Radiographic Anatomical Landmarks

O6U Dentistry Faculty / Radiology II

1. Radiographic
Anatomical Landmarks

2. The radiographic recognition of diseases requires a
sound knowledge of the radiographic appearance of
normal structure.
Intelligent diagnosis mandates an appreciation of
the wide range of variation in the appearance of
normal anatomic structure.
Most patients demonstrate many of the normal
radiographic landmarks, but it is rare patient who
shows them all.
Accordingly, the absence of one or two or even
several landmarks in any individual should not
necessarily be considered abnormal.

3. Normal Tooth Anatomy
Enamel:Enamel is the densest structure found in the
human body. Enamel is the outer most
radiopaque layer of the crown of the tooth.
Dentine:Dentine is found beneath the enamel
layer of the tooth and surrounds the
pulp cavity. Dentine appears radiopaque
and comprises most of the tooth
structure

4. Dentinoenamel junction (DEJ):
It is the junction between the dentine and the
enamel of a tooth. The DEJ appears a line
where the enamel (very radiopaque) meets the
dentine (less radiopaque).

5. Tooth structures
(A)Enamel
(B)Dentine
(C)Dentinoenamel junction

6. The alveolar process, or alveolar bone,
serves as the supporting structure for
the tooth of the jaws.
The alveolar bone: is the bone of the
maxilla and mandible that supports
and encases the root of teeth. Alveolar
bone is composed of dense cortical
bone and cancellous bone.
Supporting structures:

7. Types of bone
A) Cortical bone
Cortical bone, also referred to as compact bone,
is the dense out layer of bone.
Cortical bone resists the passage of X-ray beam,
and appears radiopaqueon the radiograph.
The inferior border of the mandibleis composed of
cortical bone and appears radiopaque.

8. Cortical bone appears very
radiopaque on a dental radiograph

9. B) Cancellous bone
Cancellous bone is the soft spongy bonelocated
between two layers of dense cortical bone.
Cancellous bone is composed of numerous bony
trabeculaethat form a lattice like network of
intercommunicated spaces filled with bone marrow.
The trabeculae resist the passage of the X-ray beam
and appearradiopaque; in contrast, the marrow spaces
permit the passage of X ray beam and appear
radiolucent.

10. Cancellousbone appears
predominantly radiolucent

11. The anatomic landmarks of the
alveolar process include the lamina
dura, the alveolar crest and the
periodontal ligament space.
Anatomy of alveolar bone:

12. Alveolar crest:
Thealveolar crest is the most coronal
portion of the alveolar bone found
between the teeth. It is made up of dense
cortical bone and is continuous with the
lamina dura.
Radiographic appearance:
The alveolar crest appears radiopaque and is
typically located 1.5 to 2.5 mmbelow the
cementoenamel junction.

13. Lamina dura:
It is the wall of the tooth socket that surrounds the root
of the tooth.
The lamina dura is made up of dense cortical
bone.
Radiographic appearance:
On the dental radiograph the lamina dura
appears as a dense radiopaque line that
surround the root of the tooth.

14. Periodontal ligament space:
It is the space between the root of the tooth
and the lamina dura.
Radiographic appearance:
It appears as a thin radiolucent linearound the
root of the tooth. In the healthy periodontium,
the PDL space appears as a continuous
radiolucent line of uniform thickness.

16. The periodontal ligament space appears
as a thin radiolucent line around the
roots of the tooth

17. Normal radiographic
landmarks

18. Maxilla
Incisor region
Radiolucent anatomical landmarks :-
Incisive foramen
Median palatal suture
Nasal cavity
Superior foramina of the Nasopalatine canal
Lateral fossa

19. Radiopaque anatomical landmarks :-
Nasal septum
Floor of nasal cavity
Anterior nasal spine
Inferior nasal conchae

20. On a maxillary periapical radiograph the
incisive foramen appears as a small ovoid or
round radiolucentarea located between the
roots of the maxillary central incisors

21. Superior foramina of the Nasopalatine canal
appear as two small rounded radiolucencies
located superior to the apices of the maxillary
central incisors

22. Median palatine suture appears as a thin radiolucent line
between the maxillary central incisors. It’s bounded on
both sides by dense radiopaque cortical bone.

