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BDS 2: Pathology and Microbiology > L14 Developmental Anomalies of the Teeth > Flashcards

L14 Developmental Anomalies of the Teeth Flashcards

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1
Q

Describe developmental anomaly classification by appearance.

A
  • Tooth number
  • Tooth size
  • Tooth form
  • Tooth position
  • Tooth structure
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2
Q

What are the effects of disruption at various stages of tooth development?

A
  • 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
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3
Q

What is the difference between anodontia, oligodontia and hypodontia?

A
  • Anodontia = no teeth
  • Oligodontia = loss of 6 or more teeth
  • Hypodontia = loss of 5 or less teeth
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4
Q

What is the prevalence of hypodontia?

A
  • 4.3% of English population have hypodontia (most likely the 3rd molar)
  • More common in women
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5
Q

What are the causes of anodontia, oligodontia and hypodontia?

A
  • Genetic
  • Endocrine
  • Drugs e.g. thalidomide
  • Radiation
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6
Q

What are neonatal teeth?

A
  • 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
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7
Q

What are supernumerary teeth?

A
  • 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
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8
Q

What is the difference between supplemental and supernumerary teeth?

A
  • Supplemental: resembles permanent tooth

- Supernumerary: deviates from normal, usually small, peg shaped

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9
Q

What is microdontia?

A
  • All teeth smaller than normal, very rare, usually associated with underlying condition e.g. pituitary dwarfism, Down’s syndrome, congenital heart disease.
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10
Q

What is relative microdontia?

A
  • Normal sized teeth in a large jaw, makes teeth appear smaller than they are.
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11
Q

What is macrodontia?

A

Teeth are larger than normal, rare, usually associated with underlying condition e.g. Giantism- increased growth hormone.

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12
Q

What is localised microdontia?

A

Single tooth smaller than others, common, usually maxillary lateral incisor.

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13
Q

What is tooth dilaceration?

A

Deviation/bend of the tooth root or crown, may be caused by physical trauma or genetics.

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14
Q

Give examples of how infection can cause abnormalities of tooth form.

A
  • Congenital syphilis: Moon’s molars, mulberry molars and central notches in incisors
  • Rubella: general distrubance of tooth shape, lack of cusps, tooth number reduced
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15
Q

Give examples of other abnormalities in tooth form.

A
  • 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
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16
Q

What is connation?

A
  • “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
17
Q

What is dens-in-dente?

A

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
18
Q

What are the differences between abnormalities of tooth structure with hereditary vs environmental causes?

A
  • 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
19
Q

What is Turner’s tooth?

A

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
20
Q

What is tooth dilaceration?

A

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
21
Q

What are common defects in dentine?

A
  • Marked zones of interlgobular dentine
  • Unusually wide dential tubules
  • Vascular inclusions
22
Q

Give examples of pre-natal, environmental causes of disturbances to enamel structure.

A
  • Rubella
  • Syphilis
  • Fluoride
  • Maternal disease
23
Q

Give examples of neonatal, environmental causes of disturbances to enamel structure.

A
  • Premature birth
  • Prolonged labour
  • Haemolytic disease of the newborn
  • Hypocalcaemia
24
Q

Give examples of post natal, environmental causes of disturbances to enamel structure.

A
  • 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
25
Q

What is amelogenesis imperfecta?

A
  • Genetic mutation leading to defects in enamel: hypoplastic phenotype = secretory phase defect, hypomineralised phenotype = maturation phase defect (hypomineralised/hypocalcified or hypomature)
  • Affects primary and secondary dentition
26
Q

Describe hypoplastic amelogenesis imperfecta.

A
  • Enamel hypoplasia
  • Secretory phase defect
  • Enamel is normal hardness but variable thickness
  • Pitting, thinning, vertical grooving
  • Teeth may be small with abnormal cusp patterns
  • Enamel lacks normal prismatic structure
  • Enamel thin but hard and glassy
27
Q

Describe hypomature amelogenesis imperfecta.

A

Maturation of enamel affected.

  • Autosomal recessive pigmented form: opaque, mottle, brownish-yellow to white appearance, enamel soft and attrition occurs but not as severe as hypocalcified AI
  • X-linked form: snow-capped appearance of teeth, white opaque enamel, heterozygoud females less severel affected with irregular vertical bands of white opaque and normal translucent enamel
28
Q

Describe hypocalcified/hypomineralised amelogenesis imperfecta.

A

Mineralisation of enamel affected.

  • Autosomal dominant
  • Most common form of AI
  • Enamel is of normal thickness
  • Enamel is soft and chalky
  • Gross attrition common
  • Enamel has similair density to dentine on radiograph
29
Q

Give examples of disturbances in dentine stucture with environmental causes.

A
  • Rickets: causes increased interglobular dentine and enlarged pulp horns
  • Hypophosphatasia: deficiency in tissue nonspecific alkaline phosphatase, reduced or complete absence of cementum, causes early loss of primary teeth
  • Hypoparathyroidism:
30
Q

What are the 3 type of dentinogenesis imperfecta?

A
  • Type I: assocaited with osteogenesis imperfecta
  • Type II: only teeth affected
  • Type III: Brandywine isolate (specific to Maryland, USA)

Autosomal dominant, uncommon.

31
Q

Describe the clinical and radiographic presentation of DI type II.

A
  • Teeth appear brown/purple in colour
  • Soft dentine
  • Teeth rapidly worn down
  • Abnormally translucent
  • Enamel easily breaks off from dentine
  • Tooth shape essentially normal
  • Obliterated pulp chamber, shortened roots
32
Q

Describe the histological presentation of DI type II.

A
  • Mantle dentine forms normally
  • Deeper layers show fewer tubules, loss of regular tubular pattern
  • Poor matrix, incomplete calcification
  • Odontoblasts degenerate
  • Loss of scalloping of ADJ

BDS 2: Pathology and Microbiology (14 decks)

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