Intraoral Radiographic Anatomy

1
Intraoral Radiographic Anatomy The following
slides identify the anatomical structures that
may be seen on intraoral films. These structures
are more likely to be seen when using the
bisecting angle technique because of the
increased vertical angulation (increased positive
in the maxilla and increased negative in the
mandible) commonly used with this technique.
Since some of the structures may be confused with
pathology, it is important to understand their
normal appearance in order to make a proper
diagnosis.
2
Maxillary Incisor
a
b
a nasal septum b inferior concha c nasal
fossa d anterior nasal spine e incisive
foramen f median palatal suture g soft
tissue of nose
c
d
e
f
g
3
facial view
palatal view
f
c
b
e
a
d
a nasal septum b inferior concha c nasal
fossa d anterior nasal spine
e incisive foramen f median palatal
suture
4
facial view
Nasal septum
5
facial view
a
Inferior concha
6
facial view
Nasal fossa
7
facial view
Anterior nasal spine
8
palatal view
Incisive foramen
9
palatal view
Median palatal suture
10
Soft tissue of the nose
11
Red arrow points to periapical lesion (post-endo).
Red arrows lip line
12
d
f
Blue arrow chronic periapical periodontitis.
Tooth 9 is non-vital (trauma) and needs endo.
Red arrow mesiodens (supernumerary tooth)
13
Superior foramina of the nasopalatine canals (red
arrows). These foramina lie in the floor of the
nasal fossa. The nasopalatine canals travel
downward to join in the incisive foramen.
14
a
b
f
d
All the incisors are non-vital and have
periapical lesions. The purple arrows point to
external resorption the blue arrow identifies
internal resorption.
The red arrows point to an incisive canal cyst
the orange arrow identifies the root of tooth
7.
15
The red arrows point to the soft tissue of the
nose. The green arrows identify the lip line.
16
Maxillary Cuspid
a
b
a floor of nasal fossa b maxillary sinus c
lateral fossa d nose
c
d
17
facial view
a
a
c
c
b
b
a floor of nasal fossa b maxillary sinus c
lateral fossa
(a b form inverted Y)
18
facial view
Floor of nasal fossa (red arrows) and anterior
border of maxillary sinus (blue arrows), forming
the inverted (upside down) Y.
Y
19
facial view
Lateral fossa. The radiolucency results from a
depression above and posterior to the lateral
incisor. To help rule out pathology, look for an
intact lamina dura surrounding the adjacent teeth.
20
Soft tissue of the nose
Red arrows point to nasolabial fold. Also note
the inverted Y.
21
The maxillary sinus surrounds the root of the
canine, which may be misinterpreted as pathology.
The white arrows indicate the floor of the nasal
fossa. The maxillary sinus (red arrows) has
pneumatized between the 2nd premolar and first
molar
22
The red arrow identifies the lateral fossa. The
pink arrow points to CPP (chronic periapical
periodontitis abscess, granuloma, etc.).
23
Maxillary Premolar
b
c
a
a malar process b sinus septum c sinus
recess d maxillary sinus
d
24
facial view
b
b
d
c
d
c
a
a
a malar process b sinus recess c sinus
septum d maxillary sinus
25
facial view
Malar (zygomatic) process. U or j-shaped
radiopacity, often superimposed over the roots of
the molars, especially when using the
bisecting-angle technique. The red arrows define
the lower border of the zygomatic bone.
26
facial view
Sinus septum. This septum is composed of folds of
cortical bone that arise from the floor and walls
of the maxillary sinus, extending several
millimeters into the sinus. In rare cases, the
septum completely divides the sinus into separate
compartments.
27
facial view
Sinus recess. Increased area of radiolucency
caused by outpocketing (localized expansion) of
sinus wall. If superimposed over roots, may mimic
pathology.
28
facial view
Maxillary Sinus. An air-filled cavity lined with
mucous membrane. Communicates with nasal cavity
through 3-6 mm opening below middle concha. Red
arrows point to neurovascular canal containing
superior alveolar vessels and nerves.
29
Blue arrows identify radiopacity which is a
mucous retention cyst. Note relatively recent
premolar extraction sites. Green arrow points to
neurovascular canal.
The red arrows point to the nasolabial fold. The
thicker cheek tissue makes the area more
radiopaque posterior to the line.
30
Pneumatization. Expansion of sinus wall into
surrounding bone, usually in areas where teeth
have been lost prematurely. Increases with age.
31
Maxillary Molar
f
e
a maxillary tuberosity b coronoid process c
hamular process d pterygoid plates e
zygoma f maxillary sinus
d
c
b
a
32
facial view
e
e
g
g
d
d
f
c
c
f
a
a
b
b
a maxillary tuberosity e zygoma (dotted
lines) b coronoid process f maxillary
sinus c hamular process g sinus
recess d pterygoid plates image of impacted
third molar superimposed
33
facial view
Maxillary Tuberosity. The rounded elevation
located at the posterior aspect of both sides of
