Impactions, Ectopic Teeth, Molar Uprighting, & Extrusion

most commonly impacted tooth in maxilla

3rd molar

most commonly impacted tooth in mandible

3rd molar

second most commonly impacted tooth after the 3rd molar

maxillary canine

the incidence of impacted teeth ranges from ___-___%

1-2.5%

ratio of palatal impacted canines to labial impacted canines

2:1

impacted canines are twice as common in [boys/girls]

girls

only ___-___% of maxillary canine impactions occur bilaterally

8-10%

why are maxillary canine impactions so common?

maxillary canines are the last tooth to erupt and replace a primary tooth

incidence of mandibular canine impactions is approximately

0.35%

maxillary central incisor impactions are rare but are often associated with a

supernumerary tooth

2nd most commonly impacted tooth in the mandible?

3rd?

4th?

2nd PM

2nd M

canine

the most common cause of the impaction of a maxillary central incisor

supernumerary tooth

[T/F]: impacted central incisors occur in the absence of supernumerary teeth

T

complications associated with canine impactions (3)

1. hinderance to orthodontic movement of adjacent teeth

2. compromised esthetics of the final smile

3. resorption of adjacent roots

approximately 80% of teeth demonstrating resorption as a result of ectopically erupting/impacted maxillary canines are

lateral incisors

lateral incisor root resorption is due to

M angulation of canines

angulation = [MD/FL] position

MD

inclination = [MD/FL] position

FL

best way to evaluate an impacted tooth

CBCT

etiology of impacted canines (2)

1. environmental factors

- most common

2. genetic factors

local factors that can cause impacted canines (9)

1. tooth size/arch length discrepancy (TSALD)

2. prolonged retention or early loss of a primary canine

3. abnormal position of tooth bud

4. presence of an alveolar cleft

5. ankylosis of canine

6. cystic or neoplastic formation

7. dilacerations of the roots

8. iatrogenic origin

9. idiopathic condition with no apparent cause

TSLAD

loss of primary canine

lateral incisors shift (midline shift)

loss of space for permanent canine

clinical examination for canine impactions (4)

1. canine bulge

2. palatal bulge

3. over-retention of primary canines

4. abnormal position or tipping of maxillary lateral incisor

over-retention of primary canines to age ___-___ suggests canine impaction

14-15

71% of canines are palpable at ___ years of age, 95% are palpable at ___ years of age, and 97% are palpable thereafter

10

11

___% of canines are palpable at 10 years of age, ___% are palpable at 11 years of age, and ___% are palpable thereafter

71%

95%

97%

necessary to confirm the position of an impacted canine

radiographs

SLOB rule

same lingual/opposite buccal

ideal way to locate the position of the impacted tooth

CBCT

palatally impacted canines:

___% have sufficient space for eruption

arch length [is/is not] a factor

orientation

[more/less] likely to erupt without surgical intervention

85%

is not

horizontal

less

facially impacted canines:

___% have sufficient space for eruption

arch length [is/is not] a factor

orientation

[more/less] likely to erupt without surgical intervention

17%

is

favorable angulation

more

palatally positioned canines are less likely to erupt without intervention due to (2)

1. thicker cortical bone on the palate

2. thicker & tougher soft tissue covering

extraction of the primary canine:

____ will erupt if the crown of the impacted canine is not crossing the midline of the root of the ipsilateral maxillary central incisor

____% will erupt if the crown of the impacted canine is not crossing the midline of the root of the ipsilateral maxillary lateral incisor

2/3

90%

[T/F]: if the impacted canine erupts after extraction of the primary canine it will likely erupt in the proper position

F

methods of evaluation of canine position (3)

1. vertical

2. root angulation

3. location of root apex & crown (M-D)

[↑/↓] height of an impacted canine = worse prognosis

↑

[↑/↓] root angulation of an impacted canine = worse prognosis

↑

the absence of a permanent lateral incisor [↑/↓] the chances of impacting a permanent canine

↑

[T/F]: the absence of a permanent lateral incisor increasing the chances of an impacted permanent canine is a causal effect

F

could be part of a genetic defect expression that also includes missing lateral incisors

what should dentists do when they diagnose an impacted tooth?

refer to an orthodontist ASAP for evaluation

types of surgical exposures (3)

1. open exposure

2. closed exposure

3. apically positioned flap

gingivectomy & bonded attachment (gold chain)

open exposure

flap & bonded attachment (gold chain)

closed exposure

apically positioned flap is usually for [lingually/labially] positioned teeth

labially

ideally, space should be opened [before/after] a canine is exposed using any method

before

mechanics to erupt the impacted tooth (4)

1. cantilever system

2. double archwire system

3. auxiliary arm from transpalatal appliance

4. double archwire system - "piggyback wire"

delayed eruption of the maxillary central incisors is due to (2)

treatment method?

