LECTURE 6INGRID REED DDS, MS

DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS

Canine Impactions Ectopic Eruption

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Impacted vs. Ectopic eruption

Impacted Condition of being firmly lodged (impacted in alveolar

bone) or wedged by a physical barrier, usually other teeth, so it is prevented from erupting

Ectopic eruption Located away from the normal position

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Eruption process3

Permanent tooth erupts

Resorption of overlying bone

Resorption of 1° tooth roots

Eruption through gingiva

Interference with eruption4

Ectopic eruption of permanent tooth Undermining resorption of the 1° tooth Non- resorption of 1° roots, may be result not cause

Supernumerary teeth – remove as indicatedHeavy fibrous gingiva – may need to expose

toothSclerotic bone – may need to expose toothAnkylosed toothLack of space – consider serial extraction or

orthodontics (age/crowding dependent)

Normal Development of Maxillary Canines

Age 3 – located high in maxillary bone –mesially & lingually directed crown

Intrabony migration – lateral roots – ‘ugly duckling’

Spontaneous closing of midline diastema as canines simultaneously upright and erupt

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4-6 monthsDevelopment (calcification) begins high in the maxilla

6 years Crown completed

10 yearsPalpable high in the buccal vestibule

11-13years Eruption

14 - 15 years Root completed

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Prevalence of Maxillary Canine Impaction

Maxillary canine 2nd most frequently impacted tooth Third molars most frequently impacted

Maxillary 50 times greater than mandibularPalatal versus buccal - range 2:1 to 12:1

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Etiology - Maxillary Canine Impaction

Availability of space in archEruption pathHorizontal angulation of toothTrauma to 1° tooth budDisturbance in eruption sequenceRotation of tooth budsPremature root closure

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Normal Development of the Maxillary Canine

4-5 monthsDevelopment (calcification) begins high in the maxilla

6 years Crown completed

10 yearspalpable high in the buccal

vestibule

11-12 years Eruption

13.5 years Root completed

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Maxillary Canine Impaction – Diagnostic Problem

Usually last tooth to replace primary tooth

Fewer radiographs taken at recall – bitewings may not show canines

Need knowledge of crown development, root development and eruption

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Impacted Maxillary Canines

The most opportune time to observe the maxillary canines beginning their eruption and detect an eventual impaction is when children are ~ 8 - 9 years of age, when the maxillary canines migrate labially

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Overretention of Primary Canines

Canine erupts 11-13 yearsPrimary canine not exfoliated, overretention

may be result of, not cause of, ectopic position of canine Permanent canine has not precipitated vertical

resorption of the primary tooth’s root Canine crown inclined too far mesially Canine crown having slipped over the root of the

permanent lateral incisor, is deprived of the eruptive guidance of the lateral incisor’s distal surface

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Extraction of Primary Canines

Canines begin to deviate from a normal eruptive position in patients ~9 years of age

If permanent canine path is errant, extract primary canines at age 10.

Teeth take the path of least resistanceImprovement usually seen in 6-18 months

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Extraction of Primary Canines

Degree of horizontal angulation importantStudy by Ericson an Kurol 78% of canines changed angulation within 18

months of 1° canine extraction91% if tip of canine cusp had not passed

midline of lateral root

Must have space for canine to erupt- maintain or create after primary extraction.

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Sequence of Eruption Permanent Teeth

MAXILLARY MANDIBULARFirst molar First molar

Central incisor Central incisor

Lateral incisor Lateral incisor

First premolar Canine

Second premolar First premolar

Canine Second premolar

Second molar Second molar

Clinical Signs of Maxillary Canine Impaction

Clinical signs1. Failure to palpate canine bulge in buccal vestibule by 10

years2. Immobility of the deciduous canine3. Palatal bulge indicating possible underlying canine4. Increased mobility, non-vital central or lateral incisors5. Inadequate space within the dental arch for canine eruption6. Flared lateral incisors – can also be normal7. Asymmetry of eruption

1. Impacted maxillary canines in individuals > 40 years susceptible to ankylosis

2. Failure of movement in an adolescent indicates ankylosis

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Lack of Space

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NA

Lack of space for canines19

9 years 4 months

NA

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Screening panoramic radiograph

Dental age 8-9

Full eruption of Maxillary central and lateral incisors Mandibular central and lateral incisors All four first molars

Anytime prior with cause

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Radiographic Signs of Probable Canine Impaction

Long axis of the canine is angled more than 10 ° to the vertical plane. The greater the angle the more likely a problem.

