Eruption and Arch Development - PowerPoint Presentation

Slide1

Eruption and Arch DevelopmentSlide2

Period of the mixed dentition

6 to 12 years of age

Mixed dentition.Slide3

Shedding of primary teeth

Causes of shedding of primary teeth.

Resorption pattern of anterior and posterior primary teeth.Slide4

Shedding of teeth

A result of the progressive resorption of the roots of teeth and their supporting tissues.

Accomplished by multinuclear

odontoclasts

.

Highly specialized cells that are identical to osteoclasts.

Periods of rest and repair.

In the end, resorption predominates.Slide5

Shedding of teeth

Causes

Pressure

from the erupting successional tooth plays a major role.Slide6

Shedding of teeth

When

a successional tooth germ is missing, shedding of the deciduous tooth is delayed but not stopped

.

The

deciduous tooth is eventually lost.Slide7

Shedding of teeth

Causes

Forces of mastication that are greater than the periodontal ligament of a deciduous tooth can withstand.

Trauma to the periodontal ligament and initiation of resorption.Slide8

Resorption pattern of anterior teeth

Permanent teeth undergo complex movements before they reach the position from which they will erupt. ‘Pre-eruptive movement’

Permanent incisors and canines first develop lingual to the deciduous tooth germs.

As their deciduous predecessors erupt, they move to a more apical position and occupy their own bony crypts.Slide9

Resorption pattern of anterior teeth

Resorption of the roots of the deciduous incisors and canines begins on their lingual

surfaces.

Later these developing teeth occupy a more apical position.Slide10

Resorption pattern of anterior teethSlide11

Resorption pattern of posterior teeth

Permanent premolars begin their development lingual to their predecessors

.

Shift so they are situated in their own crypts beneath the divergent roots of the deciduous molars.Slide12

Resorption pattern of posterior teeth

This change in position provides the growing premolars with adequate space for their continued development

.

Premolars erupt in the position of deciduous molarsSlide13

Resorption pattern of posterior teethSlide14

Eruption of permanent teethSlide15

Eruption of permanent teeth

Chronology of eruption.

Sequence of eruption, variations.

Rhythm of eruption. Slide16

Chronology of Eruption (Years)Slide17

Premature loss of primary molars

Eruption of the premolar teeth is delayed in children who lose primary molars at 4 or 5 years of age and before.

If extraction occurs after the age of 5 years there is a decrease in the delay of premolar eruption.

At 8, 9, and 10 years of age, premolar eruption resulting from premature loss of primary molars is greatly accelerated.

Posen, 1965Slide18

Sequence of eruptionSlide19

Sequence of eruption

(6-1)-2-3-4-5-7-8 most common in

mandible.

6-1-2-4-5-3-7-8 most common in

maxilla.

Eruption timing in girls generally precedes that in boys by an average of 5 months.Slide20

Sequence is Important!

Alteration of sequence of eruption alerts the practitioner to potential problems.

Always count the teeth

!Slide21

Variations in the sequence of eruption

No clinical significance to the eruption of incisors before first molars.

It is desirable that the mandibular canine erupts before the first and second mandibular premolars.

This aids in maintaining adequate arch length and in preventing lingual tipping of the incisors.Slide22

Variations in the sequence of eruption

If the mandibular second permanent molar erupts before the second premolar, a deficiency in arch length can occur.

Due to mesial migration and tipping of the first molar & encroachment on the space needed for the second premolar.Slide23

Variations in the sequence of eruption

Untimely loss of primary molars in the maxillary arch may allow the first permanent molars to drift and tip mesially, resulting in the permanent canine being blocked out of the arch.Slide24

rhythm of eruptionSlide25

Rhythm of eruption of permanent teeth

Two stages:

Incisors and first permanent molars erupt first.

Early mixed dentition.Slide26

Rhythm of eruption of permanent teeth

Premolars, canines & second molars erupt.

Late mixed dentition.

