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 greater attenuation of X-ray
75% mineral content ;less radiopaque than enamel.
Radiopacity similar to bone.
DENTINO ENAMEL JUNCTION appears as a distinct
interface separating these two structures.
50%mineral content and it appears as a very thin
layer on the root surface.
It is usually not so apparent radiographically.
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.
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 –
It should not be confused with root caries which has
It is composed of soft tissues so it appears
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
Lateral canals may end at the apex as a
discernible foramen or may exit at the side of the
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
IT IS THE DENTAL PAPILLA WITH ITS BONY
Its radiographic evaluation helps in determining the
stage of maturation of the developing tooth.
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. (hour glass)
It is a thin radiopaque layer of dense bone surrounding the
Its radiographic appearance is due to attenuation of the X-ray
beam as it passes tangentially through the thickness of the
It is thicker than the surrounding trabecular bone and thickness
increases with increase in amount of occlusal stress.
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
It shows apical recession with the age or periodontal
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
In posterior maxilla, it is similar to anterior maxilla
but marrow spaces are larger.
ANATOMIC LANDMARKS OF MAXILLA
Anterior nasal spine
Nasal fossa and Nasal septum
Superior foramina of nasopalatine canal
Zygoma & zygomatic process of maxilla
Also called as median suture.
In IOPAR, 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.
Mostly seen on IOPAR of maxillary central incisors.
Located in midline1.5-2cm above the alveolar crest.
It is radiopaque and usually V-shaped.
The nasal cavity shows the hazy shadow of the
inferior nasal conchae extending from the right
and left lateral walls
Floor of Nasal
Also called as NASOPALATINE or ANTERIOR PALATINE
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.
The nasopalatine canal originates at two foramina in floor of the
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
Also called as INCISIVE FOSSA.
Appears as depression in the maxilla near the
apex of the lateral incisor .
Appears diffusely radiolucent in the IOPA.
The nasal and maxillary bones form the
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.
The soft tissue of the nose is frequently seen in
the projections of the maxillary central and
lateral incisors ,superimposed over the roots of
Image appears uniformly opaque with a sharp
An oblique line demarcating a region that
appears to be covered by a slight radio opacity
frequently traverses periapical radiographs of
the premolar region.
MAXILLARY SINUS is an air containing cavity lined
by mucous membrane.
Appears as the three sided pyramid .
Base -formed by mesial wall adjacent to
Apex –extending laterally into the zygomatic
process of maxilla.
On the IOPAR, 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
Around the age of puberty, its floor coincides
with the floor of the nasal cavity.
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
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
The medial and lateral pterygoid plates lie immediately
posterior to the tuberosity of maxilla.
They cast a single radiopaque shadow without any evidence
Extending inferiorly from the medial pterygoid plate, the
hamular process may be seen.
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
life and is no longer radiographically apparent.
These are tiny bumps of bone that serve as attachment
for the genioglossus and geniohyoid muscles.
Present on lingual side.
On IOPAR, appears as ring shaped radiopacity below the
apices of mandibular incisors.
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.
It is a linear prominence of cortical bone located
on the external surface extending from the
premolar region to the midline and slopes
Radiographically, appears as a radiopaque band
that extends from the premolar region to the
Located above the mental ridge.
On peri apical radiograph, appears as a
radiolucent area above the mental ridge.
Located on the external surface of the mandible as
an opening in the region of the mandibular
Mental nerves and blood vessels exit through it.
Radiogarphically, it appears as a small ovoid
radiolucent area located below the apices of the
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.
Nutrient canals are tube like passage-ways
through bone that contains nerves and blood
vessels that supply the teeth.
Radiographically seen as vertical radiolucent
More prominent in anterior mandible where bone
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 IOPAR, appears as radiopaque band extending
downward from molars.
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
Depressed area of bone located on the internal surface
Submandibular salivary gland lies in this fossa.
