generals about incisors
TRANSCRIPT
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.
Learning ObjectivesLearning Objectives
Generals of incisorsGenerals of incisors Traits of incisorsTraits of incisors Particulars of maxillary central Particulars of maxillary central
incisorsincisors
Generals of Generals of IncisorsIncisors
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
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
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)
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
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
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
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
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
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
Traits of IncisorsTraits of 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
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
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
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
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
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
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
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
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
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
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
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
Particulars of Particulars of Maxillary Central Maxillary Central
IncisorsIncisors
The Maxillary Central The Maxillary Central IncisorIncisor
Incisal View
Distal ViewMesial View
Lingual View Facial View
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
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
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
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
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
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
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"
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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