Teeth erupt symmetrically in both jaws, simultaneously and in pairs.

Third stage: third molars.Slide27

The rule of ‘Four’ for permanent tooth development

At birth, four first molars have initiated calcification.

At 4 years of age, all crowns have initiated calcification.

At 8 years of age, all crowns are complete.

At 12 years of age, all crowns have emerged.

At 16 years of age, all roots are complete.Slide28

Permanent tooth development

Crown formation completed at least 3 years before eruption.

Roots completed around 3 years after eruption.

Teeth erupt when

2/3 to ¾

root development.Slide29

Hard tissue formation starts

6s

At birth or slightly before

Upper 1s and 3s

Lower 1s 2s and 3s

3-6 months of age

Upper 2s

10-12 months of age

Upper and lower premolars and second molars

1 ½ - 3 years of age

Upper and lower third molars

7-10 years of ageSlide30

Enamel completed

6s

2 ½-3 years of age

1s, 2s and 4s

4-6 years of age

3s, 5s and 7s

6-8 years of age

8s

12-16 yearsSlide31

Eruption of Permanent teethSlide32

Eruption of Permanent teeth

Lingual eruption of mandibular incisors.

Ankylosed primary molars.

Eruption

sequestrum

.

Ectopic eruption of 6s.

Incisor liability.

Leeway space.

Late mesial shift.Slide33

Lingual eruption of mandibular permanent incisors

A

cause of concern for parents

.

Seen both in patients with an obvious arch length inadequacy and in those with a desirable amount of spacing in the primary dentition.Slide34

Lingual eruption of mandibular permanent incisors

Primary

teeth may be mobile and held only by soft tissue

.

Or they may not have undergone normal resorption & thus stay solidly in place.Slide35

Lingual eruption of mandibular permanent incisors

Position will improve over several months

.

In some cases, there is justification for removal of corresponding primary tooth

.

Extraction of other primary teeth in the area is not recommended.Slide36

Lingual eruption of mandibular permanent incisors

The tongue and continued alveolar growth seem to play an important role into influencing the permanent incisors into a more normal position with time.Slide37

Lingual eruption of mandibular permanent incisors

If

the condition is

identified

before

7 1⁄2 years of age it

is unnecessary

to subject the child to the trauma of

removing the

primary teeth because the problem is almost

always self-correcting

within a few

months.

Gellin et alSlide38

Lingual eruption of mandibular permanent incisors

In an older child and when the radiograph shows no root resorption of the primary teeth, self-correction has not been achieved and the corresponding primary teeth should be removed.

Gellin et alSlide39

Lingual eruption of mandibular permanent incisors

Labial migration occurs naturally with or without extraction of the primary incisor (

Gellin

& Haley, 1982

)

Removal of a tooth during the first dental visit may not be the best introduction to the dental surgery.Slide40

Lingual eruption of mandibular permanent incisors

Still, some parents are alarmed by seeing a double row of teeth & extracting the offending incisor may lay the problem to rest.Slide41

ankylosed primary molarsSlide42

Ankylosed primary molars

Also referred to as:

Submerged teeth.

Teeth in

infraocclusion

.Slide43

Ankylosed primary molars

The ankylosed tooth is in a state of static retention

.

In the adjacent areas, eruption and alveolar growth continue.Slide44

Ankylosed primary molars

Mandibular primary molars are most commonly affected.Slide45

Ankylosed primary molars

Cause is unknown:

Familial.

Observation

of ankylosis in several members of

the same family.Slide46

Ankylosed primary molars

Absence of a permanent successor.

T

here

is a

suggested relationship

between

congenital absence

of permanent teeth and ankylosed

primary teeth.

Brown et alSlide47

Ankylosed primary molars

Normal resorption involves periods of rest.

A solid union may develop between the primary tooth and bone.Slide48

Ankylosed primary molars

Diagnosis:

Opposing molars are out of occlusion.

