Anatomy of teeth: Read up dens invaginatus / management! Canines – apical delta = 3mm root resection if apicectomy = 95% of apical anatomy/ delta removes = study by Kim et al Lower canine = 20% 2 canals Upper Premolar = 1-2% 3 canals Lower molar = 25% 2 canals 1st premolar Maxillary molars = ETC 2: Helical angle in headstrom and flexo-files