Teeth, Mastication and sinuses 1 Flashcards

1
Q

What are the primary germ layers?

A
  • Ectoderm
  • Mesoderm
  • Endoderm
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2
Q

What specifically does the ectoderm form?

A
  • epidermis of the skin, oral/nasal cavities epithelium, nervous system and sense organs
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3
Q

What specifically does the mesoderm form?

A
  • forms muscles and connective tissue, including bone and components of the circulatory, urinary and genital systems
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4
Q

What specifically does the endoderm form?

A
  • forms mucosal epithelium and glands of respiratory and digestive systems
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5
Q

What does distinct thickening of the oral epithelium form?

A
  • forms dental lamina
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6
Q

What happens after dental lamina is formed?

A
  • underlying mesenchyme condenses
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7
Q

What happens after mesenchyme condenses?

A
  • dental lamina invaginates to form the dental bud
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8
Q

As the dental bud expands what happens?

A
  • it branches to form an enamel organ to surround dental papilla
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9
Q

What does a complex of dental papilla and enamel organ form?

A
  • will form the deciduous tooth
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10
Q

What cells are involved in cell differentiation (in the tooth)

A
  • ameloblasts
  • odontoblasts
  • cementoblasts
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11
Q

What do ameloblasts do?

A
  • form epithelium
  • secrete enamel matrix
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12
Q

What do odontoblasts from?

A
  • from neural crest
  • produce dentine (surrounds tooth pulp - produce tooth root)
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13
Q

What do cementoblasts do?

A
  • from mesenchyme = secretes cementum around root
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14
Q

What do dental buds do?

A
  • give rise to individual teeth
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15
Q

What determines the size, shape, and location of the teeth?

A
  • genetically and independently determined for each tooth
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15
Q

What happens if the bud is destined to form a deciduous tooth?

A
  • An additional bud for its permanent replacement develops superficial and medial to the deciduous bud
  • this is called a lingual extension leading to successional lamina
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16
Q

How is successional lamina formed?

A
  • through the same stages of development of deciduous teeth
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17
Q

What happens if the deciduous tooth is congenitally missing?

A
  • no permanent tooth will develop
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17
Q

When does calcification occur?

A
  • from day 55 gestation to day 20 pp
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18
Q

what does the 1st premolar and the molars not have in some species?

A
  • no deciduous teeth
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19
Q

When should dogs and cats deciduous teeth have fully erupted?

A
  • fully erupted by 2 months old
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19
Q

In dogs and cats when should their deciduous teeth have been replaced by adult teeth?

A
  • 6 months
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20
Q

What is the order of eruption in dogs?

A
  • canines erupt, followed by incisors, then 4th, 3rd, 2nd premolars
  • for total of 28 primary teeth
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21
Q

When should Equine deciduous teeth erupt by?

A
  • 6 months
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21
When should the adult incisors have fully erupted in the horse?
- first incisors = 2.5 yrs - second incisors = 3.5 yrs - third incisors = 4.5 yrs
22
Describe the eruption of the temporary tooth?
- eruption after crown is fully formed, but before completion formation of the root - eruption provides space for completion of root - epithelial covering is continuous with gums upon eruption - wear removes epithelium
22
Describe how the permanent tooth replaces the deciduous tooth
- migrates into socket of temporary tooth - pressure increases = resorption of temporary tooth - tooth root loosens and shreds = permanent tooth replaces
23
What is enamel?
- from ameloblasts - hardest material in body - between dentin and cementum - no healing
24
What is dentine?
- from odontonblasts - with enamel = outer two layers - form during crown stage
24
What is a periodontal ligament?
- specialised connective tissue - inserts into root cementum and alveolar - holds teeth in sprung suspension - also has sensory function - teeth in contact (enamel insert)
24
What is cementum?
- from cementoblats within root - thickest at root apex - gives attachment to periodontal ligament
24
what is a brachydont?
- low-crowned teeth, seen in humans dogs, cats, pigs - tooth consists crown above gingiva, constricted neck at the gum line and a root embedded in the jawbone - enamel covers entire body of the tooth, but not root
24
What is a hypsodont?
- high- crowned teeth, seen in horses, cows - teeth extend usually far below the gumline - lots of extra material for wear - crown continues continues to erupt, in response to age and wear
24
What is radicular?
- the root closes after eruption (horses, cows)
24
What is aradicular?
- open-rooted, doesn't close, tooth grows continually through life = elodont (rabbits, guinea pigs, chinchillas and degus)
25
What is heterodonty?
- teeth differentiated into incisors, canines and molar
26
What is homodonty?
- teeth all, the same form
27
What is the contact surface of teeth?
- where adjacent teeth touch
28
What is the occlusal of teeth?
- where opposing teeth touch
29
Describe incisors 3/3
- tricuspid in upper jaw - bi-loped in lower jaw - smaller rostrally - single root
30
Describe premolars 4/4
- irregular, closely-spaced - complex and larger caudally - discontinuous cutting crown
31
Describe canine 1/1
- large curved laterally compressed - root longer than crown - single root
32
Describe molars 2/3
- broader than premolars - number of cusps - similar in all breeds
33
What happens to dogs gums with age?
- gums recede with age which exposes the non-enamel coated surface
34
What's is different in brachycephalic breeds teeth?
- do not possess all canine cheek teeth - often have teeth with fused roots
35
What are carnassial teeth?
- last upper premolar, paired with lower molar - laterally flattened, provides shearing action for cutting food - characteristic of carnivore dentition
36
What type of teeth do horses have?
- hypsodont - teeth continually erupt - erupted crown and un-erupted reserve crown
37
Describe horse incisors 3/3
- high crowns, folded enamel surfaces - root converge - useful for aging
38
Describe canines 1/1 in horses?
- sometimes present, uncommon in females - erupt 4-6 years of age
39
What are wolf teeth?
- sometimes present - vestigial premolars, sit against PM1 - may interfere with bit
40
Describe horse premolars PM 3-4/3
- 4 upper if wolf tooth - continuous with molars - very high wear, erupt continuously - upper wider than lower
41
Describe horse molars M3/3
- continuous with PM - very high wear, erupt continuously - upper wider than lower
42
Horse - what is the infundibulum?
- infolding of enamel
43
Horse - what is the cup? when does it wear away and what happens to it?
- centre of infundibulum - Disappears at 8yrs and leaves enamel spot = deepest part of infundibulum
44
Horse - what is the dental star?
- corresponds with pulp cavity - appears at 8 yrs in first incisor - appears as a line and then changes to a large round spot as occlusal surface is worn further
45
Describe rodent dentition
- no canines - very large diastema - no pulp cavity = thus teeth insensitive
46
Describe pig dentation
- incisors project rostrally - canine present as continuously erupting tusks for digging and tearing - PM have rounded cups for crushing and grinding
47
Describe cattle dentition
- no upper canines = replaced by hard fibrous dental pad - incisors do not erupt continuously - lower canine teeth very similar to incisors - PM increased size caudally * very similar to horse * do not erupt continuously * very pronounced enamel ridges
48
What reptiles don't have teeth?
- turtle and tortoise
49
What type of teeth do reptiles have except venomus snakes and crocodilians?
- homodont
50
What are the variations in anchors in reptile teeth?
- very loose arrangement (accordant) - stronger attachment (pleurodont) = most common - strongest (thecodont) - in sockets within jaw