23. on the maxillary periapical radiograph
the lateral fossa appears as a radiolucent
area between the maxillary canine and
lateral incisor

24. The nasal cavity appears as a large
radiolucent area above the upper incisors

25. The anterior nasal septum appear as a
vertical radiopaque partition divides the
nasal cavity

26. The floor of the nasal cavity
appears as a dense radiopaque
band above the maxillary incisors

27. The anterior nasal spine appears as a V-shaped
radiopaquearea located at the intersection of
the floor of the nasal cavity and nasal septum.

28. The inferior nasal conchae appear as a
diffuse radiopaque mass or projection
within the nasal cavity.

29. Canine region
Radiolucent anatomical landmarks :-
Nasolacrimal duct
Nasal cavity
Maxillary sinus
Lateral fossa

30. Radiopaque anatomical landmarks:-
(Inverted Y shape)
Lateral wall of nasal fossa
Anterior border of maxillary sinus
Floor of maxillary sinus

31. The inverted Y-shaped appear as a
radiopaque upside-down Y

32. Premolar region
Radiolucent anatomical landmarks :-
Maxillary sinus
Nutrient canals within the maxillary sinus
Radiopaque anatomical landmarks:-
Septa within the maxillary sinus
Borders of maxillary sinus

33. Molar region
Radiolucent anatomical landmarks :-
Maxillary sinus
Nutrient canals within the maxillary sinus

34. Radiopaque anatomical landmarks:-
Septa within the maxillary sinus
Borders of maxillary sinus
Maxillary tuberosity
Hamular process
Zygomatic process of maxilla
Zygoma
Coronoid process of the mandible

35. The maxillary sinus appears as a radiolucent
area located above the apices of the maxillary
premolars and molars. The floor of maxillary
sinus is composed of dense cortical boneand
appears as a radiopaqueline.

36. the septa appear as radiopaque lines
within the maxillary sinus.

37. Nutrient Canals with the maxillary sinus:
On a maxillary periapical radiograph
nutrient canals appear as a narrow
radiolucent bandbounded by two thin
radiopaque lines.

38. Nutrient canals appear as
narrow radiolucent lines

39. The maxillary tuberosity appears as a radiopaque
bulgedistal to the third molar region

40. Hamular process:-small hook-like projection of
bone located posterior to the maxillary tuberosity
The radiographic appearance of the hamulus
variesin length, shape, and width.

41. Zygomatic process of the maxilla:
The Zygomatic process of the maxilla is a
bony projection of the maxilla that
articulates with the zygoma or malar bone.
The Zygomatic process of maxilla is composed
of dense cortical bone.

42. The Zygomatic process of the maxilla appears
as U-shapedradiopacity superior to the
maxillary molars

43. Zygoma
The zygoma or cheek
bone (also referred to
as the malar or
Zygomatic bone)
articulates with the
Zygomatic process of
the maxilla.
The zygoma is composed
of dense cortical bone.

44. The zygoma appears as a diffuse
radiopaque band that extend distally
from the Zygomatic process of the
maxilla

45. The Coronoid process appears as a triangle
radiopaque superimposed over, or inferior to, the
maxillary tuberosity region.

46. Mandible
Anterior region
Radiolucent anatomical landmarks:-
Nutrient canals
Lingual foramen
Mental fossa

47. Radiopaque anatomical landmarks:-
Mental ridge
Genial tubercle
Inferior border of the mandible

48. Premolar region
Radiolucent anatomical landmarks:-
Metal foramen
Mandibular canal
Radiopaque anatomical landmarks:-
Mylohyoid ridge

49. Molar region
Radiolucent anatomical landmarks:-
Mandibular canal
Physiological thinning of bone
Submandibular fossa

50. Radiopaque anatomical landmarks:-
External oblique ridge
Internal oblique ridge
Borders of mandibular canal
Inferior border of the mandible

51. Lingual foramen:-small radiolucent dot inferior to
the mandibular incisors and is surrounded by the
genial tubercles, which appear as a radiopaque ring.

