MORPHOLOGY OF maxillary PERMANENT INCISORS Dental Morphology -Dr. Saleem Shaikh

A Trait is a characteristic quality or an indentifying feature. Set traits – difference between permanent and decidous dentition Arch traits – difference between maxillary and mandibular teeth Class traits- difference between incisors, canines, premolars and molars. Type traits – difference between central and lateral incisor. 1st premolar and second premolar etc.

Introduction The maxillary incisors are four in number The central incisors are in the middle and the lateral incisors are seen distal to the central incisors. The maxillary and mandibular central incisors are the only teeth with their mesial surfaces in contact with each other. Both the teeth supplement each other in function and are similar anatomically. The central incisor is the widest tooth (mesiodistally) among all anteriors

The permanent incisors Eruption sequence 41/31, 11/21, 42/32, 12/22 Mand centrals, max centrals, mand laterals, max laterals Functions Cutting Esthetics Speech Lip support

The permanent maxillary central incisors The widest MD of all incisors – type trait 3 mamelons Middle is the smallest in width Mesial has a raised shoulder Distal has a low shoulder 2 labial lobe grooves 90º mesioincisal line angle – type trait Rounded distoincisal line angle

The permanent maxillary incisors Labial aspect The crown of an average central incisor is rectangular in shape with cervical convergence. It is approximately 11 mm long from the highest point in the cervical line to the incisal edge. Mesial outline – it is slightly convex with contact area near the mesioincisal line angle. Distal outline - is more convex than mesial outline and the contact area is located at the junction of middle and incisal third. Incisal outline – this is straight and regular with sharp mesio-incisal angle and rounded disto-incisal angle. Cervical outline- is semicircular with the curvature towards the root. Root is conical & inclined distally

The permanent maxillary incisors Lingual Aspect: Scoop-like surface The lingual outline of the crown is reverse as that of the labial outline, the crown and root converge towards the lingual surface, which makes the mesial and distal aspect visible from this aspect. The lingual surface shows concavities and convexities. The concavity seen on the lingual surface is called as lingual fossa. It is ‘M’ shaped and is surrounded by cingulum and marginal ridges. The cingulum is seen in the cervical third and is continuous with the mesial and distal marginal ridges. Root is narrower seen from lingual

The permanent maxillary incisors Mesial aspect – the crown appears to be triangular or wedge shaped from this aspect, with the base near the cervix. Usually a line drawn from the center of the tooth will bisect the apex of the root and the incisal edge. Labial outline – is convex and the crest of curvature is in the cervical third. The outline is relatively straight from the crest of curvature to the incisal edge. Lingual outline – cervical third is convex due to cingulum, the lingual fossa is seen as a concavity in the middle and part of incisal third. Incisal edge is seen as a slight convexity. Cervical outline – the curvature is towards the incisal region Root is conical

The permanent maxillary central incisors Distal aspect – is very similar to the mesial aspect with a few differences. It Appears more broader and the cervical line is less curved than seen from mesial. Incisal aspect – the incisal aspect is triangular with base on the labial surface and apex towards the cingulum. The labial outline is slightly convex. Lingual fossa and marginal ridges can be seen from this aspect.

The permanent maxillary central incisors Pulp – the pulp cavity resembles the external shape of the tooth. The line of division between the pulp chamber and the canal is not distinct. The pulp chamber may have 2 horns and is thin labiolingually. Pulp canal is conical.

Maxillary central incisor

The permanent maxillary lateral incisors The maxillary lateral incisors resemble the central incisors and support them in functions. These teeth often show variations is form and size. Labial Aspect – it is smaller than the central and is more rounded. Mesioincisal angle is slightly rounded in contrast to that of central incisor. The distoincisal angle is more rounded. The contact area on the mesial outline is at the junction of incisal and middle thirds. The distal contact area is at the middle of middle third.

The permanent maxillary lateral incisors Lingual aspect – similar to the central incisor. The cingulum and the distal - mesial marginal ridges are prominent. The lingual fossa is inverted ‘V’ shaped A developmental groove (lingual developmental groove) is seen extending from the lingual fossa over the cingulum.

The permanent maxillary lateral incisors Mesial aspect – no major changes as compared to the central incisor. Cingulum more convex CEJ less curved Distal aspect – root may have a developmental groove Incisal aspect – more rounded hence the outline may appear Ovoid Pulp - Similar to central