Patho: Genetic Tooth Disorders (ch. 6c)

What are the inherited tooth disorders?

1) Amelogenesis Imperfecta

2) Dentinogenesis Imperfecta

3) Dentin Dysplasia

Amelogenesis Imperfecta is a group of __ different inherited conditions affecting enamel.

14

What is the inheritance and clinical onset of Amelogenesis Imperfecta?

-inheritance: varies = dominant/recessive/X-linked dominant

-clinical onset: 6 months → when teeth erupt (both dentitions)

What are the oral features of Amelogenesis Imperfecta?

-affects primary and permanent dentitions = all teeth

-on XR → normal dentin/normal pulp/abnormal enamel

What are the treatment modifications for Amelogenesis Imperfecta?

genetic testing for specific genes:

1) AMELX (amelogenin)

2) ENAM (enamelin)

3) MMP-20

4) KLK4

5) DLX3

6) AMBN (ameloblastin)

What are the 3 different types of AI?

1) Hypoplastic AI

2) Hypocalcified AI

3) Hypomaturation AI

What are the clinical features of hypoplastic AI?

-decreased enamel matrix = thin

-normal mineralization

-harder than dentin

-more radiopaque than dentin

-pitted, smooth, or rough

-localized or generalized

What are the clinical features of hypocalcified AI?

-normal amount of enamel

-decreased mineralization

-very soft; rapidly lost

-radiodensity like dentin

-yellow-brown/orange color → turns black (decay)

-normal shape at eruption → wears down quickly

What are the clinical features of hypomaturation AI?

-normal amount of enamel

-decreased mineralization → abnormal crystallization (enamel rods don't form)

-harder than dentin

-radiodensity like dentin

-mottled - white/brown/yellow → "snow-capped" (white cusp tips)

-normal shape at eruption → enamel chips off of dentin

What is Dentinogenesis Imperfecta?

odontoblasts lay down defective dentin then regenerate

-3 types → I, II, III

What is the inheritance and clinical onset of Dentinogenesis Imperfecta?

-inheritance: autosomal dominant

-clinical onset: 6 months → when teeth erupt (both dentitions; primary more severely affected than permanent)

What are the clinical features of Dentinogenesis Imperfecta?

-Type I is associated with Osteogenesis Imperfecta (systemic collagen defect; abnormal bone)

**collagen defect = multiple bone fractures, blue sclera

-all teeth usually lost by age 30

What are the oral features of Dentinogenesis Imperfecta?

-bulbous crowns

-bluish/translucent color of teeth

-enamel breaks off defective dentin = brown surface

-on XR → no pulp/short roots/periapical radiolucencies

What is the inheritance and clinical onset of Dentin Dysplasia?

-inheritance: autosomal dominant

-clinical onset: 6 months → when teeth erupt (both dentitions)

What are the types of Dentin Dysplasia?

-Type I: Radicular Dysplasia

-Type II: Coronal Dysplasia

**Type I is more common than Type II

What are the treatment modifications of dentin dysplasia?

-meticulous oral hygiene = decreased pulp exposure

-RCT easier in Type II than Type I

Describe the oral features of Type I Dentin Dysplasia (Radicular Dysplasia):

-roots

-crown color

-crown shape

-pulp

-Roots → very short roots = "rootless"

-Crown color → normal

-Crown shape → normal

-Pulp → obliterated + large pulp stones

**MULTIPLE periapical radiolucencies

Describe the oral features of Type II Dentin Dysplasia (Coronal Dysplasia) in PRIMARY DENTITIONS:

-roots

-crown color

-crown shape

-pulp

-Roots → thin & tapered

-Crown color → amber translucency

-Crown shape → bulbous

-Pulp → obliterated

Describe the oral features of Type II Dentin Dysplasia (Coronal Dysplasia) in PERMANENT DENTITIONS:

-roots

-crown color

-crown shape

-pulp

-Roots → normal

-Crown color → normal

-Crown shape → normal

-Pulp → "thistle shape" +/- pulp stones