Pediatric Primary Tooth Anatomy- Dr. Webb

Question 1

Life Cycle of the tooth: Stages

Answer 1

• Initiation
• Proliferation
• Histodifferentiation
• Morphodifferentiation
• Apposition
• Calcification
• Eruption

Question 2

Initiation stage

Answer 2

• Aka Bud Stage
• 6th week of embryo
• epithelial thickening that becomes dental lamina
• Permanent Molars and primary teeth arise from dental lamina
• Permanent Incisors, canines, and premolars develop from their primary predecessors

Question 3

Congenital Absence of a tooth

Answer 3

• Lack of initiation or arrest in the proliferation of cells

Question 4

Supernumerary teeth

Answer 4

Continued budding of teeth

Question 5

Proliferation

Answer 5

• Aka Cap Stage
• unequal growth of different parts of the bud
• Peripheral cells of the cap form the outer and inner enamel epithelium

Question 6

Dificiency in proliferation results in

Answer 6

Fewer than normal number of teeth

Question 7

Excessive proliferation results in

Answer 7

cysts, odontomas or supernumery tooth

Question 8

Histodifferentiation

Answer 8

• Aka Bell stage (& morphodifferentiation)
• dental papilla cells differentiate into odontoblasts
• inner enamel epithelium differentiate into ameloblasts

Question 9

Disturbances in histodifferentation results in

Answer 9

• Abnormal structure of dentin or enamel
  
  • amelogenesis imperfecta=most common

Question 10

Morphodifferentation stage

Answer 10

• Aka Bell stage (&histodifferentiation)
• Formative cells arranged to form the tooth
• Boundary between inner enamel epithelium and odontoblast become DEJ

Question 11

disturbances in morphdifferentation stage results in

Answer 11

• Abnormal forms and sizes of teeth
  
  • peg teeth (Peg Laterals)
  • Microdontia
  • Macrodontia

Question 12

Apposition Stage

Answer 12

• Ameloblasts and odontoblasts secrete tissue matrix
  
  • Begin their work at sites called growth centers

Question 13

Apposition stage disturbances result in

Answer 13

• Systemic disturbance or local trauma that injures the ameloblasts during enamel formation or arrest in matrix apposition results in ENAMEL hyperplasia

Question 14

Calcification Stage

Answer 14

• Precipitation of calcium in the matrix
• Further precipitation of original nidus with concentric laminations
• fusion of individual calcopherites
• 11th week in utero=first indication
  
  • 14th week=Primary Central Incisors
  • 15.5 week=Primary 1st Molars
  • 16th week= Primary Lateral Incisors
  • 17th week=Primary Canines
  • 18th week= Primary 2nd molar
  • 28th week=Permanent 1st molar

Question 15

Calcification stage disturbance

Answer 15

• Lack of fusino of calcospherites in dentin=Interglobular dentin

Question 16

Calcification stage: Anterior Primary Teeth, Posterior Primary teeth, Permanent molar

Answer 16

• 11th week in utero=earliest indication
  
  • 14th week=Primary Cental Incisor
  • 15.5 week=first primary molar
  • 16th week= Primary Lateral incisor
  • 17th week=Primary Canine
  • 18th week=Second Primary molar
  • 28th week= first permanent molar

Question 17

How many primary teeth are their?

Answer 17

• 20 teeth
  
  • 8 incisors
  • 4 canines
  • 8 molars
• Missing Premolars!

