The aim of the present study was to examine the morphology of root canals in
premolar teeth with completely formed root apices. The material consisted of
139 extracted premolar teeth, including 83 first premolars (59.7%) and
56 second premolars (40.3%). Maxillary teeth made up 64% of the material and
mandibular teeth 36%. In order to measure the actual root canal length an
endodontic instrument was inserted into the root canal (in teeth with a single
root canal this was instrument no. 25 and in teeth with two or three root
canals no. 20) until its tip was visible in the anatomical foramen. The silicone
limit was fixed at a reference point on the dental crown, and after removal of
the instrument the real length was read using an endodontic ruler. The results
were presented using descriptive statistical measures (mean, maximum, minimum,
median value and quartiles). In order to compare mean values of root
canal lengths the z test was used. Of the first maxillary premolars, 91% had
two root canals and 9% had three root canals. As far as the second upper
premolars are concerned, 14.7% were teeth with single root canals while as
many as 85.3% were teeth with two root canals. The majority of the first lower
premolars (89.3%) had one root canal and 10.7% of these teeth had two root
canals. Most of the second lower premolars (68.2%) had a single root canal,
while the remaining 31.8% had two root canals. None of the mandibular premolars
examined had three root canals
