Anterior Teeth

8/4/2019 Anterior Teeth

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THE PERMANENT INCISOR TEETH

Introduction/Morphology/Function/Lo

cation


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Maxillary Central Incisor

Initial calcification3-4 months

Crown completion 4-5 years

Eruption into occlusion 7-8 years

Root completion 10 years

Chronology


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Maxillary Central Incisor

The maxillary centralincisor is the first

tooth closest to the

midline.

It is the most

prominent tooth in

the mouth.


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These teeth, along with the lateral incisors,

play an important part of a person's

appearance. Their shape, color, size, and

placement directly relate to how a person

looks.


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The labial surface isconvex, both mesial todistal and gingival to

incisal. The root is about one and

a half to two times thelength of the crown. Theroot appears constrictedat the CEJ and then swellsin the body, taperingsuddenly at the apicalportion. Therefore, it

ends in a rather bluntapex. The root tends toincline slightly distally.


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Labial: It has a nearly straight

incisal edge and a gracefullycurved cervical line. Themesial presents a straightoutline; the distal aspect ismore rounded. Mamelonsare present on freshlyerupted, unworn centralincisors.

Proximal height of contourof the MESIAL surface is inthe incisal 1/3 and the distalheight of contour is at the

junction of the incisal andmiddle 1/3,

mesio-facio-incisal pointangle is quite sharp, quitepointed, and the disto-facio-

incisal angle is morerounded.

mesio-

incisal

angle

disto-

incisal

angle


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Lingual: The lingual aspect

presents a distinctive

lingual fossa that isbordered by mesial anddistal marginal ridges,the incisal edge, and theprominent cingulum atthe gingival.

The lingual surface is

concave, except thegingival one-third wherethe cingulum is present

The lingual height ofcontour is shown in thecenter of the lingualaspect of the cingulum

and is located in thegingival 1/3 of the lingualsurface, which is typicalof most BUT NOT ALLteeth.

Lingualfossa

Marginalridges

Incisalridge

cingulum


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Proximal:

When viewed mesiallyor distally, the crownappears wedge-shapedand leans lingually.

The incisal ridge of thecrown is aligned on thelong axis of the toothalong with the apex of

the tooth. The lingual surface is

concave, except thegingival one-thirdwhere the cingulum ispresent.

DistalMesial

Undulation of

cervical margin

greater on

mesial aspect


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Incisal:

The incisal edge is

nearly a straight

line, though

slightly crescentshaped.

Distal contour is

broader and more

rounded than themesial contour

D M


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Root

One tapering rootwhich, when looked at

in cross-section, is

roughly triangular

with rounded angles.There is only one root

canal but two pulp

horns one mesial and

one distal.


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GEOMETRIC FORM of the MAXILLARY CENTRAL INCISOR:

Labial

Lingual

MD


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Chronology





Maxillary lateral incissor


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Labial The maxillary lateral incisor

resembles the central incisor,but is narrower mesio-distally.

The cervical regionis narrowed mesio-distally,giving a long mesial surface

with a sharp mesio-incisalangle and a short distal surfacewith a pronounced rounding ofthe disto-incisal angle

The mesial contact is at thejunction of the incisal third and

the middle third. The distalcontact is located at the centerof the middle third of the distalsurface.

Mesial

Incisal angle

Distal inicsal

angle

MD


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Lingual

The lingual surface

has two pronounced

marginal ridges.

M D

Marginal

ridges


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NOTICE: the mesial and distal marginal ridges meet at a V-notch just incisal to thecingulum. This V-notch is often punctuated with a deep pit. (Sometimes a deepinvagination occurs here called a Dens-in-Dente; or tooth within a tooth). Youshould check on this term in the textbook. But, in any case, a deep pit, called theLINGUAL PIT is frequently present on this surface of the lateral incisor.It is important here to learn a new term: "LINGUOGINGIVAL FISSURE". This featureappears frequently on maxillary lateral incisors and some maxillary canines. It is a

vertical crack, a non-coalesced or non-fused fissure eminating from the point atwhich the mesial and distal marginal ridges meet at the crest of the cingulum. Thisvertical fissure is not seen on all maxillary lateral incisors, but it is frequentlypresent. It may run vertically from the lingual pit, up over the crest of the union ofthe two marginal ridges and then proceed apically toward the cemento-enamel

junction on the lingual aspect of the cingulum. It is rarely, but sometimes present,on maxillary central incisors and never on mandibular incisors.

The rest of the lingual surface of this tooth is not remarkable compared to thecentral inciso


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Proximal

The crownappears

wedge-

shaped

whenviewed

mesially or

distally.

