tooth eruption and normal dental development

Question 1

birth - newborn baby dental features

Answer 1

• gum pads
• upper rounded
• lower “u” shaped
  often appear class II
  AOB

Question 2

when do the first primary teeth usually erupt?

Answer 2

6 months

Question 3

By what age are all primary teeth usually erupted?

Answer 3

24-36 months

Question 4

in what order do the primary teeth erupt?

Answer 4

a-b-d-c-e

Question 5

primary dentition - occlusion features

Answer 5

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

Question 6

if there is less than 3mm space, what is the chance of crowding in the permanent dentition?

Answer 6

50%

Question 7

how much space is required between primary teeth to guarantee that there will be no crowding in the permanent dentition?

Answer 7

> 6mm

Question 8

neo natal teeth - features

Answer 8

• abnormal dental development
• lower incisors present at or just after birth
• may be supernumerary or very early normal primary central incisors

Question 9

indications for extractions of Neo-natal teeth

Answer 9

• tooth mobile and presents inhalation risk
• tooth causing difficulty with breastfeeding

Question 10

when does the pre eruptive phase begin and end?

Answer 10

starts when the crown starts to form and ends when crown formation is complete/root formation about to start

Question 11

when does the eruptive phase begin and what is it split into?

Answer 11

-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

Question 12

post eruptive phase

Answer 12

tooth movement/eruption continues as the root forms and throughout life in extremely small amounts

Question 13

in the pre-eruptive phase, how do the developing crowns move in the jaws

Answer 13

• they reposition themselves in response to increasing length, width and height in the jaws
• movement is contained within the bony crypts

Question 14

Eruptive phase - intra osseous

Answer 14

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

Question 15

eruptive phase - extra osseous stage

Answer 15

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

Question 16

What processes are happening during the eruptive phase?

Answer 16

• 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)

Question 17

What controls tooth eruption?

Answer 17

the dental follicle

Question 18

post-eruptive phase movement (once tooth has already reached occlusal plane)

Answer 18

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

Question 19

Additional space is required to accommodate the larger teeth of the permanent dentition. How is the space gained?

Answer 19

• 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

Question 20

leeway space in the upper arch =
((primary canine + first + second molar) - (permanent canine+ first premolar and second premolar))

Answer 20

1 to 1.5mm

Question 21

leeway space in lower arch
((primary canine + first molar + second molar) - (permanent canine + first premolar + second premolar))

Answer 21

2 to 2.5mm

Question 22

eruption sequence in the upper arch (permanent teeth)

Answer 22

6, 1, 2, 4, 5, 3, 7, 8

Question 23

eruption sequence in the lower arch (permanent dentition)

Answer 23

6, 1, 2, 3, 4, 5, 7, 8

Question 24

Approximately what age do permanent maxillary molars erupt?

Answer 24

age 6

Question 25

Approximately what age do permanent mandibular molars erupt

Answer 25

age 6

Question 26

Approximately what age do permanent maxillary central incisors erupt

Answer 26

age 7

Question 27

Approximately what age do permanent mandibular central incisors erupt?

Answer 27

age 6

Question 28

Approximately what age do permanent maxillary lateral incisors erupt

Answer 28

age 8

Question 29

Approximately what age do permanent mandibular lateral incisors erupt?

Answer 29

age 7

Question 30

Approximately what age do permanent maxillary canines erupt?

Answer 30

age 11

Question 31

approximately what age do permanent mandibular canines erupt?

Answer 31

age 9

Question 32

Approximately what age do permanent first and second premolars erupt?

Answer 32

10

Question 33

Approximately what age do permanent second molars tend to erupt?

Answer 33

age 12