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Flashcards in Oral Cavity Deck (310)
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61

What are Striae of Retzius, surface perikymata and cross-striations?

Striae of Retzius are growth lines representing ~7 days in between are cross-striations showing daily growth
Cross-striations grow along enamel prism perpendicular to long axis of rod
Surface perikymata are external manifestations of Retzius lines when they overlap each other forming shallow grooves

62

What pattern of enamel do humans have?

Pattern 3 - keyhole
Thick head (towards crown) and narrow tail (towards neck)

63

How many ameloblasts contribute to 1 keyhole prism

4: 1 in head and 3 in tail

64

Describe the path of enamel prisms within enamel

Parallel to each other and at oblique angle at origin (EDJ) and termination (surface)

65

What is different about surface enamel?

Aprismatic - structureless
Crystallites aligned parallel to each other and perp. to surface
Highly mineralised

66

What are Tomes processes?

Picket fence projection caused by ameloblasts moving away from new enamel, absent in final stage of enamel deposition

67

What are Hunter Schreger bands?

Optical effect of light and dark 'bands' of enamel caused by bundles crossing each other in layers at right angles as travel from EDJ

68

What is the purpose of enamel bundles overlapping?

Strengthen structure
Prevent cracks
Resist fractures

69

What are the 3 weaknesses present at the EDJ?

Tufts: hypo-calcified enamel rods, only at EDJ
Lamellae: hypo-calcified enamel rods, structural fault from EDJ to surface
Spindle: dentine tubule ends trapped in enamel

70

What is the clinical importance of enamel?

Prevent demineralisation
Promote remineralisation
Restore cavitated enamel
Diagnose and treat developmental enamel malformations

71

What are the functions of incisors?

Cutting, scooping, picking up objects, grooming

72

What are the functions of canines?

Holding prey, display, puncture, slashing and tearing while fighting

73

What are the functions of premolars?

Holding, carrying, breaking food into small pieces

74

What are the functions of molars?

Shearing, crushing, grinding food into small pieces

75

How are teeth charted?

Maxillary right central incisor = UR1 OR 11

76

What are the 5 planes of ant. and post. teeth?

Ant: mesial, labial, distal, lingual, incisor edge
Post: mesial, buccal, distal, lingual, occlusal

77

What is diphyodont?

2 successive sets of teeth

78

What is thecodont?

Teeth with roots firmly fixed in socket with ligaments

79

What is heterodont?

Different tooth types

80

What are mamelons?

Ridges on incisal edge of new teeth
Rapidly worn down

81

What are cusps?

Major elevations on masticatory surface of 3s and post. teeth

82

What are ridges?

Variable, linear elevations on crown of tooth

83

What tooth has the longest root?

U3s

84

What teeth are single rooted?

U: 1, 2, 3, 5s
L: 1, 2, 3, 4, 5s

85

What teeth have 2 roots?

U: 4s
L: 6, 7, 8s

86

What teeth have 3 roots?

U: 6, 7, 8s

87

In what direction to root usually curve?

Distally

88

What are the main differences between maxillary and mandibular teeth?

Incisors: max long, well-rounded roots; man small, flattened roots
Canines: max bulbous on M and D aspect; man flattened M
Premolars: rectangular O outline; circular O outline
Molars: square/triangular O outline, 2B, 1P root; rectangular O outline, 1M, 1D root

89

What are the distinguishing factors between maxillary teeth?

Incisors: 1 much larger than 2
Premolars: 4 has B and L roots, canine fossa and developmental groove; 5 single root and no fossa or groove
Molars: 6 4 cusps, spaced roots, 7/8 smaller, roots may be fused

90

What are the main differences between mandibular teeth?

Incisors: 2 larger than 1, 2 crown appears rotated on root
Premolars: 4 v small L cusp, ML developmental groove; 5 L and B cusp of equal height
Molars: 6 3B, 2L cusps, 7 4 cusps, 8 irregular crown arrangement, roots may be fused