Introduction to Dental Anatomy

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Introduction to Dental Anatomy

• Dental Anatomy
• Dr. Firas Alsoleihat, BDS, PhD
• Department of Conservative Dentistry

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Introduction

• Human dentition is diphyodont
• 2 sets of dentitions
• Primary/deciduous
• 20 teeth in total
• Incisors/canines/molars
• Smaller size
• Secondary/permanent
• 32 teeth in total
• Incisors/canines/premolars/molars
• Bigger size

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Deciduous permanent dentitions

• Why do we have to have 2 sets of teeth?

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Why 2 sets of dentitions?

• The jaws have to accommodate the increased number
  of permanent teeth and their bigger size

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Dental formula

• I for incisors
• C for Canines
• PM for premolars
• M for molars
• Deciduous teeth are indicated by the letter D
  before the initial

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Human dental formula

• Deciduous teeth
• DI 2/2 DC 1/1 DM 2/2 10
• Permanent teeth
• I 2/2 C 1/1 PM 2/2 M 3/3 16
• The numbers following the letter refer to the
  number of teeth of each type in the upper then
  the lower dentition for one side only

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Quadrants

• Tooth-bearing region of the jaw can be divided
  into 4 quadrants
• Right maxillary (1 or 5)
• Left maxillary (2 or 6)
• Left mandibular (3 or 7)
• Right mandibular (4 or 8)
• Quadrants in permanent dentition have the
  numbers 1 - 4 and in deciduous have the numbers 5
  - 8

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Quadrants
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Teeth order

• Each tooth in a quadrant takes a letter (A E
  for deciduous) or a number (1 8 for permanent)
  indicating its order when counting from the
  midline

8 7 6 5 4 3 2 1
1 2 3 4 5 6 7 8
E D C B A
A B C D E
8 7 6 5 4 3 2 1
1 2 3 4 5 6 7 8
E D C B A
A B C D E
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Dental nomenclature

• By words
• Set
• Deciduous or permanent
• Jaw
• Maxillary or mandibular
• Class
• Incisor/canine/premolar/molar
• Order within a class
• Central or lateral
• First/second/third
• Side
• Right or left
• By numbers, letters and/or symbols
• Palmer notation system
• Universal numbering system
• FDI numbering system

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Palmer/Zsigmondy notation system

• American Dental Association in 1947
• Tooth is represented by a number 1 8
  (permanent) or a letter A E (deciduous)
• Two lines indicates which quadrant the tooth
  belongs to
• a horizontal representing the occlusal plane and
• a vertical representing the midline
• Examples
• Maxillary right central incisor
• Mandibular left second deciduous molar

E D C B A
A B C D E
8 7 6 5 4 3 2 1
1 2 3 4 5 6 7 8
E D C B A
A B C D E
8 7 6 5 4 3 2 1
1 2 3 4 5 6 7 8
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Universal numbering system

• Palmer difficulty in keyboard typing
• ADA adopted the universal system in 1968
• Uppercase letters for deciduous teeth
• Consecutive from A to T
• Following a clockwise order from maxillary right
  second molar to mandibular right second molar
• Numbers for permanent teeth
• Consecutive from 1 to 32
• Following a clockwise order from maxillary right
  third molar to mandibular right third molar

A B C D E
F G H I J
1 2 3 4 5 6 7 8
9 10 11 12 13 14 15 16
T S R Q P
O N M L K
32 31 30 29 28 27 26 25
24 23 22 21 20 19 18 17
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FDI numbering system

• Proposed by FDI adopted by WHO
• Each tooth is allocated a two-digit number the
  left designates the quadrant and the right
  designates the tooth order
• Examples
• Mandibular right permanent canine 43
• Maxillary left deciduous lateral incisor 62

55 54 53 52 51
61 62 63 64 65
18 17 16 15 14 13 12 11
21 22 23 24 25 26 27 28
85 84 83 82 81
71 72 73 74 75
48 47 46 45 44 43 42 41
31 32 33 34 35 36 37 38
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Types of dentitions

• Diphyodont. Most mammals--humans
  included--typically develope and erupt into their
  jaws two generations of teeth. The term literally
  means "two generations of teeth."
• Monophyodont. Some mammals--such as the manatee,
  seals, and walruses have only a single generation
  of teeth.

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• Polyphyodont. Most reptiles and fishes develope a
  lifetime of generations of successional
  teeth--Such teeth have a brief functional life
  and are anatomically simple in design.
• Homodont. In many vertebrates, all of the teeth
  in the jaw are alike. They differ from each other
  only in size. The alligator is an example of
  homodontism.

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• Heterodont. Most mammals, humans included,
  develope distinctive classes of teeth that are
  regionally specialized. We will discuss classes
  of teeth in the next unit.
• Anodontia is the developmental absence of teeth.
  Among mammals, the whalebone whale and the
  anteater are toothless their ancestors had
  teeth. In humans, anodontia is a pathological
  condition. Partial anodontia is one or a few
  teeth missing.