Harvard School of Dental Medicine Department of Restorative Dentistry

1
Harvard School of Dental MedicineDepartment of
Restorative Dentistry
Predoctoral Curriculum in Dentistry Diagnosis and
Prevention Block 2002
Dental Terminology
Msd Fábio Tunes
2
Dental Terminology - Why ?
3
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.
4
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.
5
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.

6
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.
7
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 un- erupted portion is part of the
clinical root.
8
(No Transcript)
9
Crown and Root

• The root portion may be single or multi-rooted
  with a bifurca-
• tion 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
10
Dental Tissues

• Enamel
• Dentin
• Cementum
• Pulp

11
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.

12
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.

13
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)
  dentin-forming cells odontoblasts

14
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.
15
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.

16
Cementum

• The union of cementum and dentin is called the
  dentino-cemental 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

17
Pulp

• The pulp is the nourishing, sensory, and
  dentin-reparative system of the tooth.
• Composed of blood vessels, lymph vessels,
  connective tissues, nerve tissues, and dentin
  formation cells (odontoblasts)

18
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.

19
Pulp

• 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.

20
Types of Teeth

• Anterior Teeth
• Incisors
• Canines
• Posterior Teeth
• Premolars
• Molars

21
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.

22
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
CI
LI
li
ci
ci
li
23
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

24
Canines

• 4 canines total
• 2 maxillary, 2 mandibular
• Designed to function as holding or grasping teeth
• Also used as a tearing tool
• Longest teeth in the human dentition
• Canine guidance in lateral excursive movements of
  occlusion

C
C
C
C
25
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.

26
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.)

27
Molars

• 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.

28
Molars

• Maxillary (upper) and
• mandibular (lower) molars
• differ greatly from each
• other in shape, size, number
• of cusps, and roots.

29
Surfaces of Teeth

• 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

30
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

31
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.

32
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.
33
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.

34
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.

35
Line Angles

• Line Angles for Anterior Teeth

36
Line Angles

• Line Angles for Posterior Teeth

37
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-labio-incisal point angle

38
Point Angles

• Point Angles for Anterior Teeth

39
Point Angles

• Point Angles for Posterior Teeth

40
Landmarks

• 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.

41
Landmarks

• 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.

42
Landmarks

• Anterior teeth show 2 develop-mental 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.

43
Landmarks

• A concavity is a carved-out section or area -gt
  Fossa
• The opposite of a concavity
• is a convexity, a bulging out area of the tooth
  crown
• - gt Ridge, Cusp
• (no cusp on incisors!)

44
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
45
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
46
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
C
Disto-Buccal
C
Mesial
Distal
C
C
Mesio-Lingual
Disto-Lingual
Lingual
47
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.

48
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
49
Landmarks

• A transverse ridge is the union of a buccal and
  a lingual triangular ridge that cross the
  occlusal surface of a posterior tooth.