Transcript Harvard School of Dental Medicine Department of

Harvard School of Dental Medicine
Department of Restorative Dentistry
Predoctoral Curriculum in Dentistry
Diagnosis and Prevention Block 2002
Dental Terminology
Msd Fábio Tunes
Dental Terminology - Why ?
Maxillary and Mandibular Teeth
The portion of the jaw that
supports the teeth is called
the alveolar process. The
bony socket in which the
root fits is called the
alveolus.
Teeth in the upper jaw are
called maxillary teeth. In
the lower jaw they are
called mandibular teeth.
Tooth Eruption
The crown portion of the tooth erupts through the bone
and alveolar ridge mucosa. The tooth continues to erupt
from the bone and surrounding oral mucosa, now
called gingiva.
Crown and Root
Eruption of a tooth is thus moving of the tooth through
its surrounding tissues so that the clinical crown
gradually appears longer.
Crown and Root
Each tooth has a crown and root
portion. The crown is covered with
enamel, the root is covered with
cementum. Crown and root are
joined at the cemento-enamel
junction, also called the CEJ. The
line that demarcates it is called the
cervical line.
Crown and Root
The anatomical crown is the
whole crown of the tooth
that is covered by enamel,
whether erupted or not. The
clinical crown is only that
part seen above the gingiva.
Therefore, if the anatomical
crown does not fully erupt, the
part that is visible is considered
the clinical crown, and the unerupted portion is part of the
clinical root.
Crown and Root
The root portion may be single or multi-rooted with a bifurcation or trifurcation, i.e., division of the root portion into two
or three roots. Each root has one apex, or terminal end. The
root portion is held in its position relative to the other teeth in
the dental arch by being firmly anchored in the bony alveolar
process of each jaw.
Trifurcation
Alveolar
Process
A
A
Bifurcation
Dental Tissues
– Enamel
– Dentin
– Cementum
– Pulp
Enamel
•
Most densely mineralized and
hardest tissue in the human body.
•
96% unorganic and 4% organic
matter and water.
•
Forms the outer surface of the
anatomic crown.
•
Thickest over the tip of the crown,
becomes thinner as it approaches
the cervical line.
•
Color varies with thickness and
mineralization.
Dentin
•
Dentin forms the main portion or
body of the tooth (crown and
root)
•
It is wrapped in an envelope of
enamel that covers the crown,
and an envelope of cementum
that covers the root.
Dentin
•
Hard, dense, calcified tissue;
softer than enamel but harder
than bone or cementum.
•
Chemical composition is 70%
inorganic and 30% organic matter
and water.
•
Appears yellowish, has elasticity
•
Unlike enamel, dentin is capable
of adding to itself (secondary
dentin, reparative dentin); dentinforming cells = odontoblasts
Dentin
• Secondary Dentin:
Is the dentin that continues to be laid
down in the pulp chamber after tooth
eruption
• Reparative Dentin:
Is the dentin laid down in response to
caries or trauma.
Cementum
•
•
•
•
Bone-like substance that
covers the root.
Main function is to provide a
medium for attachment of the
tooth to the alveolar bone as
part of the periodontium
Not as dense or hard as
enamel or dentin but is denser
than bone to which it bears
physiological resemblance.
The chemical composition is
45% to 50% inorganic and 50%
to 55% organic components.
Cementum
•
The union of cementum and
dentin is called the dentinocemental junction.
•
2 types of cementum:
A) cellular - confined to the
apical 1/3 of root and can
reproduce itself.
acellular - covers the entire
anatomical root.
Cementum as dentin continues
to be formed after tooth eruption
by cementoblasts
B)
•
Pulp
•
The pulp is the nourishing,
sensory, and dentinreparative system of the
tooth.
•
Composed of blood vessels,
lymph vessels, connective
tissues, nerve tissues, and
dentin formation cells
(odontoblasts)
Pulp
•
•
Pulp is housed in the
center of the tooth within
the dentin surrounding
the pulp tissue.
The walls of the pulp
cavity are lined with
odontoblasts. Their chief
function is to lay down
primary and secondary
dentin.
Pulp
•
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Anatomically the pulp
chamber is divided into
two areas:
1) The pulp chamber
in the coronal
portion of the tooth.
2) The root (pulp)
canals in the roots
of the tooth.
Pulp chamber and root
(pulp) canals = pulp
cavity.
Types of Teeth
•
Anterior Teeth:
– Incisors
– Canines
•
Posterior Teeth:
– Premolars
– Molars
Types of Teeth
•
Functions of teeth vary.
•
Tooth shapes and sizes differ with their
location in the jaws.
•
The three basic functions of teeth are
cutting, holding or grasping, and grinding.
Incisors
•
Eight incisors total:
2 maxillary centrals (LI)
2 maxillary laterals (CL)
2 mandibular centrals (ci)
2 mandibular laterals (li)
•
Incisors are designed to cut
•
Cutting edge = incisal edge
LI
CI
li
CI
ci ci
LI
li
Incisors
The tongue side, or lingual
surface, is shaped like a
shovel:
• aids in guiding the food into
the mouth.
• is the major contributor to
the anterior guidance of
occIusion
Canines
•
4 canines total:
2 maxillary, 2 mandibular
•
Designed to function as
holding or grasping teeth
•
Also used as a tearing tool
C
•
Longest teeth in the human
dentition
C
•
Canine guidance in lateral
excursive movements of
occlusion
C
C
Canines
•
Canines are the best anchored
and most stable teeth, since they
have the longest roots.
•
Canines are shaped triangularly
in cross section. This makes it
possible for a canine to hold its
place in the corner of the mouth.
•
This shape resists both anterior
and posterior forces of
displacement.
