➡️ Represents a group of hereditary defects of enamel unassociated with any other generalized defects. It is entirely an ectodermal disturbance, since the mesodermal components of the teeth are basically normal.
➡️ Otherwise known as…
- Hereditary enamel dysplasia
- Hereditary brown enamel
- Hereditary brown opalescent teeth
Prevalence: 1 in 700 to 1 in 15,000
- Dental enamel is a highly mineralized tissue with over 95% of the volume occupied by unusually large, organized structures called the hydroxyapatite crystals.
- The formation of these is controlled in Ameloblasts through the interaction of a no. of organic matrix molecules that include –
Develoment of Enamel:
➡️ 3 stages:
- Formative – deposition of organic matrix
- Calcification – Matrix mineralization
- Maturation – Crystallites enlarge & mature
Types of AI classification (Witkop and Sauk)
Based on clinical, histological & genetic criteria:
🔹 TYPE I HYPOPLASTIC
- Pitted Autosomal dominant
- Local Autosomal dominant
- Local Autosomal Recessive
- Smooth Autosomal dominant
- Smooth, X-linked dominant
- Rough Autosomal dominant
- Enamel agenesis, Autosomal Recessive
🔹 TYPE II HYPOMATURATION
- Diffuse Pigmented, Autosomal Recessive
- Snow-capped teeth, X-linked
- Autosomal Dominant
🔹 TYPE III HYPOCALCIFICATION
- Diffuse Autosomal dominant
- Diffuse Autosomal Recessive
🔹 TYPE IV COMBINATION TYPE
- Hypomaturation – Hypoplastic with taurodontism
- Hypomaturation – Hypoplastic with taurodontism, Autosomal Dominant
- Hypoplastic – Hypomaturation with taurodontism, Autosomal Dominant
1) Hypoplastic – Enamel not formed to full normal thickness.
2) Hypomaturation –
- The enamel can be pierced by an explorer point under firm pressure.
- Can be lost by chipping away from the underlying normal appearing dentin.
- Teeth normal in shape but exhibit a mottled, opaque white, brown-yellow discoloration.
- Snow capped pattern – Zone of white opaque enamel on the incisal or occlusal third of crown.
3) Hypocalcified –
- The enamel is so soft that it can be removed by a prophylaxis instrument.
- Yellow, brown or orange on eruption. Stained brown to black with time.
- Rapid calculus apposition.
- Coronal enamel lost with function except for the cervical portion which is mineralized better.
- Autosomal Recessive – More severe.
- Both dentition affected
- Crown – Yellow to dark brown
- Enamel might have numerous parallel vertical wrinkles or grooves.
- Open Contact points.
- Occlusal & incisal edges frequently abraded.
- The enamel may appear totally absent.
- When present may appear as a thin layer, chiefly over tip of cusps & on inter-proximal surfaces.
- In some cases, calcification is so much affected that enamel and dentin seem to have the same radio density, making differentiation b/w the two difficult.
- Hypoplastic: Disturbance in the differentiation/viability of Ameloblasts. Defect in matrix formation.
- Hypomaturation: Alteration in enamel rod & rod sheath structures.
- Hypocalcified: Defects of matrix structure & of mineral deposition.
- Prosthetic reconstruction
References: Shafer’sTextbook Of Oral Pathology; Internet