Identification of protostylid.

The presence of the protostylid was determined on 942 extracted lower molars of recent Slovenians. Dental casts of 32 extracted molars exhibiting a protostylid pit were obtained from alginate as well as from silicone impressions. The quality of the reproduction of protostylid pits was determined and the identification of these on dental casts was compared with their identification on the extracted teeth. The presence of the protostylid pit was confirmed histologically. Compared with previous studies the results show a higher frequency of protostylid on the third molars (51.2%); 70.3% of these protostylids relate to surface irregularities and are as such much readily observable by the protostylid pit. Determination of protostylid pits from the casts made from silicone impressions is more reliable compared to the same determination from the casts obtained from alginate impressions. The former method may be even more reliable than determination on the extracted teeth. Owing to common local enamel hypoplasias on the third molars, there is a considerable possibility of misjudging the presence of a protostylid if the determination is not confirmed histologically. Though the identification of the protostylid is difficult because of its poor expressivity, the accuracy of investigations would significantly increase if protostylids on lower third molars were given more attention. By doing so the data on frequency and expressivity of this dental trait would be of more value.