This document summarizes the key radiographic structures seen in dental x-rays of the mandible and maxilla. It describes structures peculiar to each jaw such as the mandibular foramen, mental foramen and lingual foramen in the mandible. In the maxilla it outlines the intermaxillary suture, incisive foramen and maxillary sinus. Common structures like the periodontal ligament space and developing tooth crypts are also defined. Each structure is concisely described and examples are shown through radiographic images to illustrate their appearance on dental x-rays.

1. INDIAN DENTAL
ACADEMY
Leader in continuing
Dental Education

2. Introduction
The radiographic recognition of disease requires a
sound knowledge of the radiographic appearance
of normal structures

3. Radiographic structures peculiar to the
mandible
Mandibular foramen
Mandibular canal
Lingual foramen
Mental foramen
Airway shadow
Submandibular shadow
Mental fossa
Midlne symphysis
Medial sigmoid depression
Pseudo cyst of condyle
Anterior buccal mandibular
depression

4. Structures peculiar to the maxilla
Intermaxillary suture
Incisive foramen
Incisive canal and superior foramina of incisive canal
Lateral fossa
Nasal fossa
Nasolacrimal duct or canal
Maxillary sinus
Greater palatine foramina
Aberrant foramen

5. Structures common to both jaws
Pulp chamber and root canal
Periodontal ligament space
Marrow space
Nutrient canal
Developing tooth crypts

6. Intermaxillary Suture
Median suture
The intermaxillary suture is the
anterior median suture between
the two maxilla
It appears on radiograph as a thin radiolucent line
in the midline between the two portions of maxilla
The suture is limited by two parallel radiopaque
borders on each side

7. It extends from the alveolar crest between the central incisors
superiorly through anterior nasal spine and continues
posteriorly between the maxillary palatine process to the
posterior aspect of the hard palate
It usually fuses later in life and is then no longer represented
on the radiographs

8. Intermaxillary suture extending from crest of alveolar
bone between central incisors superiorly till anterior
nasal spine

9. Incisive foramen
o Nasopalatine or anterior palatine foramen
o It is the oral terminatus of the nasopalatine canal
o Lies in the midline of palate behind
the central incisors at the junction of median
palatine and incisive sutures
Radiographic image variability is due to
o Different angles of the xay beam
o Variabillity in its anatomic size

10. Incisive foramen

11. Greater palatine foramen
It can be identified on each side as a round to
oval illdefined radiolucency over or
between the apices of maxillary second and
third molars

12. Superior foramina of the
nasopalatine canal
The nasopalatine canal originates at two foramina in
floor of the nasal cavity
Radiographically,it can be recognised as two
radiolucent areas above the apices of the central
incisors in floor of the nasal cavity near its anterior and
both the sides of the septum

13. Lateral fossa
o Incisive fossa
o It is a gentle depression in the maxilla near the
apex of lateral incisor

14. Nasal fossa
o the inferior aspect of the nasal cavities is often
seen on periapical radiographs of the incisor
and canine regions
o These cavities appear as twin radiolucencies
seperated by radiopaque septum
o The inferior border of the cavities is often
projected above the apices of the incisors and
canines

15. Nasal fossa

16. Nasolacrimal duct or canal
o The nasal and maxillary bone form the
nasolacrimal canal
o It runs from the medial aspect of the
anteroinferior border of the orbit inferiorly
to drain under the inferior choncha into the
nasal cavity
o It is especially visualized when steep
vertical angle is used

17. The nasolacrimal canals are commonly
seen the maxillary premolars and molars.
as ovoid radiolucencies (arrows) on
maxillary occlusal
projections.
The nasolacrimal canal (arrow) is
occasionally seen near the apex of
the canine when steep vertical
angulation is used. Note the
mesiodens (supernumerary tooth)
superior to the central incisor

