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Dental Anomalies > Part 1 - anomalies involving number, size and shape of teeth > Flashcards

Part 1 - anomalies involving number, size and shape of teeth Flashcards

1
Q

List the stages in tooth development (8 stages)

A

Stages of tooth development:

1–4 = Growth (bud, cap, bell)

4–6 = Eruption (apposition and calcification, pre- and post-emergence)

6–8 = Attrition (early and later signs)

  1. Initation (bud stage) at 6 weeks
  2. Proliferative (cap stage)
  3. Morphodifferentiation and histodifferentiation (bell stage)
  4. Aposition and calcification
  5. Pre-emergence
  6. Post-emergence
  7. Early signs of attrition
  8. Later signs of attrition
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2
Q

Describe the abnormality which may occur due to disrupted dental lamina formation

A

Abnormality in number of teeth

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3
Q

Describe the abnormality which may occur due to disrupted morphodifferentiation

A

Abnormality in tooth size and shape

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4
Q

Describe the abnormality which may occur due to disrupted matrix deposition and mineralisation

A

Abnormality in tooth structure

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5
Q

Define anodontia

A

No teeth (very rare)

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6
Q

Define hypodontia (or partial anodontia/oligodontia)

A

Fewer than normal number of teeth

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7
Q

Define hyperdontia

A

More than the normal number of teeth

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8
Q

Recall the rate and pattern of hypodontia in the permanent dention

A

Rate of hypodontia in permanent dentition (2-10%)

Most likely third molars (35% < 1), then maxillary lateral incisors followed by lower second premolars.

Familial tendency

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9
Q

Recall the national tendency of hypodontia

A

National tendency (Japan / Sweden – L1’s)

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10
Q

Recall the formation of tooth bud for deciduous and permanent teeth

A

Successional tooth bud:

Tooth germ (bud) of permanent incisors, canines and premolars form as a result of proliferative activity within the dental lamina, lingual to the deciduous tooth germ (ABCDE)

If the developing permanent molars have no deciduous predecessor (i.e. permanent molars 678), their tooth germs originate directly from the dental lamina.

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11
Q

Recall the most common clinical signs of hypodontia (3 points)

A
  1. Retained deciduous teeth, well after the date of normal exfoliation
  2. Spaces
  3. Infraoccluding deciduous teeth
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12
Q

Recall the X-ray investigations required for suspected hypodontia

A

Radiographic images required for assessment of missing teeth (e.g. suspected hypodontia) are:-

  1. OPG X-Ray
  2. Upper occlusal X-ray

(If no upper occlusal X-rays are available P/A’s will be an alternative – but not the ideal)

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13
Q

Describe this case and name one differential diagnosis

A

Retained deciduous teeth - ?hypodontia:

Spacing

Infraoccluded deciduous teeth

Missing maxillary lateral incisors

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14
Q

Describe the buccal segment teeth and list 8 possible aetiological factors

A

The teeth are infraoccluded teeth. Aetiological factors:

  1. Ankylosis
  2. Impaction
  3. Absence of a permanent successor
  4. Trauma causing damage to Hertwigs epithelial root sheath
  5. Infection, chemical or thermal irritation
  6. Failure in bone growth
  7. Abnormal tongue pressure.
  8. A genetic aetiology has also been suggested as observed in siblings
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15
Q

Name of differential diagnosis from this radiograph

A

Hypodontia - more than normal number of teeth missing

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16
Q

What are some clinical considerations of infraocclusion?

