Lecture 1 Flashcards
Less than 6 congenitally missing teeth:
Hypodontia
More than 6 congenitally missing teeth:
Oligodontia
Abscence of all teeth:
Anodontia
Extra teeth (supernumerary teeth):
Hyperdontia
What seven conditions are known to results in congenitally missing teeth?
- ectodermal dysplasia
- Hypothyroidism
- Down syndrome
- Cleft palate
- Genetics
- Radiation
- Random
Groups of syndromes causing missing or peg shaped teeth, thin, sparse hair & absence of sweat glands:
ectodermal dysplasia
Cleft palates occur in _____ births
600-800
What is the cause of congenitally missing teeth?
Due to disturbances during the initial stages of tooth formation (initiation & proliferation)
What specific stages of tooth formation are disturbed resulting in congenitally missing teeth:
Initiation & proliferation
T/F: If a primary tooth is missing there is a chance the permanent successor will be present
False- since primary tooth buds give rise to permanent tooth buds, it is not possible for there to be a successor if the primary tooth bud is missing
Is it possible to have missing permanent teeth even when there is a primary tooth?
Yes
What is the INCIDENCE of hypodontia in the general population?
General population: 2-10% (excluding third molars)
What is the INCIDENCE of congenitally missing primary teeth?
0.1% - 0.4%
What is the INCIDENCE of congenitally missing 3rd molars?
20% - 25%
What sex is hypodontia more common in?
Females (3:2 ratio)
T/F: Hypodontia commonly runs in families
True
What is the general rule to hypodontia?
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
Missing teeth can be inherited as part of a syndrome or a:
polygenic multifactorial model of etiology
What genes are an etiologic factor in hypodontia?
MSX1
PAX9
AXIN2
List two medically induced etiologies of hypodontia:
- cytotoxic drugs
- radiotherapy
T/F: The etiology of hypodontia can be random
True
What are the most commonly missing permanent teeth?
Mandibular second premolars
Maxillary second premolars
Maxillary lateral incisors
Maxillary second molars