Radiographic anatomical landmarks By Dr. Armaan Singh

1. RADIOGRAPHIC
ANATOMICAL
LANDMARKS

2. CONTENTS
Tooth anatomy
Supporting structures
Anatomical landmarks

3. Tooth Anatomy
 Teeth are composed primarily of dentin, with an enamel cap over
the coronal portion and a thin layer of cementum over the root
surface.
Radiographic Appearance of Enamel
ENAMEL appears more radio-opaque than other tissues.
It is 90% mineral causes greator attenuation of X-ray photons.

4. RADIOGRAPHIC APPEARANCE
OF DENTIN
75% mineral content less radiopaque than enamel.
Radiopacity similar to bone.
ENAMELODENTINAL JUNCTION appears as a distinct
interface separating these two structures.

5. Radiographic appearance of
CEMENTUM
 50%mineral content and it appears as a very thin layer on the
root surface.
 It is usually not so apparent radiographically.
CERVICAL BURNOUT
 Radiographs sometimes show diffuse radiolucent areas
with ill defined borders present on the mesial or distal
aspects of the teeth in the cervical region.
 These regions appear between the edge of the enamel cap
and the crest of the alveolar ridge.

6. REASON FOR CERVICAL
BURNOUT
Normal configuration of the affected teeth, results in
decreased X-ray absorption in the areas in question.
Perception of these areas is due to contrast with the
adjacent ,relatively radiopaque enamel and alveolar –
bone.
It should not be confused with root caries which has
similar appearance.

7. Radiographic Appearance of the
Pulp
 It is composed of soft tissues so it appears radiolucent.
 Pulp chambers and root canals extend from the interiors of the
chamber till the root apices.
 It is seen radiographically also as apical foramen.
 In some cases, it may exit on the side of the canal.
 Lateral canals may end at the apex as a discernible foramen
or may exit at the side of the root.

8. ENAMEL
PULP
DENTIN

9.  The pulp canals of a developing tooth root diverge and walls of the
root taper to a knife edge.
 A radiolucent area is seen surrounding it in the trabecular bone. It
is surrounded by the hyperostotic bone.
 IT IS THE DENTAL PAPILLA WITH ITS BONY CRYPT.
 Its radiographic evaluation helps in determining the stage of
maturation of the developing tooth.

10. Supporting Structures
Periodontal ligament
space
Lamina dura
Alveolar crest
Trabecular bone

11. RADIOGRAPHIC FEATURES OF THE
PERIODONTAL LIGAMENT SPACE
It is composed of collagen so appears as a radiolucent
space between the root and lamina dura.
It is thinner in the middle of the root and slightly wider
near the alveolar crest and the apex ,suggesting that the
fulcrum of the physiologic movements is in the region
where PDL is thinnest.

12. RADIOGRAPHIC FEATURES OF
LAMINA DURA
 It is a thin radiopaque layer of dense bone surrounding the tooth
socket.
 Its radiographic appearance is due to attenuation of the X-ray beam as
it passes tangentially through the thickness of the bone.
 It is thicker than the surrounding trabecular bone and thickness
increases with increase in amount of occlusal stress.

13. RADIOGRAPHIC FEATURES OF
ALVEOLAR CREST
It is the radiopaque gingival margin of the alveolar
process which surrounds the teeth.
It is considered normal if it is 1.5mm or less from the
CEJ.
It shows apical recession with the age or periodontal
disease.

14. RADIOGRAPHIC FEATURES OF
THE CANCELLOUS BONE
 Also called as the trabecular bone or the spongiosa.
 Lies between the cortical plates in both the jaws.
 It is composed of thin radiopaque plates and rods surrounding many
small radiolucent pockets of marrow.
 In posterior maxilla, it is similar to anterior maxilla but marrow spaces
are larger.

15. ANATOMIC LANDMARKS OF MAXILLA
Intermaxillary suture
Anterior nasal spine
Nasal fossa and Nasal septum
 Incisive foramen
 Superior foramina of nasopalatine canal
 Lateral fossa
 Nose
Nasolacrimal canal
Maxillary sinus
Zygoma & zygomatic process of maxilla
 Nasolabial fold
Pterygoid plates

16. RADIOGRAPHIC FEATURES
INTERMAXILLARY SUTURE
 Also called as median suture.
 In IOPA, it appears as a thin radiolucent line in the midline
between the two portions of premaxilla.
 It extends from the alveolar crest between the central
incisors superiorly through the anterior nasal spine and
continues posteriorly between the maxillary palatine process
to the posterior aspect of the hard palate.

