Generals About Incisors

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Generals About Incisors

  1. 1. Generals AboutGenerals About Incisors AndIncisors And Particulars AboutParticulars About Maxillary CentralMaxillary Central IncisorsIncisors Howard Chi, D.M.D.Howard Chi, D.M.D.
  2. 2. Learning ObjectivesLearning Objectives  Generals of incisorsGenerals of incisors  Traits of incisorsTraits of incisors  Particulars of maxillary central incisorsParticulars of maxillary central incisors
  3. 3. Generals of IncisorsGenerals of Incisors
  4. 4. General Description Of IncisorsGeneral Description Of Incisors There are four maxillary incisors:There are four maxillary incisors:  Two centralsTwo centrals  Two lateralsTwo laterals 7 8 9 10
  5. 5. General Description Of IncisorsGeneral Description Of Incisors There are four mandibular incisors:There are four mandibular incisors:  Two centralsTwo centrals  Two lateralsTwo laterals 26 25 24 23
  6. 6. General Description Of IncisorsGeneral Description Of Incisors  Central incisors haveCentral incisors have two mesial surfacestwo mesial surfaces contacting each othercontacting each other  If a space exists, it isIf a space exists, it is known as a diastemaknown as a diastema (for all teeth)(for all teeth)
  7. 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 good3) Help support the lips and maintain good appearanceappearance 4) Help guide the mandible during its movements4) Help guide the mandible during its movements
  8. 8. MorphologyMorphology Of TeethOf Teeth  Generally, any tooth has five surfacesGenerally, any tooth has five surfaces  Four surfaces and a chewing or cuttingFour 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. 9. General DescriptionGeneral Description Of IncisorsOf Incisors Morphology OfMorphology Of The Labial SurfaceThe Labial Surface  Mamelons are usually seen onMamelons are usually seen on newly emerged incisor teethnewly emerged incisor teeth  They are three scallops on theThey 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. 10. General Description Of IncisorsGeneral Description Of Incisors Morphology OfMorphology Of The Labial SurfaceThe Labial Surface  When mamelons remainWhen mamelons remain on an adult,on an adult, suspect malocclusionsuspect malocclusion
  11. 11.  Developmental depressions are theDevelopmental depressions are the two shallow vertical depressions ontwo shallow vertical depressions on the labial surface - dividing thethe labial surface - dividing the surface into three sectionssurface into three sections  These sections are called mesial, middle andThese sections are called mesial, middle and distal lobesdistal lobes GeneralGeneral Description OfDescription Of IncisorsIncisors Morphology OfMorphology Of The Labial SurfaceThe Labial Surface D M M
  12. 12.  Perikymata - are fine horizontal lines on thePerikymata - are fine horizontal lines on the crown surfacecrown surface GeneralGeneral Description OfDescription Of IncisorsIncisors Morphology OfMorphology Of The Labial SurfaceThe Labial Surface
  13. 13. Traits of IncisorsTraits of Incisors
  14. 14. Class Traits OfClass Traits Of All IncisorsAll 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 theAre narrowest in the cervical third and broader at the incisal thirdincisal third
  15. 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 OfClass Traits Of All IncisorsAll Incisors Crowns From The FacialCrowns From The Facial
  16. 16.  Distal contact more cervical than the mesial (exceptDistal contact more cervical than the mesial (except 24+25)24+25)  Cervical lines that are convex (dip) toward the apexCervical lines that are convex (dip) toward the apex facially and linguallyfacially and lingually Class Traits OfClass Traits Of All IncisorsAll Incisors Crowns FromCrowns From The FacialThe Facial
  17. 17.  Taper from cervical line to the apexTaper from cervical line to the apex  Wider faciolingually than mesiodistallyWider faciolingually than mesiodistally (except 8+9, which are roughly equal)(except 8+9, which are roughly equal) 7 7 Class Traits OfClass Traits Of All IncisorsAll Incisors Roots FromRoots From The FacialThe Facial
  18. 18.  Longer than crownsLonger 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 OfClass Traits Of All IncisorsAll Incisors Roots FromRoots From The FacialThe Facial
  19. 19. Class Traits OfClass Traits Of All IncisorsAll Incisors Crowns FromCrowns From The LingualThe Lingual  Mesial and distal sides convergeMesial and distal sides converge forming narrower surfaceforming narrower surface  Mesial and distal marginalMesial and distal marginal ridges that converge towardridges that converge toward cingulumcingulum