Tapping with a blunt instrument. Solid vs. cushioned.Slide49

Ankylosed primary molars

Diagnosis:

The

ankylosed tooth is not mobile even in cases of advanced root resorption

.

Radiograph will show a break in the continuity of the periodontal ligament.Slide50

Ankylosed primary molars

Management:

Keep the tooth under observation.

The tooth may undergo root resorption later on and be normally exfoliated.Slide51

Ankylosed primary molars

Management:

In ankylosed primary molars with missing successors, establish functional occlusion with SSC or bonded restorations.Slide52

Ankylosed primary molars

Management:

High caries rate or loss of arch length.

Eventual treatment may include surgical removal.Slide53

ERUPTION SEQUESTRUMSlide54

Eruption

Sequestrum

Seen occasionally in children at the time of the eruption of the first permanent molar.Slide55

Eruption

Sequestrum

A

tiny spicule of nonviable bone

overlying the

crown of an erupting permanent molar just before

or immediately

after the emergence of the tips of the

cusps through

the oral mucosa.

Starkey et alSlide56

Eruption

Sequestrum

The sequestra may develop from either osteogenic or odontogenic tissue.Slide57

Eruption

Sequestrum

G

enerally overlying

the central fossa of the associated

tooth, embedded

, and contoured within the soft tissue.Slide58

Eruption

Sequestrum

Some

of these

sequestra

spontaneously

resolve without noticeable symptoms

.

It may easily be removed if it is causing local irritation. Slide59

Eruption

Sequestrum

The base of the

sequestrum

is often still well embedded in gingival tissue when it is discovered. Slide60

Eruption

Sequestrum

Application of a topical anesthetic or infiltration of a few drops of a local anesthetic may be necessary to avoid discomfort during removal.Slide61

Ectopic eruption of first permanent molarsSlide62

Ectopic eruption of first permanent molars

6s may

be positioned too far

mesially in

their eruption path with resultant ectopic

resorption of

the distal root of the second primary molar

.Slide63

Ectopic eruption of first permanent molars

Two

types of ectopic eruption—reversible and irreversible. Slide64

Ectopic eruption of first permanent molars

In the reversible type, the molar frees itself and erupts into normal alignment with the second primary molar remaining in position.Slide65

Ectopic eruption of first permanent molars

Most permanent

molars in children with reversible

patterns free

themselves by 7 years of age.Slide66

Ectopic eruption of first permanent molars

In the irreversible type, the maxillary first molar remains unerupted and in contact with the cervical root area of the second primary molar.Slide67

Ectopic eruption of first permanent molars

By

the age of 7 and 8 years, any

ectopic eruption

of a permanent

first molar should be

considered irreversibly

locked.Slide68

Ectopic eruption of first permanent molars

Prevalence low, around 3%.

Seen more frequently in boys than in girls.

Occurrence in more than one quadrant is frequent.

Most often observed in the maxilla .

Young et al Slide69

Ectopic eruption of first permanent molars

Two

thirds of ectopic molars erupted

into their

essentially normal position without corrective

treatment (reversible

).

Young et alSlide70

Ectopic eruption of first permanent molars

Children with

irreversible

ectopic eruption patterns had :

Significantly larger permanent first molars,

A more pronounced mesial angle path of eruption,

A tendency toward a shorter maxilla in relation to the cranial base.

Bjerklin and Kurol, 1983Slide71

Ectopic eruption of first permanent molars

No significant differences in these variables were found between sides with

reversible

ectopic eruption and sides with normal eruption.

Ectopic molars also show a significant familial tendency with a prevalence of 19.8% in affected siblings versus the overall 2% to 3% general occurrence.

Bjerklin and KurolSlide72

Ectopic eruption of first permanent molars

A frequent occurrence rate of ectopic first permanent molars at 25% in cleft lip and cleft palate children.

