Eruption of primary and permanent dentitions
TLDRThe video script delves into the fascinating process of tooth eruption, a biological journey that sees developing teeth emerge through the jaw bones and mucosa into the oral cavity. It highlights the diphyodont nature of humans, possessing two sets of teeth: primary (deciduous) and permanent. The eruption process is detailed in three phases: pre-eruptive, where tooth germs grow and position within the jaw; eruptive, commencing with root formation and involving tooth ascent through the bony crypt to oral contact; and post-eruptive, focusing on tooth position maintenance and jaw growth adaptation. The script also outlines the timeline for primary tooth eruption and exfoliation, and the subsequent emergence of permanent teeth, including the variable timing of wisdom teeth. This comprehensive overview emphasizes the complexity and significance of tooth development in human biology.
Takeaways
- 🦷 The eruption of teeth is a process where developing teeth move through the jaw bones and mucosa to emerge in the oral cavity.
- 👶 Humans are diphyodonts, meaning they have two sets of teeth in their lifetime: primary (deciduous) teeth and permanent teeth.
- 👶💭 Primary teeth start erupting around six months of age and are replaced by permanent teeth by about six years of age.
- 📈 Tooth eruption occurs in three phases: pre-eruptive, eruptive, and post-eruptive, each with distinct developmental tasks.
- 🤔 The exact driving force behind tooth eruption is unknown but is believed to involve signals from the dental follicle, root formation, and periodontal ligament (PDL) formation.
- 🦴 In the pre-eruptive phase, tooth germs grow within the jaw bones, moving mesially or distally as the jaw elongates, widens, and increases in height.
- 🌱 Eccentric growth helps the tooth crown reorient itself as the jawbone grows, and bodily movement involves the remodeling of bony crypts for the tooth germ's path.
- 🔑 The eruptive phase begins with root formation, where the tooth ascends through the bony crypt and oral epithelium to enter the oral cavity.
- 🔄 The PDL, including myofibroblasts, plays a crucial role in tooth eruption by providing occlusal force and stabilizing the tooth.
- 🦴 The post-eruptive phase involves maintaining the position of erupted teeth, compensating for jaw growth and wear through cemental deposition and mesial shift.
- 👶📅 The timing of tooth eruption and exfoliation varies, with primary teeth erupting from 6 months to 2 years and permanent teeth starting from 6 to 7 years of age.
- 📚 Wisdom teeth, or third molars, typically erupt between 17 to 25 years of age and sometimes remain impacted or are absent.
Q & A
What does 'diphyadon' refer to in the context of human teeth?
-Diphyadon refers to the fact that humans have two sets of teeth during their lifetime: the primary (deciduous) teeth and the permanent teeth.
At what age do primary teeth typically start to erupt in humans?
-Primary teeth, also known as deciduous or baby teeth, start erupting at around six months of age.
What is the general age range for the exfoliation of primary teeth and the emergence of permanent teeth?
-Primary teeth usually fall out and are replaced by permanent teeth between the ages of about six and twelve years.
What are the three phases of tooth eruption?
-The three phases of tooth eruption are the pre-eruptive phase, the eruptive phase, and the post-eruptive phase.
What factors are thought to contribute to the driving force behind tooth eruption?
-The driving force behind tooth eruption is thought to be a combination of signals from the dental follicle, root formation and elongation, and the formation of the periodontal ligament (PDL) which provides occlusal force aiding eruption.
How does the pre-eruptive phase contribute to the positioning of tooth germs within the jaw?
-In the pre-eruptive phase, the tooth germs grow within the jaw bones, and as the bones grow in length, width, and height, more space becomes available for the tooth germs to spread out and grow without affecting each other.
What is the role of the reduced enamel epithelium during the eruptive phase of tooth eruption?
-During the eruptive phase, the reduced enamel epithelium proliferates along with the overlying oral epithelium to form a single membrane, which the tooth pierces to enter the oral cavity.
How does the formation of the periodontal ligament (PDL) contribute to the eruption process?
-The periodontal ligament (PDL) forms as collagen bundles get invaded by fibroblasts that lay down fibrous tissue, thickening the bundles. The PDL, including myofibroblasts with contractile properties, aids in speeding along the eruption process and helps stabilize the tooth.
What happens to the bony crypt after a tooth erupts?
-After a tooth erupts, the space left behind at the bottom of the bony crypt gets filled up by fine bony trabeculae, also known as the bony ladder, which provides support to the apical tissues. This bony ladder is eventually resorbed to give way for the developing root tip.
What is the significance of the post-eruptive phase in maintaining the position of erupted teeth?
