Gnarled enamel is a description of enamel seen in histologic sections of a tooth underneath a cusp. The appearance of enamel appears different and very complex under the cusp, but this is not due to a different arrangement of dental tissues. Instead, the enamel still has the same arrangement of enamel rods. The strange appearance results from the lines of enamel rods directed vertically under a cusp and from their orientation in a small circumference.
Gnarled enamel can sometimes be a problem for dentist's, although experienced dentists have no problem identifying gnarled enamel and making the correct preparations some in experienced dentists face problems when performing a standard filling or root canal. The gnarled enamel can cause the drill problems and in some cases the dentist must replace the drill head. The toughness of gnarled enamel varies from client to client however for most this is nothing to be worried about.