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Pediatric Dentistry Boards > Malocclusion Management > Flashcards

Malocclusion Management Flashcards

1
Q

Approx what percent of the US population has some sort of malocclusion? What is the breakdown by class?

A

65%
Class I ~60%
Class II ~30 %
Class III ~5%

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2
Q

Requirements for orthodontic tooth movement?

A
  1. Intervening bioactive soft tissue (ie PDL)
  2. An initiating signal (ie a biomechanical force)-there is a direct relationship to duration of force-need at least 6 hours/day
  3. Histology/Pathology: orthodontic tooth movement is injury/repair w/the development of pro-inflammatory cytokines
  4. Osteoclastogenesis: proinflammatory cytokines, RANK/RANKL/osteoprotegerin
  5. Osteogenesis
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3
Q

How does the underlying periodontium respond to light force? What is light force? What is the process called?

A

Light Force: <300g

  • Light continuous force results in :
    1. osteoclast formation
    2. Removing lamina dura
    3. Tooth movement begins
    4. this process is called FRONTAL resorption, because frontal resorption occurs on the osseous margin adjacent to the PDL
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4
Q

Describe frontal resorption

A

Frontal resorption: occurs on the osseous margin adjacent to the PDL and is due to light continous forces

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5
Q

Describe the phases leading to frontal resorption in light force in terms of what you see (clinically) and mechanical forces coupled with cellular changes. What is the time frame for each phase?

A

Phase 1 : Mechanical compression and tension of the peridontium (occurs in 1-2 days, ie placing orthodontic separator bands, tooth just moves a little and compresses the PDL)
Phase 2: Mechanically induced cellular and genetic responses; no tooth movement (20-30days, clinically looks like nothing is happening)
Phase 3: Accelerated tooth movement due to FRONTAL bone resorption after 30days

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6
Q

What are the effects of heavy forces on the PDL?

A

Heavy, continuous forces:

  1. Blood supply to PDL OCCLUDES
  2. Aseptic necrosis
  3. PDL becomes “hyalinized/hyalinazation”
  4. This process is called UNDERMINING resorption
    - undermining because where the compression occurs there is a localized loss of vitality (necrosis) and removal of the alveolar bone in the area of pressure
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7
Q

Describe the phases in the heavy force and the timing of each

A

Phase 1: Mechanical compression and tension of the periodontium
Phase 2: Continuing mechanical compression; little cellular and genetic responses; no tooth movement
Phase 3: Cells recruited from the undermining side of lamina dura, NOT within the PDL, to induce UNDERMINING bone resorption

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8
Q

Compare light and heavy forces

A

Lag phase is longer in heavy forces however ultimately there is the same amount of tooth movement.
- Heavy forces considered pathologic by orthodontists–see more complications root resorption etc than with light

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9
Q

Pressure tension theory of tooth movement

A

When you put pressure or tension on tooth, you see resorption on the pressure, and bone deposition on the tension side.

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10
Q

Bioelectricity (piezoelectric) theory of tooth movement

A

If you put pressure on crystals it generates electrical charges, these charges are thought to play some role in the cellular initiation. If you subject the supporting tissue to electrical charges, you will get accelerated tooth movement (this is controversial).

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11
Q

What are the major theories of tooth movement?

A
  1. Pressure-tension theory

2. Piezoelectric/Bioelectric theory

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12
Q

Center of rotation:

A

The point around which rotation occurs when an object is moved. This is exactly in the middle of tooth in space. Teeth in the periodontium do not actually rotate around their “real” center of rotation.

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13
Q

Do teeth rotate around the center of rotation or the center of resistance? Describe what it rotates around.

A

Teeth in bone rotate around the Center of Resistance:
A point on the tooth around which the tooth shall move. For most teeth, COR is 2/5 way between the apex and the crest of the alveolar bone.

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14
Q

Tipping movement and its effect on the PDL; what should tipping movement not exceed?

