RD 1 Lecture 1 Flashcards
dentition
all teeth in the mouth
homodont
animals with the same teeth throughout the entire dentition
heterodont
mammals that have teeth of different classes (humans)
how many classes of teeth in primary dentition, what are they
3 (incisors, canine, molar)
how many classes of permanent dentition and what are the names
4 (incisors, canines, premolars, molars)
monophyodont
have one set of teeth (beluga whale, dolphin, porpoise)
polyphyodont
have endless succession of teeth, when one is lost it is then replaced (shark, frog)
diphyodont
has two sets of teeth (humans)
how would you classify a human in terms of their dentition
a diphyodont heterodont
how many primary teeth and how many of each category
20 total = 8 incisors, 4 canines, 8 molars
how many permanent teeth and how many of each category
32 permanent teeth= 8 incisors, 4 canines, 8 premolars, 12 molars
two types of incisors and their location
central and lateral, central are two in the middle, lateral are the ones on opposite sides of the central incisors
anterior teeth
incisors and canines
posterior teeth
premolars and molars
which teeth are present in permanent but not in primary
all premolars and third molar
3 types of tooth identification systems
Universal (most common), FDI, Palmer Notation (ortho mostly)
Universal (Permanent)
1-16 maxillary teeth going left to right (while viewing patients mouth)
17-32 mandibular teeth going right to left (while viewing patients mouth)
Universal (primary)
A-J maxillary teeth going left to right (while viewing patients mouth)
K-T mandibular teeth going right to left (while viewing patients mouth)
FDI (permanent)
-2 digits for each tooth
1st digit follows these guidelines (1-4)
1 = max, right quad
2 = max, left quad
3 = mand, left quad
4 = mand, right quad
2nd digit is the distance from the midline (1-8)
FDI (primary)
-2 digits for each tooth
1st digit follows these guidelines (5-8)
5= max, right quad
6 = max, left quad
7 = mand, left quad
8 = mand, right quad
2nd digit is the distance from the midline (1-5)
Palmer Notation
the number used is the distance from the midline (1-8)
put it in a box based on the quad
UR | UL
LR | LL
4 tissues in the teeth
enamel, dentin, cementum, pulp
which tissues of the tooth are visible in an extracted tooth
enamel and cementum
enamel
-external layer of the anatomical crown
-hardest substance in the body
what is enamel derived from
ectoderm, specialized epithelial cells called ameloblasts
cementum
-dull yellow external layer of the root
-very thin
where is cementum derived from
mesoderm, cementoblasts
dentin
-hard yellow layer under enamel and cementum
-major inner bulk
-harder than cementum, softer than enamel
where is dentin derived from
mesoderm, odontoblasts
pulp
-Connective tissue containing blood vessels and nerves
-coronal portion = pulp chamber
- root portion =root canal
apical foramen
hole at the top of the root apex where nerves and blood vessels enter
what is the pulp derived from
mesoderm, dental papilla
rank the tooth tissues in terms of hardness
enamel>dentin>cementum>pulp
anatomic crown
part covered by enamel
anatomical root
part covered by cementum
CEJ (cementoenamel junction)
line where anatomical root and anatomical crown meet
how do the anatomical root and crown change over time
they never change over a person’s life
clinical crown
tooth visible in the oral cavity
clinical root
amount of tooth not visible, covered by gingiva
how can clinical crown and root change over time
over time, gingival recession can occur, making the clinical crown appear larger and the clinical root smaller
outer surfaces of teeth
facial: labial for anterior, buccal for posterior
inner surface of teeth
lingual (where tongue touches teeth)
chewing surface of posterior teeth
occlusal
biting surface on anterior teeth
incisal ridge / edge
sides of the teeth
proximal (general term) , mesial and distal sides
mesial surface
side closer to midline
distal surface
side closer to the back of the mouth
which two teeth have mesial sides touching each other
central incisors
which surfaces are not naturally cleaned by mouth
proximal, mesial and distal (need flossing to reach)
external line angle
line where 2 surfaces meet
how to name a line angle
combine 2 names, change -al of first surface to -o
order for naming: mesial, distal, facial, lingual, occlusal, incisal
point angle
where 3 tooth surfaces meet
dimension of a tooth
the length being measured from one surface to another
the length of the root
cervicoapical dimension
dividing a crown into thirds (horizontal)
cervical, middle, occlusal/incisal
dividing a root into thirds (horizontal)
cervical, middle , apical
when dividing a crown or root into thirds (facial or lingual view) (vertical)
mesial, middle, distal
when dividing a crown or root into thirds (mesial or distal) (vertical)
facial, middle, lingual
when diving a crown into thirds (occlusal/incisal) (mesiodistally)
facial, middle, lingual
when diving a crown into thirds (occlusal/incisal view) (faciolingually)
mesial, middle, distal
root-to-crown ratio