17. RADIOGRAPHIC FEATURE
Anterior Nasal Spine
Mostly seen on IOPA of maxillary central incisors.
Located in midline1.5-2cm above the alveolar crest.
It is radiopaque and usually V-shaped.

18. RADIOGRAPHIC FEATURES
NASAL FOSSA & NASAL
SEPTUM
The nasal cavity shows the hazy shadow of the
inferior nasal conchae extending from the right and
left lateral walls
Floor of Nasal
Fossa
Nasal
Septum

19. RADIOGRAPHIC FEATURES
INCISIVE FORAMEN
Also called as NASOPALATINE or ANTERIOR
PALATINE FORAMEN.
It is the oral terminatus of the nasopalatine canal.
It transmits the nasopalatine vessels and nerves.
Lies in the midline of palate behind the central incisors at
the junction of the median palatine and incisive sutures.
Radiographic image variability is due to:
1.Different angles of the X-ray beam.
2.Variability in its anatomic size.
IT IS FREQUENTLY THE POTENTIAL SITE
OF CYST FORMATION.

20. Radiographic features of Superior
Foramina of the Nasopalatine
canal
 The nasopalatine canal originates at two foramina in floor of the
nasal cavity.
 Radiographically, it can be recognized as two radiolucent areas above
the apices of the central incisors in floor of the nasal cavity near its
anterior border and both the sides of the septum.
Lateral wall of
nasopalatine
canalSuperior
foramina

21. RADIOGRAPHIC FEATURES OF
THE LATERAL FOSSA
Also called as INCISIVE FOSSA.
Appears as depression in the maxilla near the
apex of the lateral incisor .
Appears diffusely radiolucent in the IOPA.

22. RADIOGRAPHIC FEATURES OF
THE NASOLACRIMAL CANAL
The nasal and maxillary bones form the
nasolacrimal canal.
It runs from the medial aspect of the antero inferior
border of the orbit inferiorly, to drain under the
inferior conchae into the nasal cavity.

23. RADIOGRAPHIC FEATURES OF
NOSE
The soft tissue of the nose is frequently seen in the
projections of the maxillary central and lateral
incisors ,superimposed over the roots of these
teeth.
Image appears uniformly opaque with a sharp
border.

24. RADIOGRAPHIC FEATURES
NASOLABIAL FOLD
An oblique line demarcating a region that
appears to be covered by a slight radio opacity
frequently traverses periapical radiographs of
the premolar region.

25. RADIOGRAPHIC FEATURES OF
MAXILLARY SINUS
MAXILLARY SINUS is an air containing cavity
lined by mucous membrane.
Appears as the three sided pyramid .
Base -formed by mesial wall adjacent to nasal
cavity.
Apex –extending laterally into the zygomatic
process of maxilla.

26. MAXILLARY SINUS
On the IOPA, maxillary sinus appears as a thin
,delicate radiopaque line.
It extends from the distal aspect of the canine to
the posterior wall of the maxilla above the
tuberosity.
Around the age of puberty, its floor coincides with
the floor of the nasal cavity.

27. MAXILLARY SINUS
 In response to the loss of function (associated with loss
of posterior teeth) the sinus may expand further into the
alveolar bone , occasionally extending to the alveolar
ridge.
 Thin radiolucent lines of the uniform width are found
within the image of the maxillary sinus.
 These are shadows of the neuro -vascular canals that
accommodate the posterior superior vessels and
nerves.

28. RADIOGRAPHIC FEATURES
ZYGOMATIC PROCESS AND
ZYGOMATIC BONE
The zygomatic process of the maxilla is an extension of
the lateral maxillary surface that arises in the region of the
apices of the first and the second molars and serves as
the articulation for the zygomatic bone.
Appears as a U-shaped radiopaque line with rounded
ends projected in the apical region of the first and second
molars.

29. RADIOGRAPHIC FEATURES
PTERYGOID PLATES
 The medial and lateral pterygoid plates lie immediately
posterior to the tuberosity of maxilla.
 They cast a single radiopaque shadow without any evidence of
trabeculation.
 Extending inferiorly from the medial pterygoid plate, the
hamular process may be seen.

