During the process of enamel formation, the ameloblast cells are susceptible to many external factors, the effects of which are reflected on the erupted tooth surface in the later life.
Quantitatively defective enamel having normal thickness is called Enamel hypoplasia, while qualitatively defective enamel having normal thickness is known as enamel hypocalcification.
Enamel hypoplasia actually means incomplete or defective formation of its organic matrix and is usually caused either by some hereditary factors or by some environmental factors.
Hereditary Enamel hypoplasia has already been discussed in the form of amelogenesis imperfecta.
Now the environmental factors that can cause enamel hypoplasia are given below.
- Nutritional deficiency
- Exanthematous diseases
- Traumatic birth injury
- Local infection or trauma
Nutritional deficiency (Vitamin-A,C and D) often causes injury to the ameloblast cells and results in Enamel hypoplasia.
Usually the central and lateral incisors, cuspids and first molars are affected and the teeth develop “pitting” on their surfaces.
Congenital syphilis causes Enamel hypoplasia (nonpitting type) of the maxillary and mandibular permanent incisors (Hutchinson’s incisors) and the first molars (Moon’s molars).
It is believed that in congenital syphilis the Treponema pallidum causes inflammation of the tooth germs during the morphodifferentiation stage, which results in Enamel hypoplasia of the affected teeth.
Hypocalcemia or decreased level of calcium in the blood causes pitting type of enamel hypoplasia of the teeth.
Traumatic birth injuries may cause disturbance or even cessation of enamel formation which may lead to enamel hypoplasia in deciduous as well as in some permanent teeth.
Local infection or trauma to the deciduous tooth often causes pitting type of Enamel hypoplasia to the permanent successor tooth in that region and this type of hypoplastic teeth are often called “Turner’s teeth”.
Fluorides Mottled enamel is a type of Enamel hypoplasia which is caused by the excessive consumption of fluoride (more than 1 ppm) in the drinking water.
It is believed that higher doses of fluoride cause damage to the ameloblast cells and disturbs the calcification process of enamel which eventually results in “mottling”.
The mottled teeth clinically present white flecking or pitting on the surface, which may be severe in few cases and there may be brownish discoloration of the teeth.