hypodontia Flashcards
give the definition of hypodontia
developmental abscence of one or more teeth
excluding third molars
describe the classification system for hypodontia
describe also the IOTN
mild = 1-2 missing teeth
moderate = 3-5 missing teeth
severe / oligodontia = 6 or more missing teeth
anodontia = complete abscence of any teeth
IOTN
- 4h = 1 tooth missing in any quadrant
- 5h = >1 tooth missing in any quadrant
what is the prevalence of hypodontia in the primary dentition?
0.08-1.55%
where is hypodontia more common in primary dentition?
max/mand
M/F
most common tooth??
maxilla>mandible
M=F
lateral incisors
what is the prevalence of hypodontia in the permanent denition?
6%
where is hypodontia more common in the permanent dentition?
M/F?
most common missing tooth?
F>M
lower 5s then upper 2s
what is the aetiology of hypodontia?
- strong genetic component
- MSX1, PAX9, AXIN1, SHH
- environmental
- cleft palate disruption during development
what syndromes are associated with hypodontia?
- ectodermal dysplasia
- downs syndrome
- ehlers danlos
- van der woude
- hemifacial microsomia
- syndromic / non-syndromic cleft palate
what are the clinical features of ectodysplasia?
how does it affect the dentition, sweat glands, hair, nails and saliva?
what are the extra-oral features of hypodontia?
- reduced alveolar development
- retrusive maxilla with/without retrusive mandible
- tendency towards class III malocclusion
- reduced vertical proportions
what are the intra-oral features of hypodontia?
describe the change to tooth morphology
- microdontia
- localised/generealised
- may affect crowns and roots
- contributes to spacing
- conical teeth
- localised/generalised
- enamel hypoplasia
- due to effect on dental lamina during development
- taurodontism
- enlarged pulp chamber with apical displacement of pulp floor, diagnosed radiographically
- often seen in molars
what are the intra-oral features of hypodontia?
describe the change to eruption
- ectopic position
- impaction and transposition may affect maxillary canines
- ectopic eruption in lateral incisor space
- transpositions
- teeth swap spaces
- can be pseudo - crown is in wrong place but root is in correct place
- or true- both in wrong place
- rotations
- infraocclusion
- delayed exoliation of primary teeth
- delayed eruption of permanent teeth
- average delay - 1.5 years
what are the intra-oral features of hypodontia?
describe the change to alveolar development
- increased overbite
- due to
- reduced vertical proportions
- reduced alveolar development
- retroclination of incisors
- due to
what prevention methods can be used in patients with hypodontia?
- diet analysis and advice
- oral hygiene advice
- fluoride supplementation
- fissure sealing permanent molars and pits
- mouth guards to protect protrusive maxillary incisors
- artificial saliva in patietns with xerostomia
when is early orthodontic referral suggested in the case of hypodontia?
- 7-9 years if developmental abscence of upper 2s suspected
- consider position of maxillary canine
- if 5s are absent
- consideration of extraction of Es if crowding - to allow mesial drift of 6s
- consideration of long term prognosis of Es if no crowding/spacing
what are the options when there is mild hypodontia
open or close the space
- open
- recreate, distribute and leave space for a prosthetic replacement
- close
- use orthodontics to close any residual spacing associated with the missing tooth
what factors should you consider in hypodontia on whether to open or close the space?
- incisor relationship and overjet
- molar relationship
- overbite
- crowding/spacing
- canines
- eruption of 3s
- smile
- shape/size of 3s
- patient’s wishes
- prosthesis: restorative burden
open or close the space in this case?
class III with tenuous overjet
open
- correction of reverse overjet
- maintains arch length and lip support
open or close the space in this case?
class II div II incisor relationship
deep overbite
class II canines
close space
- good in class II cases
- canines have a good colour
