Hypodontia and Supernumerary Teeth Flashcards
what is hypodontia
less than 6 congenitally missing teeth
what is oligodontia
more than or equal to 6 congenitally missing teeth
what is anodontia
absence of all teeth
what is hyperdontia
extra teeth
is anodontia common
very rare
what happens in anodontia
failure of teeth to develop- agenesis of teeth
what is another name for hyperdontia
supernumerary teeth
what can cause congenitally missing teeth
- ectodermal dysplasia
- hypothyroidism
- down syndrome
- cleft palate
- genetic
- radiation
- random
what is seen in ectodermal dysplasia
- group of syndromes
- missing or peg shaped teeth
- thin sparse hair
- absence of sweat glands
what is the cause of hypothyroidism
- thyroid
- pituitary
- hypothalamus abnormalities
how common is cleft palate
one in 600-800 births
congenital absence of teeth results from disturbances during:
initial stages of tooth formation- initiation and proliferation
is there a successor if there is no primary tooth
no
what gives rise to permanent tooth buds
primary tooth buds
is it possible to have missing permanent teeth even when primary teeth were present
yes
what is the incidence of hypodontia
- 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
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
distal
what is the etiology of hypodontia
- 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
if the primary tooth is missing _____ permanent tooth
cant have
what is the most common missing tooth and what is the incidence
second premolars
- more than 40% of all missing teeth
____ second premolars are missing more often than ______
mandibular; maxillary
what are the top 3 most common missing teeth in order of most common to least common
- mandibular second premolars
- maxillary lateral incisors
- upper second molars
what are the treatment options for hypodontia
- 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
what is the ideal substitution for a missing maxillary lateral incisor
canine substitution
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
what is the order of enameloplasty
- cusp tip
- mesial and distal
- labial ridge
- mesial composite
- line angles
in enameloplasty of canines, mesial and distal reduction is often:
underperformed
what is the disturbance that occurs during development in supernumerary teeth
disturbances during the initiation and proliferation stages of development
extra tooth has great potential to disrupt:
normal occlusion
_______ to remove supernumerary teeth is indicated
early intervention
incidence of hyperdontia is much _____ than hypodontia
lower than
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%
where is the most common location for supernumerary teeth and what is it called
maxillary midline- mesiodens
what are other common places for supernumerary teeth to appear
- laterals, premolars, and 4th molars
supernumerary teeth can be _______ in shape
typical or atypical
describe mesiodens
- often exist singularly but sometimes in combination
- most common cause of unerupted upper central incisor
- can deflect tooth
what is a 3rd molar supernumerary tooth called
a distodens
treatment for supernumerary teeth is aimed at
extraction before problems arise or minimizing effect on other teeth
what is the general rule for supernumerary teeth
more supernumeraries, more abnormal, higher their position, harder to manage
when do you remove conical supernumerary teeth
- if it erupts
- inverted- wont erupt
- displacing adjacent teeth
- producing diastema
- delaying eruption of permanent tooth
when do you NOT remove conical supernumerary teeth
- if well above the apices of the permanent tooth
- observe
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
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%
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
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
how do you diagnose impactions and ectopic eruptions
- periapical radiographs
- occlusal radiographs
- CBCT imaging
what do you need to consider when taking PA radiographs
- Clark’s technique
- SLOB rule
what is better for diagnosis: PA radiographs and occlusal radiographs OR CBCT
CBCT