A
  1. Orthodontic assessment (IOTN = 5s)
  2. Extractions
  • Ankylosed
  • Impacted
  1. Advanced restoration?
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17
Q

Name 3 conditions associated with missing teeth (hypodontia)

A
  1. Hereditary ectodermal dysplasia
  2. Cleft lip and palate
  3. Down’s syndrome (3rd molars absent 90% cases)
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18
Q

Describe hereditary ectodermal dysplasia and the tissues affected

A
  1. Hair (absent / thin and sparse)
  2. Small, conical teeth (sometimes missing but rarely 100% missing)
  3. Reduction in/absence of sweat glands (dry smooth skin)
  4. Decreased skin pigment/colour
  5. Abnormal fingernails
  6. Small maxilla (maxillary hypoplasia)
  7. Poor hearing and vision, decreased tear production
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19
Q

Name this condition

A

Hereditary ectodermal dysplasia

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20
Q

Name this condition

A

Hereditary ectodermal dysplasia

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21
Q

Describe the possible inheritance patterns of hereditary ectodermal dysplasia (3 points)

A
  1. X-linked recessive
  2. Autosomal dominant
  3. Autosomal recessive
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22
Q

Recall the incidence of cleft palate

Boys vs girls (freqency and severity)

Unilateral vs bilateral

Left side vs right side

Europe vs Africa

A

Boys are more commonly affected than girls 3:2

More boys experience the more severe cleft lip and palate 2:1

75% of clefts unilateral

The left side is more than right side

Europeans 1:750

Less frequent in African populations 1:2000

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23
Q

Recall the aetiology (causes) of cleft lip and palate

A

Unknown what causes defects – many factors suggested:-

  • Genetics (4% increase of CL&P if sibling or parent has CL&P)
  • Environment
  • Drugs (corticosteroids, phenytoin)
  • Infections in pregnancy (e.g. rubella)
  • Alcohol consumption/ smoking / some dietary deficiencies (e.g. folic acid / vitamin A)
  • Maternal age
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24
Q

List 10 dential issues associated with cleft lip/palate cases

A
  1. Can be hypodontia OR in rare cases hyperdontia.
  2. Presence of natal and neonatal teeth
  3. Microdontia
  4. Fused teeth
  5. Enamel hypoplasia
  6. Poor periodontal support
  7. Gemination and dilacerations
  8. Anterior and posterior cross bite
  9. Class III tendency
  10. Spacing and crowding
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25
Q

Which chromosome is most commonly associated with Down’s Syndrome (95% of cases)?

A

Trisomy 21 (3rd copy of chromosome 21) most common cause (95%).

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26
Q

Recall the incidence of Down’s Syndrome

A

1 in 700 births but closely associated with the maternal age

(it increases to 1 in 25 of mothers over the age of 45yrs.)

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27
Q

Recall 7 developmental issues leading to oral complications in Down’s Syndrome

A
  1. Hypoplasia of the mid-face - an underdeveloped maxilla means that most are Class III – and also have a protrusive tongue
  2. Poorly developed paranasal sinuses are common due to the small maxilla – and breathing can be difficult.
  3. Often have an anterior open bite and in many cases the lateral incisors are missing
  4. Teeth can appear smaller (microdontia) and can also be missing (hypodontia)
  5. Delayed eruption
  6. Relatively low incidence dental caries, however often rapidly progressing periodontal disease is associated
  7. They have a heavily fissured and enlarged tongue
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28
Q

Recall the clinical considerations of hypodontia for a patient with Down’s Syndrome

A
  1. Do nothing
  2. Direct restoration (disguise)
  3. Orthodontics with or without restoration
  4. Restoration of spaces with:-
  • Implants
  • Removable prosthesis (consider types)
  • Fixed prosthesis (consider design/types)
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29
Q

Define hyperdontia

A

More than the normal number of teeth

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30
Q

Recall the incidence hyperdontia

A

Relatively common (1.5 to 3.5% in UK)

Male : Female ratio = 2:1

Jaws:

  • Maxilla – 90% with 98% in pre-maxilla (anterior teeth)
  • Mandible 10%
31
Q

Recall the classification of hyperdontia

A

Classified by tooth shape:

  • Supplemental (resembles normal shape often in line with other teeth in the arch)
  • Supernumerary
    • Conical (inverted / everted) shape
    • Tuberculate shape (like a barrel)
  • Odontome - irregular mass (unerupted and can impede eruption of other teeth)
32
Q

