- Permanent incisors are eight in number, with four in the maxilla and four in the mandible. Their main functions are to incise food during chewing and to support the lips. - The permanent mandibular incisors have smaller dimensions than other teeth. They have lingually inclined incisal ridges and smoother lingual surfaces compared to maxillary incisors. - The permanent mandibular central incisor is the smallest tooth. It has a lingually inclined incisal ridge and a well-defined distal groove on the root. The mandibular lateral incisor is slightly larger with a fan-shaped crown and longer root.