Posterior tooth anatomy Flashcards
shape of lower 7’s
more oblong/squarer than 6’s
how many cusps on a lower 7
4
lower 7 - are lingual or buccal cusps higher?
lingual cusps are higher and slightly more pointed
how many occlusal fossae do lower 7’s have?
3 - mesial central distal
fissure pattern for lower 7
hot cross bun shape - midline fissure and lateral fissure
marginal fissures - short extensions from mesial and distal pits
marginal fossae - triangular (triangular fossa?)
what are axial grooves?
extend from lateral fissures between cusps
what are the marginal ridges?
mesial and distal barrier
what is the function of the marginal ridge?
keep food on the occlusal table
prevents food trapping
what is usually the largest lower tooth?
lower 6
general shape of lower 6
oblong (like lower 7)
which surface of the lower 6 is rounder, buccal or lingual?
flat lingual surface
more rounded buccal surface
how many cusps does lower 6 have?
5 cusps
order cusp sizes from largest to smallest
mesio lingual
disto lingual
mesio buccal
centro buccal
disto buccal
what is the fissure pattern for lower 6?
dryopithicus
5 cusps where the bases of the disto and mesio lingual and centrobuccal cusps meet the central fossa
which side of the lower 6 has more cusps?
buccal size has 3 cusps, lingual side has 2 cusps
axial groovers of lower 6
divides convex buccal surface into 3 lobes
what is a buccal pit?
present in 60% of lower first molars
found on buccal surface
clinical relevance of buccal pit?
difficult to clean
predilection to caries
may require sealants
marginal ridges of lower 6
mesial is shallower than distal
dissection groover crossing the distal marginal ridge is often deep
which upper molar is larger?
upper 1st molars are usually larger than upper 2nd molars (6 > 7)
shape of upper first molar
outline resembles a rhombus
how many cusps does upper 6 have?
4 cusps
how many cusps does upper 7 have?
4 cusps
where are cusp tips of upper 7 located?
corners of the rhombic outline
which cusp is largest and smallest on upper 6?
large mesiopalatal cusp
small distopalatal cusp
what is the size of the buccal cusps of upper 6?
buccal cusps are similar size
what is the cusp of carabelli?
5th cusp
extension to mesiopalatal cusp
what is the crista obliqua?
in upper first molars there are distinguished by a prominent oblique ridge (between MP and DB)
Fissure pattern of upper 6
draw in head lol
what are palatal pits?
occur commonly at the end of the palatal axial groove. on upper 6’s
shape of upper 7’s
similar to upper 6
what is the distopalatal cusp called?
hypoconus
does upper 7 have a cusp of carabelli?
usually not
how does the distopalatal cusp vary with the tooth?
distopalatal cusp diminishes in size from 6 to 7 to 8
fissure pattern of upper 7
buccal lateral fissure may be angled distally
shape of upper 5
egg-shaped, oval, rounded (oval is longer on B-P axis than M-D)
how are upper 5’s different to upper 4’s
upper 5 and 4 are similar but
5 usually more rounded and more symmetrical
is the buccal or palatal upper 5 wider?
wider buccally than palatally
how many cusps do upper premolars have?
2
what are transverse ridges?
approximately perpendicular to the tooth midline in upper 5
how many fossae in upper 5’s?
2 - one mesial and one distal
fissure pattern of upper premolars
primary fissure pattern very simple
known as h form
dissectional grooves of upper 5
less obvious than other teeth and might be absent/poorly defined
where is palatal cusp tip of upper 4 placed?
palatal cusp tip mesially placed
cusps of upper 4 compared to upper 5
upper 4 buccal cusps are higher than palatal but upper 5 have more even buccal and palatal cusps
4 has sharper cusps
how many roots of upper 4?
upper 4 may have 1 or 2 roots
which tooth has the canine groove and what is it?
single rooted upper 4’s
concavity on the mesial surface, often extending from mesial disectional groove
lower 5 shape
squarer occlusal outline
how many cusps does lower 5 have?
3 cusps
how many fossae does lower 5 have?
3 fossae
what ridges does lower 5 have?
transverse and oblique ridges
which part of the lower 5 is the most curved?
buccal cusp is more curved
what fissure pattern shape does the lower 5 have?
Y-form - 3 cusps, unique and most common
sometimes has H form
which premolar is the smallest in the mouth?
lower 4
shape of lower 4
circular outline
buccal cusp makes up the bulk of the crown
fossae and fissures of lower 4
2 fossae (distal is larger)
fissures may be poorly developed/absent
does the lower 4 have well defined transverse ridges?
yes
mesial dissectional groove orientated lingually
How do the posterior teeth occlude?
Upper 2nd premolar - cusp tip positioned between lower 2nd premolar and 1st molar
Upper 1st molar - medial buccal cusp fits into buccal groover of lower 1st molar
Upper 2nd molar - medial buccal cusp fits into buccal groover of lower second molar
