01.30 development of dentition Flashcards
when do the primary teeth begin to calcify?
In utero
-about 3.5-4.5 months in utero
what is the typical eruption sequence of primary teeth, and when does it start/end?
beings around 6-7th month (mandibular incisors) and ends about the 26th month (maxillary 2nd molars)
when do the teeth start moving occlusally (towards eruption)?
after the crown formation is complete
dental arch circumference decreases…
during the late transitional and early permanent dentition (maybe after 4 years old)
-so basically a 4 years old has a longer arch length than kids that are older
how soon after eruption is the root completely formed for both primary and permanent teeth?
- primary: 18 months post eruption
- permanent: 3 years post eruption
how many teeth does a typical one year old have?
6-8, rarely less than 2 or more than 10
teeth present at birth are called?
Natal teeth
teeth present within the first 30 days of life are called?
Neonatal teeth
which is more prevalent, Natal or neonatal teeth, and what is the ratio?
Natal 3:1 Neonatal
incidence 1:2000-3000
-90% are true primary teeth
characteristics of ideal primary dentition
- spaced anteriors
- primate spaces (around canines, distal in mandibular, mesial in maxillary)
- shallow overbite and overjet
- flush or mesial step terminal plane
- class I canine relationship
- almost vertical inclination of anterior teeth
- ovoid arch form
structures in newborns that are often confused with premature teeth
- dental lamina cysts: crest of ridge
- Bohn’s Nodules: buccal and lingual aspects of ridge palate (away from midline raphe)
- epstein’s pearls: midpalatal raphe
primate spaces
wide spaces mesial to the maxillary canines and distal to mandibular canines
-important during canine and bicuspid eruption
if a child has a distal step, what will likely be the permanent classificaiton?
class II
what is the desired inclination for permanent and primary teeth
primary incisors are upright with little overbite and overjet
-permanent incisors have labial angulation and greater overbite and overjet
mandibular intercanine width changes
-the intercanine width increases only slightly with the eruption of the permanent incisors due to divergent nature of the distal movement of the primary canine into the primate spaces
how big is the Leeway space?
- 9 mm in maxilla per side (1.8 total)
1. 7 mm in mandible (3.4 mm total)
early mesial shift
- the eruptive force of the permanent molar causes generalized spaces to close allowing the permanent molar to shift into a class I occlusion
- about 6 yrs old, primate space closed
late mesial shift
when no primate spaces exist, the permanent molar shift occurs when the second primary molar exfoliates in the mandible before the maxilla
-usually around 12 yr old
Histopathology: initiation
problems of tooth #, congenitally missing is more common than super numerary
Histopathology: proliferation
problems of tooth #, size, proportion, twinning
what is the most common congenitally missing permanent tooth?
mandibular second premolars
Histopathology: histodifferentiation
problems of enamel (AI 1 &4) and Dentin (DI)
Histopathology:morphodifferentiation
problems of size, shape
Histopathology: appostion
enamel hypoplasia, dentin dysplasia, hypercementosis, enamel pearly
Histopathology: mineralizaiton and maturation (post eruptive)
AI (2,3,4), flourosis, localized hypomineralization, intergolbular dentin
what is the sequence of clacification of primary teeth?
A, D, B, C, E
what is the first permanent tooth to begin calcification, and when does that occur?
1st molar, birth
eruption sequence of primary teeth
A, B, D, C, E
