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Generals About Incisors

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Generals About Generals About Incisors And Incisors And Particulars Particulars About Maxillary About Maxillary Central Incisors Central Incisors Howard Chi, D.M.D. Howard Chi, D.M.D.
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Page 1: Generals About Incisors

Generals About Generals About Incisors And Incisors And Particulars Particulars

About Maxillary About Maxillary Central IncisorsCentral Incisors

Howard Chi, D.M.D.Howard Chi, D.M.D.

Page 2: Generals About Incisors

Learning ObjectivesLearning Objectives

Generals of incisorsGenerals of incisors Traits of incisorsTraits of incisors Particulars of maxillary central Particulars of maxillary central

incisorsincisors

Page 3: Generals About Incisors

Generals of Generals of IncisorsIncisors

Page 4: Generals About Incisors

General Description Of General Description Of IncisorsIncisors

There are four maxillary incisors:There are four maxillary incisors: Two centrals Two centrals Two lateralsTwo laterals

7 8 9 10

Page 5: Generals About Incisors

General Description Of General Description Of IncisorsIncisors

There are four mandibular incisors:There are four mandibular incisors: Two centrals Two centrals Two laterals Two laterals

26 25 24 23

Page 6: Generals About Incisors

General Description Of General Description Of IncisorsIncisors

Central incisors have Central incisors have

two mesial surfaces two mesial surfaces

contacting each othercontacting each other

If a space exists, it is If a space exists, it is

known as a diastema known as a diastema

(for all teeth)(for all teeth)

Page 7: Generals About Incisors

Function Of All Incisor Function Of All Incisor TeethTeeth

1) Cutting food1) Cutting food

2) Enabling articulate speech2) Enabling articulate speech

3) Help support the lips and maintain good 3) Help support the lips and maintain good appearanceappearance

4) Help guide the mandible during its 4) Help guide the mandible during its movements movements

Page 8: Generals About Incisors

Morphology Morphology Of TeethOf Teeth

Generally, any tooth has five surfacesGenerally, any tooth has five surfaces Four surfaces and a chewing or Four surfaces and a chewing or

cutting surfacecutting surface Five aspects are: facial, lingual, Five aspects are: facial, lingual,

mesial, distal, and incisal or occlusalmesial, distal, and incisal or occlusal

I

F

D

L

M

Page 9: Generals About Incisors

General General Description Of Description Of

Incisors Incisors

Morphology Of Morphology Of The Labial SurfaceThe Labial Surface

Mamelons are usually seen on Mamelons are usually seen on

newly emerged incisor teethnewly emerged incisor teeth They are three scallops on the They are three scallops on the

incisal edge - beneath the three facial lobesincisal edge - beneath the three facial lobes Usually worn off after tooth in function for Usually worn off after tooth in function for

awhileawhile

Page 10: Generals About Incisors

General Description Of General Description Of Incisors Incisors

Morphology Of Morphology Of The Labial SurfaceThe Labial Surface

When mamelons When mamelons remain remain

on an adult, on an adult, suspect malocclusionsuspect malocclusion

Page 11: Generals About Incisors

Developmental depressions are the Developmental depressions are the

two shallow vertical depressions ontwo shallow vertical depressions on

the labial surface - dividing the the labial surface - dividing the

surface into three sectionssurface into three sections These sections are called mesial, These sections are called mesial,

middle and distal lobesmiddle and distal lobes

General General Description Of Description Of

Incisors Incisors Morphology Of Morphology Of

The Labial SurfaceThe Labial Surface

D M M

Page 12: Generals About Incisors

Perikymata - are fine horizontal Perikymata - are fine horizontal lines on the crown surfacelines on the crown surface

General General Description Of Description Of

Incisors Incisors

Morphology Of Morphology Of The Labial SurfaceThe Labial Surface

Page 13: Generals About Incisors

Traits of IncisorsTraits of Incisors

Page 14: Generals About Incisors

Class Traits Of Class Traits Of All Incisors All Incisors

Crowns From The FacialCrowns From The Facial

Are relatively rectangular, longer Are relatively rectangular, longer incisogingivallyincisogingivally

Are narrowest in the cervical third and Are narrowest in the cervical third and broader at the incisal thirdbroader at the incisal third

Page 15: Generals About Incisors

Are more convex on the distal than on the mesial (except Are more convex on the distal than on the mesial (except 24+25)24+25)

Mesial contact in the incisal thirdMesial contact in the incisal third Distal contact at the junction of incisal and middle thirdsDistal contact at the junction of incisal and middle thirds

