Dental Radiographic Techniques and Landmarks Guide

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www.indiandentalacademy.com

RADIOGRAPHIC
TECHNIQUES AND
LANDMARKS

CONTENTS
• Introduction
• Intraoral Radiography
– Periapical Radiography
– Bitewing Radiography
– Occlusal Radiography
• Extraoral Radiography
– Panoramic imaging
– Lateral cephalometric projection
– Submentovertex projection
– waters projection
– Reverse towne projection
– Mandibular oblique lateral projectionwww.indiandentalacademy.com

• Digital radiography
• Ultrasonography
• Computed Tomography
• Magnetic Resonance Imaging
• TMJ Radiography
• Anatomical landmarks of teeth and jaws.
• conclusion

Introduction

Intraoral Radiography

– Intraoral radiographic examinations
are the backbone for imaging for
general dentist.
– Divided into 3 categories:
• Periapical projections
• Bitewing projections
• Occlusal projections
– A typical full mouth set of radiographs
consists of 21 films
Anterior periapical – 9
Posterior periapical - 8
Bitewing (Premolars, molars) – 4.

Periapical radiography :
Paralleling Technique (right angle or long cone)

XCP instruments
Precision x-ray holderswww.indiandentalacademy.com

Maxillary central incisor
projection:
paralleling cone technique

Bisecting angle technique.

Bite blocks
Snap-A-ray holder
hemostatwww.indiandentalacademy.com

Angulation guidelines
Projection
Maxilla Mandible
Incisors +400
-150
Canines +450
-200
Premolars +300
-100
Molars +200
-50

Bite Wing Radiography

Film placement
Film holding devices

– Beam is carefully aligned between the
teeth and parallel with the occlusal plane.
– In molar region, aiming cylinder is
positioned about +100
to project the beam
parallel with the occlusal plane.

• Uses
– Detecting interproximal caries in early
stages
– Provides good perspective of alveolar
bone crest
– Effective and useful for detecting
calculus.

Vertical bitewing films usually are used when the patient
has moderate to extensive alveolar bone loss.

Occlusal Radiography
Relatively large film 7.7 x 5.8 cm is used for occlusal
radiography.
Cross sectional maxillary occlusal projectionwww.indiandentalacademy.com

Cross sectional mandibular occlusal projection

Uses
• To locate roots and supernumerary, unerupted and
impacted teeth.
• To localize foreign bodies in the jaws and stones in
the ducts of sublingual and submandibular glands
• To aid in the examination of patients with trismus,
who can open their mouths only a few mm.
• To obtain information about location, nature extent
and displacement of fractures of mandible and
maxilla.
• To determine the medial and lateral extent of
disease (eg. cysts, osteo myelitis, malignancies)

Radiography in edentulous patient.
– Edentulous areas may contain roots, residual
infection, impacted teeth, cysts, or other
pathologic entities that may adversely affect
usefulness of prosthetic appliances, or patients
health.
– Panoramic examination of edentulous jaws in
most convenient
– Cotton rolls are placed between the ridge and
the film holder so as to support film holder.
Orthodontic elastics can be used to hold cotton
rolls.
– Patient may steady the film holding instrument
with a hand or on opposing denture.www.indiandentalacademy.com

– An examination consisting of 14 intraoral films provides
on excellent survey of full mouth.
– The examination consists of 7 projections in each jaw.
CI Region – 1 projection
Lateral, canine – 2 Projections
Premolar – 2 Projections
Molar – 2 Projections
- The exposure required for an edentulous ridge is
approximate, 25% less than that for an dentulous ridge.
- The routine use of radiographs for patients who wear
complete dentures and need replacement dentures should
be discouraged.

Extraoral Radiography

PANORAMIC IMAGING
Is based on the principle of the reciprocal movement of an X-ray
source and an image receptor around a central point or plane called
image layer.

Center of rotation

Image layer
Image layer is a 3 dimensional curved zone (or
focal trough) in which the structures lying within
the layer are reasonably well defined on final
panoramic image.