Mesial Distal


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Incisal

The tooth is narrowermesiodistally than the

upper central incisor;

however, it is nearly as

thick labiolingually.M

D


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VIEW of the ROOT in

CROSS SECTION:

In this view the root of

the maxillary lateral

appears identical to

that of the maxillarycentral incisor, but

smaller in diameter

and circumference.


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Mandibular Central Incisor

Chronology






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Labial The mandibular central

incisor is the smallest

tooth in the dental arch.It is a long, narrow,symmetrical tooth. Theincisal edge is straight.Mesial and distal outlinesdescend apically fromthe sharp mesial and

distal incisal angles. The crown, when

viewed labially, appearsflat and almostsymmetrical.

The disto-incisal angle ismarginally rounder than

the mesio-incisal angle.


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Lingual:

The lingual surface hasno definite marginal

ridges. The surface is

concave and the

cingulum is minimal insize.


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Proximal: Both mesial and distal

surfaces present atriangular outline.

From the mesial or distalaspect the crown appearswedge-shaped and leans

lingually. As in the maxillary

anterior teeth thecervical undulation isgreater on the mesialsurface.

The mesial and distalsurfaces are grooved, thedistal groove being morepronounced than themesial groove.

Mesial Distal


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Incisal:

The incisal edge is atright angles to a line

passing labiolingually

through the tooth

reflecting its bilateralsymmetry.


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Root

One root which isflattened mesio-

distally.

One root canal and a

mesial and distal pulphorn.

Slender, thin

mesiodistally andwide faciolingually.


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Mandibular lateral incisor

Chronology






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Labial

This tooth resemblesthe central incisor, butis somewhat larger inmost proportions.There is a lack of the

bilateral symmetryseen in the central.

The mesio-incisalangle is sharp and thedisto-incisal angle

rounded. The mesialside is slightly longerthan the distal side.

M

D


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Mandibular

Central incisor Lateral incisor


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Lingual

Except for thelack of symmetry,

this tooth

resemble the

central. The lingual

surface is similar

to that of the

central incisor.


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Proximal Like the central, the

crown presents atriangular outline.

From the mesial or

distal aspect the

crown is wedge-shaped and leans

lingually.

The cervical

undulation is greateron the mesial

surface.

Mesial Distal


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Incisal

The incisal edge 'twisted'from the 90 degree angle

with a line passing

labiolingually through the

tooth.

Viewed from the incisal

edge the crown is slightly

twisted on the root to

follow the dental arch


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MAXILLARY AND MANDIBULARCANINES


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General characteristics of All

Canines

Class Traits


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Crowns are pentagon shaped (facial views).

Pentagon

Shape


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Cusps have mesial ridges shorter

Maxillary Right Canine

MD

than distal ridges (facial views).


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Vertical labial ridges are prominent

MD

(more so on maxillary canines).

Facial View


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Crowns are wider faciolingually

mesialdistal

labial

Lingual

than mesiodistally (similar to mandibular incisors) (incisal views).


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Type (and Arch) Traits That

Distinguish the Maxillary Caninefrom the mandibular Canine


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Both maxillary and mandibular canine crowns are oblong with themesiodistal dimension less than the incisocervical dimension,

but the dimension of mandibular canines is more narrow than onmaxillary canines.

Facial View

Maxillary Mandibular

MD D M


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Maxillary canines have mesial crown contours convex to flat cervically

versus mandibular canines which have mesial crown contours more on linewith the contour of the root.

Facial View


MD D M


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Lingual ridges with mesial and distal fossae are less prominent onmandibular canines than maxillary canines.

Lingual View


D DMM


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Cingula of maxillary canines are large and centered mesiodistally.

On mandibular canines they are often slightly to the distal.

Incisal View

MD M D



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Incisal ridges on maxillary canines are straighter mesiodistally.

On mandibular canines the distal cusp ridge bends distolingually.

Incisal View

MD M D



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The cusp tip of the maxillary canine is on or labial to the root axis

whereas the mandibular cusp tip is lingual to the root axis line.(proximal & incisal view)


labial

labialli

ngual

lingual


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Type Traits Distinguishing Maxillary 1st

from 2nd

Premolars


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Max right 1st pm


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Max right 1st pm

Mesial Distal


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Maxillary right 2nd pm

Mesial Distal


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Buccal cusps of maxillary 1st premolars are tipped more to the distal with mesial cusp

slopes longer than distal cusp slopes.

THESE ARE THE ONLY PREMOLARS WITH THESE CHARARACTERISTICS.

Maxillary 1st PM Maxillary 2nd PM

MD DM


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Buccal cusps of maxillary 1st premolars are more pointed versus maxillary 2nd premolars where

they are more obtuse.