Question 18

Primary teeth are also called

Answer 18

1. Temporary Teeth
2. Milk Teeth
3. Baby Teeth

Question 19

Eruption Sequence

Answer 19

• Mandibular teeth before maxillary teeth
• Teeth erupt in pairs (Left and Right
• Permanent teeth erupt earlier in girls than boys
• Primary Teeth
  
  • Incisors-6 month old
  • cuspids-18 month old (Canine)
  • Molars- 12 and 24 months

Question 20

Primary Vs permanent Dentition

Answer 20

• Tooth
  
  • Thinner Enamel
    
    • Primary=0.5-1mm
    • Permanent= 1-2mm
  • Ligher in color (whiter)
  • Apical enamel rods curve toward incisal/occlusal
  • Smaller in all dimensions
    
    • except mandibular molars are wider M-D than the premolars
  • Wider M-D than their height
    
    • short and squatty
  • B-L smaller bc it converges toward the occlusal
  • Cervial Ridges (Height of contour) more pronounced
• Roots
  
  • No Root Trunk
  • long, flared and thin
• Pulp Chamber
  
  • Large compared to size of the tooth
  • closer to tooth’s surface
• Contact Area
  
  • Broad and flat (Vs point contact)
  • more gingival

Question 21

Primary Dentitioin: Pulp chambers and Pulp Canal

Answer 21

• Crown widths in all direction is large compared to root trunks and cervices
  
  • roots narrow and long
  • molar roots thin and flare
• Dentin thickness b/w pulp chamber and enamel is limited
  
  • especially in lower second primary molar
• High Pulp Horns
• Large Pulp Chambers

Question 22

Primary Maxillary Cental Incisor

Answer 22

• Crown
  
  • Wide> taller
  • No developemental lines
    
    • smooth labial surface
  • straight incisal edge
  • Lingual Surface
    
    • distinct cingulum
    • well developed marginal ridge
• Root:
  
  • Cone shaped
  • tapered sides

Question 23

Primary Maxillary Lateral Incisor

Answer 23

• Crown Outline similar to cental incisor,
  
  • crown is smaller in all dimensions
    
    • Length>width
• Root outline similar to central incisor
  
  • but longer when compared to crown

Question 24

Primary Maxillary Canine

Answer 24

• Crown:
  
  • more constricted at cervical region than incisors
  • incisal and distal surfaces=more convex
• Sharp Cusp, well developed
  
  • straight incisal edge-incisors
• Root:
  
  • Long, slender, tapering root
  • more than 2x length of crown
  • curves distally-apical to middle 1/3

Question 25

Incisal View of Maxillary Primary Anteriors

Answer 25

• Incisal edge:
  
  • straight
  • centered over crown
• Labial Surface
  
  • is broader and smoother than lingual surve
• Lingual surface
  
  • tapers toward cingulum

Question 27

Primary Maxillary First Molar

Answer 27

• Crown:
  
  • Largest dimension: M-D Contact area
    
    • crown converges toward crvical region
  • ML cusp:
    
    • largest and sharpest
  • DL cusp=not well defined
    
    • small
    • rounded
  • Buccal Surface
    
    • smooth
    • little evidence of developement grooves
• Roots:
  
  • long, slender
  • widely spread/Flared

Question 28

Primary Maxillary Second Molar

Answer 28

Resembles maxillary 1st molar

• 2 well defined buccal cusps
  
  • developmental groove between them
• Crown is larger than first primary molar

Question 29

Primary Mandibular Central Incisor

Answer 29

• Crown:
  
  • Smaller than maxillary central incisor
    
    • F-L measurement=1mm less
  • Buccal
    
    • flat surface
    • development grooves
  • Lingual
    
    • marginal ridge and cingulum
  • Straight incisal edge
    
    • bisects crown labiolingually
• Root
  
  • twice as long as the crown

Question 30

Primary Mandibular Lateral Incisor

Answer 30

• Crown outline similar to central incisor
  
  • except larger in all dimensions except F-L
• Lingual surface
  
  • greater concavity b/w marginal ridges
• Incisal edge
  
  • slopes toward distal

Question 31

Primary Mandibular Canine

Answer 31

• Similar to maxillary canine except
  
  • shorter crown and roots
  • smaller F-L

Question 32

Primary Mandibular First Molar

Answer 32

• Does not resemble any permanent teeth

Question 33

Primary Mandibular Second Molar

Answer 33

• resembles mandibular first permanent molar
  
  • but smaller