Class Traits Of Class Traits Of All Incisors All Incisors

Crowns From The FacialCrowns From The Facial

Page 16: Generals About Incisors

Distal contact more cervical than the Distal contact more cervical than the mesial (except 24+25)mesial (except 24+25)

Cervical lines that are convex (dip) Cervical lines that are convex (dip) toward the apex facially and linguallytoward the apex facially and lingually

Class Traits Of Class Traits Of All Incisors All Incisors

Crowns From Crowns From The FacialThe Facial

Page 17: Generals About Incisors

Taper from cervical line to the apexTaper from cervical line to the apex Wider faciolingually than Wider faciolingually than

mesiodistally mesiodistally

(except 8+9, which are roughly (except 8+9, which are roughly equal)equal)

7 7

Class Traits Of Class Traits Of All IncisorsAll Incisors

Roots From Roots From The FacialThe Facial

Page 18: Generals About Incisors

Longer than crowns Longer than crowns May bend, usually distally, in the May bend, usually distally, in the

apical one-third (except 8+9)apical one-third (except 8+9)

Class Traits Of Class Traits Of All IncisorsAll Incisors

Roots From Roots From The FacialThe Facial

Page 19: Generals About Incisors

Class Traits Of Class Traits Of All IncisorsAll Incisors

Crowns From Crowns From The LingualThe Lingual

Mesial and distal sides converge Mesial and distal sides converge

forming narrower surfaceforming narrower surface Mesial and distal marginal Mesial and distal marginal

ridges that converge toward ridges that converge toward

cingulumcingulum

Page 20: Generals About Incisors

Class Traits Of All Class Traits Of All IncisorsIncisors

Crowns From The Crowns From The ProximalProximal

Wedge-shapedWedge-shaped Usually have the incisal Usually have the incisal

edge labial to the root edge labial to the root axis line for the axis line for the maxillary incisorsmaxillary incisors

Usually have the incisal Usually have the incisal edge lingual to the root edge lingual to the root axis line for the axis line for the mandibular incisorsmandibular incisors

Page 21: Generals About Incisors

Class Traits Of All IncisorsClass Traits Of All IncisorsCrowns From The ProximalCrowns From The Proximal

1) Labial and lingual crest of 1) Labial and lingual crest of curvature (greatest curvature (greatest bulge) that is in the bulge) that is in the cervical thirdcervical third

2) Lingual is convex-concave 2) Lingual is convex-concave

(s-shaped)(s-shaped)

3) Cervical line proximally is 3) Cervical line proximally is convex and curves incisallyconvex and curves incisally

ConcaveConvex

1

2 3

Page 22: Generals About Incisors

Class Traits Of All Class Traits Of All IncisorsIncisors

Roots From Roots From The ProximalThe Proximal

Widest at the cervical and taper Widest at the cervical and taper to a rounded apexto a rounded apex

Depression in middle third of mesial Depression in middle third of mesial

root surface (mandibular also have root surface (mandibular also have distal depression)distal depression)

Mesial ViewDistal View

Page 23: Generals About Incisors

Class Traits Of All Class Traits Of All Incisors Incisors

Crowns From The IncisalCrowns From The Incisal

A shallow concavity just incisal to the A shallow concavity just incisal to the cingulum called the lingual fossacingulum called the lingual fossa

An incisal ridgeAn incisal ridge A labial contour that is broader and A labial contour that is broader and

less curved than the lingualless curved than the lingual

lingual fossa

incisal ridge

Page 24: Generals About Incisors

Arch Traits Of IncisorsArch Traits Of Incisors

Mandibular IncisorsMandibular Incisors

1) are smaller than maxillary1) are smaller than maxillary

2) look more alike2) look more alike

3) are nearly the same size3) are nearly the same size

4) have smaller roots than maxillary4) have smaller roots than maxillary

5) are flatter on mesial and distal sides5) are flatter on mesial and distal sides

6) have crowns and roots relatively wider 6) have crowns and roots relatively wider faciolingually than mesiodistallyfaciolingually than mesiodistally