Maxillary 1st PM

MD

Maxillary 2nd PM

DM

Buccal ridges are more prominent in maxillary 1st premolars.


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Buccal ridges are more prominent in maxillary 1 premolars.

Maxillary 1st PM

MD

Maxillary 2nd PM

DM


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Maxillary 1st premolars usually have a divided root versus maxillary 2nd premolars

which usually have one root.

mesialmesial


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Maxillary premolars have their lingual cusps tipped (bent) toward the mesial.


Lingual View

D DMM

Lingual cuspdisplacedmesially


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Both maxillary premolars have mesial and distal root depressions but only the maxillary 1st premolars

exhibit a mesial crown concavity.

Mesial View

Maxillary 1st

PM Maxillary 2

nd

PM


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Mesial marginal ridge grooves are almost always present on maxillary 1st premolars

and are less common on maxillary 2nd premolars.


Occlusal View

M MD D


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The central developmental grooves on maxillary 1st premolars are longer (from mesial to distal

pit) than those of maxillary 2nd premolars where they are only 1/3 or less of the mesiodistal

dimension.


Occlusal View

M MD D


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Occlusal outlines of maxillary 1st premolars are more asymmetrical with the lingual cusp tip bent

mesially, and mesial marginal ridge straight to concave, versus maxillary 2nd premolars which are

more symmetrical overall.


Occlusal View

M MD D


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MD

Buccal cusp

Lingual cusp

Buccal triangular ridge

Lingual triangular ridge

Transverse ridgeCentral developmental

groove

Distal marginal ridge

Mesial marginal ridge

Distobuccal cuspridge Mesiobuccal

cusp ridge

Distolingual cusp ridge

Mesiolingual cusp ridge


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Buccal cusp

Mesiobuccalcusp ridge

Distobuccal

cusp ridge

Centraldevelopmental

groove

Lingualcusp

Buccaltriangular ridge

Lingual triangularridge

Tranverse

ridg

eMesiolingualcusp ridge

Distolingualcusp ridge

Distal marginalridge Mesial marginal

ridge

Maxillary right 1st PM occlusal surface

Maxillary 1st PM Mesial View


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y

Lingual cuspBuccal cusp

Mesial marginal developmentalgroove

Lingual rootBuccal root

Mesial developmentaldepression

M ill 1st PM M i l Vi


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Maxillary 1st PM Mesial View

Buccal root Lingual root

Mesial developmentaldepression

Mesial marginaldevelopmental groove

Buccal cuspLingual cusp

Mand 1st & 2nd PM
http://type%20traits%20distinguishing%20mandibular%201st%20from%202nd%20premolars.ppt/http://type%20traits%20distinguishing%20mandibular%201st%20from%202nd%20premolars.ppt/


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Type Traits Distinguishing

Mandibular 1st from 2nd Premolars

Mand right 1st pm


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g p

Mesial Distal

Mand rt 2nd pmMesial


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pMesial

Distal


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Mandibular 1st premolar buccal cusps are more pointed versus on 2nd premolar where

they are more obtuse.

Mandibular 1st PMMandibular 2nd PM

Facial View

MD MD

Mesial proximal contacts (and marginal ridges) of mandibular 2nd premolars are more occlusal than distal

contacts (following the general rule)


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contacts (following the general rule)

whereas the reverse is true on mandibular 1st premolars (EXCEPTION)where mesial contacts and marginal ridges are more cervical.

Mandibular 1st PM Mandibular 2nd PM

Facial View

MDM

D

Lingual cusps of mandibular 1st premolars are very small and nonfunctional


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Lingual cusps of mandibular 1st premolars are very small and nonfunctional.


On 2nd premolars the lingual cusps function and are relatively longer.

Mesial View


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Mandibular 1st premolars have a mesiolingual groove separating the mesial marginal ridge

from the lingual cusp while 2nd premolars do not possess this characteristic.


Lingual View Mesial View

Mandibular 2nd PMMandibular 1st PM


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Mesial marginal ridges of 1st premolars slope cervically toward the lingual at about 45

from horizontal. On 2nd premolars they are more horizontal.


Mesial View


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The mesial root surfaces of mandibular 2nd premolars are the only premolar root surface

(maxillary and mandibular, mesial and distal) not likely to have a mid-root depression.

Mandibular 2

nd

PM

Mesial


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Two types of mandibular 2nd premolars


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Two cusp type rounda. Bucal cusp

b. Lingual cusp

U type H type

Three cusp type

-Square-Buccal cusp largest-Mesiolingual cusp

-Distolingual cusp-smallest

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Anterior Teeth