Generals About Incisors

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

2. Learning ObjectivesLearning Objectives
Generals of incisorsGenerals of incisors
Traits of incisorsTraits of incisors
Particulars of maxillary central incisorsParticulars of maxillary central incisors

3. Generals of IncisorsGenerals of Incisors

4. General Description Of IncisorsGeneral Description Of Incisors
There are four maxillary incisors:There are four maxillary incisors:
Two centrals Two centrals
Two lateralsTwo laterals
78910

5. General Description Of IncisorsGeneral Description Of Incisors
There are four mandibular incisors:There are four mandibular incisors:
Two centrals Two centrals
Two laterals Two laterals
26252423

6. General Description Of IncisorsGeneral Description Of Incisors
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)

7. Function Of All Incisor TeethFunction Of All Incisor Teeth
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 movements 4) Help guide the mandible during its movements

8. Morphology Morphology
Of TeethOf Teeth
Generally, any tooth has five surfacesGenerally, any tooth has five surfaces
Four surfaces and a chewing or cutting Four surfaces and a chewing or cutting
surfacesurface
Five aspects are: facial, lingual, mesial, distal, Five aspects are: facial, lingual, mesial, distal,
and incisal or occlusaland incisal or occlusal
I
F
D
L
M

9. General Description General Description
Of Incisors Of 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 awhileUsually worn off after tooth in function for awhile

10. General Description Of Incisors General Description Of Incisors
Morphology Of Morphology Of
The Labial SurfaceThe Labial Surface
When mamelons remain When mamelons remain
on an adult, on an adult,
suspect malocclusionsuspect malocclusion

11. 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, middle and These sections are called mesial, middle and
distal lobesdistal lobes
General General
Description Of Description Of
Incisors Incisors
Morphology Of Morphology Of
The Labial SurfaceThe Labial Surface
DMM

12. Perikymata - are fine horizontal lines on the Perikymata - are fine horizontal lines on the
crown surfacecrown surface
General General
Description Of Description Of
Incisors Incisors
Morphology Of Morphology Of
The Labial SurfaceThe Labial Surface

13. Traits of IncisorsTraits of Incisors

14. Class Traits Of Class Traits Of
All Incisors All Incisors
Crowns From The FacialCrowns From The Facial
Are relatively rectangular, longer incisogingivallyAre relatively rectangular, longer incisogingivally
Are narrowest in the cervical third and broader at the Are narrowest in the cervical third and broader at the
incisal thirdincisal third

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

16. Distal contact more cervical than the mesial (except Distal contact more cervical than the mesial (except
24+25)24+25)
Cervical lines that are convex (dip) toward the apex Cervical lines that are convex (dip) toward the apex
facially and linguallyfacially and lingually
Class Traits Of Class Traits Of
All Incisors All Incisors
Crowns From Crowns From
The FacialThe Facial

17. Taper from cervical line to the apexTaper from cervical line to the apex
Wider faciolingually than mesiodistally Wider faciolingually than mesiodistally
(except 8+9, which are roughly equal)(except 8+9, which are roughly equal)
7 7
Class Traits Of Class Traits Of
All IncisorsAll Incisors
Roots From Roots From
The FacialThe Facial

18. Longer than crowns Longer than crowns
May bend, usually distally, in the apical one-May bend, usually distally, in the apical one-
third (except 8+9)third (except 8+9)
Class Traits Of Class Traits Of
All IncisorsAll Incisors
Roots From Roots From
The FacialThe Facial

19. 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

20. Class Traits Of All IncisorsClass Traits Of All Incisors
Crowns From The ProximalCrowns From The Proximal
Wedge-shapedWedge-shaped
Usually have the incisal edge Usually have the incisal edge
labial to the root axis line for labial to the root axis line for
the maxillary incisorsthe maxillary incisors
Usually have the incisal edge Usually have the incisal edge
lingual to the root axis line for lingual to the root axis line for
the mandibular incisorsthe mandibular incisors