-The post-eruptive phase is significant for checking if the teeth remain in the optimal position and correcting any abnormalities due to jaw growth and occlusal or interproximal wear. It involves the deposition of new bone along the socket floor and compensation for wear through cemental deposition or mesial shift.
What are the approximate ages for the eruption of permanent molars and incisors?
-Permanent first molars usually appear around six to seven years of age, and the lower central incisors erupt at around the same time. Upper central incisors and upper and lower lateral incisors erupt around seven to eight years of age.
Outlines
🦷 Tooth Eruption Process Overview
The paragraph explains the biological process of tooth eruption in humans, which involves the movement of developing teeth through the jaw bones and mucosa to emerge in the oral cavity. It highlights that humans have two sets of teeth: primary (deciduous) and permanent. The paragraph outlines three phases of tooth eruption: pre-eruptive, eruptive, and post-eruptive. It also discusses the unknown driving force behind this process, which is thought to involve signals from the dental follicle, root formation, and the formation of the periodontal ligament (PDL). The pre-eruptive phase is characterized by the growth of tooth germs within the jaw, while the eruptive phase involves the tooth's ascent through the bony crypt and contact with the oral epithelium. The post-eruptive phase focuses on the tooth's positioning and response to jaw growth and wear.
🌱 Eruption and Development of Tooth Roots
This paragraph delves into the specifics of tooth root development and the formation of the periodontal ligament during the eruptive phase. It describes the proliferation of the epithelial root sheath and the appearance of collagen fibers that form the PDL. The role of myofibroblasts in accelerating eruption and the dynamic attachment and detachment of PDL fibers from the tooth are also mentioned. The paragraph further explains the changes in the bony crypt and the filling of the space left behind by the bony trabeculae, which support the apical tissues. It concludes with the post-eruptive phase, which involves the tooth's maintenance in the oral cavity, including the deposition of new bone and compensation for wear.
📅 Timeline of Tooth Eruption and Exfoliation
The final paragraph provides a detailed timeline of the eruption and exfoliation of primary and permanent teeth. It starts with the eruption of primary teeth, commonly known as teething, which begins around 6 months and continues until about 24 months of age. The paragraph lists the specific ages for the eruption of different types of primary teeth and their subsequent exfoliation. It then describes the emergence of permanent teeth, beginning with the first molars around six to seven years of age, followed by incisors, canines, and premolars at various ages. The second permanent molars erupt around 12 to 13 years, and third molars, or wisdom teeth, may erupt between 17 to 25 years or remain impacted. The paragraph emphasizes the variability in eruption and exfoliation times among different teeth.
Mindmap
Keywords
💡Tooth Eruption
💡Primary Teeth
💡Permanent Teeth
💡Pre-eruptive Phase
💡Eruptive Phase
💡Post-eruptive Phase
💡Dental Follicle
💡Periodontal Ligament (PDL)
💡Root Formation
💡Occlusal Force
💡Myofibroblasts
Highlights
Humans are diphyodonts, having two sets of teeth in their lifetime: primary and permanent.
Primary teeth, also known as deciduous or baby teeth, start erupting at around six months of age.
Primary teeth are replaced by permanent teeth by the age of six years.
Tooth eruption occurs in three phases: pre-eruptive, eruptive, and post-eruptive.
The driving force behind tooth eruption is thought to involve signals from the dental follicle, root formation, and elongation.
Pre-eruptive phase involves growth of tooth germs within the jaw bones as bones grow in length, width, and height.
Bodily movement and eccentric growth are two methods of tooth germ movement during the pre-eruptive phase.
Permanent tooth germs change position in relation to primary tooth germs, influenced by jaw growth and primary tooth movement.
Permanent molars develop in a cramped space, with crowns tilted until jaw growth allows for a more vertical position.
Eruptive phase begins with root formation, the tooth ascends through the bony crypt and contacts the oral epithelium.
Eruptive pathway is cleared through bone and connective tissue, facilitated by the secretion of CSF1 and TGF beta1.
The periodontal ligament (PDL) forms as collagen fibers are invaded by fibroblasts and thicken to support the tooth.
Myofibroblasts in the PDL are thought to speed up the eruption process due to their contractile properties.
Post-eruptive phase involves maintaining the position of erupted teeth and compensating for jaw growth and tooth wear.
Mesial shift is a process that compensates for interproximal wear by a combination of forces acting on the teeth.
Eruption and exfoliation times vary among different types of teeth, with primary teeth starting to erupt at 6 months and permanent teeth at 6 years.
Wisdom teeth, or third molars, may not erupt until the ages of 17 to 25, and sometimes remain impacted or are absent.
Transcripts
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