تشريح أسنان محاضرة 2

College of DentistryCollege of Dentistry
Introduction to dentistryIntroduction to dentistry
Tooth IdentificationTooth Identification
Dr. Hazem Al AjramiDr. Hazem Al Ajrami

Standard characteristics are common toStandard characteristics are common to
most teeth. A complete understanding of themost teeth. A complete understanding of the
anatomy of a specific tooth is necessary toanatomy of a specific tooth is necessary to
ensure correct identification of the tooth.ensure correct identification of the tooth.

Tooth structureTooth structure
 EnamelEnamel
 DentinDentin
 CementumCementum
 PulpPulp

The four tooth tissues are,The four tooth tissues are, EnamelEnamel,, DentinDentin,,
CementumCementum, and, and PulpPulp. The first three are hard. The first three are hard
mineralized tissues composed of an organicmineralized tissues composed of an organic
matrix embedded by crystalline forms ofmatrix embedded by crystalline forms of
calcium phosphate salt. The pulp is softcalcium phosphate salt. The pulp is soft
connective tissue.connective tissue.

The Crown and RootThe Crown and Root
Each tooth has a crown and root portion.Each tooth has a crown and root portion.
The crown is covered with enamel, and the rootThe crown is covered with enamel, and the root
portion is covered with cementum. The root isportion is covered with cementum. The root is
embedded in the jaw bone.embedded in the jaw bone.
The crown and root join at theThe crown and root join at the
cementoenamel junction. This junction alsocementoenamel junction. This junction also
called the cervical line.called the cervical line.

Maxillary central incisor:Maxillary central incisor:
Apex of root.
Root.
Cervical line.
Crown.
Incisal edge.

The root portion of the tooth is firmly fixedThe root portion of the tooth is firmly fixed
in the bony process of the jaw, so that eachin the bony process of the jaw, so that each
tooth is held in its position relative to the otherstooth is held in its position relative to the others
in the dental arch. That portion of the jaw whichin the dental arch. That portion of the jaw which
serves as a support for the tooth is called theserves as a support for the tooth is called the
alveolar process.alveolar process.

The crown portion is never covered by boneThe crown portion is never covered by bone
tissue after it is fully erupted, but it is partlytissue after it is fully erupted, but it is partly
covered at the cervical third in young adults bycovered at the cervical third in young adults by
soft tissue of the mouth known as the gingiva orsoft tissue of the mouth known as the gingiva or
gingival tissue, or gum tissue. In older persons,gingival tissue, or gum tissue. In older persons,
all of the enamel and frequently some cervicalall of the enamel and frequently some cervical
cementum may be exposed in the oral cavity.cementum may be exposed in the oral cavity.

The CrownThe Crown
 The Anatomical Crown is that portion of theThe Anatomical Crown is that portion of the
tooth which is covered by enamel.tooth which is covered by enamel.
 The Clinical Crown is that portion of the toothThe Clinical Crown is that portion of the tooth
which is visible in the mouth regardless ofwhich is visible in the mouth regardless of
whether it corresponds to the anatomicalwhether it corresponds to the anatomical
crown.crown.
 The anatomical crown is constant in lengthThe anatomical crown is constant in length
whereas the clinical crown may change inwhereas the clinical crown may change in
length throughout life.length throughout life.

Clinical Crown
Anatomical Crown

The crown of an incisor tooth may have anThe crown of an incisor tooth may have an
incisal ridge or edge, as in the central andincisal ridge or edge, as in the central and
lateral incisors; a single cusp, as in thelateral incisors; a single cusp, as in the
canines; or two or more cusps, as on premolarscanines; or two or more cusps, as on premolars
and molars. Incisal ridges and cusps form theand molars. Incisal ridges and cusps form the
cutting surfaces on tooth crowns.cutting surfaces on tooth crowns.

The RootThe Root
 The Anatomical Root is that portion of theThe Anatomical Root is that portion of the
tooth which is covered by cementum.tooth which is covered by cementum.
 The Clinical Root is that portion of the toothThe Clinical Root is that portion of the tooth
which is not visible in the mouth. As withwhich is not visible in the mouth. As with
crown, the clinical root may changecrown, the clinical root may change
throughout life.throughout life.

The root portion of the tooth may be single,The root portion of the tooth may be single,
with one apex or terminal end, as usually foundwith one apex or terminal end, as usually found
in anterior teeth and some of the premolars; orin anterior teeth and some of the premolars; or
multiple, with a bifurcation or trifurcationmultiple, with a bifurcation or trifurcation
dividing the root portion into two or moredividing the root portion into two or more
extensions or roots with their apices or terminalextensions or roots with their apices or terminal
ends, as found on all molars and in someends, as found on all molars and in some
premolars.premolars.

Double Root,Double Root,
with a bifurcationwith a bifurcation

Triple Root,Triple Root,
with awith a trifurcationtrifurcation

Surfaces and RidgesSurfaces and Ridges

The crowns of the incisors and caninesThe crowns of the incisors and canines
have four surfaces and a ridge, and the crownshave four surfaces and a ridge, and the crowns
of the premolars and molars have fiveof the premolars and molars have five
surfaces.surfaces.

The surfaces are named according to theirThe surfaces are named according to their
positions and uses. In the incisors and canines,positions and uses. In the incisors and canines,
the surfaces toward the lips are called labialthe surfaces toward the lips are called labial
surfacessurfaces;; in the premolars and molars, thosein the premolars and molars, those
facing the cheek are the buccal surfacesfacing the cheek are the buccal surfaces.. WhenWhen
labial and buccal surfaces are spoken oflabial and buccal surfaces are spoken of
collectively, they are called facial surfacescollectively, they are called facial surfaces..

