Classification of odontogenic tumours is an academic exercise that has developed over the last 150 years. It was not until 1971 when a 5-year collaborated effort, organized by the World Health Organization (WHO), resulted in the first consensus on taxonomy of odontogenic tumours. The appearance of this first authoritative guide to the classification of odontogenic tumours marked the start of an era of quite intensive interest for studying this particular field of oral pathology. An updated 2nd edition of the WHO classification was published in 1992.