18. Maxillary sinus
o It is an air containing cavity present in maxilla
o The sinus may be considered as a three sided pyramid
o The maxillary sinuses show considerable variation in
size. They enlarge during childhood, achieving mature
size by the age of 15 to 18 years
o Although septa appear to separate the sinuses into
distinct compartments, this is seldom the case because
the septa are usually of limited extent.
o It has been reported, however, that in 1% to 10% of
examined skulls, complete septa did in fact divide the
sinus into individual compartments, each compartment
with separate ostia for drainage

19. Maxillary sinus on intral oral periapical radiographs

20. Septa in the maxillary
sinus give a
compartmentalized
appearance to the
sinus.
Maxillary sinus
showing septa that
divide it into
separate
compartments.

21. Maxillary sinus on opg

23. Airway shadow
o Airway shadow is bilateral,relatively
radiolucent area recorded on panaromic
and cephalometric and lateral oblique
radiographs
o It runs in an inferoposterior direction
across the anle of the mandible just
posterior to the molar region
o Nasopharyngeal air shadow
o Oropharyngeal airway

25. Airway shadows

26. Aberrant foramen
• They are observed in the anterior portion of
the maxilla
• Rounded formen situtated to one side of the
midline
• Uppercuspid-bicuspid area
• Size-1 to 3mm
• Peripheral thin cortex
• In place of a foramen there may be a distinct
canal varying in length from few mm to 1cm

27. Mandibular foramen
Mandibular foramen is situated just above the
midpoint in the medial surface of the ramus and
just posterior to the midpoint between the anterior
and posterior borders
It transmits inferior dental vessels
Visble on
Panaromic
Lateral oblique
Its outline varies from traingluar to oval to funnel s

28. o Mandibluar foramen is seldom larger than
1cm in diameter
o Bilateral occurrence
o Association with mandibular canal

29. Mandibular foramen

30. Mandibular canal
o The largest of the nutrient canal in the jaws
o The madibular canal appears as a relatively
radiolucent channel bounded by definite thin
radiopaque lines through out
o Mandibular foramen mental foramen
o Occasionally canal extend some distance
anterio and inferiorly from the mental
foramen ..where it is called incisive canal

31. o Great variation in width and prominence of the
mandibular canal
o Variation in postion of the canal
o The curvilinear course is normally rather
gentle;abrupt changes in outline ,whether it
narrows,broadens becomes discontinues or alters
in directiosuggest pathosis

32. Inferior alveolar canal

33. Line diagram showing the
characteristic triangular area of
bone formed by cortical outlines of
bifid canals
Cropped panoramic
radiograph of the
patient showing
bifid canals
(marked with
arrows) forming
characteristic
triangular island of
bone

34. Mental foramen
o The mental foramen is the anterior limit of the
inferior dental canal
o b/w the alveolar crest process and the lower
border of mandible
o The shape of the foramen may vary
round,oblong.slitlike or very irregular and
partially or completely corticated
The position of the mental foramen is variable
o Image of two mental foramen have also observed
o When foramen is projected over one of the
premolars it may mimic periapical disease

35. Mental foramen

38. Lingual foramen
o It is present on the lingual surface of the
midline of the mandible in the region of the
genial tubercles
o Number varies from 2 to many
o Superior foramina
o Inferior foramina
o It is typically visualized as a single round rl
canal with a well defined radiopaque border
lying in the midline

40. Symphysis
o Mandibular symphysis in infants
demonstrates a radiolucent line through the
midline of the jaw between forming decidious
central incisors
o Fuses by the end of 1st yr
o If this radiolucency is found in older
individuals,it is abnoramal and may suggest a
fracure or cleft

41. symphysis

42. Mental fossa
The mental fossa is a depression on the labial
aspect of the mandible extending laterally
from midline and above the mental ridge
Because of its relative thinness of jawbone the
image of this depression may appear rl
mimicing a perapical pathology

