2, normal and abnormal development of occlusion

Question 1

what are the four stages of development of the occlusion?

Answer 1

• gum pad: birth to 6-7 month
• primary dentition: until around age 6
• mixed dentition
• permanent dentition

Question 2

how do the primary incisors and canines compare to permanent?

Answer 2

-similar shape but smaller in size

Question 3

all the primary teeth are erupted by…

Answer 3

30 months

Question 4

what is the sequence of eruption?

Answer 4

-ci, li, first molars, canines, and second molars

Question 5

what is the overbite and over jet for primary dentition?

Answer 5

overbite can vary from edge to edge to 40%

• overjet 0-4 mm
• primary teeth usually have a lot of occlusal wear

Question 6

once a tooth has erupted, how long will it take for the antimere tooth to erupt?

Answer 6

6 months

Question 7

what are some reasons for failure of eruption of the permanent teeth?

Answer 7

trauma, supernumerary teeth, or early loss of the primary tooth with formation of scar tissue

Question 8

the difference between the sum of the mesiodistal widths of the primary canines, first and second molars and the mesiodistal width of their successors.

Answer 8

• Leeway space

- the difference should be positive to accommodate the size of the permanent teeth

Question 9

what are the averages size of leeway space for the maxillary and mandiular arches?

Answer 9

• max: 1.3 mm

- mand: 3.1 mm

Question 10

arch width in the maxilla

Answer 10

• the intercanine width increases by about 6 mm between the ages of 3-13. until the age of 45, an additional 1.7 mm increase
• the intermolar width of the permanent molars increases by 2.2 mm between the age of 8-13 and decreases 1 mm by the age of 45

Question 11

arch width in the mandible

Answer 11

• the intercanine width increases by 3.7 mm from age 3-13. from 13-45, it decreases by 1.2 mm
• the intermolar width of the primary molar increases 1.5 mm between the age of 3-5. The permanent molar width increases by 1 mm from 8-13 and decreases by 1 mm by age 45

Question 12

mixed dentition: arch length

Answer 12

-in both the maxilla and the mandible, the arch length decreases slightly due to the uprighting of the incisors and the loss of the leeway space