LECTURE 6 INGRID REED DDS, MS DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS Canine...
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Transcript of LECTURE 6 INGRID REED DDS, MS DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS Canine...
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