21. Class Traits Of All IncisorsClass Traits Of All Incisors
Crowns From The ProximalCrowns From The Proximal
1) Labial and lingual crest of 1) Labial and lingual crest of
curvature (greatest bulge) that is curvature (greatest bulge) that is
in the cervical thirdin the cervical third
2) Lingual is convex-concave 2) Lingual is convex-concave
(s-shaped)(s-shaped)
3) Cervical line proximally is convex 3) Cervical line proximally is convex
and curves incisallyand curves incisally
Concave
Convex
1
2 3

22. Class Traits Of All IncisorsClass Traits Of All Incisors
Roots From Roots From
The ProximalThe Proximal
Widest at the cervical and taper to a Widest at the cervical and taper to a
rounded apexrounded apex
Depression in middle third of mesial Depression in middle third of mesial
root surface (mandibular also have distal root surface (mandibular also have distal
depression)depression)
Mesial ViewDistal View

23. Class Traits Of All Incisors Class Traits Of All Incisors
Crowns From The IncisalCrowns From The Incisal
A shallow concavity just incisal to the cingulum A shallow concavity just incisal to the cingulum
called the lingual fossacalled the lingual fossa
An incisal ridgeAn incisal ridge
A labial contour that is broader and less curved A labial contour that is broader and less curved
than the lingualthan the lingual
lingual fossa
incisal ridge

24. 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

25. Arch Traits Of IncisorsArch Traits Of Incisors
7) have contact areas located near the incisal 7) have contact areas located near the incisal
ridgeridge
8) have smoother lingual surfaces than maxillary8) have smoother lingual surfaces than maxillary
9) have incisal ridges on or lingual to the root 9) have incisal ridges on or lingual to the root
axisaxis
10) have wear or attrition only on the incisal 10) have wear or attrition only on the incisal
edge (not on lingual surface)edge (not on lingual surface)
11) have root that are longer in proportion to 11) have root that are longer in proportion to
the crownsthe crowns

26. Particulars of Particulars of
Maxillary Central Maxillary Central
IncisorsIncisors

27. The Maxillary Central IncisorThe Maxillary Central Incisor
Incisal View
Distal View
Mesial View
Lingual View Facial View

28. Maxillary Central Incisor Maxillary Central 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

29. Maxillary Central Incisor Maxillary Central Incisor
Labial SurfaceLabial Surface
Crown - Incisal Proximal AnglesCrown - Incisal Proximal Angles
MesioincisalMesioincisal angle is slightly angle is slightly
rounded and nearly a 90 degree rounded and nearly a 90 degree
angleangle
Distoincisal Distoincisal angle is more angle is more
rounded and somewhat obtuserounded and somewhat obtuse
IncisalIncisal edge slopes cervically edge slopes cervically
towards the distaltowards the distal

30. Maxillary Maxillary
Central Incisor Central Incisor
Labial SurfaceLabial Surface
Crown - Contact AreasCrown - Contact Areas
Mesial is in the incisal third - near incisal edgeMesial is in the incisal third - near incisal edge
Distal near junction of incisal and middle thirdsDistal near junction of incisal and middle thirds
D M

31. Maxillary Central Incisor Maxillary Central Incisor
Labial SurfaceLabial Surface
Crown - ProportionsCrown - Proportions
The root is just slightly The root is just slightly
longer than the crownlonger than the crown

32. Maxillary Central Incisor Maxillary Central 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 as thick Central incisor root is the only root that is as thick
mesiodistally as faciolingually at its cervixmesiodistally as faciolingually at its cervix

33. 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

34. Maxillary Central Incisor Maxillary Central Incisor
Lingual SurfaceLingual Surface
Crown - 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 prominent Centrals with a deep fossa and prominent
marginal ridges are termed marginal ridges are termed
"shovel-shaped incisors""shovel-shaped incisors"