52. Genial tubercles:
The genial tubercles are tiny bumps of
bone that serve as attachment of the
genioglossus and geniohyoid muscles.
The genial tubercles are located on the
lingual aspect of the mandible.

53. The genial tubercles appear as a ring shaped radiopacity
below the apices of the mandibular incisors

54. Nutrient canals:
They are tube like passageways through bone
that contain nerves and blood vessels that
supply the teeth.
Inter-dental nutrient canals are most often seen
in the anterior mandible, a region that typically
has thin bone.
Radiographically, nutrient canals are readily seen
in areas of thin bone. In edentulous mandible,
nutrient canals may be more prominent.

55. Nutrient canals appear as thin
vertical radiolucent lines

56. Mental ridge:
It is a linear prominenceof cortical bone located in the external surface of the
anterior portion of the mandible.
The mental ridge extends from the premolar region to the midline and slopes
slightly upwards.
Mental fossa:-
Depressed area of bone located on the external surface of the anterior
mandible above the mental ridge.
The radiographic appearanceof the mental fossa varies and is
determined by the thickness of the bone in the anterior region of the
mandible.

57. Mental ridge appears as a thick radiopaque band
that extends from the premolar region to the
incisors region.

58. The mental fossa appears as a radiolucent area
above the mental ridge

59. Mental foramen:
It is an opening or hole in bone located on the
external surface of the mandible in the region
of the mandibular premolars.
Radiographic appearance:on a mandibular
periapical radiograph the mental foramen appears as a
small ovoid or round radiolucentarea located in the
apical region of the mandibular premolars.

60. The mental foramen appears as a small ovoid
or round radiolucent area located in the apical
region of the mandibular premolars.

61. Mylohyoid ridge:
It is a linear prominent of bone
located on the internal
surface of the mandible.
The ridge extends from the
molar region downward and
forward toward the lower
border on mandibular
symphysis.
The Mylohyoid ridge serves as
an attachment site of a
muscle of the same name.

62. The Mylohyoid ridge appears as a dense
radiopaque bandthat extends downward and
forward from the molar region.

63. External oblique ridge:
The external oblique ridge
(also known as the external
oblique line) is linear
prominence of bone located
on the external surface of
the body of the mandible.
The anterior border of the
ramus ends in the external
oblique ridge.
The external oblique ridge
typically ends in the
mandibular third molar
region.

64. The external oblique ridge appears as a radiopaque
bandextending downward and forward from the
anterior border of the ramus of the mandible.

65. Depending on the radiographic technique used
(bisecting angle vs paralleling); the internal and
external oblique ridges may be superimposed on one
another.
When the ridges appear separate, the superior
radiopaque band is the external oblique ridge, and
the inferior oblique radiopaque is the internal oblique
ridge.

66. Mandibular canal:
The mandibular canal is a
tube-like passage-way
through bone that travels
the length of the mandible.
The mandibular canal extends
from the mandibular
foramento the mental
foramenand houses the
inferior alveolar nerve and
blood vessels.

67. Radiolucent band outlined by two thin radiopaque lines
It appears below or superimposed over the apices of the
mandibular teeth.

70. Submandibular fossa:
The Submandibular fossa (also known as the
mandibular fossa or submaxillary fossa) is
scooped-out depression area of bone located on
the internal surface of the mandible inferior to
the Mylohyoid ridge.
The Submandibular salivary gland is found in the
Submandibular fossa.

71. The Submandibular fossa appears as a
radiolucent areain the molar region below the
Mylohyoid ridge.