Eruption and Occlusion of the Permanent Dentition

Mark H. Taylor, D.D.S., F.A.C.D.

Don’t Fake Knowledge!

• Know Nolla's stages of calcification

• Know time of eruption of permanent teeth

Nolla's 10 Stages of Calcification

• Stage 2 - initial calcification

• Stage 6 - eruptive movement begins (crown formation complete)

• Stage 8 - alveolar crest pierced (2/3 root development)

• Stage 9 - gingival margin pierced (3/4 root development)

• Interval between Stage 6 and full interdigitation is about 5 years

Time of Eruption (Years)Tooth Maxilla Mandible

1 7-8 6-7

2 8-9 7-8

3 11-12 9-10

4 10-11 10-12

5 10-12 11-12

6 6-7 6-7

7 12-13 11-13

8 17-21 17-21

Why Know Calcification Times?

Enamel hypoplasia

Fluorosis

Fluorosis and Hypoplasia

Fluorosis and Hypoplasia

Factors Affecting Eruption

• Genetics - sequence & timing mostly genetically controlled

• Nutrition

• Premature loss of a primary tooth

Eruption… heh heh…get it?

Eruption Facts

• Girls 5 months faster than boys

• 6-1-2-4-3-5-7 and 6-1-2-4-5-3-7 most common in maxilla

• (6-1)-2-3-4-5-7 and (6-1)-2-4-3-5-7 most common in mandible

Mesial Drift and Anterior Component of Force

• Mesial drift

• Ectopic eruption

• Axial inclination produces mesial force

• Space maintenance

Ectopic Eruption

Ectopic Eruption

Ectopic Eruption

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Space Maintenance - PHA

Space Maintenance - LLHA

Space Maintenance - BLS

Space Maintenance - Distal Shoe

Crossbites

• Unilateral vs. bilateral

• Dental vs. skeletal

• Appliance types

Functional Cross Bite

Functional Cross Bite

Functional Cross Bite

Functional Cross Bite

Quad Helix Appliance

Quad Helix Appliance

Distalizing Appliance

Absence of Permanent Teeth• 4-6% congenital absence

• Females more frequently missing teeth

• Most common congenitally absent teeth:– mandibular 2nd premolar

– maxillary lateral incisor

– maxillary 2nd premolar

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Missing Permanent Teeth

Extra Permanent Teeth

• Supernumerary teeth found most frequently in the maxillary incisor region (mesiodens), and occasionally in the premolar area

• 2-3% supernumerary teeth, males more common

Supernumerary Teeth

Supernumerary Teeth

Supernumerary Teeth

Supernumerary Teeth

Supernumerary Permanent Tooth

Supernumerary Permanent Tooth

Supernumerary Permanent Tooth

Changes in Arch Width

• Intercanine and intermolar growth– significant increases between 6 weeks and 2

years of age

– significant increases between 3 and 13 years

– mandibular intercanine width established by 8 years of age

– after permanent teeth erupted, slight decrease in arch width in the intercanine area

Bishara, et al; “Arch width changes from 6 weeks to 45 years of age” AJO, April 1997

Changes in Arch Length and Overbite

• Arch length decreases*– late mesial shift, mesial drift, interproximal

wear

– do not affect interach relationships

• Overbite– decreases in primary dentition

– increases in mixed dentition

– OB/OJ relatively stable in adult**Harris, “A longitudinal study or arch size and form in untreated adults” AJO, April 1997. (20-55 yoa)

Intercanine Growth

Angle Classification

• Class I Molar (65%)

• Class II Molar (30%)

• Class III Molar ( 5%)

Class I Molar

Distal Mesial

Class II Molar

Distal Mesial

Class III Molar

Distal Mesial

Cuspid Classification

• Neutro (Class I)

• Disto (Class II)

• Mesio (Class III)

Neutro Cuspid (Class I)

Distal Mesial

Disto Cuspid (Class II)

Distal Mesial

Mesio Cuspid (Class III)

Distal Mesial

Divisions of Class II

• Division I - excess OJ

• Division II - "rabbited" incisors

• Subdivision - one side

Divisions of Class IIDivision 1

Divisions of Class IIDivision 1

Divisions of Class IIDivision 1

Divisions of Class IIDivision 2

Divisions of Class IIDivision 2

Divisions of Class IIDivision 2

Divisions of Class IIDivision 2

Six Keys to Occlusion

• Class I molar relationship

• Mesial crown angulation

• Proper crown inclination

• No rotations

• Tight contacts

• Flat occlusal plane

Types of Faces

• Brachycephalic - broad & short

• Dolichocephalic - long & narrow

• Mesocephalic - normal

Brachycephalic

Dolichocephalic

MesocephalicFor the ladies….For the gentlemen...

Mesocephalic

For the moviegoer….

Mesocephalic

For the intellectual dental student….

You Tell Me.

Profile?

Overbite - Overjet?

Occlusion?

Huskers!!!!