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Ortho II > Hypodontia and Supernumerary Teeth > Flashcards

Hypodontia and Supernumerary Teeth Flashcards

1
Q

what is hypodontia

A

less than 6 congenitally missing teeth

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2
Q

what is oligodontia

A

more than or equal to 6 congenitally missing teeth

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3
Q

what is anodontia

A

absence of all teeth

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4
Q

what is hyperdontia

A

extra teeth

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5
Q

is anodontia common

A

very rare

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6
Q

what happens in anodontia

A

failure of teeth to develop- agenesis of teeth

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7
Q

what is another name for hyperdontia

A

supernumerary teeth

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8
Q

what can cause congenitally missing teeth

A
  • ectodermal dysplasia
  • hypothyroidism
  • down syndrome
  • cleft palate
  • genetic
  • radiation
  • random
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9
Q

what is seen in ectodermal dysplasia

A
  • group of syndromes
  • missing or peg shaped teeth
  • thin sparse hair
  • absence of sweat glands
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10
Q

what is the cause of hypothyroidism

A
  • thyroid
  • pituitary
  • hypothalamus abnormalities
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11
Q

how common is cleft palate

A

one in 600-800 births

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12
Q

congenital absence of teeth results from disturbances during:

A

initial stages of tooth formation- initiation and proliferation

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13
Q

is there a successor if there is no primary tooth

A

no

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14
Q

what gives rise to permanent tooth buds

A

primary tooth buds

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15
Q

is it possible to have missing permanent teeth even when primary teeth were present

A

yes

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16
Q

what is the incidence of hypodontia

A
  • 2-10% of general population excluding third molars
  • 0.1%-0.4% of congenitally missing primary teeth
  • 20%- 25% 3rd molars missing
  • hypodontia higher in females 3:2
  • commonly runs in families
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17
Q

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

A

distal

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18
Q

what is the etiology of hypodontia

A
  • missing teeth can be inherited as a part of a syndrome or a polygenic multifactorial model of etiology
  • genes: MSX1, PAX9, AXIN2
  • cytotoxic drugs
  • radiotherapy
  • random
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19
Q

if the primary tooth is missing _____ permanent tooth

A

cant have

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20
Q

what is the most common missing tooth and what is the incidence

A

second premolars
- more than 40% of all missing teeth

21
Q

____ second premolars are missing more often than ______

A

mandibular; maxillary

22
Q

what are the top 3 most common missing teeth in order of most common to least common

A
  • mandibular second premolars
  • maxillary lateral incisors
  • upper second molars
23
Q

what are the treatment options for hypodontia

A
  • replacement: prosthetically, transplantation
  • implant- retain primary tooth till close to time of implant for bone
  • extraction of the primary tooth and allowing permanent teeth to drift
  • extraction followed by ortho tx
  • maintain tooth or teeth, will have occlusal problems since second deciduous tooth is not same size as 2nd premolar
24
Q

what is the ideal substitution for a missing maxillary lateral incisor

A

canine substitution

25
Q

why is canine substitution ideal for missing maxillary lateral incisor replacement

A
  • similar color to central incisor
  • narrow width at the CEJ
  • relatively flat labial surface
  • narrow mid-crown buccolingual width
  • enameloplasty is needed
26
Q

what is the order of enameloplasty

A
  • cusp tip
  • mesial and distal
  • labial ridge
  • mesial composite
  • line angles
27
Q

in enameloplasty of canines, mesial and distal reduction is often:

A

underperformed

28
Q

what is the disturbance that occurs during development in supernumerary teeth

A

disturbances during the initiation and proliferation stages of development

29
Q

extra tooth has great potential to disrupt:

A

normal occlusion

30
Q

_______ to remove supernumerary teeth is indicated

A

early intervention

31
Q

incidence of hyperdontia is much _____ than hypodontia

A

lower than

32
Q

what is the incidence of supernumerary tooth in primary dentition, permanent dentition and upper jaw

A
  • primary: 0.5%
  • permanent dentition- 1%
  • upper jaw (pre- maxilla) -85%
33
Q

where is the most common location for supernumerary teeth and what is it called

A

maxillary midline- mesiodens

34
Q

what are other common places for supernumerary teeth to appear

A
  • laterals, premolars, and 4th molars
35
Q

supernumerary teeth can be _______ in shape

A

typical or atypical

36
Q

describe mesiodens

A
  • often exist singularly but sometimes in combination
  • most common cause of unerupted upper central incisor
  • can deflect tooth
37
Q

what is a 3rd molar supernumerary tooth called

A

a distodens

38
Q

treatment for supernumerary teeth is aimed at

A

extraction before problems arise or minimizing effect on other teeth

39
Q

what is the general rule for supernumerary teeth

A

more supernumeraries, more abnormal, higher their position, harder to manage

40
Q

when do you remove conical supernumerary teeth

A
  • if it erupts
  • inverted- wont erupt
  • displacing adjacent teeth
  • producing diastema
  • delaying eruption of permanent tooth
41
Q

when do you NOT remove conical supernumerary teeth

A
  • if well above the apices of the permanent tooth
  • observe
42
Q

what is typical for supernumerary teeth

A

resembles a normal tooth in morphology and commonly produces crowding or displacement
- extract the tooth most dissimilar to the contralateral tooth, unless it is severely displaced

43
Q

what is the incidence of impactions and ectopic eruptions

A
  • 1.7%
  • twice as common in females (1.17%) as in males (0.51%)
  • 8% bilateral impactions
  • mandibular canine impaction is 0.35%
44
Q

what is the etiology for impactions and ectopic eruptions

A
  • local hard tissue obstruction
  • local pathology
  • disturbance of normal development of the incisors
  • hereditary or genetic factors
45
Q

what are the canine impaction considerations

A
  • it is unerupted after 75% of its root development
  • the contralateral tooth has erupted for at least 6 months with complete root formation
  • two years after the adolescent growth spurt were passed
  • 6 months after canine root completion was passed
  • 85% of palatal impactions had sufficient space for eruption
  • 83% of labial impactions showed an arch length deficiency
46
Q

how do you diagnose impactions and ectopic eruptions

A
  • periapical radiographs
  • occlusal radiographs
  • CBCT imaging
47
Q

what do you need to consider when taking PA radiographs

A
  • Clark’s technique
  • SLOB rule
48
Q

what is better for diagnosis: PA radiographs and occlusal radiographs OR CBCT

A

CBCT

49
Q
A

Ortho II (11 decks)

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