Lecture 5 Upper Lateral Incisor PDF

Maxillary lateral incisor by/Ass. Prof. Dr/Dalia Riad 1. introduction Two in number on its mesial side : contact to maxillary central incisor on its distal side: contact to maxillary canine Function: 1-Cutting food 2-Speech and support for lips 3-Supplements central incisor in function “ It i...

Maxillary lateral incisor by/Ass. Prof. Dr/Dalia Riad 1. introduction Two in number on its mesial side : contact to maxillary central incisor on its distal side: contact to maxillary canine Function: 1-Cutting food 2-Speech and support for lips 3-Supplements central incisor in function “ It is similar to the upper central incisor but differs in: 1-Smaller in size 2-More rounded 3-The root is the same length as the upper central or maybe longer  chronology × Appearance of dental organ: 5 miu × First evidence of calcification: 10-12 month × Crown completed: 5-6 years × Eruption:8-9 years × Root completed : 11-12 years Maxillary lateral incisor incisal labial lingual mesial distal labial aspect: ×Geometric outline: ×Trapezoid in shape, the short side cervically and long side incisally ×The outline: ×Mesial outline is convex (more than upper central) with the contact area at the junction of incisal and middle thirds ×Distal outline is more convex than a mesial outline with the contact area at the middle third labial aspect: ×Incisal outline is not straight as upper central but rounded because the mesio-incisal angle is rounded and disto-incisal angle is more rounded than mesioincisal angle ×Cervical line: convex toward the root Surface anatomy: -Elevations: The labial surface is convex (more than upper central) with maximum convexity (height of contour) at the cervical third representing the cervical ridge (well developed than upper central) In newly erupted teeth, the mamelons are 3 in number -Depressions: two developmental grooves separating developing 3 lobes (mesio-labial and disto-labial developmental grooves) The root : labial and lingual outlines of the root tapers gradually to apical 3rd where it curves distally, the apex is more pointed (sharp) than upper central incisor.  1 2 *Its crown is the broadest of the *Its crown is smaller in all anterior teeth dimensions than 1 except its *It is the longest crown of all root may be longer or equal in human teeth length  1 2 Labial aspect D M D M Mesial outline: Mesial outline is convex straight or slightly Distal outline is more convex, distal ouline convex is convex rounded M I angle sharp M I angle more rounded D I angle. rounded D I angle Rounded (curved) Incisal outline Straight  1 2 Root is cone shaped and Root tapers evenly to apical 1/3 with centralized and blunt apex then curve distally with a pointed apex  2 1 Mesial contact area Mesial contact area at the junction of at incisal1/3 near the mesio- Incisal and middle thirds incisal angle Distal contact area Distal contact area at the junction of in the center of middle incisal and middle thirds thirds Lingual aspect Similar in outline to the labial surface but has lingual convergence Surface anatomy: Elevations: 1-The cingulum in the cervical third 2-Mesial and distal marginal ridges 3-Incisal ridge Depression: Lingual fossa in between are well developed (deeper) than those of the upper central incisor ×Characteristic feature: × 1-Lingual pit (fault pit) could be found in the 2 ×2-All elevations and depressions are well developed than 1 **The palatal pit (prone to decay) is enclosed by the cingulum Lingual groove: extends from the lingual pit (usually distally) and may extend over the cervical line (CEJ) Mesial aspect ×Geometric outline: ×It is wedge (triangle) shape, the base cervically and apex incisally ×The outline: ×labial outline is convex with maximum convexity at cervical 3rd (cervical ridge) ×The lingual outline is convex at cervical 3rd (cingulum) then become concave for the lingual fossa at middle third then become convex at incisal ridge Mesial aspect ×Mesial contact area at the junction between the incisal and middle thirds ×Cervical line curvature: Concave toward the root ×Root apex is centralized with the pointed end ×Line bisecting the tooth passes from the root apex to the incisal ridge  1 2 Mesial aspect Lb Lg Lb Lg The crown is long, large The crown is shorter, thinner Contact area at I 1/3 near the Near or at the junction of I M I angle & M 1/3 Distal aspect Similar to the mesial aspect of the upper lateral incisor except: 1- The cervical line is shallower 2- Developmental groove(depression) present on the root 3- Distal contact area at the middle third  1 2 Distal aspect Distal contact area Distal contact area at the center of the at the junction of Incisal & crown middle 1/3 Developmental depression on the root labial Incisal aspect Similar to upper central incisor except: 1-It is smaller in size 2-Mesio-distal dimension is nearly equal to labiolingual dimension The labiolingual dimension of upper 2 is thicker than the Labiolingual dimension of lingual upper 1 due to the well-developed cingulum and cervical ridge 3-When the palatal pit is present; it is located between the cingulum and lingual fossa)  incisal aspect 1 2 * Geometric outline Geometric outline Triangular but smaller in size triangular *M-D = Lab-Ling *M-D> Lab-Ling Labial and lingual outlines are more rounded (Due to well-developed cervical ridge and cingulum) Pulp cavity of maxillary lateral incisor It is similar but smaller than that of the central incisor  Pulp cavity of Upper lateral incisor Mesio-distal section - The pulp chamber is wide conforming the The root canal shape of the crown tapers towards (trapezoid) the apex - It presents three pulp horns corresponding to the three mamelons 27 Labio-lingual section The pulp chamber is pointed incisally, then follows the increase in the crown The root canal dimension cervically (till (one root cervical line level) canal) tapers gradually as it traverse the root ending in a constriction at the apex (the apical foramen) Clinical consideration: variation of upper lateral incisor Lingual pit Conginetally ,groove and Peg lateral missing lingual tubercle Congenitally missing of lateral incisor Peg lateral incisor: formed of two lobes only it is due to missing of middle lobe Lingual pit and lingual groove Lingual tubercle The cingulum may be enlarged and showed tubercle Thanks! Ass. Prof. Dr/Dalia Riad