Describe supplemental teeth

A
  1. Same structure as normal
  2. Erupt normally
  3. Caused by excessive but organised growth of dental lamina
  4. Usually tagged onto series.
  5. CAN BE MISSED WHEN EXAMINED!
33
Q

Describe supernumerary teeth (e.g. shape, eruption)

A
  1. Conical or tuberculate or odontome (malformed)
  2. Can prevent eruption of other teeth
  3. Inverted or everted
34
Q

Recall the common patterns of hyperdontia in the maxilla

A

Most common in maxilla are:-

  • Mesiodens
  • Paramolars (4th molars)
  • Maxillary lateral incisors
35
Q

Recall the patterns of hyperdonita in the mandible

A

Common in mandible are:-

  • Premolars
  • 4th molars (paramolars)
  • Extra incisors
36
Q

What radiograph investigations would you require to investigate hyperdontia

A

Radiographic examination:-

  • OPG
  • Upper occlusal X-ray

Similar to hypodontia!

37
Q

Idfentify an anamoloy in this radiograph

A

Supplemental ‘third’ molar LLQ

38
Q

Idenfy this pre-maxillary anomoly

A

Mesiodens - conical positioned in line of the arch between UR1 and UL1

39
Q

Define ‘mesiodens’

A

A supernumerary tooth present in the midline (hence ‘mesio’) between the two central incisors

40
Q

Describe the radiographs below (left and right)

A

Left radiograph: mesiodens conical shaped supernumerary teeth

Right radiograph: mesiodens tuberculate supernumerary teeth

41
Q

Identify this rare syndrome associated with supernumerary teeth

A

Cleidocranial dysplasia

Also has characteristic:-

  • Aplasia or hypoplasia of one or both clavicles
  • Delayed ossification of fontanelles
  • Short stature
  • Increased number of supernumerary teeth
  • Delayed eruption
  • Dentigerous cysts
  • Frontal bossing
42
Q

Recall the inheritance pattern of cleidocranial dysplasia

A

Hereditary either autosomal dominant or as a spontaneous mutation.

43
Q

Which chromosomal defect is associated with cleidocranial dysplasia

A

Short arm of Chromosome 6

44
Q

What are the clinical considerations for suplemental and supernumerary teeth?

A

Supplemental teeth:

  1. Do nothing
  2. Plaque traps / aesthetics

Supernumerary teeth:

  1. Diagnosis crucial! (Often unerupted)
  2. Affect on rest of dentition i.e. prevention of eruption.
  3. Possible resorption of adjacent teeth
  4. Aesthetics
45
Q

Define microdontia

A

One or more teeth that are smaller than normal

Can be generalised or localised

46
Q

Define macrodonita

A

One or more teeth that are larger than normal

Can be generalised or localised

47
Q

Recall the differences between true generalized and relative generalized microdontia

A

True generalised:

  • Uncommon – pituitary dwarfism

Relative generalised:

  • Jaw size larger than normal, but teeth normal size – so teeth spaced (illusion)
  • Spaced due to strong tongue (Down Syndrome)
48
Q

Describe localized microdontia

A

Most common presentations of localized microdontia:-

  • Lateral incisors (peg laterals)
  • Maxillary third molar (not second premolars)

Often both smaller and conical

49
Q

Recall the differences between true generalized, relative generalized, and regional macrodontia

A

True generalised

  • Uncommon – pituitary gigantism

Relative generalised (illusion)

  • Jaw size smaller than normal, but teeth normal size – so teeth crowded (illusion)

Regional macrodontia (illusion)

  • Hemifacial hypertrophy
  • Segmented odontomaxillary dysplasia
50
Q

What is rhyzomegaly?

A

Rhizomegaly (radiculomegaly) – uncommon – roots of teeth are longer than normal (normally mandibular canines)

Type of localised macrodontia

Rare – and should not be confused by the fusion of two teeth.

51
Q

Identify this condition

A

Localized macrodontia

52
Q

Abormality in the shape of a tooth may occur following disruption of which tooth development stage?