A

In tipping movement only half of the area of PDL is loaded

therefore Tipping forces should NOT EXCEED 50 grams

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15
Q

How much force is needed to create bodily movement (translation)?

A

100grams of force is needed to produce bodily movement, but must consider friction, it may exceed 100grams

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16
Q 
What are the lightest forces used on? How much force is required for:
Root uprighting
Rotation 
Extrusion
Intrusion
A

Lightest forces are required for intrusion 10-20gm
Root uprighting 50-100
Rotation and Extrusion require 35-60

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17
Q

Orthodontic treatment and dental health: Which of the following are reduced or related to ortho treatment?

  • Dental caries
  • Periodontal disease
  • TMD
  • Dental trauma
A

None of these are relieved or treated by orthodontic treatment with fairly high levels of evidence. In over 90% of cases it is a totally elective procedure.

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18
Q

Potential dentoalveolar changes related to non nutritive sucking habits:

A
  • Increased OJ
  • Anterior open bite
  • Posterior crossbite
  • Class II malocclusion
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19
Q

Relative to non nutritive sucking habits, what is most important in terms of severity?

A

Duration > magnitude (an active vs passive sucker) > frequency

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20
Q

What is the prevalance of non-nutritive sucking habits at age 3? What is likely to occur if there are maintained until age 4? age 5-6?

At what age do most children stop their habit?

A

at age 3 10-40% of children have oral habits.
If maintained to age 4 or less: likely no adverse effects
Greater than age 4 see altered occlusions: open bites, posterior xbites; it will no longer self correct

-Most stop by age 4 (10% continue)

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21
Q

What sort of malocclusions does thumb sucking cause? pacifier?

A

Thumbs: anterior open bite, increased overjet
Pacifier: posterior xbite

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22
Q

Bruxing: prevalence? is it related to the occlusal relationship? Why do patients brux? Treatment in the mixed dentition?

A

Prevalence: 15-40% of kids in primary/early mixed dentition

  • weak support of relationship of brux to occlusal relationship
  • Etiologies include anxiety etc
  • Most patients “outgrowth” condition
  • No tx indicated in primary dentition
  • Macy consider night guard in permanent dentition
  • Rule out GERD
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23
Q

Is there facial muscle involvement during normal swallowing?

A

No. This is an indication of a possible tongue thrust habit

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24
Q

What percent of the population are missing permanent teeth? Which are most often missing and in what order?

A

25% are congenitally missing permanent teeth including 3rd molars, 5% excluding 3rds
3rd molars > Mandibular 2nd PM> Maxillary lateral > Maxillary 2nd PM

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25
Q

Congentially missing lateral:

- what elements making correcting the problem easier? What makes it favorable to correct by canine substitution?

A

-Premolar moving back is easier than the molars moving forward. Therefore, incisor crowding which necessitates PMs moving back is favorable.
-Canine position:
Class II canines with a small mesio-distal width, or that are erupting mesially are favorable in correcting congenitally missing laterals.

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26
Q

Treatment options regarding replacing a congenitally missing teeth?

A
  1. Maintain primary tooth (unless the primary is ankylosed/below the plane of occlusion or root resorption has occured)
  2. Pros (Maryland bridge, implants)
  3. Orthodontic space closure:
    - -If a premolar is missing, this is easy if they are crowded
    - -Canine replacement
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27
Q

Canine replacement therapy: what makes this a more favorable option for replacing a missing lateral?

A

If the patient has:

  • Class II relationship
  • Canine has a small mesio-distal dimension
  • If the canine is erupting mesially
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28
Q

What is the prevalance of supernumerary teeth in the primary dentition?

  • -Of the supernumerary teeth, what percent is found in the maxilla?
  • -What percent of primary supernumeraries are assoc with permanent ones?
A

.5-2% in primary and mixed
80-90% of those in the maxilla
30% of primary supernumerary teeth are assoc w/permanet supernumeraries

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29
Q

Supernumerary teeth in the primary dentition (morphology)?