Page 25: Generals About Incisors

Arch Traits Of IncisorsArch Traits Of Incisors7) have contact areas located near the 7) have contact areas located near the

incisal ridgeincisal ridge8) have smoother lingual surfaces than 8) have smoother lingual surfaces than

maxillarymaxillary9) have incisal ridges on or lingual to the 9) have incisal ridges on or lingual to the

root axisroot axis10) have wear or attrition only on the 10) have wear or attrition only on the

incisal edge (not on lingual surface)incisal edge (not on lingual surface)11) have root that are longer in 11) have root that are longer in

proportion to the crownsproportion to the crowns

Page 26: Generals About Incisors

Particulars of Particulars of Maxillary Central Maxillary Central

IncisorsIncisors

Page 27: Generals About Incisors

The Maxillary Central The Maxillary Central IncisorIncisor

Incisal View

Distal ViewMesial View

Lingual View Facial View

Page 28: Generals About Incisors

Maxillary Central Maxillary Central Incisor Incisor

Labial SurfaceLabial Surface

Crown - Shape and SizeCrown - Shape and Size Crown is the longest of all human Crown is the longest of all human

crown and widest of all incisorscrown and widest of all incisors Usually longer (incisogingivally) Usually longer (incisogingivally)

than wide (mesiodistally)than wide (mesiodistally) Crown is narrowest in the Crown is narrowest in the

cervical thirdcervical third

Facial View

Page 29: Generals About Incisors

Maxillary Central Maxillary Central Incisor Incisor

Labial SurfaceLabial SurfaceCrown - Incisal Proximal Crown - Incisal Proximal

AnglesAngles MesioincisalMesioincisal angle is angle is

slightly rounded and nearly slightly rounded and nearly a 90 degree anglea 90 degree angle

Distoincisal Distoincisal angle is more angle is more rounded and somewhat rounded and somewhat obtuseobtuse

IncisalIncisal edge slopes edge slopes cervically towards the distalcervically towards the distal

Page 30: Generals About Incisors

Maxillary Maxillary Central Incisor Central Incisor

Labial SurfaceLabial Surface

Crown - Contact AreasCrown - Contact Areas Mesial is in the incisal third - near incisal Mesial is in the incisal third - near incisal

edgeedge Distal near junction of incisal and middle Distal near junction of incisal and middle

thirdsthirds

D M

Page 31: Generals About Incisors

Maxillary Central Maxillary Central Incisor Incisor

Labial SurfaceLabial Surface

Crown - ProportionsCrown - Proportions The root is just slightly The root is just slightly

longer than the crownlonger than the crown

Page 32: Generals About Incisors

Maxillary Central Maxillary Central Incisor Incisor

Labial SurfaceLabial Surface

Root - Shape Root - Shape

From The LabialFrom The Labial

Root is thick in the cervical third, narrowsRoot is thick in the cervical third, narrows

through the middle to a blunt apexthrough the middle to a blunt apex Central incisor root is the only root that is Central incisor root is the only root that is

as thick mesiodistally as faciolingually at as thick mesiodistally as faciolingually at its cervixits cervix

Page 33: Generals About Incisors

Maxillary Maxillary Central Incisor Central Incisor

Labial SurfaceLabial Surface

Root - Shape From The LabialRoot - Shape From The Labial Because it is short and conical,Because it is short and conical,

this tooth is a poor risk to this tooth is a poor risk to

support prostheticssupport prosthetics

Page 34: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Lingual SurfaceLingual SurfaceCrown - Lingual FossaCrown - Lingual Fossa

Lingual fossa is developed to Lingual fossa is developed to different degrees (from shallow different degrees (from shallow to deep)to deep)

Centrals with a deep fossa and Centrals with a deep fossa and prominent prominent

marginal ridges are termed marginal ridges are termed "shovel-shaped incisors""shovel-shaped incisors"

Page 35: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Lingual SurfaceLingual SurfaceCrown - CingulumCrown - Cingulum

Usually well developed and Usually well developed and

toward the distal toward the distal

(X marks the spot)(X marks the spot)

Distal to the root axis line Distal to the root axis line bisectingbisecting

the root longitudinallythe root longitudinally

X

Page 36: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Lingual SurfaceLingual SurfaceCrown - Marginal RidgesCrown - Marginal Ridges

Marginal ridges are Marginal ridges are

prominentprominent

Mesial marginal ridge is longer Mesial marginal ridge is longer

than distal due to the distal than distal due to the distal

placement of the cingulumplacement of the cingulum

Page 37: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Lingual SurfaceLingual Surface

Crown - Lingual Anatomy VariationsCrown - Lingual Anatomy Variations

1) the fossa may be deep but smooth 1) the fossa may be deep but smooth (no lingual ridges)(no lingual ridges)

2) may possess accessory lingual 2) may possess accessory lingual ridges (1 to 4)ridges (1 to 4)

3) may possess a lingual pit near 3) may possess a lingual pit near incisal border of cingulum where m incisal border of cingulum where m + d marginal ridges meet+ d marginal ridges meet

Page 38: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Lingual SurfaceLingual Surface

Root - Shape From The LingualRoot - Shape From The Lingual Like all anterior teeth this surface Like all anterior teeth this surface

is convex and narrower is convex and narrower mesiodistallymesiodistallythan the labial surfacethan the labial surface

