Introduction

Maxillary Incisors

The incisors as a class of teeth have similar geometrical shapes and have similar functions. Each is triangular or wedge-shaped from the proximal view and as the name implies, incisors function by "incising" food. They are also important aesthetically as well. All of the incisors are succedaneous teeth. Each quadrant contains a central and a lateral incisor so there are a total of 8 incisors in each of the primary and secondary dentition. The maxillary incisors are normally single-rooted teeth. The crowns are trapezoidal in shape from the facial view (shorter of the two parallel sides adjacent to the cervix) and triangular from the proximal view. A cross-section of the root at the cervix reveals a conical or triangular shaped root that tapers to the lingual. The maxillary central incisors are located adjacent to the midline and the mesial surfaces of the maxillary right and left central incisors are in contact. Mesial surfaces in contact only occur between the two maxillary central incisors and between the two mandibular central incisors. All other teeth have their mesial surface in contact with the distal surface of the adjacent tooth. The maxillary lateral incisors are located distal (or further from the midline) to the maxillary central incisor in each quadrant. Each of the incisors has an incisal ridge which functions in cutting or shearing food. All other teeth (canines, premolars and molars) have cusps. With wear, the incisal ridge becomes an incisal edge. The secondary (permanent) maxillary central incisors generally erupt after the permanent first molars between the ages of 7 and 8 years. The secondary (permanent) maxillary lateral incisors normally erupt between the ages of 8 and 9 years of age.