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54777765-Morphology-of-Deciduous-Dentition

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					MORPHOLOGY OF DECIDUOUS TEETH




         Dental Anatomy & Occlusion
                  Dent 202
         Deciduous dentition
              Set traits
   Smaller in size
   Smaller crown height/tooth length ratio
   Greater crown width/height ratio
                 Set traits
   More bulging B & L cervical ridges
      Constricted cervix
   Buccal cervical ridges on deciduous
    molars
      Occlusal aspect: constricted occlusal table
            Deciduous dentition

 Set traits
      Molar roots
        • More slender & relatively longer
        • More bowed & flared outward
        • Shorter root trunk
      Milk-white in color
      Enamel is thinner & pulp chamber is large
             Some class, arch & type traits in permanent
             dentition are applied to deciduous dentition
                  Only new traits will be discussed
           Deciduous incisors
 Eruption
     Mandibular before maxillary incisors
     Central before lateral incisors
 No mamelons, labial grooves or lobes
        Maxillary Central incisor
 The only incisor with MD breadth >
  crown height
 M & esp. D profiles overhang root
  profiles
 No labial grooves, depressions or
  lobes
 Cingulum
      Bulging & more incisally located
      May extend further toward the incisal
       edge – lingual ridge
      Unmarked by pits or grooves
 MRs are clearly evident
      Maxillary Central incisor

 Constricted cervix from
  all aspects
 In proximal surfaces
  CL is more convex
  incisally
 Conical root with
  rounded apex
 Diamond-shaped from
  incisal aspect
        Maxillary lateral incisor
 Much smaller than central
 M & D profiles are more in line
  with root profiles
 Distal incisal angle is more
  rounded
 Labial surface is more convex
  MD
 Lingual fossa is deeper
 MRs more prominent
 CL is similar to that of central
 Rounded from incisal aspect
      Mandibular central incisor
 Bilaterally symmetrical
 90 degree MI & DI angles
 Incisal margin is horizontal
 Prominent cingulum with lingual
  margin extending incisally
 MRs are less marked than those of
  max. incisors
 Lingual fossa is shallower
         Mandibular central incisor
 Labial surface is flat MD
 CL is similar to that of Max. incisors
 Root
      3 times the height of the crown
      Narrow & conical with pointed apex
        Mandibular lateral incisor

   Incisal edge slopes distally
   DI angle is rounded
   D profile is more rounded
   Greater crown height/MD ratio than mand. central
   LL diameter > MD
         Mandibular lateral incisor
 Cingulum, fossa & MRs
  are similar to those of
  mand. Central
 Root
     Narrow & conical
     Apex has D inclination
     D surface has narrow
      vertical depression
             Maxillary canine
 MD width > crown height
 Labial or lingual views: diamond in
  shape
 M & D profiles overhang root’s
 HOCs are much near the cervix than in
  permanent
 Labial & lingual cervical 1/3s are
  markedly convex
 MR prominence is related to race
      Minimal in Caucasians
      Prominent in Mongoloid
 No labial ridge or depressions
Mandibular canine
 Crown height > MD width
 Less cervically converging M & D
  profiles
 Labial or lingual aspects: arrow in
  shape
 No labial ridge or grooves
 HOCs are much near the cervix than
  in permanent
 LL diameter < that of deciduous
  max. canine
 Less prominent cingulum or MRs &
  shallower fossae than in deciduous
  max. canine
          Maxillary       1 st   molar

