Review of terminology, classifications, and indices of developmental defects of enamel.

A wide variety of terms and definitions are used to describe various developmental defects of enamel. Some are simple descriptive clinical terms, and others are linked with the causative agent or the histopathology of the defect. Some confusion exists as to the most appropriate type of index to use to measure defects of enamel due to fluoride ingestion (dental fluorosis). This is primarily due to difficulties some researchers have in distinguishing between defects of fluoride and non-fluoride origin. This problem has resulted in the development of specific fluorosis indices and purely descriptive indices. The main fluorosis indices are those of Dean, Thylstrup and Fejerskov, and the TSIF Index. Dean's Index does not provide adequate information on the distribution of fluorosis within the dentition and is not sensitive at high fluorosis levels. The Thylstrup and Fejerskov Index is related to the histology of florosis; however, the initial minute changes observed on dry enamel surfaces are of little esthetic importance. The TSIF Index does overcome some of the limitations of Dean's Index. The DDE Index has replaced the Al-Alousi Index as the main descriptive index. The DDE Index is time-consuming, and the analyses of data are complicated. Modifications have now been proposed to make it simpler to use and the data more meaningful. Further research needs to be carried out into both the validity of the fluorosis indices and making the DDE Index more universally acceptable.