Maxillary Incisors PDF

Maxillary Incisors By Dr. Asmaa Ahmed Foad  Maxillary Central Incisor is the widest mesiodistally of any of the anterior teeth. Chronology of maxillary central incisor 1-Appearance of dental organ: 5miu (month intrauterine life) 2-First evidence of calcification: 3-4 months 3-Crow...

Maxillary Incisors By Dr. Asmaa Ahmed Foad  Maxillary Central Incisor is the widest mesiodistally of any of the anterior teeth. Chronology of maxillary central incisor 1-Appearance of dental organ: 5miu (month intrauterine life) 2-First evidence of calcification: 3-4 months 3-Crown completed: 4-5 years 4-Eruption: 7-8 years 5-Root completed:10-11 years All anterior teeth (incisors and canines) formed of four lobes, three labially and one lingually. The maxillary central incisor is the first tooth from the midline. The crown is the longest of all human teeth Labial aspect 1-Geometrical outline of the crown: Trapezoid in shape, the short side cervically and long side incisally. The outline: The mesial outline is straight or slightly convex with the contact area with another central incisor at an incisal third near the mesio-incisal angle. Mesio-incisal angle is sharp. The distal outline is more convex with the contact area with the The lateral incisor at the junction between the middle and incisal mesial The outline thirds (more cervical than mesial). Disto-incisal angle is distal rounded. outline  Contact area: The upper central incisors contact each other mesially at the midline at the incisal third but distally contact with the mesial surface of the upper lateral incisor at the junction of the incisal and middle thirds. Incisal outline: In newly erupted tooth has 3 mamelones, the middle lobe is the smallest. After the function becomes straight, and named the incisal ridge is perpendicular to the long axis of the tooth. Cervical line is convex toward the root. Surface anatomy Elevation: The labial surface is smooth and convex with the maximum convexity at the cervical third (due to present of called the cervical ridge). Depression: Shallow 2 developmental grooves separating 3 lobes called mesio-labial and disto-labial developmental groove. The root The root surface is smooth and convex The root is cone shaped with the mesial and distal outline of the root tapered to a blunt apex The apex is centralized on the long axis so extraction could be done by rotation movement Lingual Aspect It has the same outline as the labial surface, but the crown and root taper lingually (lingual convergence) to accommodate a horseshoe-shaped arch The lingual surface of all teeth is smaller in size than the facial due to the lingual convergence This convergence of the teeth is to accommodate the larger arch size facially than lingually. Surface anatomy cingulum. Elevations: 1-The lingual surface has its cervical third around elevation called the cingulum. Mesial distal 2-Two linear elevations at the boundaries called mesial and marginal marginal ridge ridges distal marginal ridges. 3- Linear elevation at incisal third, called incisal ridge. Depression: incisal ridge. Between the incisal ridge, marginal ridges and cingulum, there is a depression called the lingual fossa. Mesial aspect Geometric outline: It is wedge (triangular) shape, the base cervically and apex incisally The outline Labial outline is convex with maximum convexity at cervical third, where the cervical ridge present Lingual outline is convex at cervical 3rd, representing the cingulum, then becomes concave for the fossa and ends convex at incisal ridge Cervical line Cervical line: It is concave toward the root Contact area is at Junction between incisal and middle third near the mesio-incisal angle. The root It is cone-shaped with blunt apex Contact The outlines tapered from the cervical line to a blunt apex area The line bisecting the root passes from the apex of the root till the incisal ridge Distal Aspect It is similar to the mesial outline but it differs in: 1- Cervical line curvature is shallower than mesial 2-The contact area is more cervically at the middle of middle theird. Incisal Aspect: Geometrical outline 1-it is triangular in shape, the base located labially and apex lingually Mesiodistal dimension (width) is greater than labiolingual dimension (thickness) (M-D > lab-ling). The labial outline is broad and slightly convex, the crown tapers lingually toward the cingulum (lingual convergence) -The crown superimposes the root -The elevation and depressions of the crown present on the labial and lingual aspects appeared from this aspect The cervical ridge (labially), Cingulum, marginal ridges, incisal ridge, and lingual fossa (lingually).  Maxillary lateral incisor 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 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 Cervical thirds line -Distal outline is more convex than a mesial outline with the contact area at the middle third. -Incisal outline is not straight as upper central but Distal Mesial rounded because the mesio-incisal angle is rounded, and outline outline disto-incisal angle is more rounded than mesioincisal angle Incisal outline -In newly erupted tooth, the mamelons are 3 in number 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. 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 presents between the elevations. 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 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 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. 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 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 upper 1 due to the well-developed cingulum and cervical ridge 3-When the palatal pit presents, it is located between the cingulum and lingual fossa) Clinical consideration: variation of the upper lateral incisor Thank you