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Orthodontics II > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

Less than 6 congenitally missing teeth:

A

hypodontia

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2
Q

More than 6 congenitally missing teeth:

A

oligodontia

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3
Q

Abscence of all teeth:

A

anodontia

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4
Q

Extra teeth (supernumerary teeth):

A

hyperdontia

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5
Q

What 7 things are known to result in congenitally missing teeth?

A
  1. ectodermal dysplasia
  2. hypothyroidism
  3. down syndrome
  4. cleft palate
  5. genetics
  6. radiation
  7. random
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6
Q

Group of syndromes causing missing or peg shaped teeth, thin, sparse hair, and absence of sweat glands:

A

ectodermal dysplasia

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7
Q

Cleft palates occur in _____ briths

A

600-800

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8
Q

What is the cause of congenitally missing teeth?

A

due to disturbances during the initial stages of tooth formation (initiation & proliferation)

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9
Q

What specific stages of tooth formation are disturbed resulting in congenitally missing teeth?

A

initiation & proliferation

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10
Q

T/F: If a primary tooth is missing, there is a chance the permanent successor will be present

A

false- since primary tooth buds give rise to permanent tooth buds, it is not possible to be a successor if the primary tooth bud is missing

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11
Q

Is it possible to have missing permanent teeth even when there was a primary tooth?

A

yes

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12
Q

What is the INCIDENCE of hypodontia of in the general population?

A

General population: 2-10% (excluding 3rd molars)

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13
Q

What is the incidence of congenitally missing primary teeth?

A

0.1-0.4%

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14
Q

What is the incidence of congenitally missing 3rd molars?

A

20-25%

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15
Q

What sex is hypodontia more common in?

A

females (3:2 ratio)

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16
Q

T/F: Hypodontia commonly runs in families

A

true

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17
Q

What is the general rule to hypodontia?

A

As a general rule, if only one or a few teeth are missing, the absent tooth will be the most DISTAL tooth of any given type

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18
Q

Missing teeth can be inherited as part of a syndrome or a:

A

polygenic multifactorial model of etiology

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19
Q

What genes are etiologic factor in hypodontia?

A

MSX1, PAX9, AXIN2

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20
Q

List 2 medically induced etiologies of hypodontia:

A
  1. cytotoxic drugs
  2. radiotherapy
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21
Q

T/F: The etiology of hypodontia can be random

A

true

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22
Q

What are the most commonly missing permanent teeth?

A

mandibular 2nd premolars
maxillary 2nd premolars
maxillary lateral incisors
maxillary second molars

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23
Q

Are maxillary or mandibular 2nd premolars missing more often?

A

mandibular 2nd premolars

24
Q

What are the REPLACEMENT options for hypodontia?

A
  1. prosthetically
  2. transplantation
  3. implant
25
Q

What are the treatment options for hypodontia?

A
  1. replacement
  2. extraction of primary tooth to allow tooth drift
  3. extraction followed by ortho
  4. maintain tooth or teeth (occlusal problems to be expected)
26
Q

What must be considered if replacement via implant is the chose treatment for hypodontia?

A

retain primary tooth until close to time of implant placement to ensure good bone

27
Q

What do you need for proper canine substitution?

A
  1. similar color to central incisor
  2. narrow width at CEJ
  3. relatively flat labial surface
  4. narrow mid-crown BL width
  5. enameloplasty
28
Q

What is the order of canine enameloplast?

A
  1. cusp tip
  2. mesial and distal (often underperformed)
  3. labial ridge
  4. add mesial composite
  5. line angles
29
Q

Extra, supernumerary teeth have great potential to:

A

disrupt normal occlusion

30
Q

What is indicated with supernumerary teeth?

A

early intervention to remove them as indicated

31
Q

Is the incidence of HYPERdontia higher or lower than HYPOdontia?

A

Lower

32
Q

What is the incidence of HYPERdontia in primary dentition, then permanent dentition?

A

primary = 0.5%

permanent= 1.0%

33
Q

If hyperdontia occurs, what percent of the time does it occur in the maxilla?

A

85%

34
Q

T/F: Hyperdontia occurs in the upper jaw/ pre-maxilla area 85% of the time

A

true

35
Q

Where are mesiodens commonly located?

A

maxillary midline

36
Q

Do mesiodens often exist singularly or in combination?

A

They are most often singular, however CAN also exist in combination

37
Q

Can mesiodens deflect teeth?

A

yes

38
Q

What is the general treatment for supernumerary teeth?

A

extraction before problems arise

39
Q

The more supernumeraries, the more ___, the ____ the position, the ___ it is to manage.

A

abnormal; higher; harder

40
Q

List the indications for removal of conical supernumerary teeth?

A
  1. if it erupts
  2. inverted
  3. displacing adjacent teeth
  4. producing diastema
  5. delaying eruption of permanent tooth
41
Q

When should you NOT remove conical supernumerary teeth?

A

If the tooth is well above the apices of the permeant tooth, just observe

42
Q

What does the typical supernumerary tooth resemble?

A

Resembles a normal tooth in morphology & commonly produces crowding or displacement

43
Q

What is the recommended treatment for typical supernumerary teeth?

A

Extract the tooth most dissimilar to the contralateral tooth unless it is severely displaced

44
Q

The recommended treatment for typical supernumerary teeth is to extract the tooth more dissimilar to the contralateral tooth unless:

A

it is severely displaced

45
Q

What is the incidence of impactions and ectopic eruptions?

A

incidence= 1.7%
Females (1.17%); males (0.51%)

46
Q

What percent of the time do bilateral impactions occur?

A

8% of the time

47
Q

What percent of the time do mandibular canine impactions occur?

A

0.35%

48
Q

List the etiologies for impactions and ectopic eruptions:

A
  1. local hard tissue obstruction
  2. local pathology
  3. disturbance of normal development of the incisors
  4. hereditary or genetic factors
49
Q

List the signs that might lead you to believe that the canines are impacted:

A
  1. canine is unerupted after 75% of its root development
  2. the contralateral tooth has erupted for at least 6 months with complete root formation
  3. two years after the adolescent growth spurt were passed
  4. 6 months after canine tooth completed was passed
  5. sufficient space for eruption (yet not erupted)
  6. arch length deficiency
50
Q

What percent of palatal canine impactions had sufficient space for eruption?

A

85%

51
Q

83% of labial canine impactions showed an:

A

arch length deficiency

52
Q

What can be used to diagnose impacted teeth?

A
  1. PA radiographs
  2. Occlusal radiographs
  3. CBCT imaging
53
Q

With PA radiographs, what technique should be used?

A

Clark’s Technique (SLOB rule)

54
Q

What degree to the occlusal plan can you see impacted canines on an occlusal radiograph?

A

110 degree vertex occlusal

55
Q

Are convention radioagraphs or CBCT better for accurate and precise examination methods for displaced maxillary canines?

A

CBCT- conventional radiographs demonstrated a more subjective diagnosis

56
Q
A

Orthodontics II (7 decks)

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