35. Maxillary Central Incisor Maxillary Central Incisor
Lingual SurfaceLingual Surface
Crown - 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 bisectingDistal to the root axis line bisecting
the root longitudinallythe root longitudinally
X

36. Maxillary Central Incisor Maxillary Central Incisor
Lingual SurfaceLingual Surface
Crown - 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

37. Maxillary Central Incisor Maxillary Central Incisor
Lingual SurfaceLingual Surface
Crown - Lingual Anatomy VariationsCrown - Lingual Anatomy Variations
1) the fossa may be deep but smooth (no lingual 1) the fossa may be deep but smooth (no lingual
ridges)ridges)
2) may possess accessory lingual ridges (1 to 4)2) may possess accessory lingual ridges (1 to 4)
3) may possess a lingual pit near incisal border 3) may possess a lingual pit near incisal border
of cingulum where m + d marginal ridges of cingulum where m + d marginal ridges
meetmeet

38. Maxillary Central Incisor Maxillary Central Incisor
Lingual SurfaceLingual Surface
Root - Shape From The LingualRoot - Shape From The Lingual
Like all anterior teeth this surface is Like all anterior teeth this surface is
convex and narrower mesiodistallyconvex and narrower mesiodistally
than 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 longitudinal A mesial depression running longitudinal
is often presentis often present
M

39. Maxillary Central Incisor Maxillary Central Incisor
Proximal SurfacesProximal Surfaces
Crown - 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, flat
to broadly curved in the middle and to broadly curved in the middle and
incisal thirdsincisal thirds
Distal View
Mesial View

40. 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 distalCurvature is greater on the mesial than the distal
Distal View
Mesial View

41. 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

42. Maxillary Central Incisor Maxillary Central 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 cervical Lingual outline nearly straight in cervical
third, curving labially in middle and third, curving labially in middle and
apical thirdsapical thirds
Labial outline slightly convexLabial outline slightly convex
Distal View
Mesial View

43. Maxillary Central Incisor Maxillary Central Incisor
Proximal SurfacesProximal Surfaces
Root DepressionRoot Depression
Mesial surface is somewhat flattened with a Mesial surface is somewhat flattened with a
longitudinal depression in the middle thirdlongitudinal depression in the middle third
Mesial depression is located at junction of Mesial depression is located at junction of
middle and lingual thirds of the rootmiddle and lingual thirds of the root

44. Maxillary Central Incisor Maxillary Central 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

45. Maxillary Central Incisor Maxillary Central Incisor
Incisal AspectIncisal Aspect
Crown WidthCrown Width
Crown outline noticeably wider mesiodistally that Crown outline noticeably wider mesiodistally that
faciolinguallyfaciolingually

46. Maxillary Central Incisor Maxillary Central Incisor
Incisal AspectIncisal Aspect
Crown OutlineCrown Outline
Crown is roughly triangular, somewhat Crown is roughly triangular, somewhat
curved labial outlinecurved labial outline

47. Maxillary Central Incisor Maxillary Central Incisor
Incisal AspectIncisal Aspect
Incisal Ridge ContourIncisal Ridge Contour
Ridge 1.5 to 2 mm thick and slightly curved Ridge 1.5 to 2 mm thick and slightly curved
from mesial to distalfrom mesial to distal
Distoincisal angle is slightly lingual to the Distoincisal angle is slightly lingual to the
mesioincisal anglemesioincisal angle
1.5 - 2mm

48. Maxillary Central Incisor Maxillary Central Incisor
Incisal AspectIncisal Aspect
CingulumCingulum
Cingulum is off-center to the distal, with a Cingulum is off-center to the distal, with a
longer mesial marginal ridgelonger mesial marginal ridge

49. 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 flatOn some teeth a portion may be nearly flat
Possess two slight depressions (mesial and Possess two slight depressions (mesial and
distal) on the labial surface in middle and distal) on the labial surface in middle and
incisal thirdsincisal thirds