Flashcards in Oral Cavity Deck (310)
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
What pattern of enamel do humans have?
Pattern 3 - keyhole
Thick head (towards crown) and narrow tail (towards neck)
How many ameloblasts contribute to 1 keyhole prism
4: 1 in head and 3 in tail
Describe the path of enamel prisms within enamel
Parallel to each other and at oblique angle at origin (EDJ) and termination (surface)
What is different about surface enamel?
Aprismatic - structureless
Crystallites aligned parallel to each other and perp. to surface
What are Tomes processes?
Picket fence projection caused by ameloblasts moving away from new enamel, absent in final stage of enamel deposition
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
What is the purpose of enamel bundles overlapping?
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
What is the clinical importance of enamel?
Restore cavitated enamel
Diagnose and treat developmental enamel malformations
What are the functions of incisors?
Cutting, scooping, picking up objects, grooming
What are the functions of canines?
Holding prey, display, puncture, slashing and tearing while fighting
What are the functions of premolars?
Holding, carrying, breaking food into small pieces
What are the functions of molars?
Shearing, crushing, grinding food into small pieces
How are teeth charted?
Maxillary right central incisor = UR1 OR 11
What are the 5 planes of ant. and post. teeth?
Ant: mesial, labial, distal, lingual, incisor edge
Post: mesial, buccal, distal, lingual, occlusal
What is diphyodont?
2 successive sets of teeth
What is thecodont?
Teeth with roots firmly fixed in socket with ligaments
What is heterodont?
Different tooth types
What are mamelons?
Ridges on incisal edge of new teeth
Rapidly worn down
What are cusps?
Major elevations on masticatory surface of 3s and post. teeth
What are ridges?
Variable, linear elevations on crown of tooth
What tooth has the longest root?
What teeth are single rooted?
U: 1, 2, 3, 5s
L: 1, 2, 3, 4, 5s
What teeth have 2 roots?
L: 6, 7, 8s
What teeth have 3 roots?
U: 6, 7, 8s
In what direction to root usually curve?
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
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