Refers to teeth and tissues towards the back of the mouth (distal to the canines); maxillary and mandibular premolars and molars. The designation of permanent posterior teeth in the Universal/National tooth numbering system include teeth 1 through 5 and 12 through 16 (maxillary), and 17 through 21 and 28 through 32 (mandibular); primary teeth in the Universal tooth numbering system are designated A, B, I and J (maxillary), and K, L, S and T (mandibular).