The mesial surfaces of the maxillary and mandibular central incisors are on one line at the median plane. Maxillary incisors overlap the mandibular incisors, vertically and horizontally producing what is called overjet and overbite. The incisal tip from the proximal aspects is on one line with the root apices (root axis) in maxillary incisors, while there is a lingual tilting in mandibular incisors as the incisal tip is lingually positioned in relation to the root apices. In some instances, they have vertical mesial and distal developmental depressions on the root surfaces to prevent tooth rotation and provide tooth anchorage. The geometric outlines of the labial and lingual (palatal) surfaces are trapezoid while those for the proximal surfaces are triangular in shapes. These mamelons are worn down with use to flat edge.Īll incisors except the mandibular central incisor have rounded distoincisal angle compared to the mesioincisal angle as the mandibular central incisor has almost symmetrical anatomy. Unworn, newly erupted incisors have three small mamelons forming the incisal ridge. Each labial lobe of the incisor terminates incisally in rounded eminence known as mamelon. They developed from four lobes, three labially and one lingually (palatally), the lingual (palatal) lobe being represented by the cingulum. The mesiodistal dimension is greater than the labiopalatal dimension in the maxillary incisors, while the labiolingual dimension is greater than the mesiodistal dimension in mandibular incisors. The maxillary central is larger in all dimensions than the maxillary lateral, but the reverse is the true for the mandibular central and lateral. The maxillary and mandibular lateral incisors are the teeth located distally from either maxillary or mandibular central incisors and mesially from either maxillary or mandibular canines. In some individuals, the two maxillary central incisors are separated by a space called diastema. The maxillary and mandibular central incisors are the first teeth centralized in both sides of the midline, with the mesial of each one is on contact with the mesial surface of the other. They are eight in number four maxillary and four mandibular, two on each side of the middle line, one central and one lateral. Maxillary incisors exist in the premaxilla mandibular incisors are the teeth that occlude with them. They are located in the premaxilla above and the mandible below. They are the front teeth existing in most heterodont mammals. The word incisor is derived from the Latin word incidere, “to cut.”
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