Basic Terminology, Dentition, Numbering, Morphology of Crowns Flashcards
Dentition
Primary-6 mo-2 yr
Permanent- 6yr new teeth erupt, start losing
-at 21 permanent complete
Arch
Maxillary or Mandibular
Quadrant
half an arch
Anterior teeth
canines and incisors
- behind lips
- first 3 from midline in each quadrant
Midline
separates arches into quadrants
Name the 4 classes of teeth
Incisors
Canines
Premolars
Molars
Incisors
cut food
Canines
Pierce food
Premolars
piercing and minor grinding of food
Molars
Solely for grinding food, large surface area for smashing food well
3 Types of teeth
1) Central and lateral (just single canine in each quadrant, no types)
2) 1st and 2nd (premolars)
3) 1st, 2nd, and 3rd (molars)
Primary teeth
Deciduous teeth
Only 20 teeth
-NO premolars
1st and second premolars, 3rd molars NOT present
A-T in UNS (NO numbers)
Adult teeth are numbered _ - _ in the Universal Numbering System
1-32
Start maxillary right (9oclock) 1st tooth #1 is 3rd Molar
top right clockwise
Name the 4 tissues of the tooth
Enamel
Dentin (shaded gray)
Cementum
Pulp
Enamel
Strongest tissue in body
- ameloblasts
- white but lots translucency
Dentin
shaded gray 70% Ca hydroxyapetite -odontoblasts -yellow in color -right inside enamel, can't be seen unless looking at rad
Cementum
surrounds root of tooth, thin layer, cementoblasts
yellowish in color, has 50-65% Ca hydroxyapet.
same density of bone
Pulp
inside, only soft tissue on tooth
made of connective tissue with
blood vessels and nerves,
makes tooth vital organ
Cervical area of tooth
Neck
Apical foramen
apex=tip of root
foramina=openings
Root canal
innermost channel of pulp leading to pulp chamber
Pulp chamber
below dentin, reaches slightly into anatomical crown
Cementodentinal Junction
CDJ
Cementoenamel Junction
CEJ
-where crown and root anatomically separate
Dentinoenamel junction
can’t see cause inside tooth
pulp horns
projections, have to stay away
so you dont expose pulp
enamel covers anatomical ____
cementum covers anatomical ____
crown
root
anatomical crown never changes
but clinical _____ changes during life for
different reasons
clinical root and crown changes
Anatomical crown
covered with enamel
Anatomical root
covered with cementum
When do the terms clinical crown and root apply?
ONLY when tooth is in mouth and at least partially erupted
Periodontium
surrounding tissues of tooth
- gingiva (free vs attached)
- cementum
- periodontal ligament
- bone (alveolar bone)
labial or facial
anterior teeth surface toward lips
buccal or facial
posterior teeth
surface toward cheeks
lingual or palatal
maxillary teeth surface toward tongue
lingual
mandibular teeth toward the tongue
incisal edge or ridge
anterior teeth biting surface
occlusal surface
posterior teeth biting surface
each tooth has __ proximal surfaces
2
mesial
distal
Mesial
proximal surfaces that face the midline of an arch
Distal
proximal surfaces that face away from the midline of an arch
divisions of crown from facial/lingual view
mesial, middle, distal
-occlusal/incisal (top), middle, cervical
divisions of crown from proximal views
facial, middle, lingual
occlusal/incisal, middle, cervical
List of surfaces for naming LAs, PAs
Mesial=1 Distal=2 Facial/Labial/Buccal=3 Lingual=4 Occlusal or Incisal=5 Cervical and Apical=6
surface junctions
two surfaces that join (line angle)
ex: distolabial, mesiobuccal
lose -al and +o
Dimension
the distance between two
opposite surfaces, such as:
Mesiodistal dimension
Root-to-Crown Ratio
Small ratio (smallest: 1.16-maxillary central incisor)
denotes nearly equal
crown and root length
Larger ratio (1.56-right maxillary canine)
denotes a relatively
larger root compared to
the crown
optimum root/crown ratio
2/3
minimum root/crown ratio
1/1
What is the longest crown?