It appears as a radiolucent area in the molar region
below the mylohyoid 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 and forward from
coronoid process, in a horizontal position, stop
at the third molar area or become cotinuous with
the mylohyoid line.Its placed below the external
Occasionally, seen as a dense broad
radiopaque band of bone.
It is a marked prominence of bone on the ant. ramus of
Not seen on a mandibular IOPAR but appears on a
maxillary molars IOPAR.
It is seen as a triangular radiopacity superimposed over
or inferior to maxillary tuberosity.
Vary in their radiographic appearance.
Depend primarily on their thickness, density and
A variety of restorative materials may be
recognized on intra oral radiographs.
RO- silver amalgam,gold crown & inlay,stainless
steel pins,GP cones,silver
CaOH- RL but mostly RO
RL- mainly silicates.
Radiographic evaluation of bone changes in
periodontal disease is based mainly on the
appearance of the interdental septa because
the ralatively dense root structure obscures
the facial and lingual bony plates.
The IDS normally presents a thin,radiopaque
border adjacent to PDL and at the alveolar
crest known an LAMINA DURA.
It appears radiographically as continous
white line,but is relatively perforated by
numerous small foramina and traversed by
blood vessel,lymphatic and nerve.
Because LD represents the bone surface
lining the tooth socket,the shape and
position of root and changes in the
angulation of the X-ray beam produce
considerable variation in its appearance.
Variations in technique produce artifacts
that limit the diagnostic value of the RG.
Pattern of bone destruction
Width of PDL space
Marginal contour of IDS
Long cone paralleling technique : projects
most realistic image of the level of the
Bisecting angle technique : increase the
projection and make the bone margin appear
closer to the crown.
Shifting the cone mesially or distally without
changing horizontal plane projects the X-ray
obliquely and changes the :
a) Shape of interdental bone on RG
b) RG width of PDL space
c) Appearance of LD
d) It also distorts the extent of furcation
Prichard established following 4 criterias to
determine adequate angulation of PA RG:
i. The RG should show the tips of molar cusps
with little or none of the occlusal surface
ii. Enamel caps and pulp chambers should be
iii.Interproximal spaces should be open
iv.Proximal contacts should not overlap unless
teeth are out of line anatomically.
An additional IO projection that can be used for
evaluation of alveolar crest is the bitewing
For bitewing the film is placed behind the
crowns of upper and lower teeth parallel to long
axis of teeth
The X-ray beam is directed through contact area
of teeth and perpendicular to film
Thus projection geometry of bitewing allows the
evaluation of the relationship between
interproximal alveolar crest and CEJ without
If bone loss is severe and bone level cannot be
visualised on regular bitewing ; film can be
placed vertically to cover larger areas of jaw.
Enamel caps and pulp chamber distinct
Tip of molar cusp seen with little
or no occlusal surface
Open interproximal spaces
Interproximal areas should not
Radiopaque horizontal line across the roots:
this line demarcates the portion of root where
labaial or lingual bony plate has been
partially or completely destroyed from the
remaining bone supported portion.
Vessel canals in alveolar bone :
HIRSCHFELD described linear and circular
radiolucent areas produced by interdental
canals and their foramina. The RG image of
canals is often so prominent in mandibular
anterior region that they might be confused
with radiolucency resulting from periodontal
Differentiation between treated and
untreated periodontal disease:
Its sometimes necessary to determine whether
the reduced bone level is the result of
periodontal disease that is no longer
destructive or whether destructive
periodontal disease is present .
The RG is an indirect method for determinig
the amount of bone loss in periodontal
disease; it shows the amount of bone
remaining rather than the amount of bone
lost and it does not reveal minor destructive
changes in bone . Therefore ,slight RG
changes in periodontal tissues mean that
disease has progressed beyond its earliest
Clinical periodontology – Carranzas 10th
Oral radiology – principles and
interpretations : White and Pharoah 6th