L14 Developmental Anomalies of the Teeth Flashcards
(32 cards)
Describe developmental anomaly classification by appearance.
- Tooth number
- Tooth size
- Tooth form
- Tooth position
- Tooth structure
What are the effects of disruption at various stages of tooth development?
- Dental lamina = adontia, neoplasia
- Tooth germ histodifferentiation = abnormalities in tooth number
- Tooth germ morphodifferentiation = abnormalities in size, form, position
- Dentine, enamel, cementum formation = defects in structure, thickness and shape
- Eruption = failure to erupt
- Development of successor tooth = abnormalities in tooth number
What is the difference between anodontia, oligodontia and hypodontia?
- Anodontia = no teeth
- Oligodontia = loss of 6 or more teeth
- Hypodontia = loss of 5 or less teeth
What is the prevalence of hypodontia?
- 4.3% of English population have hypodontia (most likely the 3rd molar)
- More common in women
What are the causes of anodontia, oligodontia and hypodontia?
- Genetic
- Endocrine
- Drugs e.g. thalidomide
- Radiation
What are neonatal teeth?
- Present at birth or in the first month of life
- Thin dentine, large pulp chamber, short roots, hypomineralised enamel
- 95% incisor region, 80% mandible, 20% maxilla
- Prevalence of 0.1-3.6% of the population
What are supernumerary teeth?
- Additional teeth
- 0.1-3.6% prevalence, usually only 1 extra tooth
- Twice as common in men
- Aetiology: atavism, dichotomy (split of tooth germ), local hyperactivity of dental lamina or cleft palate and lip
What is the difference between supplemental and supernumerary teeth?
- Supplemental: resembles permanent tooth
- Supernumerary: deviates from normal, usually small, peg shaped
What is microdontia?
- All teeth smaller than normal, very rare, usually associated with underlying condition e.g. pituitary dwarfism, Down’s syndrome, congenital heart disease.
What is relative microdontia?
- Normal sized teeth in a large jaw, makes teeth appear smaller than they are.
What is macrodontia?
Teeth are larger than normal, rare, usually associated with underlying condition e.g. Giantism- increased growth hormone.
What is localised microdontia?
Single tooth smaller than others, common, usually maxillary lateral incisor.
What is tooth dilaceration?
Deviation/bend of the tooth root or crown, may be caused by physical trauma or genetics.
Give examples of how infection can cause abnormalities of tooth form.
- Congenital syphilis: Moon’s molars, mulberry molars and central notches in incisors
- Rubella: general distrubance of tooth shape, lack of cusps, tooth number reduced
Give examples of other abnormalities in tooth form.
- Abnormal crown form: peg shaped lateral incisor, cusp of Carabelli
- Extra root: lower third molars, or 3 rooted lower first molar
- Enamel pearls: droplet of enamel at root furcation on molars
- Connation
- Dens-in-dente
What is connation?
- “Double tooth”
3 causes: - Germination: attempt by tooth bud to divide, incomplete division
- Fusion: of 2 tooth germs
- Concrescence: occurs after root formation, 2 teeth join via cementum
What is dens-in-dente?
Aka invaginated odontome
- Tends to affect upper lateral incisors
- Rare
- Occurs during morphogenesis when enamel organ folds
- Invagination of enamel into dentine
- Enamel lining invagination is thin
- Leads to pulp necrosis and periapical abscess
What are the differences between abnormalities of tooth structure with hereditary vs environmental causes?
- Hereditary anomalies tend to involve both primary and secondary dentition, environmental usually only one or the other
- Hereditary affect either enamel or dentine, environmental affect both enamel and dentine
- Hereditary usually have vertical orientation of derangements, environmental structural anomalies are usually horizontally arranged
What is Turner’s tooth?
An area of localised enamel hypoplasia causing discoloured enamel (brown).
- May affect 1 or several teeth
- Usually associated with deposition of cementum on the crown
- Caused by localised trauma e.g. periapical infection of deciduous teeth or physical trauma
What is tooth dilaceration?
Irregular curve of root or crown.
- Occurs during tooth development, caused by physical trauma e.g. falling
- The mineralised portion of the crown is then dislocated from the developing dental papilla
- Involved tooth may fail to erupt
What are common defects in dentine?
- Marked zones of interlgobular dentine
- Unusually wide dential tubules
- Vascular inclusions
Give examples of pre-natal, environmental causes of disturbances to enamel structure.
- Rubella
- Syphilis
- Fluoride
- Maternal disease
Give examples of neonatal, environmental causes of disturbances to enamel structure.
- Premature birth
- Prolonged labour
- Haemolytic disease of the newborn
- Hypocalcaemia
Give examples of post natal, environmental causes of disturbances to enamel structure.
- Severe infection e.g. measles, chicken pox
- Congenital heart disease
- Hypoparathyroidism
- Fluoride
- Vitamin A, C, D deficiency
- Drugs e.g. tetracycline binds to calcium and cause hypomineralisation
