Microscopic studies performed on extracted human teeth after their preparation in advance is helpful in a relatively good reestablishment of the treatment steps that have been applied to these teeth, as well as an evaluation of the quality of such treatments. Therefore, we have used stereo- and optical microscopy, highlighting aspects of external morphology, as well as root canal space of an extracted mandibular second premolar, subjected to prosthetic and endodontic treatment. In order to verify some technical errors that might occur during the endodontic and restorative treatment, we tried to appreciate the quality of the root canal filling and cervical defect and access cavity restoration of an extracted premolar #45.Without having the data from clinical records, we concluded that the method used for root canal filling was the warm lateral condensation technic; we also appreciated the quality of the fusion of the gutta-percha cones used, so the introduction of heated spreaders only in the central part of the bunch of cones makes it possible to clearly detect the boundaries between these cones towards the outside of the filling.