3. Tooth Morphology Flashcards

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1
Q

How to compare permanent and primary teeth?

A
  • smaller in size for each tooth category
  • more bulbous
  • more proteins, less mineral so whiter (perm more ivory since transparent enamel shows underlying dentine)
  • enamel is thinner and less hard - physically softer - wear/attition happens faster
  • less crowded - less interproximal caries
  • roots thinner and shorter - molar roots more divergent
  • pulp cavities large with thinner dentine - pulp horns higher and close to amelodentinal junction
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2
Q

Primary anterior teeth are … than permanent successors due to what?

A
  • plumper
  • transverse diameter of crown is greater relative to length
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3
Q

Features of the upper right primary central incisor

A
  • similar structure to permanent
  • but smaller
  • low rounded labial cingulum beside cervical line
  • transverse diameter of crown equal to vertical diameter
  • lower palatal cingulum and marginal ridges with shallow palatal fossa
  • conical root slightly compressed in labio-palatal direction with single root canal (while root often slightly compressed in mesio-distal direction in upper)
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4
Q

Upper primary lateral incisors

A
  • similar to upper but less variable, rounded labial cingulum and low lingual cingulum
  • resembles upper primary central but smaller and mesial angle more acute and distal angle more rounded
  • root is similar to upper primary centrals
  • may be difficult to distinguish upper primary lateral from lower of opposite side as both have rounded roots (unlike lower perm)
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5
Q

Lower primary central incisors

A
  • centrals are symmetrical and similar to lower perm
  • but crown is shorter than perm and has low labial cingulum
  • roots are shorter and rounded unlike perm
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6
Q

Lower primary lateral incisors

A
  • asymmetrical and similar to lower perm but
  • wider and low labial cingulum
  • root is rounded (unlike perm)
  • if distal incisal angle is markedly rounded, may closely resemble upper primary of opposite side as both have rounded roots
  • root is longer than that of lower primary centrals
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7
Q

Upper primary canines

A
  • similar to perm
  • symmetrical teeth so hard to see what side
  • much fatter
  • if crown is symmetrical cusp tip often displaced distally (unlike perm)
  • low labial cingulum - joins labial ridge (like perm). Lingual surface has low marginal ridges, palatal ridge separates two shallow palatal fossae
  • root comparatively long, triangular in cross section, single root canal
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8
Q

Lower primary canines

A
  • more slender than upper and asymmetrical crown as cusp tip displaced mesially (like perm, unlike upper)
  • mesial slope shorter and more vertical than distal slope
  • labial cingulum and root/root canal similar to upper primary
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9
Q

Characteristics of both upper and lower primary 1st molars

A
  • crown irregular quadrilateral
  • buccal side is wider and palatal is shorter - both are parallel to each other
  • mesial surface slopes distally as it passes towards palatal
  • buccal cingulum extended mesially to form molar tubercle (on mesio-buccal corner)
  • convergence of tip of buccal/palatal cusps towards the midline of crown - reducing occlusal area
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10
Q

Cusps and roots of upper primary 1st molar

A
  • 4 cusps (2 buccal, 2 palatal)
  • mesio-buccal cusp is largest
  • 3 roots (2 buccal, 1 palatal - largest) with 3 root canals similar to perm
  • disto-buccal and palatal roots partially fused
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11
Q

Lower primary first molar

A
  • crown elongated mesio-distally (compared to upper) - has molar tubercle
  • mainly 4 cusps (2 buccal, 2 lingual) where mesial are bigger than distal and buccal bigger than lingual
  • ridge of enamel can connect mesial cusps, called transverse ridge and divides central fissure into distal fissure and mesial pit
  • like lower perm, 2 roots (mesial and distal) with 2 root canals. mesial root often grooved and its canals may divide into 2
  • 2 roots diiverge to accomodate developing lower 1st premolar. Tips of roots sometimes embrace tooth germ
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12
Q

Lower primary second molar

A
  • similar to lower 1st but 5 cusps (3 buccal, 2 lingual)
  • smaller, narrower, whiter and widely diverging roots
  • buccal cingulum more pronounced than 1st and mesial/distal surfaces more convex
  • 2 roots (mesial and distal) - mesial root may be grooved dividing root canal in 2
  • roots always widely divergent but tips may curve back towards one another at apex embracing tooth germ
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13
Q

Primary 1st molars have … and then primary 2nd molars resemble …

A
  • tubercle molar on mesio-buccal corner
  • resemble first molars
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