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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
why is canine substitution ideal for missing maxillary lateral incisor replacement
- similar color to central incisor - narrow width at the CEJ - relatively flat labial surface - narrow mid-crown buccolingual width - enameloplasty is needed
26
what is the order of enameloplasty
- cusp tip - mesial and distal - labial ridge - mesial composite - line angles
27
in enameloplasty of canines, mesial and distal reduction is often:
underperformed
28
what is the disturbance that occurs during development in supernumerary teeth
disturbances during the initiation and proliferation stages of development
29
extra tooth has great potential to disrupt:
normal occlusion
30
_______ to remove supernumerary teeth is indicated
early intervention
31
incidence of hyperdontia is much _____ than hypodontia
lower than
32
what is the incidence of supernumerary tooth in primary dentition, permanent dentition and upper jaw
- primary: 0.5% - permanent dentition- 1% - upper jaw (pre- maxilla) -85%
33
where is the most common location for supernumerary teeth and what is it called
maxillary midline- mesiodens
34
what are other common places for supernumerary teeth to appear
- laterals, premolars, and 4th molars
35
supernumerary teeth can be _______ in shape
typical or atypical
36
describe mesiodens
- often exist singularly but sometimes in combination - most common cause of unerupted upper central incisor - can deflect tooth
37
what is a 3rd molar supernumerary tooth called
a distodens
38
treatment for supernumerary teeth is aimed at
extraction before problems arise or minimizing effect on other teeth
39
what is the general rule for supernumerary teeth
more supernumeraries, more abnormal, higher their position, harder to manage
40
when do you remove conical supernumerary teeth
- if it erupts - inverted- wont erupt - displacing adjacent teeth - producing diastema - delaying eruption of permanent tooth
41
when do you NOT remove conical supernumerary teeth
- if well above the apices of the permanent tooth - observe
42
what is typical for supernumerary teeth
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
what is the incidence of impactions and ectopic eruptions
- 1.7% - twice as common in females (1.17%) as in males (0.51%) - 8% bilateral impactions - mandibular canine impaction is 0.35%
44
what is the etiology for impactions and ectopic eruptions
- local hard tissue obstruction - local pathology - disturbance of normal development of the incisors - hereditary or genetic factors
45
what are the canine impaction considerations
- 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
how do you diagnose impactions and ectopic eruptions
- periapical radiographs - occlusal radiographs - CBCT imaging
47
what do you need to consider when taking PA radiographs
- Clark's technique - SLOB rule
48
what is better for diagnosis: PA radiographs and occlusal radiographs OR CBCT
CBCT
49

Ortho II (11 decks)

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