<prompt> A mesialdistal projection of cone adjustment during working length radiograph is indicated for which tooth?Maxillary anterior teethMaxillary molars with a mesiolingual canalMandibular incisorsNone of the above  <response>: When two superimposed canals are present for example buccal and palatal canals of maxillary premolar, mesial canals of mandibular molar one should take following steps:Take two individual radiographs with instrument placed in each canal.Take radiograph at different angulations, usually 20 to 40 at horizontal angulation.Insert two different instruments, e.g. K file in one canal, H filereamer in other canal and take radiograph at different angulations.Apply SLOB rule; expose the tooth from both mesial or distal horizontal angle, canal which moves to same direction, is lingual where as canal which moves to opposite direction is buccal.Textbook of Endodontics Nisha GARG 3rd ED 