THE PERMANENT MAXILLARY LATERAL INCISOR INTRODUCTION Crown bears

THE PERMANENT MAXILLARY LATERAL INCISOR

INTRODUCTION • Crown bears a close resemblance to central incisor • Lateral incisor is smaller in all dimensions except root length • Shows morphological variation more than any other tooth

FUNCTIONS • Cutting food • Enabling articulate speech • Helping to support the lip & maintain a good appearance • To help guide the mandible posteriorly during the final phase of closure just before the posterior teeth contact

CHRONOLOGY • • First evidence of calcification: 1 year Enamel completed : 4 to 5 years Eruption : 8 to 9 years Root completed : 11 years

MEASUREMENT TABLE FOR CARVING • • Cervicoincisal length of crown Length of root Mesiodistal diameter of crown Mesiodistal diameter at cervix Labiolingual diameter of crown Labiolingual diameter at cervix Curvature of cervical line- Mesial Curvature of cervical line- Distal : 9 mm : 13 mm : 6. 5 mm : 6 mm : 5 mm : 3 mm : 2 mm

LABIAL ASPECT • More curvature with a rounded incisal ridge • Mesial outline resembles Central Incisor with a more rounded mesioincisal angle • Distal outline is more rounded • Crest of contour mesially is at the juntion of middle & incisal thirds • Crest of contour distally is in the center of the middle third

• Labial surface of crown is more convex than that of CI • Narrow mesiodistally usually about 2 mm than that of CI • Crown is smaller cervicoincisally but the root is as long as CI

LINGUAL ASPECT • Mesial & Distal marginal ridges are marked • Cingulum is usually prominent • Tendency toward deep developmental grooves within the lingual fossa where it joins the cingulum • The linguoincisal ridge is well developed • Lingual fossa is more concave & circumscribed than CI • The tooth tapers toward the lingual

MESIAL ASPECT • Similar to CI except that the root appears longer • Crown is shorter, root is relatively larger • Labiolingual measurement of the crown & root is a mm or so less than max. CI • The curvature of the cervical line is marked

• The heavy development of the incisal ridge makes the incisal portion appear somewhat thicker than that of CI • The root appears as a tapered cone with a bluntly rounded apical end • A line drawn through the center of the root tends to bisect the incisal ridge of the crown

DISTAL ASPECT • The curvature of the cervical line is usually less in depth than on the mesial side

INCISAL ASPECT • Cingulum & incisal ridge are large • Labiolingual dimension is greater when compared to mesiodistal dimension • Exhibits more convexity labially & lingually than CI

PRIMARY MAXILLARY LATERAL INCISOR • Similar to primary CI from all aspects, but its dimensions differ • Crown is smaller in all directions • Cervicoincisal length of LI crown is greater than its mesiodistal width • Distoincisal angles are more rounded than those of CI • Although the root has a similar shape, it is much longer in proportion to its crown than the CI ratio