root length divided by crown length
normal root to crown ratio
normally > 1.0
what is the clinical significance of a root-to-crown ratio
a small root-to-crown ratio is not the best choice for attaching false teeth
a cusp
pyramidal elevation, on occlusal surfaces of molars/premolars, and incisal edges of canines
how many cusp ridges does a single cusp have
4
naming a 2-cusped premolar
buccal or lingual, based on surface they are adjacent to
naming a 4-cusped molar
after adjacent line angles: mesiobuccal, distobuccal, mesiolingual, distolingual
ridges on anterior teeth
mesial and distal marginal ridge
-located on each respective side on lingual surface and converge to cingulum
triangular ridge
on each major cusp on posterior teeth
-extends from cusp tip to sulcus in middle of tooh
when triangular ridge on facial joins triangular ridge on lingual
transverse ridge
when triangular ridge on facial joins triangular ridge on diagonal lingual cusp
oblique ridge (only maxillary molars)
mamelons
3 small tubercules/scallops on incisal edge of incisors
perikymata
minute horizontal ridges on enamel of new permanent teeth
-closer together in cervical third than in incisal third
tooth sulcus
v-shaped depression running mesiodistally on occlusal surfaces of posterior teeth
function of sulci
allow for chewing food to escape through the grooves
developmental grooves
major, sharply defined, linear depressions
-formed during tooth development
-separates lobes of teeth
main developmental grooves
central groove runs mesiodistal
fossa developmental grooves at ends of central groove
additional grooves (not developmental)
supplemental grooves
-don’t occur at the junction of lobes
fissure
narrow cleft at the depth of any groove (lines on tooth)
cause of a fissure
incomplete fusion of enamel during tooth development
fossa
small hollow depression between marginal ridges
-on lingual surface of anteriors
-on occlusal surface of posterior
pits
occur at the depth of fossa where 2 or more grooves join
apex
tip at the end of the root
apical foramina
visible openings where nerve and blood vessels enter the pulp
cervix
neck of the tooth, union of the crown and root
root trunk
part of the root that hasn’t split into multiple roots
furcation
spot on root trunk where it divides into separate roots
-bifurcation for 2 roots
-trifurcation for 3 roots
furcal region
space between 2 or more roots usually filled with gingiva
Cervical Line Curvature
-curves convex toward incisal/occlusal surface
the amount of curvature of CEJ on the _____ surface is greater than on the ____ surface
mesial, distal
When moving from the central incisors to the molars, the curvature _______
decreases as you move distally
mid-root axis line
imaginary line through the center of the root
-important for describing landmarks
height of contour
aka crest of curvature
-shape of greatest bulge on facial and lingual surfaces
height of contour function
help determine the direction that food particles are deflected
where do anterior teeth have facial and lingual heights of contour
in the cervical third of the crown
where do posterior teeth have heights of contour on the facial and lingual surfaces
facial = cervical third
lingual = middle third
Contact areas
greatest heights of contour on proximal surfaces
-where one tooth touches an adjacent tooth
proximal contact functions
-stabilize position of teeth
-prevent food impaction
-protects interdental papillae
proximal contact areas lie ________
along the height of contour line
proximal contact area lies in the _____ and ________
faciolingual dimension and incisocervical dimension
diastema
space between 2 teeth not caused by 2 missing teeth
which teeth have mesial contact areas most incisally
central incisors
(means that they touch closest to the incisal edge)
typically, the ______ contact is more cervical than the _______ contact
distal, mesial
(cervical means closer to root)
when viewing from facial, contact areas are located where
incisal/occlusal third, middle third, or in between
contact areas are normally NOT in which area
cervical third
when viewing anterior teeth from an incisal view, the contact are nearly centered _______
faciolingually
when viewing posterior teeth from an incisal view, the contact are located _ ______
slightly more facial of the midline buccolingually
embrasure spaces
v-shaped space formed by curved tooth surfaces
-allow chewed food to escape from occlusal surface
when adjacent teeth contact, how many embrasure spaces are formed
4 triangular embrasure spaces
occlusal view shows which embrasure spaces
facial and lingual
facial view shows which embrasure spaces
incisal and interproximal
interproximal embrasure space
cervical to contact area between 2 teeth
interdental papillae
projection of free gingival tissue in the interproximal area
col
slightly sagging tent, shape of healthy interdental papilla
compare sizes of lingual vs. facial embrasure space
lingual > facial
occlusal embrasure
area between marginal ridges on 2 teeth
-where dental floss passes before going into interproximal space
