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Environmental Effects on Tooth Structure Development: Systemic and Local

The ameloblasts in the developing tooth germ are extremely sensitive to external stimuli, and many factors can result in abnormalities in the enamel

Factors Associated with Enamel Defects

Systemic

  • Birth-related trauma

  • Chemicals: Amoxicillin, antineoplastic chemotherapy, cigarette smoke, fluoride, lead, tetracycline, thalidomide, vitamin D

  • Chromosomal abnormalities: Trisomy 21

  •  Infections: Chicken pox, cytomegalovirus (CMV),

  • Inherited diseases: 

  • Malnutrition: Generalized malnutrition, vitamin-D deficiency

  • Medical conditions: Asthma, cardiac disease, celiac disease,

  • Neurologic disorders: Cerebral palsy, intellectual disability

Local

  • Local acute mechanical trauma: Falls, gunshots
  • Electrical burn
  • Irradiation
  • Local infection: Acute neonatal maxillitis, periapical inflammatory disease

Enamel defect: Clinical and Radiographic Features

Almost all visible environmental enamel defects can be classified into one of three patterns:

1. Hypoplasia

2. Diffuse opacities

3. Demarcated opacities

Subtle enamel defects can be masked by saliva, plaque, or poor illumination.

Enamel hypoplasia: Quantitatively defective enamel, when of normal hardness, is known as enamel hypoplasia.Metabolic injury, if severe enough and long enough, can cause defects in the quantity and shape of enamel or in the quality and color of enamel. 

Dental enamel hypoplasia are areas of decreased enamel thickness that occur during a disturbance of ameloblast deposition on the developing crowns of permanent and deciduous teeth

It is a quantitative defect and occurs in the form of pits, grooves, or larger areas of missing enamel












Enamel Hypoplasia: Rickets


Fluorosis


Turner Hypoplasia

Another frequent pattern of enamel defects seen in permanent teeth is caused by periapical inflammatory disease of the overlying deciduous tooth.

Turner’s tooth Hypoplasia

Panoramic radiograph of a 7-year-old patient at diagnosis who was submitted to chemotherapy and 1,800 cGy irradiation. Note microdontia of the lower left premolars and second permanent molar.

Dental Fluorosis

The severity of dental fluorosis is dose dependent, with greater ingestion of fluoride during critical periods of tooth development causing more severe fluorosis compounded by  genetic influence.

 

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