The standard lateral view of the maxillary fourth premolar results in an image with the two mesial roots superimposed. In ordet to separate these two roots, an additional, slightly oblique view is indicated, 'SLOB' is an acronym for Same/Lingual-opposite/Buccal and refers to the direction of the incoming X-ray beam as an aid in identification of roots of multirooted teeth. The root on the radiograph closest to the incoming X-ray beam is the more lingual(palatal) root. When the radiograph is taken with the X-ray beam directed slightly from caudally, the mesiopalatal root will be projected distally to the mesiobuccal root