A

Bell stage:

Morphodifferentiation and histodifferentiation

53
Q

Define this condition

A

Dilaceration - a sharp bend or angulation involving the root of a tooth

54
Q

Recall 3 common causes of tooth dilaceration

A

1. Trauma to a developing tooth

2. Disrupted root formation along a tortuous path, can cause the root to form at an angle to the normal axis of the tooth.

3. Odontogenesis disrupted

55
Q

Define taurodontism

A

A molar with an elongated crown and apically placed furcation of the roots, resulting in an enlarged rectangular coronal pulpal chamber.

56
Q

Identify this condition

A

Dens invaginatus

57
Q

Define dens invaginatus

A

Developmental anomaly with deep enamel-lined pit extending to varying lengths into the underlying dentine, often displacing the pulp, and often altering the root shape.

58
Q

List 3 types of supernumerary cusps

A
  1. Carabellis cusp
  2. Dens evaginatus
  3. Talon cusp
59
Q

Identify this condition

A

Cusp of carabelli - found on mesiopalatal cusp surface of maxillary first molars (upper 6’s)

60
Q

Define this condition

A

Dens evaginatus - a developmental anomaly characterised by a cusp-like supernumerary focal enamel protrusion (spur) on the occlusal or lingual surface of the crown.

Affects mainly premolar teeth

61
Q

Describe dens evaginatus (4 points)

A
  1. Affects mainly premolar teeth
  2. Abnormal globe-shaped projection of enamel in central groove
  3. More common in Chinese, Japanese, Filipino and American Indian populations. In Singapore/Malaysia – Leong premolar
  4. If fractured can expose the pulp.
62
Q

Define this condition and identify one risk associated with reducing this anomoly

A

Talon cusp

  • Uncommon
  • Lingual aspect maxillary lateral (or central) incisors – looks like an eagles talon
  • Can extend to incisal edge.
  • Deep lingual pits – need restoration/ F-S
  • Prominent pulp horn, so easily exposed if reduced

Risk - prominent pulp horn, so easily exposed if reduced!

63
Q

Recall two types of ‘double’ teeth

A

Fusion

Gemination

(Both more common in deciduous dentition)

64
Q

Define fusion of a tooth

A

A developmental anomaly characterised by abnormally shaped tooth with either a wide crown and one root, or a normal crown with an additional root (or a combination)

65
Q

Describe tooth fusion

A

Combination of two adjacent tooth germs united by dentine

Deciduous and permanent

Some hereditary link

Pulp can be separate or fused

If fused one less tooth in the arch

Vulnarable to periodontal disease, caries, aesthetics compromised

66
Q

Define tooth gemination

A

A developmental dental anomaly single rooted tooth and unusually wide, partly divided crown or two separate crowns.

67
Q

Describe tooth gemination

A

Partial division or twinning of a single tooth germ

Developmental anomaly – perm or deciduous

Microscopically same as fusion, but different developmental pathways.

68
Q

Define hypercementosis

A

An apposition of excessive amounts of cementum

69
Q

Recall 5 causes of hypercementosis (including one systemic disease)

A
  1. Aging
  2. May be caused by inflammation.
  3. Functionless and unerupted teeth
  4. Can be in association with resorption
  5. As a consequence of Paget’s Disease – may produce an irregular mass of cementum with a histological “mosaic” pattern.
70
Q

Define concrescence

A

Union of roots caused by confluence of cementum only.

71
Q

Describe this condition (3 points)

A

Concrescence

  • Type of fusion
  • May be as a result of trauma / crowding with interseptal bone loss
  • Can occur before OR after tooth eruption.
72
Q

Describe this anomoly

A

Ectopic droplets of enamel that primarily occur in the bifurcation or trifurcation areas on roots of molar

  • Uncommon
  • Radiographically 1-3 mm radiopacities
  • May have a central core of dentine
  • Treatment avoided as may create root caries, external resorption or pulpitis
73
Q

What can cause the formation of enamel pearls?

A

Caused by ameloblasts displaced below the cementoenamel junction

74
Q
A

Dental Anomalies (3 decks)

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