Figure 4
Positive relationship among the cusps, the cervical tongues and the roots. (a) A schematic diagram and formulas to predict maximum number of cervical tongues (Y) and roots (Z) depending on the cusp arrangement and cusp number (X) in mammalian teeth. The variety of cusp patterns is organized in columns (A) and rows (B). (b) Each of three graphs based on the formulas show a positive relationship between the estimated maximum number of roots and the cusp number. There is a strict linear relationship between cusp number and maximum root number in teeth where the number of cusp columns is one or two. All the actual numbers of roots are the same or less than the estimated maximum number of roots. (c) Lingual or buccal, occlusal and apical view of the crown and root and their numbers in various mammalian premolars and molars. HS: Homo sapiens, MF: Martes flavigula, MS: Mustela sibirica, PL: Phoca largha, PB: Prionailurus bengalensis, MM: Mus musculus, CU: Callorhinus ursinus, RN: Rattus norvegicus, SS: Sus scrofa. P1: first premolar, P2: second premolar, P3: third premolar, dP4: deciduous fourth premolar, M1: first molar, M2: second molar, M3: third molar.