30. Anatomic Landmarks of Mandible
Symphysis
Genial tubercles
Lingual foramen
Mental ridge
Mental fossa
Mental foramen
Mandibular canal
Nutrient canals
Mylohyoid ridge
Submandibular gland fossa
External oblique ridge
Inferior border of mandible
Coronoid process

31. RADIOGRAPHIC FEATURES
SYMPHYSIS
The region of mandibular symphysis in infants
demonstrate a radiolucent line through the midline
of the jaw between the images of the forming
deciduous central incisors.
The suture usually fuses by the end of 1st
year of
life and is no longer radiographically apparent.

32. RADIOGRAPHIC FEATURE
GENIAL TUBERCLES
These are tiny bumps of bone that serve as attachment
for the genioglossus and geniohyoid muscles.
Present on lingual side.
On IOPA, appears as ring shaped radiopacity below the
apices of mandibular incisors.

33. RADIOGRAPHIC FEATURE
LINGUAL FORAMEN
 It is a hole or tiny opening located on the internal surface of mandible
and surrounded by the genial tubercles.
 Radiographically, appears as a radiolucent dot inferior to the apices
of the mandibular incisors.

34. RADIOGRAPHIC FEATURES MENTAL
RIDGE
 It is a linear prominence of cortical bone located on the external
surface extending from the premolar region to the midline and slopes
upward.
 Radiographically, appears as a radiopaque band that extends from the
premolar region to the incisor region.

35. RADIOGRAPHIC FEATURE
MENTAL FOSSA
Located above the mental ridge.
On peri apical radiograph, appears as a
radiolucent area above the mental ridge.

36. RADIOGRAPHIC FEATURE
MENTAL FORAMEN
Located on the external surface of the mandible as an
opening in the region of the mandibular premolars.
Mental nerves and blood vessels exit through it.
Radiogarphically, it appears as a small ovoid
radiolucent area located below the apices of the
premolars.

37. RADIOGRAPHIC FEATURES
MANDIBULAR CANAL
Tube like passage extending from the mandibular
foramen to the mental foramen and contains
inf.alv. Nerves and blood vessels.
Appears as a radiolucent band outlined by two
radiopaque lines of cortical plate.

38. RADIOGRAPHIC FEATURES
NUTRIENT CANALS
Nutrient canals are tube like passage-ways
through bone that contains nerves and blood
vessels that supply the teeth.
Radiographically seen as vertical radiolucent lines.
More prominent in anterior mandible where bone is
thin.

39. RADIOGRAPHIC FEATURES
MYLOHYOID RIDGE
Linear prominence of bone located on the internal surface
of mandible.
Extends from the molar region downward and forward
towards the lower border of mandibular symphysis.
On IOPA, appears as radiopaque band extending
downward from molars.

40. RADIOGRAPHIC FEATURES
EXTERNAL OBLIQUE RIDGE
Linear prominence of bone located on external
surface of mandible extending downwards and is a
continuation of anterior border of ramus.
It appears as a radiopaque band extending
downwards and forwards from ant. border of
mandible & ends in 3rd
molar region.

41. RADIOGRAPHIC FEATURES
SUBMANDIBULAR GLAND
FOSSA
Depressed area of bone located on the internal surface of
mandible.
Submandibular salivary gland lies in this fossa.
It appears as a radiolucent area in the molar region below
the mylohyoid ridge.

42. RADIOGRAPHIC FEATURES
INTERNAL OBLIQUE RIDGE
 Linear prominence of bone located on internal surface of
mandible extending downwards and forwards from ramus.
 It appears as a radiopaque band extending downwards from
ramus.

43. RADIGRAPHIC FEATURES
INFERIOR BORDER OF THE
MANDIBLE
Occasionally, seen as a dense broad radiopaque band of
bone.

44. RADIOGRAPHIC FEATURES
CORONOID PROCESS
It is a marked prominence of bone on the ant. ramus of
the mandible.
Not seen on a mandibular IOPA but appears on a
maxillary molars IOPA.
It is seen as a triangular radiopacity superimposed over
or inferior to maxillary tuberosity.

45. RESTORATIVE MATERIALS
Vary in their radiographic appearance.
Depend primarily on their thickness, density and
atomic number.
A variety of restorative materials may be
recognized on intra oral radiographs.

46. Thank You