  20. 20. Class Traits Of All IncisorsClass Traits Of All Incisors Crowns From The ProximalCrowns From The Proximal  Wedge-shapedWedge-shaped  Usually have the incisal edgeUsually have the incisal edge labial to the root axis line forlabial to the root axis line for the maxillary incisorsthe maxillary incisors  Usually have the incisal edgeUsually have the incisal edge lingual to the root axis line forlingual to the root axis line for the mandibular incisorsthe mandibular incisors
  21. 21. Class Traits Of All IncisorsClass Traits Of All Incisors Crowns From The ProximalCrowns From The Proximal 1) Labial and lingual crest of1) Labial and lingual crest of curvature (greatest bulge) that iscurvature (greatest bulge) that is in the cervical thirdin the cervical third 2) Lingual is convex-concave2) Lingual is convex-concave (s-shaped)(s-shaped) 3) Cervical line proximally is convex3) Cervical line proximally is convex and curves incisallyand curves incisally Concave Convex 1 2 3
  22. 22. Class Traits Of All IncisorsClass Traits Of All Incisors Roots FromRoots From The ProximalThe Proximal Widest at the cervical and taper to aWidest at the cervical and taper to a rounded apexrounded apex Depression in middle third of mesialDepression in middle third of mesial root surface (mandibular also have distalroot surface (mandibular also have distal depression)depression) Mesial ViewDistal View
  23. 23. Class Traits Of All IncisorsClass Traits Of All Incisors Crowns From The IncisalCrowns From The Incisal  A shallow concavity just incisal to the cingulumA 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 curvedA labial contour that is broader and less curved than the lingualthan the lingual lingual fossa incisal ridge
  24. 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 wider6) have crowns and roots relatively wider faciolingually than mesiodistallyfaciolingually than mesiodistally
  25. 25. Arch Traits Of IncisorsArch Traits Of Incisors 7) have contact areas located near the incisal7) 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 root9) have incisal ridges on or lingual to the root axisaxis 10) have wear or attrition only on the incisal10) 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 to11) have root that are longer in proportion to the crownsthe crowns
  26. 26. Particulars ofParticulars of Maxillary CentralMaxillary Central IncisorsIncisors
  27. 27. The Maxillary Central IncisorThe Maxillary Central Incisor Incisal View Distal ViewMesial View Lingual View Facial View
  28. 28. Maxillary Central IncisorMaxillary Central Incisor Labial SurfaceLabial Surface Crown - Shape and SizeCrown - Shape and Size  Crown is the longest of all humanCrown 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 theCrown is narrowest in the cervical thirdcervical third Facial View
  29. 29. Maxillary Central IncisorMaxillary Central Incisor Labial SurfaceLabial Surface Crown - Incisal Proximal AnglesCrown - Incisal Proximal Angles  MesioincisalMesioincisal angle is slightlyangle is slightly rounded and nearly a 90 degreerounded and nearly a 90 degree angleangle  DistoincisalDistoincisal angle is moreangle is more rounded and somewhat obtuserounded and somewhat obtuse  IncisalIncisal edge slopes cervicallyedge slopes cervically towards the distaltowards the distal
  30. 30. MaxillaryMaxillary Central IncisorCentral 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. 31. Maxillary Central IncisorMaxillary Central Incisor Labial SurfaceLabial Surface Crown - ProportionsCrown - Proportions  The root is just slightlyThe root is just slightly longer than the crownlonger than the crown
  32. 32. Maxillary Central IncisorMaxillary Central Incisor Labial SurfaceLabial Surface Root - ShapeRoot - 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 thickCentral incisor root is the only root that is as thick mesiodistally as faciolingually at its cervixmesiodistally as faciolingually at its cervix
  33. 33. MaxillaryMaxillary Central IncisorCentral 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 tothis tooth is a poor risk to support prostheticssupport prosthetics
  34. 34. Maxillary Central IncisorMaxillary Central Incisor Lingual SurfaceLingual Surface Crown - Lingual FossaCrown - Lingual Fossa  Lingual fossa is developed toLingual fossa is developed to different degrees (from shallowdifferent degrees (from shallow to deep)to deep)  Centrals with a deep fossa and prominentCentrals with a deep fossa and prominent marginal ridges are termedmarginal ridges are termed "shovel-shaped incisors""shovel-shaped incisors"
  35. 35. Maxillary Central IncisorMaxillary Central Incisor Lingual SurfaceLingual Surface Crown - CingulumCrown - Cingulum  Usually well developed andUsually well developed and toward the distaltoward 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. 36. Maxillary Central IncisorMaxillary Central Incisor Lingual SurfaceLingual Surface Crown - Marginal RidgesCrown - Marginal Ridges  Marginal ridges areMarginal ridges are prominentprominent  Mesial marginal ridge is longerMesial marginal ridge is longer than distal due to the distalthan distal due to the distal placement of the cingulumplacement of the cingulum