A

Frequently fused

30
Q

What are the indications for removal of a mesiodens?

A

Delayed/inhibited/displaced eruption of central incisors

  • -associated pathology
  • -Spontaneous eruption of mesiodens
31
Q

Prevalance of ectopic eruption in population? Prevalence in cleft patients
Is there a genetic predisposition?

A

5% gen pop
22% of cleft pts
20% of sibs of patients w/ectopic eruption; yes

32
Q

Main etiology factors regarding ectopic eruptions?

Are all people with ectopic eruption doomed?

A
  1. Greater mesial angulation of 1st permanent molar
  2. greater width of 1st permanent molar
    No, without management ~60-70% will self correct
33
Q

How can you determine whether an ectopically erupting tooth will self correct or require intervention? What are the grades of overlap?

A 
Grade I (mild): enamel overlap only
Grade II (moderate): ~1/4 overlaps
Grade III-IV (severe): 1/2 or more of the tooth overlaps. These require interventions.
34
Q

For each grade of overlap for ectopically erupting 1st molars, what are the likely treatments

A

Grade I - Mild- watch (1/4 overlap)
Grade II - Moderate (1/3 overlap) watch or if slight more than 1/3, brass ligature, spring clip, distalizing appliance
Grade II - Severe (1/2 overlap or more): extract primary molar, distalize permanent molar

35
Q

Ectopically erupting canines- the 1st indication?

A

Should begin palpating for canines at age 7.

36
Q

Describe the sector analysis for predicting maxillary canine impaction using sectors and angular measurement

A

When teh canine starts the cross the midline of the lateral incisor the likelihood of the tooth being impacted is very high (on a pano)

37
Q

Treatment of the ectopically erupting canine detected early?

A
  • Extract the primary canine (and maybe the primary 1st molars)
  • If class II consider headgear therapy
38
Q

Treatment for impacted canines?

A
  1. Active tx: full thickness flap, with tissue reapproximation
  2. Passive tx: surgically expose crown down to CEJ and allow to passively erupt
39
Q

Ectopically erupting premolars: treatment?

A

Extract primary molar, consider space maintainer

- 2nd max PMs almost always erupt

40
Q

Ectopically erupting 2nd molars: treatment?

A

More common w/”E” space preservation

  • May require ortho uprighting
  • Eval 3rd molar position (may require 3rds EXT)
41
Q

What teeth is ankylosis most commonly observed in? What is the best diagnostic criteria (xray? etc)?

A

Mandibular primary molars (1st>2nd)

Sound/tapping on tooth; radiographs of limited value

42
Q

What is the most common etiology of ankylosis? How long is the typical eruption of the succedaneous tooth delayed by?

A

Anteriors- trauma, molars- may be inidcative of missing succedaneous tooth.

  • There is a familial tendency
  • 6m delay
43
Q

Treatment of ankylosed primary molars?

A

1st primary molar: observe, generally these exfoliate on their own
- 2nd primary molar: may be inidcative of agenesis of succadenous tooth. Percuss, check mobility. Observe–but if we start to have tipping over the ankylosed tooth (as it submerges) then either extract the tooth OR the occlusal build up.

44
Q

Treatment for ankylosis in permanent teeth?

A
  1. Surgical manipulation followed by orthodontic traction. Actively extrude the tooth so area of ankylosis no longer aligned with one another. Prognosis extremely guarded.
  2. Distraction: individual tooth is moved with its bone (corticotomy)
  3. EXT
45
Q

How do you determine the severity of crowding?

A

Severity dictates treatment approach:

1. Moyers, Tanaka Johnson, or Rule of 23/21

46
Q

Moyers- how to use this space analysis? What do you measure?

A

Measure lower incisors, take summation and look for the 75% as the amt of space one needs to accommodate the canines

47
Q

Tanaka Johnson- How do you use this space analysis? What do you measure?