The inner surface of any maxillary tooth isThe inner surface of any maxillary tooth is
called Palatal since it faces the palate of thecalled Palatal since it faces the palate of the
mouth, and that of the mandibular teeth ismouth, and that of the mandibular teeth is
called Lingual since it faces the tonguecalled Lingual since it faces the tongue..

The surfaces of the premolars and molarsThe surfaces of the premolars and molars
which come in contact with those in thewhich come in contact with those in the
opposite jaw during the act of closure (calledopposite jaw during the act of closure (called
occlusion) are called occlusal surfaces. Inocclusion) are called occlusal surfaces. In
incisors and canines, those surfaces are calledincisors and canines, those surfaces are called
incisal surfaces.incisal surfaces.

 Facial:Facial: term used to designate the surface of theterm used to designate the surface of the
tooth toward the face:tooth toward the face:
BuccalBuccal {adjacent to the cheek}.{adjacent to the cheek}.
LabialLabial {adjacent to the lip}.{adjacent to the lip}.
 Lingual:Lingual: adjacent to the tongue.adjacent to the tongue.
 Palatal:Palatal: adjacent to the palate.adjacent to the palate.
 Occlusal (incisal):Occlusal (incisal): adjacent to the contactingadjacent to the contacting
surface of opposing teeth.surface of opposing teeth.

 The surfaces of the teeth facing toward adjoiningThe surfaces of the teeth facing toward adjoining
teeth in the same dental arch are called proximalteeth in the same dental arch are called proximal oror
proximate surfaces.proximate surfaces. The proximal surfaces may beThe proximal surfaces may be
called eithercalled either mesialmesial oror distal.distal. These terms haveThese terms have
special reference to the position of the surfacespecial reference to the position of the surface
relative to the median linerelative to the median line of the face.of the face.
 This line is drawn vertically through the center ofThis line is drawn vertically through the center of
the face, passing between the central incisors atthe face, passing between the central incisors at
their point of contact with each other in both thetheir point of contact with each other in both the
maxilla and the mandible.maxilla and the mandible.

Those proximal surfaces which, are facedThose proximal surfaces which, are faced
toward the median line, are called mesialtoward the median line, are called mesial
surfacesurface,, and those most distant from theand those most distant from the
median line are called distal surfacesmedian line are called distal surfaces..

Four teeth have mesial surfaces that contactFour teeth have mesial surfaces that contact
each other: the maxillary and mandibular centraleach other: the maxillary and mandibular central
incisors. In all other instances, the mesial surfaceincisors. In all other instances, the mesial surface
of one tooth contacts the distal surface of itsof one tooth contacts the distal surface of its
neighbor, except for the distal surfaces of thirdneighbor, except for the distal surfaces of third
molars of permanent teeth and distal surfaces ofmolars of permanent teeth and distal surfaces of
second molars in deciduous teeth, which have nosecond molars in deciduous teeth, which have no
teeth distal to them. The area of the mesial orteeth distal to them. The area of the mesial or
distal surface of a tooth which touches itsdistal surface of a tooth which touches its
neighbor in the arch is called theneighbor in the arch is called the contact areacontact area..

 Proximal:Proximal: surface of a tooth that is adjacent tosurface of a tooth that is adjacent to
another tooth.another tooth.
 Mesial:Mesial: situated in the middle, median, towardsituated in the middle, median, toward
the middle line of the body or toward thethe middle line of the body or toward the
centerline of the dental arch.centerline of the dental arch.
 Distal:Distal: away from the median sagittal plane ofaway from the median sagittal plane of
the face and following the curvature of the dentalthe face and following the curvature of the dental
arch.arch.
 Anterior:Anterior: situated in front of; the forwardsituated in front of; the forward
position.position.
 Posterior:Posterior: situated behind.situated behind.

TheThe RootsRoots of the teeth may be single orof the teeth may be single or
multiple.multiple.
 Both maxillary and mandibular anterior teethBoth maxillary and mandibular anterior teeth
have only one root each.have only one root each.
 Mandibular first and second premolars, and theMandibular first and second premolars, and the
maxillary second premolar are single-rooted.maxillary second premolar are single-rooted.

 Maxillary first premolar has two roots in mostMaxillary first premolar has two roots in most
cases, one buccal and one palatal.cases, one buccal and one palatal.
 Mandibular molars have two roots, one mesialMandibular molars have two roots, one mesial
and one distal.and one distal.

 Maxillary molars have three roots, oneMaxillary molars have three roots, one
mesiobuccal, one distobuccal, and one palatal.mesiobuccal, one distobuccal, and one palatal.

M3M3 M2M2 M1M1 P2P2 P1P1 CaCa LL CeCe CeCe LL CaCa P1P1 P2P2 M1M1 M2M2 M3M3

It must be understood that description inIt must be understood that description in
anatomy can never follow a hard-and-fast rule.anatomy can never follow a hard-and-fast rule.
Variations frequently occur. This is especiallyVariations frequently occur. This is especially
true regarding tooth roots, e.g., facial andtrue regarding tooth roots, e.g., facial and
lingual roots of mandibular canine.lingual roots of mandibular canine.

تشريح أسنان محاضرة 2

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تشريح أسنان محاضرة 2