  37. 37. Maxillary Central IncisorMaxillary Central Incisor Lingual SurfaceLingual Surface Crown - Lingual Anatomy VariationsCrown - Lingual Anatomy Variations 1) the fossa may be deep but smooth (no lingual1) 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 border3) may possess a lingual pit near incisal border of cingulum where m + d marginal ridgesof cingulum where m + d marginal ridges meetmeet
  38. 38. Maxillary Central IncisorMaxillary Central Incisor Lingual SurfaceLingual Surface Root - ShapeFrom TheLingualRoot - ShapeFrom TheLingual  Likeall anterior teeth thissurfaceisLikeall anterior teeth thissurfaceis convex and narrower mesiodistallyconvex and narrower mesiodistally than thelabial surfacethan thelabial surface  Somewhat flat on mesial sideSomewhat flat on mesial side approaching thelingualapproaching thelingual  A mesial depression running longitudinalA mesial depression running longitudinal isoften presentisoften present M
  39. 39. Maxillary Central IncisorMaxillary Central Incisor Proximal SurfacesProximal Surfaces Crown - Incisal EdgeCrown - Incisal Edge  Slightly labial to long axis of the rootSlightly labial to long axis of the root (can be mid-root)(can be mid-root)  From distal, the distoincisal edge may beFrom distal, the distoincisal edge may be just lingual to the axis line due to slightjust 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 andto broadly curved in the middle and incisal thirdsincisal thirds Distal View Mesial View
  40. 40. Maxillary Central IncisorMaxillary Central Incisor Proximal SurfacesProximal Surfaces Crown - Cervical Line (CEJ)Crown - Cervical Line (CEJ)  Like all anterior teeth the cervical line curvesLike 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 ViewMesial View
  41. 41. Maxillary Central IncisorMaxillary 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 incisalis 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. 42. Maxillary Central IncisorMaxillary Central Incisor Proximal SurfacesProximal Surfaces Root - OutlineRoot - Outline  Root trunk thick or wide at cervix andRoot trunk thick or wide at cervix and tapers evenly to a rounded apextapers evenly to a rounded apex  Lingual outline nearly straight in cervicalLingual outline nearly straight in cervical third, curving labially in middle andthird, curving labially in middle and apical thirdsapical thirds  Labial outline slightly convexLabial outline slightly convex Distal View Mesial View
  43. 43. Maxillary Central IncisorMaxillary Central Incisor Proximal SurfacesProximal Surfaces Root DepressionRoot Depression  Mesial surface is somewhat flattened with aMesial surface is somewhat flattened with a longitudinal depression in the middle thirdlongitudinal depression in the middle third  Mesial depression is located at junction ofMesial depression is located at junction of middle and lingual thirds of the rootmiddle and lingual thirds of the root
  44. 44. Maxillary Central IncisorMaxillary Central Incisor Proximal SurfacesProximal Surfaces Root DepressionRoot Depression  Distal similar to mesial, exceptDistal similar to mesial, except distal is convex not flatteneddistal is convex not flattened  Distal lacks a depressionDistal lacks a depression
  45. 45. Maxillary Central IncisorMaxillary Central Incisor Incisal AspectIncisal Aspect Crown WidthCrown Width  Crown outline noticeably wider mesiodistally thatCrown outline noticeably wider mesiodistally that faciolinguallyfaciolingually
  46. 46. Maxillary Central IncisorMaxillary Central Incisor Incisal AspectIncisal Aspect Crown OutlineCrown Outline  Crown is roughly triangular, somewhatCrown is roughly triangular, somewhat curved labial outlinecurved labial outline
  47. 47. Maxillary Central IncisorMaxillary Central Incisor Incisal AspectIncisal Aspect Incisal Ridge ContourIncisal Ridge Contour  Ridge 1.5 to 2 mm thick and slightly curvedRidge 1.5 to 2 mm thick and slightly curved from mesial to distalfrom mesial to distal  Distoincisal angle is slightly lingual to theDistoincisal angle is slightly lingual to the mesioincisal anglemesioincisal angle 1.5 - 2mm
  48. 48. Maxillary Central IncisorMaxillary Central Incisor Incisal AspectIncisal Aspect CingulumCingulum  Cingulum is off-center to the distal, with aCingulum is off-center to the distal, with a longer mesial marginal ridgelonger mesial marginal ridge
  49. 49. Maxillary Central IncisorMaxillary 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 andPossess two slight depressions (mesial and distal) on the labial surface in middle anddistal) on the labial surface in middle and incisal thirdsincisal thirds

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