mixed dentition

Mixed Dentition

the period during which both primary and permanent teeth are in the mouth together.

Mixed Dentition

• AKA transitional dentition.

Mixed Dentition

• The teeth present are in constant change.

Mixed Dentition

• Begins from the eruption of the first permanent tooth.

(6-7)

Early Mixed Dentition age

(7-9)

Middle Mixed Dentition age

(7-9)

Late Mixed Dentition age

ABCDE6

Early Mixed Dentition sequence

12CDE6

Middle Mixed Dentition sequence

12C4567

Late Mixed Dentition sequence

Successional Teeth

Those permanent teeth that follow into a place in the arch once held by a primary tooth.

Accessional Teeth

• Permanent, incisors, cuspids, bicuspids.

second premolar

Eruption of the First Permanent Molars is guided into its occlusal position during eruption by the distal surface of the

terminal plane

Relationship with antagonist is determined by the ______ relationship of the second primary molars.

upper and lower second primary molars

The location and relationship of first permanent molar depends much upon the distal surface relationship between the

flush terminal plane

If the distal surface of maxillary and mandibular deciduous second molar are in the same vertical plane; then it is called a

1. Straight/flush terminal plane

2. Mesial step

3. Distal step

The molar relationship in the primary dentition can be classified into 3 types:

Flush Terminal Plane

typically provides an end-to-end relationship of the first permanent molars.

‘primate spaces’

Eruption of the 1st mandibular molar closes the ________ from the posterior thus decreasing arch perimeter

Nance Leeway space

Size difference between the primary molars and the permanent premolars.

Late Mesial Shift

Utilization of Nance Leeway Space

Late Mesial Shift

When no spaces exist, the erupting first permanent molar is not able to close spaces.

Late Mesial Shift

In these cases when the primary molars exfoliate the permanent molars migrate mesially to use up the Leeway space

Mesial Step

still considered good for the permanent dentition

Mesial Step

If reflective of a skeletal discrepancy it will result to a class III.

Distal Step

the primary dentition reflects a likely skeletal imbalance and likely will result in a Class II occlusion in the permanent dentition.

Ugly Duckling Stage

Teeth of the child appears too big for the face

Ugly Duckling Stage

persistence of a midline between the upper central incisors.

Diastema

• A temporary characteristic

Diastema

Normally occurs from ages 6-9 years old or until there are primary teeth present.

Diastema

It should not be touched because when the maxillary cuspids slide on the lateral slope of the laterals it will push the centrals thus closing the

Permanent mandibular incisors

________ develop lingually to resorbing roots of the primary incisors forcing the latter to be labially exfoliated

lateral incisors

Normally there are some crowding after

the _______ have erupted.

Maxillary central incisors

_______ erupt with a distal

inclination and some midline space

between them.

mandibulars

Maxillary anteriors are supported by the

_______ which are formed earlier,

providing the functional stops against

which the maxillary incisors erupts.

Incisor liability

• AKA Negative Leeway

Incisor liability

Difference in the summation of mesiodistal

width of the 4 primary incisors against the

sum of mesiodistal width of 4 permanent

incisors

Incisor liability

• Characteristic of the permanent dentition

which occurs because the size of the

permanent maxillary anterior are bigger

than the primary maxillary anterior.

Incisor liability

• Difference between the amount of space

needed for the accommodation of the

incisors and the amount of space

available.

Nature’s Compensation for Incisor Liability

Interdental Spacings of Primary Incisors

Intercanine Arch Width Growth

Labial Positioning of Permanent Incisors

More Favorable Tooth Size ratio

intercanine width

Increased ______ creates more

room for the permanent incisors.

Mandibular intercanine

increases mostly during permanent

incisor eruption.

Maxillary intercanine

growth occurs

during incisor eruption and continues

unpredictable

labially

Permanent incisors erupt to a more _____

position and are angled more _____,

thereby increasing the arch length.

large primary, small

permanent.

Intercanine Arch Width Growth Favorable:

small primary, large

permanent.

Intercanine Arch Width Growth Unfavorable:

Overjet

Slightly wider than the primary because

they are more labioverted

• Ideal overbite relation.

• Excessive incisal overbite.

• Incomplete overbite.

• Anterior open bite.

Incisal Overbite

Bicuspid Eruption

Favorable development of occlusion in

this region is largely dependent on four

factors

second molars

Eruption of ______ ahead of

premolars in the mandibular arch

decreases the space for second

premolars, which get partially blocked

out.

maxillary canines

Eruption of _____ ahead

of premolars will cause the ______ to

be forced out labially.

first molar

The _____ must not be allowed to

move mesially until the second bicuspid

had a chance at its proper position in the

arch.

Mandibular second molar

_______ typically erupts

into the mouth before the maxillary

second molar

Class II malocclusion

Eruption of the maxillary second molar

ahead of the mandibular second molar is

said to be symptomatic of a developing