Anatomical features of first maxillary premolars may greatly affect endodontic and following restorative treatments. The aim of this study was to evaluate root canal configuration and root wall thickness of first maxillary premolars using a preexisting CBCT database. A CBCT database of 400 first maxillary premolar was used to study canal configuration, presence of furcation-facing groove on the buccal root and root wall thickness. Root wall thickness was measured from axial CBCT slices at three critical points of the root: The most coronal part of the furcation-facing groove in the buccal root, when present, the CEJ level of the palatal root and 5 mm apically to the CEJ level of the palatal root. Vertucci Type IV configuration was the most common among all teeth, but in single-rooted teeth, Vertucci Type II was predominant. The mean thickness of the buccal root in the area of a furcation-facing groove was 1.1 (±0.2) mm, but in 39% of the cases, it was thinner than 1 mm. The mean thickness of the palatal root at 5 mm from the CEJ was 1.1 (±0.2), but in 28% of the cases, it was thinner than 1 mm. Thickness of root dentin walls of first maxillary premolars varies and may be limited at critical points in both buccal and palatal roots. In case the patient has a previous CBCT scan it may be useful for planning treatment of first maxillary premolars, in order to recognize and avoid potential risks such as furcation-facing groove, thin dentin walls in critical areas and presence of Type II Verucci canal, all of which may dictate less invasive procedures, using smaller files.Endodontic treatment requires knowledge of and familiarity with root anatomy, root canal morphology and their commonly occurring variations. Such variations may include the number of roots, the number and configuration of the root canals and the frequency of their occurrence 1-3 .Cone-beam computed tomography is an accepted method to study and visualize the ambiguous morphology of an individual tooth 4 . Traditional radiographic methods present the anatomy of the root as a two-dimensional plenary projection. On the other hand, CBCT provides three-dimensional imaging that offers the possibility to view an individual tooth in any plane, rather than only in the predetermined "default views" of periapical radiographs 4 .Recently, the AAE and AAOMR Joint Position Committee (2015) indicate in its 3 rd recommendation that "Limited FOV CBCT should be considered the imaging modality of choice for initial treatment of teeth with the potential for extra canals and suspected complex morphology, such as mandibular anterior teeth, and maxillary and mandibular premolars and molars" 5 . However, the same committee also clearly stated in its Recommendation #1 that "Intraoral radiographs should be considered the imaging modality of choice in the evaluation of the endodontic patient" 5 . Thus, CBCT should not be used for routine dental screening.Nevertheless, large databases of CBCT images, which were previously acquired for a variety of clinical reasons, may provide va...