the maxilla. Aids in the retention of dentures.
34
facial view
Coronoid process. A mandibular structure
sometimes seen on the maxillary molar periapical
film when using the bisecting angle technique
with finger retention (The mouth is opened wide,
moving the coronoid down and forward). Note the
supernumerary molar.
35
facial view
Hamular process (white arrows) and pterygoid
plates (purple arrows). The hamular process is an
extension of the medial pterygoid plate of the
sphenoid bone, positioned just posterior to the
maxillary tuberosity.
36
facial view
Zygomatic (malar) bone/process/arch. The
zygomatic bone (white/black arrows) starts in the
anterior aspect with the zygomatic process (blue
arrow), which has a U-shape. The zygomatic bone
extends posteriorly into the zygomatic arch
(green arrow).
37
facial view
Maxillary sinus. As seen in the above film, the
floor of the maxillary sinus flows around the
roots of the maxillary molars and premolars. The
walls of the sinus may become very thin. As a
result, sinusitis may put pressure on the
superior alveolar nerves resulting in apparent
tooth pain, even though the tooth is perfectly
healthy. Note coronoid process (green arrow),
zygomatic bone (blue arrow), sinus septum (yellow
arrow) and neurovascular canal (orange arrows).
38
This film shows the coronoid process (green
arrow) and a distomolar (blue arrow) that has
erupted ahead of the third molar (red arrow). A
distomolar is a supernumerary tooth that erupts
distal (posterior) to the other molars.
The maxillary sinus is evident anterior to the
second molar (black arrows) but it disappears
posteriorly due to the superimposition of the
zygomatic bone. The orange arrows identify a
mucous retention cyst (retention pseudocyst)
within the sinus.
39
The zygomatic process (green arrows) is a
prominent U-shaped radiopacity. Normally the
zygomatic bone posterior to this is very dense
and radiopaque. In this patient, however, the
maxillary sinus has expanded into the zygomatic
bone and makes the area more radiolucent (red
arrows). The coronoid process (orange arrow), the
pterygoid plates (blue arrows) and the maxillary
tuberosity (pink arrows) are also identified.
40
This film shows the expansion of the borders of
the maxillary sinus through pneumatization (red
arrows). This expansion increases with age and it
may be accelerated as a result of chronic sinus
infections. It is most commonly seen when the
first molar is extracted prematurely, as in the
film at right (the second and third molars have
migrated anteriorly to close the space). The
coronoid process is seen in the lower left-hand
corner of each film. The green arrow identifies a
sinus recess. Note the two distomolars in film at
right (blue arrows).
41
Mandibular Incisor
a. lingual foramen b. genial tubercles c. mental
ridge d. mental fossa
d
a
b
c
42
facial view
lingual view
c
d
a
b
a lingual foramen
c mental ridge
b genial tubercles
d mental fossa
43
lingual view
Lingual foramen. Radiolucent hole in center of
genial tubercles. Lingual nutrient vessels pass
through this foramen.
44
lingual view
Genial tubercles. Radiopaque area in the midline,
midway between the inferior border of the
mandible and the apices of the incisors. Serve as
attachments for the genioglossus and geniohyoid
muscles. May have radiolucent hole in center
(lingual foramen), but not on this film. Note
double rooted canine (red arrows).
45
facial view
Mental ridge. These represent the raised portions
of the mental protuberance on either side of the
midline. More commonly seen when using the
bisecting angle technique, when the x-ray beam is
directed at an upward angle through the ridges.
46
facial view
Mental fossa. This represents a depression on the
labial aspect of the mandible overlying the roots
of the incisors. The resulting radiolucency may
be mistaken for pathology.
47
The radiolucent area above corresponds to the
location of the mental fossa. However, this slide
represents chronic periapical periodontitis
these teeth are non-vital, due to trauma.
The orange arrows above identify nutrient canals.
They are most often seen in older persons with
thin bone, and in those with high blood pressure
or advanced periodontitis.
48
Mandibular Canine
a mental ridge b genial tubercles/
lingual foramen c mental foramen
c
b
a
49
facial view
lingual view
d
b2
b2
d
a
d
c
d
b1
a mental ridge c mental foramen
b1 genial tubercles
b2 lingual foramen
50
facial view
Mental ridge. The raised portions of the mental
protuberance, sloping downward and backward from
the midline.
51
lingual view
Lingual foramen/genial tubercles. (See
description under mandibular incisor above).
52
facial view
The red arrows identify the mandibular canal and
the blue arrow points to the mental foramen.
53
Mandibular Premolar
a mylohyoid ridge b mandibular canal c
submandibular gland fossa d mental foramen