45. Submandibular gland fossa
o On the lingual surface of the mandibular
body,immediately below the mylohyoid ridge
in the molar area,there is frequently a
depression in the bone
o This area appears as a radiolucent area with
sparse trabecular pattern
superiorly by mylohyoid ridge
Inferiorly lower border of the mandible
Ant-premolar region
Posteriorly- ascending ramus

47. Nutrient canals
o Nutrient canals carry neurovascular bundles and
appear as a radiolucent lines of fairly uniform
width
o They are seen on mandibular periapical
radiographs running vertically from ian to the
apex of a tooth or into the interdental spaces
o Visible in about 5% of patients
o Older individuals with high blood pressure
o At times they orient in perpendicular to the cortex
and appear as a small round radiolucency

48. NUTRIENT
CANALS

49. Median sigmoid depression
It is a depression present below and just anterior
to the greatest depth of the sigmoid notch if
the mandibular ramus
Its depression is defined by tempora crest and the
crest of the mandibular neck
10% of the films exposed

50. Median sigmoid fossa

51. Pseudo cyst of condyle
o It is seen as a well defined rafiolicen in the
anterior aspect of the condyle in aapanaromic
radiograph
o 1 in 100 patients
o 0.5cm
o Surrounded by a discrete sclerotic rim
o The image represents marked cupping of the
anterior surface of the condyle
o Produced by pterygoid fovea and the dense
medial lateral ridge

52. Anterior buccal mandibular
depression
o It is an anatomic variation occuring just
lateral to the mental fossa
o Bilateral
o Canine region
o Young children
o Depression range from obvious
radiolucency to most imperceptible
o Trabecular pattern similar to bone

53. Pulp chamber & root canal
o The pulp of a normal tooth is composed of a soft
tissue and consequently appearas a radiolucent
structure
o The chambers and root canals containing the
pulp extends from interior of the crown to the
apices of the root
o At the end of a developing tooth root the pulp
canal diverges and walls of the root rapidly
taper to a knife edge

54. Pulp chamber and rootcansls

55. Periodontal ligament space
Periodontium occupies pdl space and is located
between cementum and periodontal surface of
alveolar bone
It is composed of collagen
It appears as a rl space between tooth root and
lamina dura
The space begins at the alveolar crest extends
around the portions of the tooth root
It is thinner in the middle root and slightly wider
near the alveolar crest and root apex

56. A double periodontal ligament space lamina
dura (arrows) may be seen when there is a
convexity of the proximal surface of the root.

57. The mandibular canal superimposed over the
apex of a molar causes the image of the periodontal
ligament space to appear wider (arrow). The presence of an
intact lamina dura, however, indicates that there is no
periapical
disease.

58. Marrow spaces
The cancellous bone lies between cortical plaes in
both jaws
It is composed of thin ro plates and rods
surrounding many rl pockets of marrow
The trabeculae in ant maxilla –thin and tumerous
forming a fine granular dense pattern and
marrous spaces are small and numerous
In post maxilla-maroows spaces may be sligltly
large

59. Ant mand- trebeculae are thicker coarse pattern
marrow spaces are correspondingl larger
Post mand-larger than ant mandible
Absence of trabecular indicates presence of
disease

60. The trabecular pattern in the
anterior mandible
is characterized by coarser
trabecular plates and larger
marrow spaces (arrow) than
in the anterior maxilla.
The trabecular
pattern in the
anterior maxilla
is characterized by
fine trabecular plates
and multiple small
trabecular spaces (
The trabecular pattern in the
posterior mandible is quite variable,
generally showing large marrow
spaces and sparse trabeculation,

61. Developing tooth crypt
o At birth tooth follicles are present for all the
decidious teeth
o Tooth follicle is a cavity in bone which has
a think lining of slightly denser bone ,the
cortex
o It appears as a pericoronal rl
o Pericoronal space greater than 2.5mm
should be regarded as suspicious

62. Developing tooth crypt

63. 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

64. Thank you