ABSTRACT
Several tooth numbering systems exist for efficient written or verbal communication regarding the oral cavity. The most commonly used system is the modified Triadan system. Each quadrant of the mouth is given a number, as is each tooth. The right maxillary quadrant is the 100 arch (500 for deciduous teeth), left maxillary is 200 (600), left mandibular 300 (700), and right mandibular is 400 (800). Teeth are numbered beginning with the first incisor and moving distally (or caudally) as 01-10 in the canine maxilla and 01-11 in the canine mandible. Therefore, the permanent right maxillary canine tooth would be termed 104. The maxillary fourth premolars are 108 (right) and 208 (left), and the mandibular first molars are 309 (left) and 409 (right). These teeth are typically referred to as the carnassial teeth (Figures 3.1a, b).
