Maxillary Lateral and Mandibular Incisors
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Maxillary Lateral and Mandibular Incisors

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Maxillary Lateral and Mandibular Incisors Maxillary Lateral and Mandibular Incisors Presentation Transcript

  • Anatomy Of The Maxillary Lateral Incisors And Mandibular Central And Lateral Incisors Howard Chi D.M.D.
  • Learning Objectives • Anatomy of the maxillary lateral incisors • Anatomy of the mandibular central incisors • Anatomy of the mandibular lateral incisors
  • Anatomy of the Maxillary Lateral Incisors
  • Morphology Of The Crown From The Labial • Similar to that of a central incisor • More convex, or less flat mesiodistally
  • Morphology Of The Crown From The Labial • Appears more oblong cervicoincisally • Mamelons and labial depression less prominent than central
  • Crown Size And Shape From The Labial • Narrower by about 2mm from that of a central incisor • This yields a long, slender look • Outline is less symmetrical than a central incisor + 2 mm
  • Crown Incisal Proximal Angles From The Labial • Both the mesio and distoincisal angle are more rounded than central incisor • Mesioincisal angle is more acute than central incisor
  • Crown Incisal Proximal Angles From The Labial • Distoincisal is wider and more obtuse than maxillary central incisor • Incisal angle slope more cervically towards the distal on a maxillary lateral
  • Crown Contact Areas From The Labial • Mesial contact is in the incisal near the junction of the incisal and middle thirds • Distal contact is at the junction of the incisal and middle thirds
  • Tooth Proportions From The Labial • The root is narrower, but can be longer than that of a maxillary central incisor • This makes the root longer in proportion to the crown than a central incisor
  • Root From The Labial • The root tapers evenly toward the rounded apex • The root commonly curves distally
  • Lingual Fossa Of The Crown • Is smaller in area than a central incisor • More pronounced than a central incisor • May appear either shallow or deep
  • Cingulum Of A Maxillary Lateral Incisor • Narrower than a central incisor • Almost centered on the long axis of the root
  • Marginal Ridges Of A Maxillary Lateral Incisor • Developed to different degrees on different teeth • May be prominent or inconspicuous • Can be worn from attrition
  • Marginal Ridges Of A Maxillary Lateral Incisor • Mesial marginal ridge outline is nearly straight • Distal marginal ridge is shorter and curved incisocervically • Shortness of the distal marginal ridge is due to slope of the incisal ridge
  • Lingual Anatomy Of The Crown • May possess lingual accessory ridges near cingulum • Fewer and less common than the central incisor's • A lingual pit is frequently present and often restored to arrest decay
  • Root From The Lingual • Narrower on the lingual side than the labial • Surface root depression present on the mesial
  • Incisal Ridge From The Proximal Aspect • Usually 1.0 to 1.5 mm thick and labial to the root axis • Sloped cervically toward the lingual from its most labial portion
  • Cervical Line From the Proximal Aspect • Curvature is deep on the mesial (2.5mm) • More curved on mesial than on the distalMesial #7 Distal #7 2.5mm
  • Root Outline From The Mesial • Appears blunt from the proximal • Root ratio is slightly greater than the central incisor Mesial #7
  • Root Depressions From The Proximal • Similar to the central, found on the mesial mid-root Mesial #7 Distal #7
  • Root Depressions From The Proximal • Mesial surface is the least convex of the four sides (another way of saying its the flattest) Mesial #7 Distal #7
  • Crown Proportion From The Incisal Aspect The mesiodistal measurement is greater than the faciolingual • On some this dimension may be the same
  • Crown Outline From The Incisal • Is less symmetrical, but in general, resembles the central • It is narrower mesiodistally than the central • Cingulum is nearly centered mesiodistally
  • Incisal Ridge Contour • Incisal ridge straighter mesiodistally than a central incisor
  • Cingulum From An Incisal Aspect • Centered mesiodistally and noticeably more convex than the central incisor
  • Labial Contour From The Incisal Aspect • Noticeably more convex than the maxillary central incisor (type trait)
  • Anatomy Of The Mandibular Central Incisors
  • Mandibular Central Incisor From The Labial Aspect • The surface of the crown is nearly smooth • Can have two shallow depressions in the incisal third (similar to maxillary, but far less pronounced)
  • • Mamelons are usually present on newly emerged teeth • Quickly worn off with contact with maxillary teeth (if not, suspect malocclusion) Mandibular Central Incisor From The Labial Aspect
  • • Crown is five-eighths the width of a maxillary central • Crown is proportionally narrow in comparison to its length Mandibular Central Incisor From The Labial Aspect
  • • The tooth is so symmetrical it is difficult to tell left from right • Only difference is the mesial cervical line curve more incisally than the distal Mandibular Central Incisor From The Labial Aspect
  • • The mesial and distal outlines is straight in the incisal third • The crown tapers to the cervical third • Contacts are well within the incisal one third Mandibular Central Incisor From The Labial Aspect
  • • Labial surface is convex mesiodistally in the cervical third • Mesio and distoincisal angle is nearly 90 degrees Mandibular Central Incisor From The Labial Aspect
