Dental Radiology

Parallel Technique

1) Long axis of tooth and film are parallel to eachother
2) The central ray is directed perpendicular to the long axis of the tooth and film

Periapical Film

Used to show root apex of tooth and surrounding structures

Bitewing exposure

Used to detect interproximal decay and height of alveolar bone

Occlusial

Used to view cross section of the teeth and complete palatal structure or floor of mouth

5 safety precautions for operator

1) Never hold film in patients mouth
2) Stand behind a protective barrier
3) stand 6 feet away from x-ray unit
4)Never stand in direct line of primary beam
5) Use lead lined open cone

Care of x-ray unit

1) Don't force unit arm to be extended
2) Don't leave the arm extended after use
3) allow 5 seconds between exposures to let the tube cool
4) Don't let the tube head hit the wall
5) always turn off unit when finished

Inverse Square Law

Using a longer target object diminishes intensity of radiation

Horizontal angulation (Parallel Technique)

Central ray must pass through the teeth parallel to the proximal surfaces

Vertical Angulation (Parallel Technique)

The film is parallel to the long axis of the teeth

Elongation

Vertical angulation too low

Foreshortening

Vertical angulation too high

Overlapping

Result of incorrect horizontal angualtion

Target Film Distance

16"

Full Mouth Series

Anterior- 8
Posterior-8
Bitewing-4

Maxillary Anterior Films

Maxillary Right Cuspid
Maxillary Right Lateral
Maxillary Centrals
Maxillary Left Lateral
Maxillary Left Cuspid

Mandibular Anterior Films

Mandibular Right Cuspid
Mandibular Lateral central incisors
Mandibular left cuspid

Posterior Maxillary Films

Right molar
Right Bicuspid
Left bicuspid
Left molar

Posterior Mandibular Films

Right Molar
Right Bicuspid
Left Bicuspid
Left Molar

Bitewings

Right Molar
Right bicuspid
left bicuspid
left molar

Anatomical Landmarks

Those normal structures and areas which appear in a routine series of radiographs

Radiolucent

Black; dark gray

Radiopaque

White; light gray

Enamel

Most dense structure in human body; radiopaque; can see

Dentin

Internal portion of tooth; radiopaque; less dense than enamel; cannot see

Cementium

Cannot see; less dense than dentin

Pulp

Radiolucent; can see; composed of nerves and blood vessels

Cortical Bone

Radiopaque; immediately surrounds and supports teeth.

Cancellanious Bone

Appears less radiopaque than cortical bone; less dense

Alveolar Bone

Radiopaque; composed of cortical and cancellanious bone; part of bone where tooth eruption occurs

Periodontal Ligament

Radiolucent line; between tooth and cortical bone (lamina dura)

Nutrient Canals

Radiolucent lines in bone; contains blood vessels and exhibit radiopaque borders

Incisive Canal Foramen/ Anterior Palatine Foramen

Radiolucent; Oval shaped between the apices of the central incisors

Median Palatine Suture

Radiolucent; extends posteriorly through the midline of the palate

Nasal Fossae

2 radiolucent areas in upper portion of radiograph; air spaces

Nasal Septum

radiopaque; between the nasal fossae

Maxillary Sinus

Airspace above bicuspids

Typical "Y" of maxillary sinus

Radiopaque; where the upper front wall of maxillary sinus joins with floor of nasal fossa

Zygomatic Process

U shaped; in apical region of 1st and 2nd molars

Zygomatic Arch

Superimposed over maxillary molar sinus- radiopaque

Maxillary Tuberosity

Hamular Process

Tenious attachment for muscle fibers

Coronoid Process

Point of muscle attachment

Lingual Foramen

Radiolucent' between apices of mandibular central incisors

Genial Tubercles

Surrounds lingual foramen

Mental Ridge

Inferior border of the mandible

Thick radiopaque band

Mental Foramen

Lines inferior to the mandibular apices of bicuspids

Mylohyoid Ridge

Below apices of the molars

External Oblique Ridge

Submandibular Fossa

below roots of mandibular molar

Mandibluar Canal

Bisecting Angle Technique

Central Ray is directed perpendicular to an imaginary line which bisects the long axis of the tooth and the film

Least amount of film in FMS

14
7-Max
7-Mand

Vertical Angulation (BAT)

The opening of the cone is vertically parallel to the bisector

Horizontal Angulation (BAT)

The opening of the cone is horizontally parallel to the angle of the arch of the teeth to be exposed

Cone cut prevention (BAT)

Front and back: Cone is 1/4'' anterior to the film.
Top and bottom: Cone is 1/4'' above (maxillary) or below (mandibular) the occlusial plane.

5 most common errors in technique

foreshortening
elongation
horizontal overlap
cone cutting
excessive bending