Premolars (or Bicuspids)
•
•
•
•
A cross between canines and
molars.
8 premolars: 1st and 2nd in
each tooth quadrant
Not as long as canines, and
usually have two cusps, rather
than one large ridge.
Like canines they aid in holding
food, and they also help grind
rather than incise it (the
pointed buccal cusps hold the
food while the lingual cusps
grind it.)
Molars
•
•
•
•
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Larger than premolars
Most posterior teeth: 1st, 2nd and
3d molars
The function of the 12 molars is to
chew or grind up food.
They do not have incisal edges,
instead they have cusps, which
are designed to interlock upper
and lower molars.
There are 4 or 5 cusps on the
occlusal surface of each molar.
Molars
Maxillary (upper) and
mandibular (lower) molars
differ greatly from each
other in shape, size, number
of cusps, and roots.
Surfaces of Teeth
•
•
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Crowns of the teeth are
divided into surfaces
named according to the
direction in which they
face.
Anterior teeth have
4 surfaces (m, f, d, l) plus
the incisal ridge or edge
Posterior teeth have
5 surfaces. The 5th
surface is the occlusal
surface
Surfaces of Teeth
•
Surfaces facing the
tongue = lingual
surfaces.
•
Surfaces facing the
cheeks = facial
surfaces, or labial (lip)
surface for anterior
teeth, buccal (cheek)
surface for posterior
teeth
Surfaces of Teeth
•
A tooth surface facing that of
a neighboring tooth in the
same arch (next to each
other) is called a proximal
surface.
•
Each tooth has two proximal
surfaces: mesial and distal.
The mesial proximal surface
of a tooth is closest to the
midline of the face. The distal
proximal surface faces away
from the midline.
Division of Surfaces
For the purpose of facilitating the
location of various areas within a
specific surface of a tooth, the
surface is divided into thirds mesial, middle and distal third - of
each the facial and lingual surface.
Division of Surfaces
•
The proximal (mesial and distal)
surfaces of a tooth are divided
into a facial, a middle, and a
lingual third.
•
Surfaces are further divided into
sections perpendicular to the
above, i.e. any of the proximal,
facial, or lingual surfaces are
divided into an incisal, a middle,
and a cervical third.
•
Posteriorly, the incisal 1/3
is called the occlusal 1/3.
Line Angles
The line angle forms the junction
between two tooth surfaces; e.g.,
the junction of the buccal surface
and the occlusal (incisal) surface
of a tooth is a line angle.
Line Angles
• Line Angles for Anterior Teeth
Line Angles
• Line Angles for Posterior Teeth
Point Angles
A point angle is the
point at which three
surfaces meet; e.g. the
point at which the
mesial, labial and
incisal surfaces join is
called the mesio-labioincisal point angle
Point Angles
• Point Angles for Anterior Teeth
Point Angles
• Point Angles for Posterior Teeth
Landmarks
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The crown portion of teeth
develops from 4 or more
growth centers or lobes.
The lobes grow and
eventually fuse leaving but a
line or groove on the erupted
tooth where fusion of the
lobes took place.
These shallow grooves or
lines that separate the
original growth centers are
called developmental
grooves.
Landmarks
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•
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Incisors, canines and most
premolars are developed
from 4 lobes, 3 facial and
1 lingual.
1st molars are developed
from 5 lobes: the upper
from 2 facial and 3 lingual,
the lower from 2 lingual
and 3 facial lobes.
2nd molars are developed
from 4 lobes, 2 facial and 2
lingual.
Landmarks
•
•
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Anterior teeth show 2 developmental grooves on their labial
surfaces. These 2 grooves
separate the 3 lobes that formed
the labial surface.
The fourth developmental lobe
of anterior teeth is located at the
lingual surface of the crown.
This fourth lobe is called the
cingulum, and it makes up the
bulk of the cervical third of the
lingual surface of an anterior
tooth.
Landmarks
•
A concavity is a carved-out
section or area -> Fossa
•
The opposite of a concavity
is a convexity, a bulging out
area of the tooth crown
- > Ridge, Cusp
(no cusp on incisors!)
Landmarks
•
•
A fossa (plural fossae) is a
depression or concavity, on an
area of the tooth crown.
A tubercle is a small elevation of
enamel on some portion of the
crown of a tooth.
Fossae
Landmarks
•
Anterior teeth have a lingual
fossa between the marginal
ridges and incisal to the
cingulum.
•
A pinpoint hole within the
fossa, is called a pit.
•
Pits are named after their
location on a tooth; e.g.
a lingual pit occurs on the
lingual surface of a tooth.
C
Landmarks
•
•
•
A cusp is a mound on the
crown portion of the tooth
that makes up a major
division of its occlusal or
incisal surface.
Cusps are found on
premolars, molars and
canines, not on incisors.
Cusp are name after their
location (MB, DB, ML, DL)
Buccal
Mesio-Buccal
Disto-Buccal
C
C
Mesial
Distal
Disto-Lingual
C
C
Lingual
Mesio-Lingual
Landmarks
•
Marginal ridges are the
rounded borders of
enamel that form the
mesial and distal
shoulders of the occlusal
surfaces of posterior teeth
and the mesial and distal
shoulders of the lingual
surface of the anterior
teeth.
Landmarks
Triangular ridges (TR)
are the main ridges
on each cusp that run
from the cusp tip to
the central part of the
occlusal surface, i.e.
the central, mesial,
distal grooves and
pits
MR = Marginal ridge
TR
TR
MR
MR
TR
TR
Landmarks
A transverse ridge is
the union of a buccal
and a lingual triangular
ridge that cross the
occlusal surface of a
posterior tooth.