Hypodontia Flashcards
Hypodontia
The developmental absence of 1 + teeth excluding 8s
0.1-0.9% primary dentition
3.5-6.5% permanent dentition
Oligodontia
Developmental absence of large numbers of teeth (6+)
Anodontia
Complete developmental absence of all primary and/or permanent teeth
Prevalence of hypodontia
3rd molars most freq missing (20% of population lack at least one)
Mandibular 5s (2.8%)
Maxillary laterals (1.6%)
Maxillary 5s and mandibular incisors (0.23-0.08%)
Hypodontia associations
microdontia including peg laterals
ectopic permanent molars and maxillary canines
enamel hypoplasia/hypocalcification
delayed eruption
infraocclusion of primary molars
Aetiology of hypodontia
physical obstruction/disruption of dental lamina
space limitation
functional abnormalities of the dental epithelium
failure of initiation of the underlying mesenchyme
CLP
Delayed dental development
impacted 6s
hypodontia
microdontia
hypoplasia
supernumeraries
impacted cleft canine
Role of genetics in hypodontia
PAX9
MSX1
AXIN1
EDA
PAX 9
Transcriptase factor expressed in tooth mesenchyme and is associated with maxillary lateral incisor agenesis
MSX1
Homeobox gene, associated with severe hypodontia.
AXIN1
Associated with lower incisor agenesis and is seen in syndromic hypodontia
EDA
Involved in maxillary lateral incisor agenesis and mutations cause hypohydrotic ectodermal dysplasia
Down Syndrome
75% have delayed eruption and exfoliation
25% have absence of lateral incisors
10% have peg shaped laterals
increased risk of periodontal disease
Ectodermal dysplasia
Fine hair
Dry skin
Eversion of lips
Dysplastic nails
Pigmentation around lips and eyes
most common inheritance x-linked hypohidrotic
hypodontia
teeth small and conical
maxillary hypoplasia
