maxillary central incisors

8/4/2019 Maxillary Central Incisors

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Maxillary Central Incisors

Permanent Notation

Left Central Incisor Right Central Incisor

Palmers Notation 1 1

FDI (Universal) 8 9

Two-Digit 11 21

Deciduous Notation

Left Central Incisor Right Central Incisor

Palmers Notation A A

FDI (Universal) E F

Two-Digit 61 51

Chronology

First evidence of calcification 3-4 mo

Enamel completed 4-5 yr

Eruption 7-8 yr

Root completed 10 yr


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General Characteristics

They are the largest incisors and the most prominent teeth in the mouth.Labial Aspect (Crown)

Is the longest tooth inciso-gingivally of all human tooth crowns, averaging to 10.5 mm;although sometimes a mandibular canine may appear to be a slightly longer overall, averaging

to about 11 mm.

Is by far the widest mesio-distally of all four incisors.

The crown is narrowest in the cervical third and broadens as it approaches the incisal third. So the geometric outline of the crown is that of a trapezoid . The incisal margin of the newly erupted, unworn tooth reveals 3 tubercles, called mamelons.

The central is the smallest while the two beside it are approximately equal. These mamelons

soon wear off, giving a straight regular incisal edge.

The cervical line, which is seen as the border between the crown and the root of the tooth, iscloser to the apex of the root in the center of the tooth. This makes the cervical line appear as

a semicircle in shape.

The mesial outline of the tooth is straight or slightly convex, whereas thedistal outline is much more convex.

The mesial and incisal sides of the tooth join at a nearly right angle. The distoincisal corner is somewhat obtuse and is more rounded than the

mesioincisal angle.


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Labially, The root is cone-shaped with a blunt apex. Although there is a large amount ofvariation between people, the length of the root is usually 23 mm longer than the length of

the crown.

It is narrower than the labial aspect due to the convergence of the proximal surfaces lingually. The cervical line is similar to that of the labial side. It has convexities and concavities.

The Cingulum Smooth large convexity

immediately below the cervical line.

Usually well developed and islocated off-center toward the distal

side. Therefore, it lies distal to the

root axis line.

Lingual Fossa It is a broad concave depression in the central portion of the lingual

surface, immediately incisal to the to the cingulum.

It is bounded by the mesial distal marginal ridges and the incisal ridge. It varies in depth, in some teeth it is

shallow; in others, deep.

Marginal Ridges Mesial and distal marginal ridges vary in prominence from one person to another. The mesial marginal ridge is longer than the distal marginal ridge. They converge at the cingulum

and extended to the incisal incisal ridge.

Lingual Aspect (Root)

The lingual surfaces of the root is convexand is narrower mesio-distally than

the labial surface due to the lingual

convergence of the proximal sides.

It is flattened on the mesial with alongitudinal depression and convexon the distal like the labial side.


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Mesial Aspect (General Shape)

The geometric outline is a wedge-shaped ortriangular crown with its base at the cervix and the

apex at the incisal ridge.

May sometimes appear chisel-shaped.

Mesial Aspect (Labial Outline)

Convex at the cervical third, slightlyconvex or nearly flat in the middle

and incisal thirds.

The crest of curvature, orthegreatest bulge, is in the

cervical third just incisal to the

cervical line.

Mesial Aspect (Lingual Outline)

Convex over the cingulum, concave atthe mesial marginal ridge, and slightly

convex at the incisal ridge.

The crest of curvature is on thecingulum.

Mesial Aspect (Incisal Outline)

The incisal outline is in line with the root axis. It is rarely labial to the root axis and occasionally lingual to it.

Mesial Aspect (Cervical Outline)

The cervical line from this viewcurves tremendously toward

the incisal.

The cervical curvature on themesial surface of surface of maxillary central incisor is greater than any surface on any other

tooth.


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Mesial Aspect (Root)

Thick and wide at the cervix andtapers evenly to a rounded apex.

It is somewhat flattened with alongitudinal depression in the

middle third.

Distal Aspect (Crown)

Similar to the mesial aspect but with little differences. It appear somewhat thicker toward the incisal third. The distal curvature of the cervical line is less in extent than on the mesial aspect.

Incisal Aspect

The crown is roughly triangular with somewhat curved labial outline forming the base and theproximal sides converge toward the cingulum.

The crown is wider mesiodistally than faciolingually .

The cingulum cingulum is located off-center to distal. The labial contour usually appears broad and convex but sometimes may be

nearly flat.

The incisal incisal edge is edge is 1 .5 -2 mm thick. The lingual fossa is seen as broad concavity between the two marginal

ridges.

Interproximal Contacts

Mesially The central incisors touch in the incisal third of the teeth.

Distally Near the junction of the incisal and the middle third; it is more cervical than the mesial

side.

Occlusion

The central incisors are usually located facially to the mandibular teeth when the mouth isclosed.


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In instances when the maxillary anterior teeth are lingual to the mandibular teeth, thecondition is referred to as an anterior crossbite.

When the teeth are biting down, the maxillary central incisors occlude with the mandibularcentral and lateral incisors. The contact point of the mandibular teeth is in the lingual fossa of

the maxillary central incisor about 4 mm gingivally from the incisal edge.

In this position, the maxillary incisors cover nearly half of the mandibular incisors' crowns. When the maxillary and mandibular incisors do not contact even when the mouth is fully

closed, an anterior open bite occurs. This misalignment of teeth may result from some habits,

such as thumb-sucking.

On the other hand, when the contact of the mandibular incisors to the maxillary incisors isnear or completely on the gingiva, a deep bite occurs.

maxillary central incisors

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