Dentinogenesis Imperfecta and Amelogenesis Imperfecta

Question 1

What is dentinogenesis also known as? (1)

Answer 1

Hereditary opalescent dentine

Question 2

What is the prevalence of dentinogenesis imperfecta? (1)

Answer 2

1/8000

Question 3

What is the inheritance for dentinogenesis imperfecta? (1)

Answer 3

Autosomal dominant inheritance – Ch4 & DSPP gene mutation

Question 4

Which dentitions are more affected in dentinogenesis imperfecta? (1)

Answer 4

Primary > Secondary affected

Question 5

What are the two types of dentinogenesis imperfecta? In what syndrome can dentine changes also be seen? (3)

Answer 5

• Type I – associated with Osetogenesis Imperfecta (OI) (collagen type I gene mutation Ch7 or Ch17)
• Type II – teeth only affected (Ch4)
• Can see dentine changes in Ehlers Danlos Syndrome (collagen type I mutation)

Question 6

Summarise Osteogenesis Imperfecta (5)

Answer 6

• Fragile bones – Hx of fractures from mild trauma like walking into furniture
• Blue sclera
• Deafness (normal hearing in childhood but deafness develops >30s)
• Lax ligaments around joints
• Patient may have dentine changes subtle>severe

Question 7

What are the clinical features of Dentinogenesis Imperfecta? (6)

Answer 7

• Teeth are opalescent with grey or brown colouring
• Severity varies even within the same family
• Enamel may chip easily – attrition (can be to gingival level in primary dentition) & pulpal exposure
• May have obliterated pulps – initially pulps are large but steadily obliterated by haphazard abnormal dentine deposits (normal dentine around ADJ)
• Bulbous crowns
• Short, thinner roots

Question 8

Draw a table to describe the differences in radiographic appearance of AI and DI (6,5)

Answer 8

Amelogenesis Imperfecta

1. Thin/absent enamel (or normal thickness)
2. AOB, multiple open contacts
3. Failure of permanent denition eruption
4. Taurodontism
5. Radiopacity of enamel = dentine
6. Permanent dentition affected more than primary dentition

Dentinogenesis Imperfecta

1. Bulbous molar crowns
2. Initially large pulps (flame shaped) that becomes obliterated
3. Short roots
4. Shell teeth (type III DI) enormous pulps = very thin dentine
5. Primary dentition affected more than permanent dentition

Question 9

What is Amelogenesis Imperfecta? (1)

Answer 9

Defect in enamel development

Question 10

Which dentitions are affected in Amelogenesis Imperfecta? (2)

Answer 10

• Primary and secondary teeth affected

- Primary dentition affected more than permanent dentition

Question 11

What is the prevalence of Amelogenesis Imperfecta? (1)

Answer 11

Varies from 1/700 (Sweden) to 1/14000 (USA)

Question 12

How is Amelogenesis Imperfecta classified? (2)

Answer 12

• By the type of defect (phenotype)

- Mode of inheritance or part of a syndrome (e.g. nephrocalcinosis)

Question 13

What are the three phenotypes in Amelogenesis Imperfecta? (3)

Answer 13

• Hypoplastic
• Hypocalcified
• Hypomaturation

Question 14

What are the clinical features and common genetic inheritance of the Hypoplastic phenotype of Amelogenesis Imperfecta? (3)

Answer 14

• Decreased quantity of enamel
• Thin enamel – smooth, pitted or rough
• Most autosomal dominant

Question 15

What are the clinical features and common genetic inheritance of the Hypocalcified phenotype of Amelogenesis Imperfecta? (6)

Answer 15

• Dull, opaque enamel
• White, honey or brown
• May break down rapidly
• Increased sensitivity
• Increased deposits of calculus
• Most autosomal dominant

Question 16

What are the clinical features and common genetic inheritance of the Hypomaturation phenotype of Amelogenesis Imperfecta? (3)

Answer 16

• Mottled or frosty white
• Opaque
• Sometimes incisal ½ “snow-capped teeth”

Question 17

What are the types of inheritance patterns of Amelogenesis Imperfecta? (4)

Answer 17

• Autosomal Dominant
• Autosomal Recessive
• X-Linked
• Can be sporadic

Question 18

Describe the inheritance and associated clinical features in Amelogenesis Imperfecta Autosomal Dominant inheritance pattern (9)

Answer 18

• F>M
• 2 > 1 dentition
• 50% pass to offspring
• CH4 enamelin gene mutation (e.g. ENAM, AMELEX)
• Up to 50% AOB, taurodontism in some
• Enamel thin and hard (Hypoplastic)
• Enamel difficult to see on rads
• Some have normal thickness but abnormal translucency and decreased mineralisation
• Tricho-dento-osseous syndrome (AI, taurodontism, curly hair, bone changes)

Question 19

Describe the inheritance and associated clinical features in Amelogenesis Imperfecta Autosomal Recessive inheritance pattern (6)

Answer 19

• Blood relatives e.g. 1st cousins
• Both parents can be affected or unaffected carriers
• 25% offspring inherit 2 copies of mutated genes
• Uncommon (increased in Polynesia)
• Gene on Ch2 associated with ocular defects
• Hypoplasia +/- hypomineralisation “pigmented enamel

Question 20

Describe the inheritance and associated clinical features in Amelogenesis Imperfecta X-linked inheritance pattern (6)

Answer 20

• Affects F (XX) and M (XY)
• Mutation amelogenin gene on X-Ch
• No F to M transmission
• F receives 2x X-Ch so all daughters inherit
• Varying severity
• Heterzygote F pass on maturated gene to F and M

Question 21

What are the treatment aims in Amelogenesis Imperfecta? (4)

Answer 21

• Prevention – OHI, fluoride, diet counselling, fissure sealants
• Aesthetics – microabrasion, composites (direct or indirect)
• Reduce sensitivity – composites, full coverage crowns
• Prevent further tissue loss – fissure sealants, composites, gold onlays on posterior teeth, PFM crowns on young uncooperative patients