A

Mathematic approach that utilizes Moyers but without needing a table.

  1. (Sum of m-d of the lower incisors)/2 + 10.5 necessary mandibular space,
  2. add 11mm will give you necessary space for maxillary arch
48
Q

23/21 rule- how do you use this space analysis? What do you measure?

A

Most simplistic of the space analyses.

- on average you take the M-D of the premolars and canines in the max it would be 23 mm; in the mandibular arch 21mm

49
Q

If there is 1-4 mm of crowding per quadrant, what would your treatment goals and plan be? When should tx occur?

A

Treatment goals:
1. Maintain arch-length 2. Create eruption space
In order to so can:
- Strip primary canines, extract primary canines
- Place lingual arch
Timing of treatment:
- Based on 2nd primary molar. Want to take advantage of leeway space, which disappears with the exfoliation of the 2nd primary molar. Need to hold the Leeway (E) space, can do with an arch.

50
Q

If there is more than 4mm of crowding per quadrant: what would your tx goal be? and plan?

A

Greater than 4mm crowding per arch:
- Consider serial extractions
Also consider: profile, depth of bite and periodontium

51
Q

Profile considerations relative to extraction therapy?

A

Maxillary incisor position determines maxillary lip position. The maxillary incisor position is determined by the mandibular incisor position. Use the mandible to dx whether will use EXT therapy.
- If you retract the maxillary incisors, if they have a large nasolabial angle, it will get larger and be ugly.

52
Q

Leeway space preservation: what does it treat? How does it treat it? And is it effective?

A

Leeway space preservation can treat mild crowding in 65-76% of patients with less than 4-5 mm of incisor crowding.

  • Can treat with: lingual arch, lip bumper, utility arch, edgewise appliances
  • its effective in 65-75% of people
53
Q

Is mandibular expansion possible?

A

Mandibular symphysis fuses by age 1.

  • Schwartz appliance: in a mixed dentition patient you are only moving teeth, you are not expanding the underlying bone.
  • True mandibular expansion requires destractor (heavy metal expander) and a corticotomy cut of the symphisis
54
Q

What does serial extraction treat? What is the sequence?

What is the likely outcome of serial extractions? How does it effect the eruption sequence?

A

Treats crowding of greater than 4mm
1. Extract first primary canines
- allows for spontaneous aligning of incisors
- also DELAYS the eruption of the man canine
2. Extract 1st primary molars when PMs have 1/2 root development
- encourages mandibular PM to erupt ahead of canine
3. Extract 1st PMs
- Allows for spontaneous distalization of canine during its eruption
Likely outcome: shorter period of appliance therapy. Changes the eruption sequence (can>PM1>PM2 to PM1>can>PM2)

55
Q

Bolton analysis: what does it measure? What is the likely treatment following analysis?

A

Measures whether the natural ratio of the tooth size in the maxillary arch correlates with the tooth size in the mandibular arch
–Tx: can reduce tooth mass in the unaffected arch OR create mass in the affected arch.
– Bonding in affected arch or stripping in unaffected
A ‘bolton discrepancy’ size discrepancy between arches bugs bunny

56
Q

When is it appropriate to tx maxillary diastemas? Other considerations?

A

Defer tx until the maxillary perm canines have erupted.

–Consider permanent retention, high relapse potential. Frenectomy AFTER orthodontic closure of diastema

57
Q

How do you dx whether lingual frenectomy is necessary?

A

pull on lip, check for gingival displacement and blanching

58
Q

What are the priority teeth in space maintenance? (incisors, canines, primary molars) Which need space maintainers and when?