Position of mandible in focal trough
5mm anterior
Center of trough
5mm posterior

Scanora multimodality
machine
ProMax panoramic
machine

Normal panoramic viewwww.indiandentalacademy.com

When chin and occlusal plane are rotated…
upward
downward

Advantages :
• Broad coverage of the facial bones and teeth.
• Low patient radiation dose
• Convenience of the examination for the patient.
• Ability to be used in patients unable to open their
mouths
• Short time required to make image (3-4 min)
• Patients ready understandability of panoramic films.

Disadvantages
• Images do not display fine anatomic detail available on
intraoral periapical radiographs
• Unequal magnification and geometric distortion across the
image
• The presence of overlapping structures, such as cervical
spine can hide odontogenic lesion particularly in incisor
region.
USES
• Most useful clinically for diagnostic problems requiring broad
coverage of the jaws.
• Evaluation of trauma
• Location of 3rd molars
• Extensive disease, known or suspected large lesions
• Tooth development, retained teeth or root tips and
developmental anomalies

Lateral
ceph SMV waters
PA
ceph

Reverse
Towne
Oblique lateral
body ramus

Submentovertex projection

Waters projection

PA Ceph

Reverse Towne
projection

Oblique lateral- body

Oblique lateral- ramus

DIGITAL RADIOGRAPHY

• Conventional X-ray films are considered to be on
analog medium whereas digital image are numeric
and discrete, in 2 ways:
 In terms of spatial distribution of the picture
elements (Pixels)
 In terms of different shades of gray to each of the
pixels.
• Production of digital image requires a process
called analog to digital conversion. It consists of 2
steps.
Sampling
Quantization

Voltage signal from detector
Analog signal
Large sampling
Narrow samplingwww.indiandentalacademy.com

• Advantages
– Eliminates chemical processing
– Hazardous wastes (Processing chemicals, pd foils)
are eliminated
– Images can be electronically transferred to other
health care providers without alteration in image
quality.
– Digital intraoral receptors require less radiation
than film.
• Disadvantages :
– Initial expense of setting up of digital imaging
system
– Components if damage are costly to replace.www.indiandentalacademy.com

DIGITAL DETECTORS :
• Charge coupled Device (CCD) :
– Was the first direct digital image receptor to be
adopted for intra oral imaging and was introduced to
dentistry in 1987.
– CCD uses a thin wafer of silicon as the basis for image
recording
– Gadolinium oxybromide compounds or cesium iodide
are examples of scintillators used in CCDs.

Basic structure of CCD

• Complementary mental oxide semiconductors
(CMOS)
– Silicon based but are fundamentally different
from CCDs in the way that pixel charges are
read.
– Each pixel is isolated from its neighboring pixels
and is directly connected to transistor
– Less expensive than CCDs.
• Photostimulable phosphor plates (PSP)
– PSP absorb and store energy from X-rays and
then release this energy as light
(Phosphorescence)
– Photostimulate phosphor material used is
Europium – doped’ barium fluorohalide.www.indiandentalacademy.com

• Flat Panel Detectors :
– Detectors provide relatively large matrix
areas with pixel size less than 100 microns.
– This allows direct digital imaging of larger
areas of the body, including the head.
DIGITAL DETECTOR CHARACTERISTICS
1) Contrast Resolution
Is the ability to distinguish different
densities in the radiographic image.

2) Spatial Resolution
Is the capacity for distinguishing fine detail
3) Detector Latitude
The ability of an imaging receptor to
capture a range of x-ray exposures
4) Detector Sensitivity.
Is the ability to respond to small amounts of
radiation

• Hard Copies
The main types of printing technologies available
for image printing include laser, inkjet and
dyesublimation with the use of either film or paper.
• Image enhancement
– Term image enhancement implies that the
adjusted image is as improved version of the
original one.
– This can be accomplished by increasing contrast,
optimizing brightness and reducing unsharpness
and noise.
– Image enhancement operations are often task
specific.

brightness contrast
standard Edge detect embossed

Digital subtraction Radiography
• When two images of the same object are
registered and the image intensities of
corresponding pixels are subtracted , a
uniform difference image is produced.
• Subtraction images are well suited for
acquiring quantitative information such as
linear, area and density measurements.