 Most atypical of all primary or permanent molars
 Intermediate between a premolar & a molar
 Smallest molar in all but BL diameter
          Maxillary 1st molar
 Cusps
     Bicusped (only MB & ML cusp
      are present)
     A small DB cusp is frequently
      present on the D cusp ridge of
      the MB cusp
     Parastyle on the M ridge of MB
      cusp
     DL cusp rarely occurs
     In some cases, a nodular
      tubercle on the L portion of the
      D MR resembles a DL cusp
             Maxillary 1st molar
 Buccal aspect
     MD diameter >> crown height
     M part is higher OC than D
      because it is more projected
      cervically onto the root area
     Marked cervical constriction
     Root
       • Very little root trunk
       • 3 roots strongly divergent
       • L root is midway between the 2 B
         roots
            Maxillary        1 st   molar
 Mesial aspect
     Mesial marginal groove
     B HOC is more cervically
      located than L
     Buccal cervical ridge is more
      prominent in 1st molars than
      in 2nd
     Roots
       • B roots are straight & buccally
         directed
       • L root is banana shaped with
         strong B curved apical 1/3
                 Maxillary            1 st   molar
 Occlusal aspect
      Trapezoidal
      M & D profiles are straight & slightly L convergent
      B cusp > L
      B triangular ridge more prominent than L
      B groove separates DB cusp from MB
      Central pit
      Central groove
      Transverse ridge (oblique ridge?) between B groove & D MR
      H-shaped pit/groove pattern
        • Central groove
        • Triangular supplemental grooves
      M & D marginal grooves
            Maxillary         2 nd   molar
 Morphologically considered
  a model for the permanent
  1st maxillary molar
 Allows prediction of what
  the 1st maxillary molar will
  look like
 This concordance is called
  isomorphy
 Set traits
      Cervical constriction
      Cervical 1/3 bulging
      Little root trunk
      Roots thinner & divergent
             Mandibular              1 st    molar
 Molariform unlike max. 1st
 4-cusped tooth
 Buccal aspect
      2 cusp: MB & DB
      M half > D half
      M half projects more occlusally &
       occupies 2/3s of crown area
      M profile is straight
      D profile is curved and overhanging
      CL inclines downward from D to M
      Roots
        • 2 divergent roots; M & D
        • M is longer
            Mandibular          1 st   molar
 Lingual aspect
     2 cusps: ML & DL
     ML cusp is conical & larger
      than DL
     Outlines of B cusps are
      visible
     CL is more straight &
      horizontal than that of the B
      aspect
               Mandibular           1 st    molar
 Mesial aspect
     Buccal cervical ridge (BCR)
     From MB cusp tip a straight incline to
      BCR
     Transverse ridge connecting MB & ML
     M MR is high & prominent
     Mesial marginal groove separates M MR
      from ML cusp ridge
     CL is convex occlusally & lower on the
      B end
     Root
       • Extremely broad BL (sometimes as
         broad as the crown)
       • Frequently bifid apex
          Mandibular          1 st   molar
 Distal aspect
     All 4 cusps & M root profiles
      are visible
     B profile is less bulging than
      from mesial aspect
     D MR is lower and less
      prominent than M MR
     CL is more straight &
      horizontal than that of M
      aspect
                Mandibular               1 st   molar
 Occlusal aspect
      Without the BCR, it is rectangular
      BL width is grater from M than D
      MB cusp is the largest, followed by
       ML, DB & DL
      M Transverse groove, interrupted by
      Central groove; extends from M pit to
       central pit
      M pit
        • 2 supplemental grooves; of which ML
          crosses M MR
      Central pit
      B& L grooves
      Often a D pit
          Mandibular              2 nd   molar
 Morphologically considered
  a model for the permanent
  1st mandibular molar
 Allows prediction of what
  the 1st mandibular molar
  will look like
 This concordance is called
  isomorphy
 Set traits
     Cervical constriction
     Cervical 1/3 bulging
     Little root trunk
     Roots thinner & divergent
   Deciduous teeth - size & eruption

           Crown    MD crown BL crown   Tooth      Age at
Tooth
           height   diameter diameter   length    eruption
51 or 61   6.0 mm    6.5 mm   5.0 mm    16.0 mm    7.5 mths
52 or 62   5.6 mm    5.1 mm   4.0 mm    15.8 mm     8 mths
81 or 71   5.0 mm    4.2 mm   4.0 mm    14.0 mm    6.5 mths
82 or 72   5.2 mm    4.1 mm   4.0 mm    15.0 mm     7 mths
53 or 63   6.5 mm    7.0 mm   7.0 mm    19.0 mm   16-20 mths
83 or 73   6.0 mm    5.0 mm   4.8 mm    17.0 mm   16-20 mths
54 or 64   5.1 mm    7.3 mm   8.5 mm    15.2 mm   12-16 mths
55 or 65   5.7 mm    8.2 mm   10.0 mm   17.5 mm   20-30 mm
84 or 74   6.0 mm    7.7 mm   7.0 mm    15.8 mm   12-16 mm
85 or 75   5.5 mm    9.9 mm   8.7 mm    18.8 mm   20-30 mm

				
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posted:6/4/2012
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Description: Dentistry inrtoduxtion anatomy occlusion incisor premolar class JUSST detailws