Intra-oral

Question 1

indications of PA radiograph

Answer 1

evaluation and diagnosis of:

1. apical status - infection/inflammation
2. dental caries
3. periodontal status

assessment of:

4. presence of buried tooth
5. wisdom tooth
6. root morphology before extraction
7. teeth and alveolar bone after trauma
8. root fracture
9. FB
10. during various treatment steps
11. evaluation of post-operative periodontal/apices surgeries
12. post-op evaluation of implants

Question 2

what are the 2 PA techniques

Answer 2

1. parallel technique:
   - receptor and teeth are parallel to each other
   - x-ray beam is aligned to the long axis of tooth and receptor at right angles
2. bisected angle technique:
   - receptor and teeth are not parallel to each other
   - x-ray beam is aligned to the plane that bisects the teeth and receptor at right angles

Question 3

what are the 2 types of holder

Answer 3

• sensor holder

- film/PSP holder

Question 4

what are the 2 types of receptors

Answer 4

• digital sensor

- PSP plate

Question 5

what are the holder parts

Answer 5

• bite blocks
• aiming ring
• indicator arms

Question 6

patient positioning - parallel technique

Answer 6

1. patient is positioned with head supported and the occlusal plane horizontal to the floor
2. drape on the thyroid shield for the patient
3. the holder + receptor is placed in the mouth
4. teeth being radiographed must touch the biteblock
5. cotton rolls may be used to help support the bite block
6. patient bites together gentle
7. aiming ring is moved close to but not touching the patient’s face
8. PID aligned to the aiming ring + rod

Question 7

advantage and disadvantages of parallel technique

Answer 7

advantage:

1. geometrically accurate
   - teeth
   - periapical tissue
   - periodontal bone levels
2. holders help to
   - produce reproducible images
   - automatically determine horizontal and vertical angulations
   - avoid cone-cutting if x-ray beam is accurately centered

disadvantage:

1. not possible with the following anatomy
   - flat/shallow palate
   - torus palatinus
   - shallow floor of mouth
2. problems with positioning
   - uncomfortable for patient, esp posterior teeth
   - difficult to position in lower 3rd molar region
   - gagging reflex from patient

Question 8

advantages and disadvantages of bisecting angle technique

Answer 8

advantages:

• more comfortable for patient than paralleling technique
• fewer anatomic limitations
• easier to position IR
• technique can be done without a holder

disadvantages:

• technique sensitive
• often results in distorted images
• incorrect vertical angulation will result in foreshortening/elongation
• incorrect horizontal angulation will result in overlapping of crowns and roots limits detection or proximal caries
• operator dependent
• cone-cutting occurs if xray beam is not aimed centrally
• images are not reproducible

Question 9

what is periapical radiograph

Answer 9

an intra oral technique which record the entire tooth and supporting bone

Question 10

what is bitewing radiograph

Answer 10

• an intra-oral technique which shows the crowns of the premolar and molar teeth on each side of the jaw
• may be horizontal or vertical

Question 11

purpose of BW

Answer 11

to observe the interproximal and occlusal surfaces of the enamel, enamel-dentine junction and alveolar crestal bone levels

Question 12

indications of a BW

Answer 12

1. detection of caries/carious lesion
2. monitoring progression of caries
3. assessment of existing restorations, crowns and bridges
4. assessment of periodontal status

Question 13

positioning of BW

Answer 13

1. IR is positioned centrally within the holder
2. teeth and receptor should be in contact
3. alignment of teeth within the arch and receptor should be parallel
4. horizontal plane: beam meets the teeth and IR at right angles and passes through all contact areas
5. vertical plane: xray tubehead is aimed at 5-8deg to compensate for curve of monson
6. positioning should be reproducible