Intraoral Radiography Techniques Flashcards
(64 cards)
What are the principles of radiation protection?
Justification, optimisation , limitation
What is optimisation in intraoral radiography?
•DC x-ray tube is more efficient and allows shorter exposure times
•Rectangular collimator for the majority of intraoral radiographs.
What is the aim for the penumbra to achieve the best quality image?
To be as small as possible with minimal magnification
Ideal situation is D
–Small focal spot
–Long distance between focal spot and object
–Short distance between object and image detector.
What steps should u take to get the best quality intraoral radiographs?
•Using a film holder with a bite block achieves:
–Film and tooth as close together as possible
–Film parallel to tooth
•Using a beam aiming device attached to the film holder achieves:
–X-ray beam perpendicular to tooth and film
•Using a long cone, rectangular colimator
–X-ray source to tooth distance as great as possible
–Good size match between the xray beam and the image detector.
Types of intraoral radiography
•Bitewings (BW)
•Periapicals (PA/IOPA)
•Occlusals
What do bitewings show?
• Show the crowns of premolars and molars of both jaws
•No or minimal overlap of enamel
–Up to half thickness of enamel is acceptable
Where should u see the bitewing?
Should see from contact point between canine and first premolar to the most distal contact point
Horizontal bitewings show superficial bone levels if bone loss is more than ..
6mm
Indications of bitewing radiographs
•Detection of approximal caries
•Detection of occlusal caries
•Detection of recurrent caries
•Assess depth of caries
•Monitor caries progression
•Check for overhangs
•Check for calculus deposits
•Assess superficial bone levels/architecture
•May see pins/perforations
What film size do we use for adults?
Size 2
What film size do we use for children?
Size 0 or 1
How to take bitewing radiograph
Use film holder with beam aligning devices
What is the horizontal bitewing technique?
•Long axis of film horizontal
•Bite block in middle of film
–Film held as close to the teeth as possible
–Film parallel to teeth
•Beam projects at right angles to the film (horizontally and vertically)
What is vertical bitewing technique?
•Long axis of film is vertical
•Each film covers fewer teeth but shows more alveolar bone
–Indicated if > 6mm bone loss
•Usually need at least 2 each side to cover the posterior teeth.
Advantages of film holders for bitewings
–Simple
–Film not displaced by tongue
–Beam always at right angles to film
–Less chance of cone cutting
–Reproducible technique
Disadvantages of film holders for bitewing
–More expensive initially
–May be uncomfortable
Incorrect technique for taking bitewings
- Open mouth= missed anatomy/ contact points
- Incorrect alignment of x-ray tube w the beam aiming ring = cone cutting (incomplete image)
- horizontal beam angulation error= overlapping contacts
Second type of technique for bitewings
•Original technique used sticky tab attached to the middle of the film
•Patient would bite on a wing which projects at right angles to the film
•Tab technique still useful for children who can’t cope with larger film holders in their mouths.
Advantages of adhesive tab technique
•Cheap
•Simple
•Good for small children
Disadvantages of adhesive tab technique
•Not reproducible
•More change of coning off
•Operator dependent
What does periapical radiographs include?
•Periapical radiographs should include
–All of tooth (crown and root)
–Periapical tissues (approximately 3 mm beyond the apex)
Indications for taking a periapical
•Apical pathology
–e.g. rarefying osteitis, cysts, root resorption
•Periodontal disease
•Endodontics
•Root morphology prior to extraction
•Impacted teeth
•Implant assessment
•Trauma
What is the periapical paralleling technique?
•Film holder and beam aiming ring
–Holds film parallel to tooth
–Aids correct alignment of beam with image detector
•Anterior periapicals
–Film size 0
–Blue bite block/ring
•Posterior periapicals
–Film size 2
–Yellow bite block/ring
Where is the cotton wool roll placed?
Cotton wool roll placed between bite block and OPPOSING teeth NOT the tooth being x-rayed