Anatomic radiopacities / dental implant courses

ANATOMIC RADIOPACITIES OF
JAWS
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

Common to both jaws
Teeth
Bone
Cancellous bone
Cortical plates
Lamina dura
Alveolar process

Peculiar to maxilla
 Nasal septum and boundaries of nasal fossa
 Anterior nasal spine
 Canine eminence
 Walls and floor of maxillary sinus
 Zygomatic process of maxilla and zygomatic bone
 Maxillary tuberosity
 Pterygoid plates, pterygoid hamulus
 Coronoid process

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• www.indiandentalacademy.com
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Peculiar to mandible
 External oblique ridge
 Mylohyoid ridge
 Internal oblique ridge
 Mental ridge
 Genial tubercles
Superimposed radiopacities:
 Soft tissue shadows
 Mineralised tissue shadows

Teeth
• Enamel covers the coronal portion of tooth most
dense tissue in the body.
• Dentin is less r/o than the enamel.
• Enamel and dentin of developing tooth germ is
completely surrounded by thin layer of cortical
bone.

Teeth

Cancellous bone
• The cancellous bone (also called trabecular bone or
spongiosa) lies between the cortical plates in both
jaws. It is composed of thin radiopaque plates and
rods (trabeculae) surrounding many small
radiolucent pockets of marrow.

• anterior maxilla- trabeculae are typically thin and
numerous, forming a fine, granular, dense
pattern(marrow spaces are small and numerous).
• Post maxilla- marrow spaces are larger.
• anterior mandible- trabeculae are thicker than in
the maxilla,coarser pattern, trabecular plates that
are oriented more horizontally.
• Post man- marrow spaces are larger.

ant man-coarser
trabecular plates and
larger marrow spaces
than in the anterior
maxilla
anterior maxilla is
trabecular plates and
multiple small
trabecular spaces

Posterior mandible
showing large marrow
spaces and sparse
trabeculation, especially
inferiorly

Cortical plates
• Maxilla and mandible are covered by thin layer of
compact bone ,cortical plates seen in occlusal r/g s.
• Cortical plates of mandible are thicker than maxilla.

Man and max occlusal r/gs showing
cortical plates

Lamina dura
• The part of alveolar bone that surrounding the tooth socket is
thin layer of dense cortical bone called e lamina dura.
• In r/g s it appears as a r/o line surrounding each root.
• x-ray beam passes tangentially through many times the
thickness of the thin bony wall, which results in its observed
attenuation.
• Developmentally the lamina dura is an extension of the lining
of the bony crypt that surrounds each tooth during
development.

• double lamina dura-if the mesial or distal surfaces
of roots present two elevations in the path of the x-
ray beam.
• A common example of this is seen on the buccal and
lingual eminences on the mesial surface of
mandibular first molar roots.

radiographs of lamina dura
white r/o line around roots

Doulble PDL space and
lamina dura- due to
convexity on root surface
Developing tooth
surrounded by bony
crypt r/o

Alveolar process
• Alveolar process, lamina dura and spongy bone make
up alveolar process.
• Gingival margin of alveolar process termed as
alveolar crest.

Nasal septum
• Seen on films of max incisors.
• Wide, vertical r/o shadow, deviates slightly from
midline.
• Nasal fossa is lined by compact bone.
• Floors are extended bilaterally from inferior limit of
septum.
• Maxillary premolar and molar r/g s floor of the
nasal fossa is superimposed with maxillary sinus.

r/gs of nasal septum and floor of
nasal fossa

Anterior nasal spine
• It is a projection of maxilla at the lower borders of
nasal fossa
• Seen as small white v-shaped opaque shadow below
nasal septum.

Nasal spine

Walls and floor of maxillary sinus
• Margins of sinus are formed by thin layers of dense cortical
bone that appear as fine white lines.
• Outline of sinus extends from area of canine to tuberosity.
• an X or an inverted Y is produced on sup aspect of canine
and 1st premolar area, where ant med wall of sinus is
superimposed with lateral wall of nasal chamber.(Y-line of
ennis)
• X is produced when lines cross, inverted Y is produced sup
portion of ant wall of sinus is indistinguishable.
• Sinus septa present vary in number and location.

r/gs of maxillary sinus appears
multilocular and floor as white r/o line

r/g s of maxillary sinus
wallls extended in b/n
roots

anterior border of the
maxillary sinus (white
arrows) crosses the floor
of the nasal fossa

Panoramic r/g of maxillary sinus

Zygomatic process of maxilla
• It is an extension of the lateral maxillary surface in
the region of 1st and 2nd maxillary molar serves
articulation of zygomatic bone.
• U-shaped r/o shadow above the roots of max 1st
molar.
• When sinus receded deep in to the process the image
of sinus with in process as a dark, walls are well
defined and thin.

The zygomatic
process of the maxilla
(arrows) protrudes
laterally from the
maxillary wall.

Zygomatic bone
• Inf border of zygomatic bone may appear in sup
aspect of max molar area as dense, more or less
horizontal r/o extending from zygomatic process
postly.
• It can be identified as a uniform grey or white
radiopacity over the apices of the molars.

r/g of inferior border
of zygomatic arch

Maxillary tuberosity
• Posterior boundary of max alveolus.
• It is around projection cancellous bone lined by
compact bone.

r/s of maxillary tuberosity

Perygoid plates and hamular process
• Rarely appear on r/g s post to 3rd molar.
• single radiopaque homogeneous shadow without
any evidence of trabeculation.

A.Pterygoid plates
B.Hamular process

Coronoid process
• Appears on r/g s of max 3rd molar region.
• Generally cone shaped with apex pointing upward
and forward.

Coronoid process

External oblique ridge
• Continuation of ant border of ramus.
• It is prominent r/o line passing across molar region.

External oblique ridge

Mylohyoid ridge(internal oblique ridge)
• Originates on the medial portion of ramus over
lingual surface of mandible.
• Seen in post region crossing retromolar area
,parallel to external oblique ridge.

r/g of mylohyoid ridge

Mental ridge
• Ant and inf part of chin thickend by triangle of
denser bone –mental triangle or mental ridge.
• Apex is formed by Two bilateral r/o lines
occasionally run anteriorly from premolar area to
midline where they meet.
• This image is seen when long expense of cortical
bone over the chin is projected by x ray beam
directed tangentially o the cortical surface of mental
tubercle.(excessive -ve angulation)
• Hallmark of bisecting angle technique.

Mental ridge (arrows) on the anterior
surface of the mandible, seen as a
radiopaque ridge.

Genial tubercles
• In the midline of lingual surface of mandible , an
elevation below the roots of incisors-genial
tubercle(geniohyoid tubercle)
• Appears as localized area of increased density in the
centre of which a small dark spot(foramen for
transmission of vessels)

Genial tubercles (arrow)
on the lingual surface of
the mandible in this
cross-sectional
mandibular occlusal view.
The genial tubercles
appear as a radiopaque
mass, without evidence
of the lingual foramen.

Superimposed
radiopacities
Soft tissue shadows:
• outline of lip-max and man ant projections
• soft tissue of tip of nose-max ant teeth
• Nasolabial fold- canine and premolar projections
• Shadow of gingival tissue, fibrous tissue.

Nasolabial fold -shadow

Inferior border of mandible

References
• Principles practice oral radiologic interpretation
H.m worth
• Oral radiology principles and interpretation 5th
edition white & pharaoh
• Differential diagnosis of orol and maxillofacial
lesions 5th edition norman.k and wood,paul w.goaz

Anatomic radiopacities / dental implant courses

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