mixed dentition

Question 1

incisor liabilty

Answer 1

dif in sizes btwn the primary and permanent incisors

Question 2

result of lower incisor eruption location

Answer 2

lingual to primary= loss of space

Question 3

result of upper incisor eruption location

Answer 3

labial=increase in space

Question 4

Dental Arch measurements

Answer 4

length
width
perimeter
intercanine distance

Question 5

Arch length (depth)
becomes stable when?
displacement?

Answer 5

Measured at the midline to a tangent touching the distal surfaces of the second primary molars

arch length is stable once the incisors erupt

displaced in space with growth

Question 6

Arch length changes

Answer 6

Lose arch length in the lower arch (lower
incisor eruption)
Gain arch length in the upper arch (upper
incisor eruption)

Question 7

Arch width

Answer 7

• Measured between the cups of the canines in the transverse plane
• Measured between the occlusal grooves of the second primary molars or the upper/lower permanent first molars

Question 8

changes to arch width

Answer 8

increases by about 4mm from 3-4yrs to 11yrs, small loss after 12 (.5mm)

Question 9

lower arch changes to arch width
intercanine space?
leeway space due to?

Answer 9

Some significant changes from primary to mixed dentition in the lower arch
intercanine space will increase by 3mm
leewat space appears due to succ teeth being smaller

Question 10

Arch perimeter

Answer 10

Measured from the distal surface of the second primary molar (or mesial of the permanent first) around the arch over the contact points and incisal edges in a smoothed curve

Question 11

when should we use arch perimeter

Answer 11

before treatments as a baseline to examine amount of space available

Question 12

elongation of perm roots and exfoliation

Answer 12

the elongation of perm teeth roots has nothing to do with exfoliation

Question 13

mixed dentition period

first perm tooth to erupt? succ or non-succ?

Answer 13

• From 6 to 13 years old, the primary dentition is replaced by the permanent dentition ( mixed dentition period)
• The permanent first molars erupt to the distal of the primary dentition (no primary tooth replacement)

Question 14

permanent eruption

Answer 14

Primary root resorption allows Permanent tooth eruption
Crown of the permanent tooth is formed
Then the root develops and the primary tooth starts to resorb
When the root is totally resorbed, the primary tooth exfoliates and the permanent tooth erupts
The permanent tooth will stop erupting when it reaches the occlusal plane

Question 15

why is a mesial inclination of incisors good initially

Answer 15

helps to guide canines eruption, will sefl correct typically

Question 16

tooth replacement variable in?

Answer 16

Sequence
Timing
Position
Numbers

Question 17

Variability in Sequence

Answer 17

some teeth may erupt out of the typical pattern

this can have adverse effects such as preventing other teeth from erupting or completing development

Question 18

Variable Timing

Answer 18

can be slow or accelerated

do not treat with primary extraction unless the root of the perm tooth is 2/3 formed

Question 19

variability in spacing

Answer 19

can vary in where the teeth are erupting= loss of spacing and lead to malocclusions
teeth erupting out of position may also negatively impact other teeth

Question 20

Variability in numbers

Answer 20

Congenitally missing teeth: rare 3-5% of population
Maxillary lateral incisor: most frequent
Mandibular second premolar
Maxillary central incisor

Missing primary tooth = no permanent successor (dd. Delayed eruption)

Question 21

ethnic effect on missing teeth, asia?

Answer 21

different ethnicities may have different missing teeth commonly
Asians often missing the Lower CI or LI

Question 22

Ankylosis

Answer 22

Refers to the fusion of the root of a primary tooth to the underlying bone, which stops the tooth from erupting
May be due to localized defect during eruption process in periodontal ligament whereby osseous bridging occurs between root and bone

Question 23

when does ankylosis become evident

Answer 23

Becomes more evident in later primary and mixed
dentition where occlusal level of ankylosed tooth
does not keep up with vertical level of adjacent
teeth (dentoalveolar development keeps the
teeth in contact during growth)

Question 24

ankylosis treatment

Answer 24

Treatment is usually to simply monitor these teeth (50% self correction)

If they fail to exfoliate, it may be advisable to extract the tooth to avoid damages to the permanent dentition

Question 25

ectopic eruption

Answer 25

eruption of tooth out of position, can occur at any tooth but most likely canines

Question 26

mixed dentition importance

Answer 26

• The mixed dentition is a very important period in dental development
• Time when succedenous teeth erupt and replace the primary dentition
• High variability among patients
• Understanding the events taking place allow for guided and appropriate
treatments.