Possibly caused by maxilla positioning and basal arch size.Slide73

Ectopic eruption of first permanent molars

Irreversible ectopic molars that remain locked, if untreated, can lead to

Premature loss of the E with a resultant decrease in quadrant arch length,

Asymmetric shifting of the upper first molar toward class II positioning, Slide74

Ectopic eruption of first permanent molars

Irreversible ectopic molars that remain locked, if

untreated, can

lead to

:

Supraeruption

of the opposing

molar with distortion

of the lower curve of

Spee

and potential occlusal interferences.Slide75

Ectopic eruption of first permanent molars

If detected at 5 to 6 years of age, an observation approach of “watchful waiting” with appropriate monitoring is indicated.

With self-correction being unlikely approaching 7 years of age, continued “locking” of the first molar with advanced resorption of the primary second molar usually warrants intervention. Slide76

Ectopic eruption of first permanent molars

Another timing clue is that when the opposing molar reaches the level of the lower occlusal plane, intervention is indicated to establish proper vertical control and prevent

supraeruption

.Slide77

Ectopic eruption of first permanent molars

Approaches include:

Separators.

Distalizing appliances.Slide78

Ectopic eruption of first permanent molars

Orthodontic elastic separators are the first choice if access is sufficient to allow insertion for engagement in the contact areas of entrapment. Slide79

Ectopic eruption of first permanent molars

Progressive use of larger separators facilitates this approach. Slide80

Ectopic eruption of first permanent molars

Separating springs can also be used provided sufficient eruption for insertion between the contact areas. Slide81

Ectopic eruption of first permanent molars

Brass ligature wire threaded between the contact areas of the affected teeth may facilitate distal movement of the permanent molar.

Periodic tightening of the looped wire every 3-5 days is indicated as a separating force. Slide82

Ectopic eruption of first permanent molars

Treatment

with any

of the

separator techniques requires that only a

minimal lock

be evidenced and that minimal resorption of

the primary

second molar has occurred. Slide83

Ectopic eruption of first permanent molars

Distally directed forces from the second primary molars may be needed to disengage and allow eruption of the first permanent molar.

Ortho appliances may be used to

distalize

the first permanent molar.Slide84

Incisor liabilitySlide85

Incisor liability

Permanent incisors are larger than primary incisors.

How does the body create enough room for the larger permanent incisors?Slide86

Incisors

Interdental spacing of primary incisors.

Intercanine arch width growth.

Labial positioning of the permanent incisors.

Favorable size ratio between the primary and permanent incisors.Slide87

Interdental spacing of primary incisors.

Good interdental spacing of the primary incisors allows for better positioning of the permanent incisors.Slide88

Arch length prediction from alignment of primary teeth

Primary alignment

Permanent outcome

Crowding

Almost certain extraction

No spacing

Possible extraction

Fair spacing

Mild to moderate crowding

Good spacing

No or mild crowding

Excess spacing

No crowding/excessSlide89

Intercanine arch growth

Width growth creates more room for the permanent incisors.

Mandibular intercanine growth occurs mostly during permanent incisor eruption.

Maxillary intercanine growth occurs during incisor eruption, and continues.

Unpredictable. Slide90

Labial positioning of the permanent incisors

Permanent incisors erupt to a more labial position

Permanent incisors are angled more labially.

The above creates more arch length Slide91

Favorable size ratio between the primary and permanent incisors

Size ratio between the primary and permanent incisors may be favorable or unfavorable.

Favorable: large primary, small permanent.

Unfavorable: small primary, large permanent. Slide92

Leeway spaceSlide93

Leeway space

The amount by which the combined size of the primary canine and molar teeth exceeds the combined mesiodistal widths of the permanent canine and premolar teeth.Slide94

Leeway space

Sum of (C-D-E) greater than sum of (3-4-5)

This allows more space for 3,4,5.

Averages 1.5 mm in the upper arch and 2.5 mm in the lower arch.Slide95

Occlusal changes in the mixed dentition

Distal step

Flush terminal plane

Mesial step

Class II

ETE

Class I

Class IIISlide96