1. Tooth Morphology Flashcards
1
Q
Roots usually divert …
A
distally
2
Q
Explain crown in anterior permanent teeth
A
- incisal aspect
- labial and palatal surfaces
- palatal cingulum (below cervical line)
- cervical line
3
Q
Which is the broadest incisor?
A
upper permanent central
4
Q
Features of upper permanent central incisors
A
- mesial surface almost parallel to long axis of tooth (mesial angle of incisal edge almost right angle)
- distal surface angled to a variable degree so incisal edge is wider than neck of tooth
- distal angle rounded so crown can appear square, rectangular or ovoid in labial view
- labial surface convex at gingival third and becomes virtually flat towards incisal edge amd has two planes
- cingulum is well marked on palatal surface and mesial and distal marginal ridges diverge towards incisal edge enclosing depression (palatal fossa)
5
Q
Features of upper permanent lateral incisors
A
- most variable tooth after 3rd molars
- resembles upper central but smaller and narrower
- mesial angle is more acute than in central and distal angle more obtuse and rounded
- root is conical but slightly compressed and grooved in a mesio-distal direction
6
Q
How to distinguish upper from lower incisors?
A
- roots of lower are markedly more mesio-distally compressed
- poor development of marginal ridges and low cingulum (shallower palatla fossa in lower)
7
Q
Features of the lower permanent central incisors
A
- smallest permanent tooth
- crown is symmetrical - twice as long as broad almost
- both mesial and distal angle are around 90 degrees - mesial and distal sides are parallel converging slightly towards apex
- crown is tilted in lingual direction slightly
- root compressed mesio-distally and markedly grooved on mesial and distal side (distal generally deeper)
8
Q
What’s the smallest permanent tooth?
A
lower central incisors
9
Q
2 main differences between lower central and lower lateral incisors
A
- lateral is wider
- and longer
10
Q
Features of lower lateral incisor
A
- crown is asymmetrical fan shape
- distal surface diverges at greater angle from long axis of tooth
- mesial angle nearly 90 but distal is more acute and slightly rounded
- incisal edge curved distally in lingual direction (unlike central which is at right angle to labio-lingual axis)
- root is flattened mesio-distally and grooved on distal surface
11
Q
Differences between upper and lower incisors?
A
- upper crowns are broad compared to height, lower are more narrow
- upper have more palatal relief than lowers
- upper roots are more circular, lower are more compressed
12
Q
If given an upper central and lateral incisor and a lower central and lateral incisor, how would you identify them (including left or right?)
A
- for upper central vs lateral, central is larger and more symmetrical in labial view, root of central is relatively shorter and stouter
- for lower central vs lateral, lower central are smaller and more symmetrical, shorter roots than lateral, lateral more curved occlusal outline
- left or right? upper and lower have a distal corner more rounded than mesial
13
Q
Features of upper canine
A
- longest tooth with longest strongest root
- mesial of crown forms almost straight line with root but distal meets root at obtuse angle
- mesial slope of incisal edge is shorter than distal
- palatal ridge passes from tip of cusp nearly to the cingulum seperated from marginal ridges by mesiopalatal and distopalatal fossa
- labial surface wider than lingual
14
Q
Features of lower canine
A
- similar to upper but more slender
- crown is more symmetrical
- root is compressed mesio-distally (can be grooved or divided at apex)
15
Q
Main differences between upper and lower permanent canine
A
- difference in length and inclination of mesial/distal slopes is less in lower canine
- lingual surface has rounded cingulum and low marginal ridges enclosing shallow lingual fossa in lower
- tip of cusp is displaced lingually
- enamel of labial surface may extend further apically than enamel on lingual surface
