page_title: Maxillary central incisor
section_title: Variation
hierarchical_section_title: Maxillary central incisor / Variation
caption_attribution_description: English: The 5 different lingual views of maxillary central incisor
context_page_description: The maxillary central incisor is a human tooth in the front upper jaw, or maxilla, and is usually the most visible of all teeth in the mouth. It is located mesial to the maxillary lateral incisor. As with all incisors, their function is for shearing or cutting food during mastication. There is typically a single cusp on each tooth, called an incisal ridge or incisal edge. Formation of these teeth begins at 14 weeks in utero for the deciduous set and 3–4 months of age for the permanent set.
  There are some minor differences between the deciduous maxillary central incisor and that of the permanent maxillary central incisor. The deciduous tooth appears in the mouth at 8–12 months of age and shed at 6–7 years, and is replaced by the permanent tooth around 7–8 years of age. The permanent tooth is larger and is longer than it is wide. The maxillary central incisors contact each other at the midline of the face. The mandibular central incisors are the only other type of teeth to do so. The position of these teeth may determine the existence of an open bite or diastema. As with all teeth, variations of size, shape, and color exist among people.
context_section_description: Sinodonty, a genetic variation occurring in Native Americans and some East Asian populations, is possibly a trait retained from an indigenous East Asian archaic human ancestor Homo Erectus Pekinensis. Among its features are shovel-shaped incisors that derive their name from the deeper-than-normal lingual fossa and prominent marginal ridges of the teeth. When seen from lingual view, the tooth is said to resemble a shovel and are rotated slightly inward. It is also common to see signs of attrition, which is wear over time from other tooth contact. The lingual of maxillary incisors and the facial of mandibular incisors are the most common places for attrition to occur.
  When space exists between the contacts of the maxillary central incisors, the condition is referred to as a diastema or "gap tooth." One frequent cause of the space is the presence of a large labial frenum from the upper lip extending near the teeth. Treatment depends upon the cause and extent of the gap.  Periodontal surgery may be required to reduce the frenum.  A small space may be corrected with a filling, veneer, or crown. Larger spaces may require orthodontics.
  The maxillary incisors, both the central and lateral, are the most likely teeth to have a talon cusp, which is an extra cusp on the lingual surface. Talon cusps range from less than 1% to 6% of the  population, and 33% of cases occur on the permanent maxillary central incisor.  Deciduous teeth are unlikely to have talon cusps. Also, the permanent maxillary incisors are the most likely teeth to have a dilaceration, which is a sharp curve on a tooth.
  All incisors have the potential to be affected by a case of congenital syphilis, which can cause a notch to form on the incisal edges of these teeth. These teeth, sometimes described as screwdriver-shaped, are called "Hutchinson's incisors."  They serve as part of Hutchinson's triad, which also includes interstitial keratitis and eighth nerve deafness.
caption: The five different lingual views of maxillary central incisor.
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