54
facial view
lingual view
b
c
b mandibular canal d mental foramen
a mylohyoid ridge (internal oblique) c
submandibular gland fossa
55
lingual view
Mylohyoid (internal oblique) ridge. This
radiopaque ridge is the attachment for the
mylohyoid muscle. The ridge runs downward and
forward from the third molar region to the area
of the premolars.
56
facial view
Mandibular canal. (Inferior alveolar canal). Runs
downward from the mandibular foramen to the
mental foramen, passing close to the roots of the
molars. More easily seen in the molar periapical.
57
lingual view
Submandibular gland fossa. The depression below
the mylohyoid ridge where the submandibular gland
is located. More obvious in the molar periapical
film.
58
facial view
Mental foramen. Usually located midway between
the upper and lower borders of the body of the
mandible, in the area of the premolars. May mimic
pathology if superimposed over the apex of one of
the premolars.
59
The mental foramen (blue arrow) is adjacent to a
periapical lesion associated with tooth 21 (red
arrow). There is slight external resorption on
21.
The green arrow points to the mental foramen. The
yellow arrow identifies a periapical lesion on
30. Note the overextension of the silver point in
the distal root, the perforation of the mesial
root and the amalgam protruding through the
perforation from the pulp chamber.
60
Mandibular Molar
a external oblique ridge b mylohyoid ridge c
mandibular canal d submandibular gland fossa
61
facial view
lingual view
b
b
a external oblique ridge c mandibular canal
b mylohyoid ridge d submandibular gland
fossa
62
a external oblique ridge b mylohyoid ridge c
mandibular canal d submandibular gland fossa
63
facial view
External oblique ridge. A continuation of the
anterior border of the ramus, passing downward
and forward on the buccal side of the mandible.
It appears as a distinct radiopaque line which
usually ends anteriorly in the area of the first
molar. Serves as an attachment of the buccinator
muscle. (The red arrows point to the mylohyoid
ridge).
64
lingual view
Mylohyoid ridge (internal oblique). Located on
the lingual surface of the mandible, extending
from the third molar area to the premolar region.
Serves as the attachment of the mylohyoid muscle.
65
facial view
Mandibular (inferior alveolar) canal. Arises at
the mandibular foramen on the lingual side of the
ramus and passes downward and forward, moving
from the lingual side of the mandible in the
third molar region to the buccal side of the
mandible in the premolar region. Contains the
inferior alveolar nerve and vessels.
66
lingual view
Submandibular gland fossa. A depression on the
lingual side of the mandible below the mylohyoid
ridge. The submandibular gland is located in this
region. Due to the thinness of bone, the
trabecular pattern of the bone is very sparse and
results in the area being very radiolucent. The
fact that it occurs bilaterally helps to
differentiate it from pathology.
67
The external oblique ridge (red arrows) and the
mylohyoid ridge (blue arrows) usually run
parallel with each other, with the external
oblique ridge always being higher on the film.
68
The mandibular canal (red arrows identify
inferior border of canal) usually runs very close
to the roots of the molars, especially the third
molar. This can be a problem when extracting
these teeth. Note the extreme dilaceration
(curving) of the roots of the third molar (green
arrow) in the film at left. The film at right
shows kissing impactions located at the
superior border of the canal.
69
Identify the anatomical structures on the
following eight slides. The answers are on the
last slide.
70
Slide 1
A. The red arrows identify the ?
71
Slide 2
A. The red arrow points to the ? B. The white
arrows identify the ? C. The blue arrow points
to the ? D. The yellow arrow identifies the ?
72
Slide 3

• The small radioluceny identified by
• the green arrow is the ?

73
Slide 4

• The radiopacity identified by the
• blue arrows is the ?
• B. The orange arrow identifies the ?

74
Slide 5

1. The yellow arrows point to the ?
2. The red arrows identify the ?

75
Slide 6

• The red arrow points to the ?
• The orange arrow points to the ?
• The blue arrows point to the
• radiolucent line known as the ?

76
Slide 7
A. The red arrows point to the ?
77
Slide 8

• The red arrows identify the ?
• What is the name of the radiolucent
• area surrounding the canal?

78
KEY Slide 1 A.
Floor of the nasal fossa Slide 2 A. Coronoid
process B. Maxillary sinus
(pneumatized into
maxillary tuberosity) C. Sinus
septum D. Zygomatic
process Slide 3 A. Lingual foramen Slide 4
A. Mylohyoid ridge B.
Submandibular gland fossa Slide 5 A.
Zygomatic process B. Maxillary
sinus Slide 6 A. Inferior concha
B. Nasal septum C. Median
palatal suture Slide 7 A. Mental ridge Slide
8 A. Mandibular canal B.
Submandibular gland fossa