How to take radiographs

Question 1

Outline the procedure of taking a radiograph

Answer 1

• 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

Question 2

What are the issues with taking radiographs

Answer 2

• 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

Question 3

What do periapical radiographs show

Answer 3

the entire tooth and surrounding structures (2-3mm)

Question 4

Outline the paralleling technique

Answer 4

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

Question 5

Outline the bisecting angle technique

Answer 5

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

Question 6

What does a horizontal plane error result in

Answer 6

overlapping teeth in radiograph

Question 7

What does a vertical plane error result in

Answer 7

elongation or forshortening of teeth in radiograph

Question 8

What are the indications of taking a periapical radiograph

Answer 8

• 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

Question 9

What are the indications of a maxillary occlusal radiograph

Answer 9

• when intra oral PA cannot be tolerated
• detecting pathology
• paralax for unerupted teeth
• fractures of teeth or alveolar bone
• assess antrum / roots displaced

Question 10

What are the types of maxillary occlusal radiographs

Answer 10

1. upper standard (60-70 degrees)

2. upper oblique occlusal

Question 11

What needs to be provided with an upper oblique occlusal radiograph

Answer 11

thyroid collar

Question 12

What are the types of mandibular occlusal radiographs

Answer 12

1. lower 90 degree true occlusal
2. lower 45 degree occlusal
3. lower oblique occlusal

Question 13

What are the indications of a mandibular occlusal radiograph

Answer 13

• radiopaque calculi in submandibular salivary ducts
• buccolingual position on teeth
• expansion due to tumours/cysts
• assessing mandible width for implants

Question 14

What is an exraoral radiograph

Answer 14

A panoramic showing all teeth and structures

Question 15

What are the indications for a panoramic radiograph

Answer 15

• 3rd molar assessment before extraction
• orthodontics
• mandibular fractures
• TMJ problems
• bony lesions/unerupted teeth

Question 16

Outline the process of panoramic tomography and why positioning is important

Answer 16

• 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

Question 17

What are cephalometric radiographs used for

Answer 17

orthodontic treatment planning because it shows teeth, jaw and profile

Question 18

What is the role of a cephalostat

Answer 18

To stabalise head position into a standardised position

Question 19

Outline the process of taking cephalometric radiographs

Answer 19

1. Patient positioned in cephalostat
2. Teeth are in occlusion
3. Head is immobilised with ear rods in EAM
4. Ruler dropped to nasal bridge