1. premature loss of primary centrals

2. development of a very thick fibrotic gingival overlying the central incisors

open exposure

recommendations for labial impactions:

canine cusp is coronal to the MGJ, adequate amount of keratinized gingiva is present, & canine is not covered by bone

open exposure (gingivectomy)

recommendations for labial impactions:

canine crown is apical to the MGJ & amount of keratinized gingiva is minimal (<3mm)

apically positioned flap

recommendations for labial impactions:

canine crown is significantly apical to the MGJ & tooth is in the center of alveolus

closed exposure

advantages of the technique for labial impactions:

1. open exposure

2. apically positioned flap

3. closed exposure

easy to perform/less traumatic

conservation of keratinized gingiva

greater esthetics & ease of tooth movement

which technique is commonly used?

which technique is only occasionally used?

apically positioned flap

open exposure (gingivectomy)

disadvantages of the technique for labial impactions:

1. open exposure (3)

1. loss of attached gingiva

2. damage to periodontium

3. gingival overgrowth at surgical site

disadvantages of the technique for labial impactions:

2. apically positioned flap (3)

1. increased risk of gingival recession

2. height differences & ortho relapse

3. more traumatic

disadvantages of the technique for labial impactions:

3. closed exposure (3)

1. patient discomfort

2. secondary surgery may be necessary

3. possible mucogingival problems

surgical techniques for exposing palatally impacted maxillary canines (4)

1. closed flap

2. open eruption

3. open window eruption

4. tunnel traction

recommendations for palatal impactions:

canine is located near the lateral and central incisors, horizontally positioned, & higher in the roof of the mouth

closed flap or open window eruption

recommendations for palatal impactions:

late mixed dentition or permanent dentition

open eruption

recommendations for palatal impactions:

the presence of primary canine in the arch

tunnel traction

advantages of the technique for palatal impactions:

1. closed flap

immediate orthodontic traction

advantages of the technique for palatal impactions:

2. open eruption (6)

1. improved bone levels

2. little to no root resorption

3. fewer re-exposures

4. shorter overall treatment time

5. less operating time

6. improved oral hygiene during treatment

advantages of the technique for palatal impactions:

3. open window eruption (2)

1. visualization of the crown & better control of the direction of movement

2. avoidance of moving the impacted tooth into the roots of the adjacent teeth

advantages of the technique for palatal impactions:

4. tunnel traction (2)

1. reduced amount of bone around the impacted tooth

2. permanent canine is guided into the primary canine socket site

disadvantages of the technique for palatal impactions:

1. closed flap (5)

1. bone necrosis

2. root resorption

3. longer operation time

4. repeat surgeries

5. bond failure due to blood/saliva contamination

disadvantages of the technique for palatal impactions:

2. open eruption (2)

1. failure to erupt may extend total treatment time

2. unable to influence path of eruption

disadvantages of the technique for palatal impactions:

3. open window eruption (3)

1. gingival overgrowth at incision site

2. gingival is subject to infection

3. patient discomfort

disadvantages of the technique for palatal impactions:

4. tunnel traction (1)

1. requires presence of a primary canine

molar uprighting:

commonly mandibular _______ due to _______ missing

2nd molar

1st molar

problems associated with loss of mandibular 1st molars (9)

1. M tipping/migration posterior molars

2. D tipping of PMs & canines

3. supraeruption of maxillary antagonist teeth

4. pseudopockets

5. misdirected occlusal forces

6. functional deviations

7. spaces

8. food traps

9. midline discrepancies

treatment planning considerations for molar uprighting (6)

1. multidisciplinary process

2. amount of overeruption of antagonist tooth

3. amount of space to be opened

4. root angulation (M/D)