Somewhat flat on mesial side Somewhat flat on mesial side approaching the lingualapproaching the lingual

A mesial depression running A mesial depression running longitudinal is often presentlongitudinal is often present

M

Page 39: Generals About Incisors

Maxillary Central Maxillary Central Incisor Incisor

Proximal SurfacesProximal SurfacesCrown - Incisal EdgeCrown - Incisal Edge Slightly labial to long axis of the root Slightly labial to long axis of the root

(can be mid-root)(can be mid-root) From distal, the distoincisal edge may be From distal, the distoincisal edge may be

just lingual to the axis line due to slight just lingual to the axis line due to slight twisting of incisal edgetwisting of incisal edge

Labial outline is convex in cervical, flatLabial outline is convex in cervical, flatto broadly curved in the middle and to broadly curved in the middle and incisal thirdsincisal thirds

Distal View

Mesial View

Page 40: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Proximal SurfacesProximal Surfaces

Crown - Cervical Line (CEJ)Crown - Cervical Line (CEJ) Like all anterior teeth the cervical line curves Like all anterior teeth the cervical line curves

incisally on mesial and distal surfacesincisally on mesial and distal surfaces Curvature is greater on the mesial than the Curvature is greater on the mesial than the

distaldistal

Distal ViewMesial View

Page 41: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Proximal SurfacesProximal Surfaces

Crown - Crest Of CurvatureCrown - Crest Of Curvature

The labial crest (height of contour)The labial crest (height of contour)

is in the cervical third just incisal is in the cervical third just incisal

to the cervical lineto the cervical line

On the lingual in the cervical thirdOn the lingual in the cervical third

Mesial View

L

Page 42: Generals About Incisors

Maxillary Central Maxillary Central Incisor Incisor

Proximal SurfacesProximal Surfaces

Root - OutlineRoot - Outline Root trunk thick or wide at cervix and Root trunk thick or wide at cervix and

tapers evenly to a rounded apextapers evenly to a rounded apex Lingual outline nearly straight in Lingual outline nearly straight in

cervical third, curving labially in cervical third, curving labially in middle and middle and

apical thirdsapical thirds Labial outline slightly convexLabial outline slightly convex

Distal View

Mesial View

Page 43: Generals About Incisors

Maxillary Central Maxillary Central Incisor Incisor

Proximal SurfacesProximal Surfaces

Root DepressionRoot Depression Mesial surface is somewhat flattened Mesial surface is somewhat flattened

with a longitudinal depression in the with a longitudinal depression in the middle thirdmiddle third

Mesial depression is located at junction Mesial depression is located at junction of middle and lingual thirds of the rootof middle and lingual thirds of the root

Page 44: Generals About Incisors

Maxillary Central Maxillary Central Incisor Incisor

Proximal SurfacesProximal Surfaces

Root DepressionRoot Depression Distal similar to mesial, except Distal similar to mesial, except

distal is convex not flatteneddistal is convex not flattened Distal lacks a depressionDistal lacks a depression

Page 45: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Incisal AspectIncisal Aspect

Crown WidthCrown Width Crown outline noticeably wider Crown outline noticeably wider

mesiodistally that faciolinguallymesiodistally that faciolingually

Page 46: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Incisal AspectIncisal Aspect

Crown OutlineCrown Outline Crown is roughly triangular, Crown is roughly triangular,

somewhat curved labial outlinesomewhat curved labial outline

Page 47: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Incisal AspectIncisal Aspect

Incisal Ridge ContourIncisal Ridge Contour Ridge 1.5 to 2 mm thick and slightly Ridge 1.5 to 2 mm thick and slightly

curved from mesial to distalcurved from mesial to distal Distoincisal angle is slightly lingual Distoincisal angle is slightly lingual

to the mesioincisal angleto the mesioincisal angle

1.5 - 2mm

Page 48: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Incisal AspectIncisal Aspect

CingulumCingulum

Cingulum is off-center to the Cingulum is off-center to the distal, with a longer mesial distal, with a longer mesial marginal ridgemarginal ridge

Page 49: Generals About Incisors

Maxillary Central Incisor Maxillary Central Incisor

Incisal AspectIncisal Aspect

Labial ContourLabial Contour Labial contour is broadly convexLabial contour is broadly convex On some teeth a portion may be nearly On some teeth a portion may be nearly

flatflat Possess two slight depressions (mesial Possess two slight depressions (mesial

and distal) on the labial surface in and distal) on the labial surface in middle and incisal thirdsmiddle and incisal thirds


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