Final Exam Flashcards
primary teeth begin to form in
3rd month in utero
calcification 14-17 weeks
short term growth cessation at birth can leave a development line in bone/enamel called
neonatal line
in the primary teeth, the first tooth to erupt is ___ at ___ age
mandibular central incisor at 6-8 months
all primary teeth should be erupted by
30 months (concern if later than 36 mo) *6 mo fluctuation
the rule that the primary teeth follow is
4 month rule–>once teeth do start erupting anticipate to see a new tooth every 4 months
dentition is relatively stable at what age
3-6 years
normal features of primary dentition
- spaced anteriors and primate space
- shallow overbite and excess overjet
- flush terminal plane
- vertical inclination of incisors
- ovoid arch form
primate space is
space between Mx lateral and canine / Mn canine and 1st molar
*due to permanent teeth being about 1.5-2.5 mm bigger than primary
primary teeth tend to have more ____ overbite and ____ overjet
- shallow overbite
- excess overjet (Class II)
- due to maxilla growing A-P faster than vertically
once posterior teeth in primary dentition deveope, the molar relationship is classified on basis of terminal primary molars. How do you know what class they will become in permanent teeth?
- with flush terminal plane of posterior molars = Class I (71%)
- with distal step of mandibular = Class II (10%)
- with medial step of mandibular = Class I or Class III (19%)
pattern of exfoliation/eruption of permanent teeth
- elongation of root of permanent tooth
- resorption of the root of the deciduous tooth and/or bone overlying tooth
- movement of permanent tooth
- vertical growth of alveolar process
in the process of pre-emergent eruption, what are the 2 things that need to happen
- resorption - of overlying bond and roots of primary teeth
2. eruption - mechanism itself pushes tooth into created space
eruptive movement in pre-emergent eruption begins
soon after root formation begins (during crown formation virtually no movement)
rate of bone resorption and rate or tooth eruption are controlled by different mechanisms, but molecular studies show…
tightly coordinated process between dental follicle and alveolar bone
possibilities for eruption mechanism
Not as likely:
- PDL contraction theory: collagen/fibroblast maturation
- root elongation theory: proliferation of cells at apex
- bone remodeling theory: bone pushes the tooth- apical base remodeling
Likely:
- hydrostatic pressure theory: fluid/vasulature pressure similar to post-emergent
- dental follicle theory: stellate reticulum cells secrete chemo-attractants that cause osteoclastogenisis
post emergent spurt
rapid eruption to occlusal surface after gingival penetration (up to 4mm in 6-8 weeks), then slows considerably as teeth occlude
juvenile occlusal equilibrium
eruption matches vertical Mn growth during adolescence
adult occlusal equilibrium
after growth has stopped, rate of attrition during adulthood
active vs passive eruption
- active: tooth moves in direction of occlusal plane
- passive: exposure of tooth by apical migration of gingiva
how much of the root is usually formed when teeth erupt
3/4 of root formed
root formation is completed how long after full eruption
2-3 years
the general rule for eruption for a permanent tooth is: a permanent tooth on one side erupts within ___ of its counterpart on the other side
6 months
essential factors for a smooth transition to permanent dentition
- anterior spacing in primary teeth (incisors)
- posterior spacing (Leeway space)
- changes in arch form
- tooth size and jaw in harmony
what is C space, D space, and E space
- leeway spaces in primary dentition
- C space = primary canine - permanent canine
- D space = primary 1st molar - Mx 1st premolar
- E space = primary 2nd molar - Mx 2nd molar
incisor liability
- transitional crowding
- erupting permanent incisors are larger than space available at the time
