that last for the rest of our lives.

When do primary teeth typically start erupting?

Primary teeth typically start erupting at around six months of age.

How many phases are involved in tooth eruption, and what are they?

Tooth eruption occurs in three phases: the pre-eruptive phase, the eruptive phase, and the post-eruptive phase.

What factors are believed to contribute to the eruption of teeth?

The eruption of teeth is believed to be driven by a combination of factors, including signals from the dental follicle, root formation and elongation, and the formation of the periodontal ligament (PDL), which provides occlusal force to aid eruption.

What happens during the pre-eruptive phase of tooth eruption?

During the pre-eruptive phase, tooth germs grow within the jaw bones as the bones grow in length, width, and height. The growth of the jaw provides space for the tooth germs to spread out without interfering with each other.

How does the positioning of permanent teeth change during the pre-eruptive phase?

At the beginning of the pre-eruptive phase, permanent tooth germs are positioned lingual to the primary teeth, and by the end of the phase, they move into a position where the permanent anterior teeth are lingual and apical to the primary teeth, and the premolars rest under the primary molars' roots.

What role do osteoclasts play during the eruptive phase?

Osteoclasts are attracted to the eruptive pathway by signals from the dental follicle. They resorb the bony crypt overlying the tooth, helping create a clear path for eruption.

What happens during the post-eruptive phase of tooth eruption?

In the post-eruptive phase, the tooth remains in the oral cavity, and adjustments are made to maintain its position. This phase involves compensating for jaw growth, occlusal wear, and interproximal wear through processes like mesial shift and cemental deposition.

At what age do primary teeth typically start to exfoliate?

Primary teeth typically begin to exfoliate around the age of six years, with the process continuing until about twelve years of age.