OE L13 Eruption Patterns Flashcards
What are the 4 stages of tooth eruption?
- Pre-eruptive phase
- Intra-osseus eruption
- Mucosal penetration
- Supra-osseus eruption
What sequence do the deciduous teeth erupt in?
- A
- B
- D
- C
- E
Mandibular teeth erupt before maxillary teeth
Tooth A eruption, calcification beginning and enamel completion dates
- 6-10 months
- 4 months iu
- 2 months
Tooth B eruption, calcification beginning and enamel completion dates
- 8-12 months
- 4 and a half months iu
- 3 months
Tooth D eruption, calcification beginning and enamel completion dates
- 12-15 months
- 5 months iu
- 6 months
Tooth C eruption, calcification beginning and enamel completion dates
- 18-20 months
- 5 months iu
- 9 months
Tooth E eruption, calcification beginning and enamel completion dates
- 24-36 months
- 6 months iu
- 12 months
What sequence do the teeth of the mandibular arch erupt in?
Mandibular arch
- 1st molar
- central incisor
- lateral incisor
- canine
- 1st premolar
- 2nd premolar
- 2nd molar
What sequence do the teeth of the maxillary arch erupt in?
Maxillary arch
- 1st molar
- central incisor
- lateral incisor
- 1st premolar
- 2nd premolar
- canine (long distance to travel)
- 2nd molar
Eruption dates of the teeth of the mandibular arch
6-7: first molar 6-7: central incisor 7-8: lateral incisor 9-10: canine 10-12: 1st premolar 11-12: 2nd premolar 11-13: second molar 17-21: third molar
Eruption dates of the teeth of the maxillary arch
6-7: first molar 7-8: central incisor 8-9: lateral incisor 10-11: 1st premolar 10-12: 2nd premolar 11-12: canine 12-13: 2nd molar 17-21: 3rd molar
Are these eruption dates completely accurate?
No they are approximate, give or take 6 months.
Teeth also tend to erupt sooner in girls than boys.
Dates of calcification beginning in permanent dentition
Calcification date =
crown eruption date minus 6/7 years
Dates of crown completion (enamel completion) in permanent dentition
Crown completion date = crown eruption date minus 3/4 years
Root development in decidous teeth
Roots complete 12 months after eruption
Root development in permanent dentition
Roots complete 3 years after eruption
What does root development entail?
Root apex closes.
Walls of root change from thin to thick.
Describe the first stage of eruption: pre-eruptive phase.
- Tooth remains in bony crypt
- Initiation of root formation stimulates dental follicle to initiate tooth eruption
- Dental follicle recruits growth and transcription factors and hormones for osteoclastogenesis and osteogenesis
Describe the second stage of eruption: intra-osseus eruption.
- Bone resoprtion on coronal side of the tooth creates an eruption pathway
- Bone is deposited in apical follicle, translocating tooth occlusally
- Bone deposited in bucco-lingual aspect forming dento-alveolar process
Describe the third stage of eruption: mucosal penetration.
- As tooth reaches mucosa, reduced enamel epithelium fuses with oral epithelium to form CT complex which eventually becomes an epithelial plug
- Cells of enamel epithelium form an epithelial lined canal through which the tooth erupts, means eruption without bleeding
- Junctional epithelial cells transform to squamous mucosal cells with time
Describe the fourth stage of eruption: supra-osseus eruption phase.
- Tooth continues to erupt at fast rate of 25-75um per day
- Movement occurs when sleeping
- Drift continues throughout life due to remodelling of the periodontal ligament
- PDL contains the chemical mediators required for tooth movement
What factors control the speed of intra-osseus movement?
- Genetic factors
- Local environmental factors e.g. crowding, trauma, supernumeraries or cysts, premature loss of deciduous teeth
- Distance a tooth must travel e.g. upper canine longest distance, 1st permanent molar shortest distance
What is the pathway in the alveolar bone called?
The gubernacular canal.
Directional patway allowing movement of permanent tooth upwards, widened by bone resorption.
What does the gubernacular canal contain?
A structure called the gubernacular cord.
Contains remnants of the dental lamina and connective tissue.