Orthodontics Flashcards

1
Q

Diastema rule for closure

A

if >2mm, it will not close on its own (not developmental)

close with retainers: TPA/nance/hawley with finger springs or through ortho (do oath first, then cut the frenum)

Closure least likely to occur with early loss of primary CI

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2
Q

upright and stabilize a molar

A

upright: 6-12 months
stabilize: 2-6 months

via fixed edgewise orthodontic appliance

second molars that are uprighted should be banded, b/c brackets may easily come off from the muscles of mastication

Most difficult to upright: lingually tipped mandibular molar

High angle cases result in excessive VDO (bite opening)

0.018 or 0.022 inch wire

Steps:

  1. Separate
  2. Band
  3. Upright
  4. crown lengthen
  5. crown
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3
Q

Mechanism for ortho forces

A

Heavy Force = early hyalinization (necrosis) and osteoclast resorption of underlying PDL. Delayed movement.

Light Force = little hyalinization and osteoclast resorption on the front side. Earlier movement.

Compression = osteoclast *Main factor in ortho
Tension = osteoblast

To have oath movement, you need PDL. Thus, implants are subjected to oath movement no matter how slow.

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4
Q

Mandibular Growth

A
  • Infants have ramus at 1M site.
  • Growth occurs at condyle and posterior surface of rams
  • Body of mandible grows via periosteal apposition
  • Condyle growth via endochondral replacement and surface remodeling on the anterior surface of the ramus

Maxilla growth pattern resembles neural tissue
Mandible pattern resembles genital tissue (grows later)

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5
Q

Most common tooth to have a supracrestal circumferential fibrotomy

A

Rotated maxillary central incisor

PDL reorganizes in 3-4 months

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6
Q
  1. Long face predisposes people to what type of malocclusion?
  2. Short face?
A
  1. Class II

2. Class III

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7
Q

Treatment Planning Priority:

A
  1. Crossbite: Posterior > Anterior
  2. impacted teeth
  3. inter-arch relations > intra-arch relations
  4. habits
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8
Q

Ideal angles:

  1. SNA
  2. SNB
  3. ANB
A

Sella Turcica to Nasion THEN from Nation to Point A or B

  1. SNA = 82 degrees
  2. SNB = 80 degrees
  3. ANB = 2 degrees (4 = Class II, 0 = Class III)
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9
Q

Cross bite is most often due to

A

retained primary teeth

RISK: loss of arch length if not corrected.
Tx: increase space MD of the arch
Retained: Best by the natural dentition of the incisors, not by appliances

Premature exfoliation of primary canines may indicate deficient arch length, leading to a lingual collapse of the incisors.

Anterior crossbites = Reverse overjet = Class III
Posterior cross bites take priority and are the most common type of active tooth movement in PEDO

Scissor bite = lingual cross bite = collapsed mandible with over extended maxilla

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10
Q

Thumb Sucking

A

Thumb sucking ONLY during the mixed dentition stage causes malocclusion via:

A. increased pressure on buccinators (not negative pressure) → narrow/constricted max arch (expanded arch) → mandible shift to one side on closure → bilateral cross bite

B. max. incisors procline with reclined mand. Incisors → anterior open bite → Class II Malocclusion

Results:
cross bite
anterior open bite (collapsed arch)
proclaimed max incisors
Retroclined mand. incisors
class II

Tx: palatal expander (TPA, Hawley, Hyrax, Quad-helix, Haas) turned every 1-2 months. Need 3 months to stabilize.

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11
Q

Most common:

  1. Anterior open bites
  2. Deep Bites
  3. Class III
A
  1. Blacks - mostly asymmetrical
  2. Whites
  3. Asians

Class III are rare in the U.S. than Class II

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12
Q

Tongue Thrust

A

open bite

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13
Q

Skeletal vs functional cross bite

A

Skeletal corset will show a smooth transition in CO/MI.

Functional corset occurs from thumb sucking, where the patient will tend to function on one side during closure.

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14
Q

Moyer’s Analysis

A
  • MD width of MAND. Incisors (Max incisors show too much unpredictability in size for PEDO)
  • mixed dentition analysis
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15
Q

most common cause of Class I malocclusion

A

tooth size and supporting bone (length) discrepancy

Class I (70%) > Class II (20%) > Class III

Class III “subdivision” means you have a class III on one side and a class I on the other

When both jaws are protruded, you will see lip incompetence, lip opening and lip strain.

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16
Q

Serial EXT

A
  • EXT required to make space when > 4mm is needed.
  • primary 2M are not typically removed
  • Used in Class I malocclusion with limited arch space int he mixed dentition stage

EXT sequence

  1. primary canine
  2. primary 1M
  3. Permanent 1PM (prior to erupting canine)

6-12 months are EXT intervals

Adult dentition crowding almost always requires EXT for proper alignment

17
Q

Sunday bite versus pseudo class III malocclusion

A

Sunday Bite = Class II individual purposefully shifts jaw forward for esthetics

Pseudo class III = Patient shifts jaw forward to prevent hitting incisors

18
Q

Malocclusion is best identified at what age and why?

A

7-9 years old because the eruption of the permanent incisors reveal tooth-arch length discrepancies

19
Q

Define:

  1. Torque
  2. tipping
  3. most difficult movement to accomplish
A
  1. Movement of the root when the crown is stable (not like tipping) = molar uprighting
  2. requires two areas of compression and tension. Easy with anterior incisors
  3. Translation and Intrusion
20
Q

Hand and Wrist x-ray landmark

A

Ulnar sesamoid and hamate bones

- Just used for locating patient’s position on growth chart, not to determine continuation or progression.

21
Q

An anterior crossbite in a primary dentition usually indicates what?

A

skeletal growth problems