Amelogenesis Imperfecta Types, Symptoms, Causes, Treatment

Amelogenesis Imperfecta is a hereditary defect of the tooth and it is not associated with any other generalized defects. Since it is absolutely an ectodermal disorder, mesodermal structures of tooth-like dentin, pulp etc are always normal in this disease. Amelogenesis Imperfecta is a group of conditions caused by defects in the genes encoding the enamel matrix.

What are the Amelogenesis Imperfecta Causes?

1. Nutritional deficiency- Vitamin- A, C, and D cause injury to the ameloblast. Central, lateral incisor, cuspid, 1st molar are affected – teeth develop pitting on their surface.

(C- help in formation of collagen)

(D- help in deposition of mineral)

(A- harm to ameloblast)

2. Exanthematous disease-

Measles
Chickenpox
Scarlet fever

3. Hypocalcemia- decreases the level of calcium in the blood cause pitting type of enamel hypoplasia

4. Infection(congenital syphilis)- Treponema palladium causes inflammation of the tooth germs during the morpho-differentiation stage which results in enamel hypoplasia (Hutchinson’s incisors)

5. Traumatic birth injury: Premature baby Plaemolytic disease

6. Trauma or local infection: Pitting type enamel due to deciduous tooth infection (Turner's teeth)

7. Injection of chemical e.g. fluoride

8. Idiopathic

What are the Amelogenesis Imperfecta Symptoms and Important Features?

Both the deciduous and permanent dentition can be affected by Amelogenesis imperfect.
The contact point between teeth are mostly open and occlusal surface and incisal edge are severely abraited.
The teeth in this defect tend to become stained but not susceptible to caries
Brown or yellow discoloration of teeth
Thin, soft and smooth tooth enamel
Defects of tooth enamel which is easily damaged
Tooth enamel may be thin, soft, smooth rough or, pitted.
Missing teeth
Fragile or, small teeth

What are the Amelogenesis Imperfecta Types?

1. Hypoplastic type:

It occurs if the disease affects the enamel during its formative stage so that the enamel matrix could not be formed.

Signs-
Complete lack of enamel formation. The enamel is randomly pitted, grooved or very thin, but hard and translucent. The defects tend to become stained, but the teeth are not especially susceptible to caries unless the enamel is scanty and easily damaged.

Histological Features-
This type of amelogenesis imperfect shows lack of differentiation of ameloblast cells with no matrix formation.

2. Hypocalcification type:

It occurs if the disease affects enamel during the stage of its calcification.

Signs-

Enamel matrix is formed in normal quantity but poorly calciﬁed. When newly erupted, the enamel is normal in thickness and form, but weak and opaque or chalky in appearance.

The teeth tend to become stained and relatively rapidly worn away. It can be easily removed by dental explorers.

The upper incisors may acquire a shouldered form due to the chipping away of the thin, soft enamel of the incisal edge. There are dominant and recessive patterns of inheritance.

Histological Features-
This type of amelogenesis imperfect shows defective matrix formation and abnormal mineral deposition.

3. Hypomaturation type-

It occurs if the disease affects enamel during mineralization or maturation process, which results in the formation of a hypomineral enamel.

Signs-

The enamel is normal in form on eruption but opaque, white to brownish-yellow. The teeth appear similar to mottled ﬂuoride effects. However, they are soft and vulnerable to attrition, though not as severely as the hypocalciﬁed type. The enamel is normal thickness but it can be pierce by explorer point under firm pressure and lost easily by chipping away during mastication.

Histological Features-
This type of amelogenesis imperfect shows alteration in the enamel rod and rod sheath structure.

What are the Amelogenesis Imperfecta Radiological Features?

Radiograph shows a total absence of enamel from the tooth surface in many cases and where ever present it is mostly seen on the tip of the cusps and on the proximal areas.
The radio-opacity of enamel in this disease is much less and is very close to that of the dentine.