  • • Distoincisal angle may be more rounded (slightly) than the mesioincisal angle Mandibular Central Incisor From The Labial Aspect
  • • Mesial and distal contact areas are within the incisal third at roughly the same height (type trait) • Root longer than crown proportionally compared to the maxillary incisors Mandibular Central Incisor From The Labial Aspect
  • • The root is narrow mesiodistally, but wide faciolingually • The root is tapered evenly on both sides from the cervical line to the apex, root tip may curve to the distal Mandibular Central Incisor From The Labial Aspect
  • Mandibular Central Incisor From The Lingual Aspect • The outline is much more symmetrical than all other incisors • The lingual crown surface is smooth and shallow with a slight concavity in the middle and incisal thirds
  • • The cingulum is convex, small and centered • The marginal ridges and lingual fossa are scarcely discernible, if at all • No grooves, pits or accessory ridges are present Mandibular Central Incisor From The Lingual Aspect
  • Mandibular Central Incisor From The Proximal Aspect • The incisal edge is on or lingual to the long axis of the root • Mesial cervical line (CEJ) extends 2mm incisally • Distal cervical line extends .4 mm less than the mesial
  • • The facial height of contour is located in the cervical third • The lingual height of contour is located on the cingulum, within the cervical third Mandibular Central Incisor From The Proximal Aspect
  • • The labial contour is so slightly curved that it often appears flat • The lingual contour is convex on the cingulum, concave in the fossa and flat towards the incisal Mandibular Central Incisor From The Proximal Aspect
  • • The facial and lingual sides of the root are nearly straight from the cervical line to the middle third • The root then tapers to its apex Mandibular Central Incisor From The Proximal Aspect
  • • Roots are flat mesiodistally compared to their maxillary counterparts • Roots are wider faciolingually than mesiodistally by approximately 2mm Mandibular Central Incisor From The Proximal Aspect
  • Root depressions can be found on both the mesial and distal aspects in the middle third of the roots Mandibular Central Incisor From The Proximal Aspect #25 Mesial #25 Distal
  • Mandibular Central Incisor From The Incisal Aspect • The labiolingual measurement of the crown is greater than the mesiodistal measurement (this is quite different from the maxillary counterparts)
  • • The labial and lingual height of contour is centrally located • The incisal edge runs in a straight line mesiodistally and is roughly 2mm thick Mandibular Central Incisor From The Incisal Aspect
  • • The cingulum is centered, smooth and has a convex outline • The labial surface is slighly convex in the incisal one third and noticeably convex in the cervical third Mandibular Central Incisor From The Incisal Aspect
  • Anatomy Of The Mandibular Lateral Incisors
  • Mandibular Lateral Incisor From The Facial View • Similar to the central, smooth and minimal depressions • Labial surface is convex mesiodistally, more in the cervical third and less in the incisal third
  • • Crown is tilted distally on the root, giving a bent appearance • This makes the distal outline of the crown shorter than the mesial aspect Mandibular Lateral Incisor From The Facial View
  • • The distoincisal angle is noticeably more rounded than the mesioincisal angle • This aids in telling left from right Mandibular Lateral Incisor From The Facial View
  • • The mesial contact is in the incisal third, near the incisal edge • The distal contact is in the incisal third, but cervical to the level of the mesial contact Mandibular Lateral Incisor From The Facial View
  • • Crown is narrower with respect to its length • Root is narrow mesiodistally, tapering gradually from the cervical line to the apex. It may have a distal curvature Mandibular Lateral Incisor From The Facial View
  • Mandibular Lateral Incisor From The Lingual View • Similar to the central, but not bilaterally symmetrical • Crown is tilted distally, and tapers lingually in the middle and cervical thirds
  • • The cingulum is slightly distal to the long axis of the root, similar to the maxillary central • This makes the mesial marginal ridge longer than the distal Mandibular Lateral Incisor From The Lingual View
  • • Marginal ridges and lingual fossa are not conspicuous and generally smooth • The root is narrower lingually than facially Mandibular Lateral Incisor From The Lingual View
  • Mandibular Lateral Incisor From The Proximal View • The incisal edge is on or lingual to the long axis of the root • From the mesial a distolingual twist of the incisal edge places the distal portion more lingual Central Lateral
  • • The C.E.J. curves 2 mm incisally on the mesial aspect • The C.E.J. curve 1.4 mm incisally on the distal aspect Mandibular Lateral Incisor From The Proximal View
  • • The facial and lingual heights of contour are in the cervical third • The labial outline is nearly flat in the middle and incisal thirds Mandibular Lateral Incisor From The Proximal View
  • • The root is straight from cervical to middle third • The distal portion of the root contains a depression that is more distinct than the mesial Mandibular Lateral Incisor From The Proximal View
  • Mandibular Lateral Incisor From The Incisal View • The crown is broader faciolingually than mesiodistally • Not bilaterally symmetrical, distal is twisted
  • • The cingulum is off center to the distal with a barely dicernible lingual fossa • The labial outline is slightly convex in the incisal one third Mandibular Lateral Incisor From The Incisal View