mandibular canine or
maxillary central incisor
Longest tooth
maxillary canine
Widest crown
mandibular first molar
Narrowest crown
mandibular central incisor
Cusps
rounded
-pyramid shaped with
four ridges
- Mesial cusp ridge
- Distal cusp ridge
- Facial cusp ridge
- Triangular ridge
Ridges
linear/linear bulges
Triangular ridge
from cusp tip to middle of tooth
present ONLY on POSTERIOR teeth
1-5 cusps
canines and posterior teeth
cusp ridges
cusp slopes or cusp arms
mesial and distal
Transverse (Oblique) Ridge
Two Triangular ridges joined together (triangular of DB and DL meet/line up from buccal to lingual)
Buccal (labial) cusp ridge
very subtle
Buccal Cervical Ridge
subtle
-near CEJ mesially
Mamelons
Three bumps form on adult
Incisors from three labial lobes; Usually
wear away
Mamelons
Three bumps form on adult
Incisors from three labial lobes; Usually
wear away
Perikymata
Very small horizontal
wave-like ripples of Enamel on newly erupted
adult teeth
Depressions in teeth
fossae and grooves
Grooves
linear depressions
Major vs. Minor
Major Grooves
(developmental)
– Central groove
– Fossa grooves
Minor Grooves
(supplemental)
– Marginal ridge grooves
– Extra grooves
Central grooves
located in the
buccolingual center of
the tooth and run
mesiodistally
Fossa grooves
named for the surface
or line angle they “aim”
toward
Fossae
Shallow bowl-like depressions
Fossae on occlusal surfaces are located in
the intersection of the grooves
Pit and fissure
Decay starts in grooves and
spreads out more quickly once into Dentin
(softer than Enamel)
Pits
-often found within fossae (depressions)
Incisors (especially maxillary) have one broad, shallow fossa (sometimes with a lingual pit)
Two-cusped premolars have _ fossae
TWO
Mesial
Distal
Three-cusped premolars and most molars have ____
fossae
THREE
– Mesial
– Central
– Distal
furcal area
area between roots if split
CEJ on proximal curves toward
occlusal/incisal
CEJ mesial curves ___ than distal
MORE than
CEJ on facial (or lingual)
curves toward ____
root apex
CEJ curvature _______
from anterior to
posterior crowns
diminish
Root Axis Line
An imaginary line that splits the root in half (Mesiodistally or Faciolingually)
Height of Contour
Crest of Curvature)
Contact Areas
(or Proximal Heights of
Contour): Protect Gingiva; Prevent Food Impaction
Embrasure Spaces
are ONLY present
when two adjacent teeth touch
• Four embrasures – Facial – Lingual (larger than facial) – Occlusal or incisal (often quite small) – Cervical = interproximal space (filled with gingiva)
Maxillary teeth from lateral view
Anteriors are mesially inclined
Posteriors are not
Mandibular teeth from lateral view
all mesially inclined
Tilt from frontal view
Maxillary teeth tilt facially
Mandibular teeth tilt lingually
Anteroposterior Curve (of Spee)
Maxillary curve is
convex
Mandibular curve is
concave
Mediolateral Curve (of Wilson)
-Maxillary curve is
convex
-Mandibular curve is
concave
Ideal Occlusion
Occlusion is the contact of the occlusal and incisal surfaces ofbmaxillary and mandibular teeth
Ideal Class I Occlusion Relationship (Angle’s Classes)
Class I jaw relationship is when the mesiobuccal cusp of maxillary first molar fits into mesiobuccal groove of mandibular first molar (that is, the most mesial of the two buccal grooves)
Maximal intercuspal
position
Maxillary teeth are
FACIAL to mandibular
Buccal cusps of maxillary teeth are facial to mandibular • Buccal cusps of mandibular fit into maxillary fossae • Lingual cusps of maxillary fit into mandibular fossa • Lingual cusps of mandibular are lingual to maxillary
Tooth Development From Lobes
Anterior teeth form
from four lobes (three
facial and one lingual)
Premolars form from
three facial lobes and
one lobe per lingual
cusp
Molars form from one
lobe per major cusps
functional/working cusp
cusp doing majority of the work
maxillary: lingual
mandibular: buccal
