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PERMANENT MAXILLARY INCISORS PERMANENT MAXILLARY INCISORS • the maxillary incisors are four in number • the maxillary central incisors are centered in the maxilla, one on either side of the median line with the mesial surface of each in contact with the other. • shearing or cutting teeth • their major function is to punch and cut food material during the process of mastication. • have incisal edges or ridges rather than cusps MAXILLARY CENTRAL INCISOR - widest mesiodistally of any of the anterior teeth LABIAL ASPECT average crown length is 10 to 11 mm long from the highest point on the cervical line to the lowest point on the incisal edge. mesiodistal measurement is 8 to 9 mm wide at the contact areas. The crown is narrowest in the cervical third and becomes broader toward the incisal third The mesial outline of the crown is only slightly convex, with the crest of the curvature approaching the mesioincisal angle MAXILLARY CENTRAL INCISOR LABIAL ASPECT Mesioincisal angle is slightly rounded and distoincisal angle is more rounded Distal outline of the crown is more convex than the mesial outline , the crest of the curvature being higher toward the cervical line Distoincisal angle is not as sharp as the mesioincisal angle The incisal outline is usually regular and straight in a mesiodistal direction after the tooth has been in function long enough to obliterate mamelons MAXILLARY CENTRAL INCISOR LABIAL ASPECT The cervical outline of the crown follows a semicircular direction with the curvature root-wise The outline and shape of the root is much like an ice cream cone (coneshaped) with a blunt apex MAXILLARY CENTRAL INCISOR LINGUAL ASPECT the large lingual fossa, immediately incisal to the cingulum and bounded by the two marginal ridges is developed the cingulum on this tooth is usually well-developed and is located off-center toward the distal. The mesial and distal marginal ridges vary in prominence on the central incisors from one person to another Due to the distal placement of the cingulum, the mesial marginal ridge is longer than the distal marginal ridge MAXILLARY CENTRAL INCISOR LINGUAL ASPECT Small or narrow lingual ridges may be present which extend vertically from the cingulum toward the center of the fossa There may be a lingual pit at the incisal border of the cingulum where the mesial and distal marginal ridges come together. The lingual surface of the root is convex and is narrower mesiodistally than the labial surface The root is flattened on the mesial side approaching the lingual side. MAXILLARY CENTRAL INCISOR MESIAL ASPECT the crown is wedge shaped, or triangular with the base of the triangles at the cervix and the apex is the incisal ridge labially and lingually, immediately coronal to the cervical line are the crests of curvature the cervical line outlining the cementoenamel junction mesially curves incisally to a noticeable degree (greater curvature on the mesial aspect than on the distal MAXILLARY CENTRAL INCISOR MESIAL ASPECT the root from this aspect is cone shaped and the apex is usually bluntly rounded the mesial surface of the root is somewhat flattened with a longitudinal depression in the middle third MAXILLARY CENTRAL INCISOR DISTAL ASPECT the crown gives the impression of being somewhat thicker toward the incisal third because of the slope of the labial surface distolingually, more of the surface is seen from the distal aspect creating an illusion of greater thickness. the curvature of the cervical outlining the CEJ is less in extent on the distal than on the mesial surfaces the shape of the distal root surface is similar to the shape from the mesial aspect except that its surface is convex rather than flattened and it does not have a depression MAXILLARY CENTRAL INCISOR INCISAL ASPECT from this aspect, the labial face of the crown is relatively broad and flat in comparison with the lingual surface the outline of the lingual portion tapers lingually toward the cingulum the crown outline is noticeably wider mesiodistally than faciolingually the cingulum is off-center to the distal, resulting in the mesial marginal ridge measuring longer than the distal marginal ridge MAXILLARY LATERAL INCISOR resembles a maxillary central incisor but smaller in all dimensions except in root length there is a great morphologic variation in this tooth it may be asymmetrical, pointed form (peg lateral), or entirely missing LABIAL ASPECT although the crown is smaller in all dimensions, its proportions usually correspond to those of the central incisor it has more curvature with a rounded incisal ridge and rounded incisal angles mesially and distally MAXILLARY LATERAL INCISOR LABIAL ASPECT the mesial outline of the crown from the labial aspect resembles that of the central incisor, with more rounded mesioincisal angle the distal outline is always more rounded, and the crest of contour is more cervical, usually in the center of the middle third the labial surface of the crown is more convex than that of the central incisor except in some square and flat-faced forms this tooth is relatively narrow mesiodistally, usually about 2mm narrower than the central incisor MAXILLARY LATERAL INCISOR LABIAL ASPECT its root length is greater in proportion to its crown length than that of the central incisor the mesioincisal angle is more acute and the distoincisal angle is wider or more obtuse than on the central incisors the incisal edge slopes cervically toward the distal Crown contact areas from the labial Mesial – in the incisal third or near the junction of incisal and middle thirds Distal – more cervical than the mesial contact area at the junction of incisal and middle thirds or in the middle third MAXILLARY LATERAL INCISOR LABIAL ASPECT the root tapers evenly from the cervical line to a point approximately two thirds of its length apically the root curves sharply from this location in a distal direction and ends in a pointed apex ( although the curvature distally is typical, some roots are straight ) MAXILLARY LATERAL INCISOR LINGUAL ASPECT mesial and distal marginal ridges are marked and the cingulum is usually prominent the linguoincisal ridge is well-developed and the lingual fossa is more concave and more pronounced than on the central incisor as on the central incisor, there may be small vertical accessory lingual ridges on and incisal to the cingulum, only they are fewer in number and less common the root is narrower on the lingual side than on the labial side MAXILLARY LATERAL INCISOR MESIAL ASPECT the mesial aspect of the maxillary lateral incisor is similar to that of a small central incisor except that the root appears longer the crown is shorter, the root is relatively longer, and the labiolingual measurement of the crown and root is a millimeter or less than the maxillary central incisor of the same mouth the curvature of the cervical line is marked in the direction of the incisal ridge MAXILLARY LATERAL INCISOR MESIAL ASPECT the root appears as a tapered cone from this aspect the labial outline of the root from this aspect is straight similar to the central incisor, a shallow longitudinal depression is often found on the middle of the mesial surface extending about half of the root length MAXILLARY LATERAL INCISOR DISTAL ASPECT the width of the crown distally appears thicker than it does on the mesial aspect from marginal ridge to labial face the curvature of the cervical line is usually a millimeter or so less in depth than on the mesial side MAXILLARY LATERAL INCISOR INCISAL ASPECT this tooth exhibit more convexity labially and lingually from the incisal aspect than maxillary central incisors on some lateral incisors, the mesiodistal measurement and labiolingual measurement are the same the cingulum is centered mesiodistally
