ICP innit Flashcards
three growth periods in post-natal growth
0-6 years primary dentition (deciduous)
6-12 years mixed dentition
12-18 years permanent dentition
primary dentition
6-9 months
- lower a’s -> lower b’s and upper a’s -> upper b’s
1-1.5 years
- lower first molars d’s -> upper first molars d’s
1.5-1.75 years
- lower canines c’s -> upper canines c’s
1.75-2 years
- lower second molars e’s -> upper second molars e’s
generally for tooth growth periods
lower then upper
anterior then posterior
mixed dentition
6 years
- first permanent molar 6’s
6-9 years
- lower 1’s -> lower 2’s and upper 1’s -> upper 2’s
9-11 years
- lower canines 3’s -> upper canines 3’s
10-12 years
- lower first molars 4’s -> upper first molars 4’s + lower second molars 5’s -> upper second molars 5’s
12 years
- second permanent molar 7’s
permanent dentition
17-21 years
- third permanent molar 8’s
clinical crown
from top of enamel to gum line
anatomical crown
from top of enamel to cervical line
what is enamel made up of
calcium hydroxyapatite arranged as crystalline units from enamel-dentine junction called enamel prisms/ rods
cell that produces enamel
ameloblasts
lost when erupted, do not regenerate
decussation
emanel prisms/ rods cross over so it is harder to fracture
difference between deciduous and permanent teeth
deciduous teeth have thinner enamel
deciduous teeth have less scalloped enamel-dentine junction as they form faster
deciduous teeth have higher pulp horns
amelogenesis
process of enamel formation
odontogenesis
formation and development of teeth
what is dentine made up of
collagen fibres (I) and dentinal tubules which contain fluid
formation of dentine
predentine formed by odontoblasts (line pulp border) unmineralised
primary dentine is until root formation is complete
secondary dentine reduces pulp chamber and root canal size
tertiary dentine is protective, responds to stimuli
tertiary reactionary dentine
original odontoblast function in response to weak stimuli/ injury
tertiary reparative dentine
newly recruited odontoblasts begin depositing dentine in response to severe injury
sclerotic dentine
dentinal tubles are occluded with calcified material
what is pulp made up of
fibroblasts maintain pulp matrix with collagen fibres and ground substances
where do vessels and nerves enter tooth
apical foramen
accessory canals
what covers dentine of roots
cementum - mineralised, avascularised connective tissue
periodontal ligaments insert into it
tooth supporting structures
cementum
alveolar bone (lamina dura is compact part where periodontal ligament attaches)
periodontal ligament
gingiva
alveolar bone
mineralised connective tissue part of maxilla and mandible
what is periodontal ligament made up of
collagen I and III, cementoblasts (cementum), fibroblasts (fibres) and osteoblasts (bone)
Sharpey’s fibres
ends of periodontal ligaments that insert into lamina dura of periodontal ligament and cementum
act as shock absorber against masticatory forces
what are gingiva covered in
keratin to protect against abrasive forces during mastication
root completion
1-1.5 years after eruption for primary teeth
<2 - >3 years after eruption for permanent teeth