25° - impactionCanine overlaps the lateral or central incisor

rootParallax technique shows buccal/palatal

position

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Clark’s rule – Horizontal change

The lingual object moves in the same direction as the x-ray source

The buccal object moves in the opposite direction of the x-ray source because it is farther away from the film than the root of the lateral incisor

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10/31/05 Age 9 yrs 3 mos Patient A

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Patient A40°

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2 yrs 5 mo later Age 11 yrs. 8 mosPatient A

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Age 12yrs. 7 mosPatient B

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4 years 3 months later Age 16 yrs 10 months Patient B

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Mandibular canine impactionsMandibular canine impaction

Management of Impacted CaninesExtractDeciduous Canine

Age 10May help normalize eruptive path in palatally

displaced canine•Radiographic improvement in 6-18 months

No Treatment•Poorly motivated patient•Inform of resorption risk and cystic change within canine follicle•Monitor radiographically every 12 months

OrthodonticAlignment

•Following surgical exposure•Gold chain bonded to the tooth•Space created •TPA in place

Surgical Removal

•Very unfavorable canine position•Poorly motivated patients•Orthodontic treatment contraindicated•Severe crowding (substitute 1st premolar)

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Impacted teeth - considerations40

Surgical exposure

Attachment to the tooth

Orthodontic mechanics to bring the tooth into the arch

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KF

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KF

4/13/07

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KF

12/1/07

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KF

8/7/08

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KF

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KF

KF 2-2009 47

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Impacted second molar

OUT OF NORMAL POSITION

Ectopic Eruption50

Ectopic Eruption

Maxillary first molarsMaxillary caninesMandibular caninesMaxillary premolarsMandibular premolarsMaxillary lateral incisors

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Ectopic eruption52

Malposition of a permanent tooth bud Eruption in the wrong place

Most common – maxillary first permanent molars

Ectopic eruption of other teeth rare but can lead to transposition

pgs 139, 249-252,453-458

Ectopic eruption53

Permanent tooth causes resorption of tooth other than the one it is supposed to replace or

Resorption of an adjacent permanent tooth

Lateral incisors54

Ectopic eruption causes resorption of primary canine – indicates lack of space

Loss of only one primary canine can cause midline shift – need to maintain lateral incisor position with appliance or

Extract contralateral canineLoss of mand. 1° canines causes incisors to tip

lingually with loss of arch perimeterSpace analysis important – passive LLA or active

LLA

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Prevalence 2-6% (20-25% if cleft lip/palate)

Etiology Crowding / large crown / mesial eruption

MANAGEMENT

OBSERVE Active Treatment

•May correct spontaneously

•Rarely after age 8 years

•Brass wire or elastic separator – mild cases

•Distalizing appliances more serve cases

•Extract primary if pulpal involvement – space maintainer or regainer

Ectopic Maxillary First Molar

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Age 8yr. O months

Patient Y

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Patient Y

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8 years 2 monthsPatient Z

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6 weeks

Patient Z corrected

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Age: 7 years 8 months

Missing 2nd premolars

DOB 11-1-02, Pano 7-20-10 age 7 years 8 months W.E.

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W.E.

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Transposed Teeth S.N.

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Early Loss of Primary Teeth64

Early loss of 2nd 1° molar Mesial drift of first permanent molar Greater if no occlusal forces are on it

Early loss of 1° first molar or canine Distal drift of incisors

Force from active contraction of transseptal fibers Pressure from the lips and cheeks

pgs – 139-141