Prediction of tetracycline-induced tooth discoloration.

Forty-six deciduous teeth from 17 children with cystic fibrosis who had a 
recorded history of tetracycline therapy were sectioned vertically and horizontally. Teeth 
in three representative staining categories (mild, moderate, and severe) were photographed 
under visible and ultraviolet illumination to determine the extent of tetracycline 
incorporation into tooth enamel and dentin. Tetracycline incorporation into enamel was 
minimal or nonexistent, whereas tetracycline incorporation into dentin was always observed. 
The severity of general surface discoloration was directly related to the 
proximity of the tetracycline incorporation to the dentinoenamel junction. This was 
dependent on dosage, duration, and period of initiation of tetracycline therapy 
as it related to odontogenesis. Critical periods to avoid tetracycline therapy 
and thereby to minimize potential tooth discoloration were determined. 