5. presence of 3rd molar

6. periodontal status

[T/F]: opening space is easier than closing space

T

distal crown tipping:

[more/less] predictable

[easier/complex] biomechanics

[↑/↓] pontic space

more

easier

↑

mesial root movement:

[easier/complex] biomechanics

consider [opening/closing] space

needs _________ anchorage

[↑/↓] treatment time

[↑/↓] risk

needs _______ to move 2nd molar mesial

[enhanced/inhibited] by presence of 3rd molar

complex

closing

anterior

↑

↑

alveolar bone

enhanced

uprighting a tipped molar [↑/↓] the crown height & [↑/↓] the depth of the mesial periodontal pocket

↑

↓

[T/F]: when uprighting a molar some extrusion always occurs

T

when uprighting a molar some extrusion always occurs which may (3)

1. interfere with efficient movement

2. produce functional problems

3. reduce pseudopockets

options to minimize extrusion (3)

1. crown reduction

2. biomechanics of force application

3. miniscrew anchorage

considerations before uprighting a 3rd molar (3)

1. occlusal relationship with antagonist

2. restorability

3. oral hygiene/periodontal status

when should a removable appliance be used?

tooth tipping only

useful with multiple missing posterior teeth or advanced PD involvement

[fixed/removable] appliances give more control of tooth movement

fixed

fixed appliance designs (4)

1. T-loop

2. coil spring

3. cantilever/helix spring

4. uprighting spring with miniscrew anchorage

[T/F]: failure to eliminate occlusal interferences will prolong molar uprighting treatment

T

molar uprighting treatment time:

simple cases

complex cases

often much [shorter/longer] than initially anticipated

8-10 wks

20-24 wks

longer

types of space retention (2)

1. extracoronal splint

2. intracoronal or facially bonded splint

in an [intracoronal/extracoronal] splint, the 19x25 ss is engaged in the brackets passively

extracoronal

in an [intracoronal/extracoronal] splint, the 19x25 ss is bonded in place with composite resin

intracoronal

[T/F]: orthodontic extrusion requires a multidisciplinary team

T

indications for orthodontic extrusion (3)

1. fracture

2. caries

3. bony pocket

advantages to orthodontic extrusion (4)

1. conservative procedure that allows retention of a tooth without the disadvantages of a fixed bridge

2. does not involve loss of bone or periodontal support, as commonly occurs during extraction

3. simple technique requires a relatively easy movement of the tooth

4. gingival margins remain same height as adjacent teeth

disadvantages to orthodontic extrusion (5)

1. wearing an orthodontic device

2. esthetics of appliances

3. oral hygiene

4. duration of treatment

5. periodontal surgery

contraindications to orthodontic extrusion (8)

1. ankylosis or hypercementosis

2. root proximity

3. short roots

4. insufficient prosthetic space

5. exposure of furcation

6. presence of chronic, uncontrollable inflammatory lesions, including combined endodontic-periodontic lesions and fractured roots

7. inability to control inflammation and acute infection

8. absence of attachment apparatus because forced eruption only relocates the existing attachment, it does not create a new attachment

force for orthodontic extrusion of lower incisors

15 grams

force for orthodontic extrusion of molars

60 grams

[T/F]: force for orthodontic extrusion should be applied along the axis of the tooth to prevent tipping

T

orthodontic extrusion involves applying traction forces in all regions of the periodontal ligament to stimulate

marginal apposition of crestal bone

the __________ follows the vertical movement of the root during the extrusion process

similarly, the __________ is attached to the root by the PDL and is in turn pulled along by the movement of the root

gingiva

alveolus

periodontal effects of extrusion:

orthodontic extrusion forces coronal migration of the root and increases (2)

1. bone ridge

2. quantity of attached gingiva

periodontal effects of extrusion:

the amount of attached gingiva is increased through ________ of the sulcular epithelium, appearing first as immature nonkeratinized tissue ("red patch") and then as keratinized tissue

the process of keratinization requires ___-___ days

eversion

28-42 days

prosthodontics & extrusion:

the __________ of crowns must not be exaggerated to compensate for the reduction in diameter

____________ should not be filled to prevent an overcontour, which could adversely affect the marginal periodontium

ideally the crown to root ratio should be __:__ or a bare minimum of __:__ in extreme cases

contour shape

embrasures

1:2

1:1