tooth eruption and normal dental development Flashcards
(33 cards)
birth - newborn baby dental features
- gum pads
- upper rounded
- lower “u” shaped
often appear class II
AOB
when do the first primary teeth usually erupt?
6 months
By what age are all primary teeth usually erupted?
24-36 months
in what order do the primary teeth erupt?
a-b-d-c-e
primary dentition - occlusal features
incisors more upright
spaced - presence of anthropoid spaces and may present with generalised spacing
tooth wear
- incisors after a period of time may tend towards edge to edge
if there is less than 3mm space, what is the chance of crowding in the permanent dentition?
50%
how much space is required between primary teeth to guarantee that there will be no crowding in the permanent dentition?
> 6mm
neo natal teeth - features
- abnormal dental development
- lower incisors present at or just after birth
- may be supernumerary or very early normal primary central incisors
indications for extractions of Neo-natal teeth
- tooth mobile and presents inhalation risk
- tooth causing difficulty with breastfeeding
when does the pre eruptive phase begin and end?
starts when the crown starts to form and ends when crown formation is complete/root formation about to start
when does the eruptive phase begin and what is it split into?
-starts as soon as root starts to form and ends when teeth reached the occlusal plane
- split into intra-osseous stage and extra osseous stage
post eruptive phase
tooth movement/eruption continues as the root forms and throughout life in extremely small amounts
in the pre-eruptive phase, how do the developing crowns move in the jaws
- they reposition themselves in response to increasing length, width and height in the jaws
- movement is contained within the bony crypts
Eruptive phase - intra osseous
root formation - starts with proliferation of the epithelial root sheath and continues with production of dentine and pulp
movement of developing tooth in occlusal or incisal direction
reduced enamel epithelium fuses with oral epithelium
eruptive phase - extra osseous stage
penetration of tooth’s crown tip through epithelial layers
crown continues to move through mucosa in an occlusal direction until contact is made with opposing tooth
environment factors such as muscle forces from cheeks, lips and tongue help determine final tooth posiyion
What processes are happening during the eruptive phase?
- resorption of overlying bone
- propulsive mechanism moving the tooth towards the oral cavity
(note - the rates of each of these do not seem to be controlled by the same mechanism)
What controls tooth eruption?
the dental follicle
post-eruptive phase movement (once tooth has already reached occlusal plane)
in response to increases inn height of growing alveolar bone and jaws
in response to attrition and abrasion
- teeth erupt slightly to compensate for wear on occlusal surfaces
- proximal surface tooth wear leads to mesial drift
in response to loss of opposing teeth = over-eruption
Additional space is required to accommodate the larger teeth of the permanent dentition. How is the space gained?
- increase in inter canine width through lateral growth of the jaws
- upper incisors erupting onto a wider arc
- primary canines moving back into the anthropoid spaces (mandible)
- the leeway space
leeway space in the upper arch =
((primary canine + first + second molar) - (permanent canine+ first premolar and second premolar))
1 to 1.5mm
leeway space in lower arch
((primary canine + first molar + second molar) - (permanent canine + first premolar + second premolar))
2 to 2.5mm
eruption sequence in the upper arch (permanent teeth)
6, 1, 2, 4, 5, 3, 7, 8
eruption sequence in the lower arch (permanent dentition)
6, 1, 2, 3, 4, 5, 7, 8
Approximately what age do permanent maxillary molars erupt?
age 6
