Module 5 Flashcards
Bitewings Advantages
• Simple and straightforward • Difficult for tongue to displace the receptor • Beam aiming device determines angulation • Cone cutting avoided • Autoclavable/disposable holders
Bitewings Disadvantages
- Not 100% reproducible
- Uncomfortable for patients
- Expensive holders
- Holders unsuitable for children
Bitewings- Receptor positioned too far posterior
No premolars
Bitewings - Receptor incorrectly placed
Displacement of receptor by tongue, Distortion
Bitewings - ncorrect beam alignment in horizontal plane
- Too far posterior or anterior – coned off
* Not aimed through contact areas – overlapping
Bitewings- Incorrect beam alignment in vertical plane
No superimposition of buccal and lingual cusps
Bitewings - Incorrect exposure settings
Over exposed – burn out – poor contrast - dark image
• Underexposed – poor contrast – pale image
Bitewings - movement of patient
Blurring
Selection for Bitewings every 6 months
High risk
Selection for Bitewings every 12 months
Moderate Risk
Selection for Bitewings 12 -18 months primary / 2 years permanent dentition
Low Risk
PA - Maxillary incisors and canines
- Accommodate height of palate
* Posterior position
PA - Mandibular incisors and canines
- In floor of mouth
* In line with lower canines or premolars
PA - Maxillary premolars and molars
- In midline
* Accommodate height
PA- Mandibular premolars and molars
- Lingual sulcus
* Next to appropriate teeth
PA Errors - Dentures and appliances not removed
Superimposed
Pa Errors - Incorrect position of receptor
- Not over area of interest – no apicies or periapical tissues
- Bending - distortion
PA Errors - Incorrect orientation
• no image (back to front)
PA Errors- Poor alignment
- Horizontal – cone cutting, overlapping contact areas
* Vertical – cone cut, foreshortening, elongation
Pa Errors - Poor communication
• movement, blurring
PA Errors - Incorrect Settings
Poor contrast
PA Errors - Double exposure
Receptor Used Twice
Bisected Angle Technique
Advantages
- Comfortable positioning for patient
- Positioning is relatively simple and quick
- Dependant on correct angulation, image is same length as tooth
- Adequate for most diagnostic purposes
Bisected Angle Technique
Disadvantages
Distortion due to many variables
• Elongation/ foreshortening – vertical angulation wrong
• Periodontal bone levels not seen
• Zygomatic shadow overlies roots of upper teeth
• Skill required for angulation assessment
• Not reproducible
• Cone cutting
• Roots and crowns overlap – horizontal angulation wrong
• Distortion of crowns common
• Foreshortened buccal roots of maxillary posterior
• teeth
BA Errors - Elongation
Angulation too shallow, long image
BA Errors - Foreshortening
Angulation too steep, short image
BA Error - Coning
Angulation not central to film, partial exposure
BA Error - Blurred image
Movement of patient or collimator
BA Error - Transparent film
Film inserted the wrong way round
BA Error - Fogged Film
Exposure to light before x-ray beam
BA Error - Blank filme
Machine not switched on
Upper standard occlusal
Standard occlusal
Upper oblique occlusal
oblique occlusal
true occlusal Mandibular
Lower 90° occlusal
standard occlusal Madibular
Lower 45° occlusal
Lower oblique occlusal madibular
oblique occlusal