Measurement tool

Ultrasonography

– Periodicity of ultrasound is greater than 20
KHz.
– Diagnostic ultrasonography, the clinical
application of ultrasound uses vibratory
frequencies in the range of 1 to 20 MHz.
– Scanners used for sonography generate
electrical impulses that are converted into
ultra-high frequency sound waves by a
transducers
– Most important component of transducer is a
thin piezoelectric crystal (Lead, Zirconate
Titanate (PZT)]

Uses
– Ultrasonography can be used to detect changes in TMJ ,
caries,sialoliths, advanced Autoimmune lesion (Sjogren’s)
– Primary application of US is in the differentiation of
solid masses from cystic ones.
-Assesment of the development of fetus (OB/GYN).
-Evaluation of blood flow (Cardiology).
Advantages
• Relatively inexpensive
• Widely available
• Painless
• Easy to perform
• Non invasive www.indiandentalacademy.com

Long arrow- calvarium
Short arrow-maxilla and mandible
TMJ area

Computed Tomography

– Permits the imaging of thin slices of tissue in a
wide variety of planes.
– Most CT is done in the axial plane. Many CT scans
also provide coronal views; sagittal slices.
– Slice thickness is usually 10mm through the body
and brain
5 mm through the head and neck
3 dimensional reconstruction – 1 to 1.5 mm

First Generation
One detector
Translation-rotation
Parallel-beam

Second Generation
Multiple detectors
Small fan-beam

Third Generation
Multiple detectors
Large fan-beam

Fourth Generation
Detector ring
Source-rotation
Large fan-beam

Third & Fourth Generations
(From Picker)
(From Siemens)

Helical/spiral CT

• Images are usually viewed in 2 modes
Bone windowing
Soft tissue windowing
Bone windowing Soft tissue windowing

Advantages
• Thin slices of tissue can be viewed in multiple
planes without superimposition by adjacent
structures.
• Fascial planes between muscle groups can be
identified, as can lymphonodes and blood
vessels.
• 3 dimensional images can be made. finite
element analysis can be done.
• Colouring of certain structures (like tumors)
can be done to simplify visualization of the
lesion.
• 3 Dimensional models can be milled out of
plastic, based on data from CT scans.

3-Dimensional imaging

Disadvantages
• Relatively high cost
• High dose of radiation
• Metallic restorations produce streak
artifacts that may obscure portions of
teeth anatomy.

USES IN DENTISTRY
To evaluate
• The extent of lesions suspected with
other radiographic techniques
• The degree of maxillofacial involvement in
cases of trauma.
• The integrity and condition of the
paranasal sinuses
• Quality and quantity of bone in proposed
dental implant sites.

Magnetic resonance imaging

-MRI uses electrical and magnetic fields and
radiofrequency pulses to produce an image

Relaxation
• T1 relaxation: Describes the release of
energy from the proton to its immediate
environment
• T2 relaxation: Designates the interaction
between adjacent protons

– Time of repetition (TR)
– Time of echo (TE)
– In T1 weighted mage, fats produce a bright
signal. Fluids, muscles produce intermediate
signal
– In T2 weighted image, fluids become bright
and fat becomes darker

Uses in dentistry
• Evaluation of various pathologic lesions (tumors)
• Assessment of TMJ
• MRI can accurately depict the location, morphology
and function of the articular disk.
Advantages
• Capability of imaging soft tissue in virtually any
plane.
• No ionizing radiation.

Disadvantages
• High cost
• Contraindicated for certain patients with cardiac pacemakers.
• Patients with ferromagnetic metallic objects in strategic
places (such as aneurysm clips in brain and metallic
fragments in eye) SHOULD NOT BE PLACED IN MAGNET.
• Some patients feel claustrophobic inside the magnet and
may need to be selected for the procedure.
• Because of length of time for each scan in series (several
minutes) , patients who cannot remain motionless are not
good candidates for MRI.

