How to take radiographs Flashcards
Outline the procedure of taking a radiograph
- tooth and sensor should be close together
- long axis of tooth and sensor/film should be parallel
- x-ray beam should meet tooth and sensor/film at 90
- position should be reproducible
What are the issues with taking radiographs
- teeth lie in bone so the root direction cannot be determined
- multi-rooted teeth
- palate/floor of mouth prevent direct contact without bending the image receptor
What do periapical radiographs show
the entire tooth and surrounding structures (2-3mm)
Outline the paralleling technique
placing the film parallel to the tooth along its long axis and the x-ray tube is angled perpendicular to this to give a reproducible image
Outline the bisecting angle technique
Sensor/film is close to tooth without bending ; angle between long axis of tooth and film is estimated and the x-ray tube is at 90 to bisecting line central beam
this is operator dependant as there are no positioning aids
What does a horizontal plane error result in
overlapping teeth in radiograph
What does a vertical plane error result in
elongation or forshortening of teeth in radiograph
What are the indications of taking a periapical radiograph
- detecting apical infections
- assessing periodontal status
- post trauma assessment of teeth and alveolar bone
- presence and position of unerupted teeth
- pre extraction to look at root morphology and post op.
- endodontics, apical cysts, bone lesions
What are the indications of a maxillary occlusal radiograph
- when intra oral PA cannot be tolerated
- detecting pathology
- paralax for unerupted teeth
- fractures of teeth or alveolar bone
- assess antrum / roots displaced
What are the types of maxillary occlusal radiographs
- upper standard (60-70 degrees)
2. upper oblique occlusal
What needs to be provided with an upper oblique occlusal radiograph
thyroid collar
What are the types of mandibular occlusal radiographs
- lower 90 degree true occlusal
- lower 45 degree occlusal
- lower oblique occlusal
What are the indications of a mandibular occlusal radiograph
- radiopaque calculi in submandibular salivary ducts
- buccolingual position on teeth
- expansion due to tumours/cysts
- assessing mandible width for implants
What is an exraoral radiograph
A panoramic showing all teeth and structures
What are the indications for a panoramic radiograph
- 3rd molar assessment before extraction
- orthodontics
- mandibular fractures
- TMJ problems
- bony lesions/unerupted teeth
Outline the process of panoramic tomography and why positioning is important
- patient is stood still while tube head and sensor moves around their head
- causes blurring of all structures out of the focal plane
- a 3D area where structures are well defined takes a horse-shoe shape mimicing the dental arches
- this is why the head positioning is important otherwise the structures will be blurred out
What are cephalometric radiographs used for
orthodontic treatment planning because it shows teeth, jaw and profile
What is the role of a cephalostat
To stabalise head position into a standardised position
Outline the process of taking cephalometric radiographs
- Patient positioned in cephalostat
- Teeth are in occlusion
- Head is immobilised with ear rods in EAM
- Ruler dropped to nasal bridge