A
  • *2nd primary M> 1st primary molar> incisors
  • premature loss of primary incisors has no lasting fx on speech.
  • 2nd primary molar CRITICAL prior to 1st molar eruption
  • 1st primary molar space loss, statistically but clinically insignificant; controversial space maintainer if necessary
  • *Mandibular canines> maxillary canines- canine loss may result in midline shift. If premature, EXT contralateral canine or place a lingual arch w/ a spur
59
Q

Maxillary space regaining?

Mandibular space regaining?

A

Maxilla: headgear, fixed or removable appliance possible to get bodily and distal tipping of the molar.
Mandible: can only tip, not distalize

60
Q

Single tooth crossbite in permanent dentition: wait to tx? comorbidities?

A

Reason to treat in the permanent dentition:
- mucogingival defects and perio problems can spontaneously resolve with orthodontic correction (as long as there is still gingival attch).

61
Q

Single tooth x-bites in primary dentition: wait to treat?

A

Reasoning to wait:
Single tooth tips, the root then tips the permanent tooth as well, resulting in need for treatment in both dentitions. By this reasoning, wait to treat.

62
Q

Describe some clinical clues that a patient in the primary dentition has a “pseudo-class III”. Some Radiographic clues on the cep?

A
  • Maxillary incisors are recumbent
  • mandibular incisors are procumbent
  • On the ceph, can see 2-3 mm of space between the posterior ramus and the vertebral column if NORMAL. If greater than this, indicates the patient is posturing forward (pseudo class III).
63
Q

What is the most common posterior x-bite we see in the primary dentition? How does it occur?
What do we see clinically? typicall tx?

A 
Bilateral w/functional shift
- assoc w/non-nutritive sucking habit
Maxillary dental midline coincidental with facial midline.
- mandibular path of closure deviated
Treatment:
- maxillary expansion 
- canine occlusal adjustment
64
Q

Why do class II malocclusions occur? What % are due to this anomaly?

Clinically, what are some signs we associate with class II malocclusions?

A

Mandibular deficiency = 75% of class II malocclusions

  • Retrognatic profile
  • Normal nasolabial angle
  • Deep labiomental fold
65
Q

What are treatment options for correcting class II early and late? What are some caveats of each tx?

A
  1. Encourage mandibular growth
    - fxnal appliances (little scientific evidence)
  2. Retard maxillary growth
    - Headgear (works in moving the entire maxilla)
    - Class II elastics
  3. ‘Camouflage’
    - Maxillary incisor retraction w/ or w/o EXT
    - W/o ext requires distalization of molars
  4. Orthognatic surgery
66
Q

Headgear: how and why is it effective? What does it do to the molars? the jaws? Min tx time?

A
  1. It is effective in distal movement of the molars
  2. The class II correction is not due to the distal movement of the molars but of the movement of the maxilla as a whole
  3. 6 months at least, best if used until all perm teeth have erupted
67
Q

What level of head gear forces promote dentoalveolar changes? Orthopedic effects? Elastics?

A

Heavy (250-500g/side) orthopedic changes

Light (100-200g/side) dental changes

68
Q

Class III malocclusion tx of the Prognatic Mandible?

A
  • Chin cup therapy
  • Questionable, requires 7+ years of wearing for long periods of time.
  • useful in aiding vertical control
69
Q

Class III malocclusions due to a retrognathic maxilla: Ceph findings? Treatment? favorable/unfavorable?

What can improve the long term prognosis?
Relapse rate?

A

SNA smaller than 82 (normal); SNB is normal; ANB is negative (less than 2, which is normal).

Tx: Reverse pull headgear.

Caveat: ANB can only change ~2-4 degrees, cannot tx w/reverse pull for severe class III, best treatment time is late primary, eary mixed; RPE does not improve effectiveness.

  • Deep bite/hypodivergent facial pattersn has best long term prognosis (tx turns condyles, increasing facial height)
  • relapse rate ~33%
70
Q

What is considered a severe class III? What is the tx?

A

Severe: ANB more negative (smaller than) -3 to -4. Candidate for orthognatic sx. Defer until growth complete.

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