MRI of normal TMJ

MRI of brain

TMJ Radiography
Hard tissue imaging
 Panoramic imaging
 Transcranial projection
 Transpharyngeal projection
 Transorbital projection
 Submentovertex projection
 Computed tomography
Soft tissue imaging
 Arthrography
 MRI www.indiandentalacademy.com

Transcranial
projection

Transpharyngeal
projection

Transorbital projection

Arthrography

Maxillary and Mandibular
Anatomic Radiographic Landmarks

Enamel
Dentin
Dentin-enamel
junction
Cemento-
enamel junction
Pulp space
Lamina dura
pdl space
Alveolar boneImage(s) courtesy © Dr. Allan G. Farman

Anatomic
Landmarks
MAXILLA
ZYGOMATIC BONE

Anterior Nasal Spine

Incisive Fossa / Foramen

Nasal Septum

Pre-maxillary / Median Palatine Suture

Inferior Concha / Turbinates

Incisive / Nasopalatine Canal

Ala Cartilage Nose & Lip Line

Incisive fossa
Cartilagenous nasal
septum
Bony nasal septum
Edentulous
anterior maxilla
Inferior conchae
Image(s) courtesy © Dr. Allan G. Farman www.indiandentalacademy.com

Canine Fossa

Anterior wall of
nasal passage
Soft tissue shadow
of nose
Canine ‘fossa’

Inverted
“Y”

Lateral wall of
nasal fossa
Anterior wall of
maxillary sinus
(antrum)
Inverted “Y”

Anterior Sinus

Nasolabial Fold

Maxillary Sinus

Floor of maxillary sinus

Maxillary molar region showing septum in sinus
Septum in
sinus
Zygomatic
process of
maxilla
Soft tissue
over
tuberosity

Zygomatic
bone
Zygomatic
process of
maxilla
Zygomatic process (temporal bone)
Structures anterior
to green line seen
on intraoral
radiographs
Zygomatic
Arch

Zygomatic process
of the maxilla
Zygomatic
arch
shadow
Floor of
maxillary
sinus
Maxillary
tuberosity
Endodontically
treated tooth

Zygomatic
arch
Zygomatic process
of maxilla
Floor of
maxillary
sinus
Nutrient
canal

Pterygoid
hamulus
(medial
Pterygoid)
Lateral
pterygoid
plate
Maxillary tuberosity

Pterygoid hamulus

Coronoid
process of
mandible
Zygomatic
process
of maxilla
Zygomatic
arch

Zygomatic process of maxilla
Pterygoid
hamulus
Pterygoid
plate
CORONOID
PROCESS

MANDIBLE

Facial
Mental
depression
Mental
ridge
Lingual
groove
Genial
tubercles
Lingual

Mental ridge
Soft tissue
shadow of lower lip
Cortex of
lower border of
mandible

Nutrient canals

Nutrient canals in
anterior mandible

Lingual foramen
Embossed dot

Mental
foramen

Mental foramen
Mylohyoid
ridge
Submandibular fossa

Periapical granuloma, abscess or cyst
(periodontal ligament space not intact)
Mental
foramen

Mandibular canal

External oblique ridge of mandible

Internal oblique (mylohyoid) ridge of mandible

Lower cortex of mandible
External
oblique
ridge
Internal
oblique
ridge

Mandibular torus

Maxillary torus

conclusion

References
 Oral Radiology. Principles and interpretation
White and Pharoah
5th
edition
 Atlas of oral diagnostic imaging.
Tomomitsu Higashi
 Oral and maxillofacial diagnostic imaging
Farman, Nortje, Wood
 Dental radiology- Principles and techniques.
Haring, Jansen
2nd
edition
 Burket’s oral medicine- diagnosis and treatent.
10th
edition.
 Journal of oral rehabilitation.1997 jul;24(7):512-6
 Dental materials journal.2005 sep;24(3):362-7
 JPD 2003jul;90(1):86-91
 Dental materials journal.2005sep;24(3):362-7www.indiandentalacademy.com

Thank youwww.indiandentalacademy.com

Dental Radiographic Techniques and Landmarks Guide

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Dental Radiographic Techniques and Landmarks Guide