Dens invaginatus is an uncommon malformation of teeth due to infolding of the dental papilla during tooth development. Most often it is detected by chance on a radiograph. A deep foramen caecum is the first indication of this condition. Due to the tortuous lingual anatomy, it is possible for caries to develop without any clinically detectable lesion. As the enamel lining is thin and close to the pulp chamber, caries can cause pulp involvement rapidly. Maxillary lateral incisors are most commonly affected, followed by maxillary central incisors, premolars, canines and molars. This case report discusses the diagnosis and management of a case of Oehlers Type II dens invaginatus in a maxillary lateral incisor. The technique of proper cleaning and obturation of such complex canal systems, namely irrigation followed by ultrasonic agitation and use of sectional obturation together with thermoplasticised backfilling, is also discussed. Schlagwörter: dens invaginatus, maxillary lateral incisor, thermoplasticised obturation, ultrasonic agitation