Intro to Radiographic Interpretation and Caries in Radiographs (caries symposium)

Question 1

as a rule of thumb, how long does it take the roots to form after eruption

Answer 1

3 years

Question 2

what are mesiodens

Answer 2

In between the upper central incisors we’ve got a supernumerary tooth - this is a fairly typical position for an extra tooth as it is in the midline of the maxilla (there is a special name for a supernumerary in this position ~ mesiodens

Question 3

what is likely if there are missing teeth in the primary dentition

Answer 3

Are the teeth also missing in the deciduous dentition? If so, very likely to then be missing from the permanent dentition

Question 4

which teeth are most likely to be congenitally absent

Answer 4

Think of teeth as belonging to different groups
So the last in each of those groups are the most likely to be congenitally absent:

• Incisors
  ○ Lateral incisor
• Cuspets
  ○ Second premolar
• Molar
  ○ Third molar (these are so common we don’t really think of them as a developing abnormality ~ can even be a good thing to not have these teeth as most of us don’t have room in our mouth for functioning 3rds)

Question 5

why are clinical evaluation reports important

Answer 5

• Legal requirement

• Clinical evaluation of the outcome of each exposure is (must be) recorded in accordance with the employer’s procedures
○ By who?
§ For normal radiographs in GDH&S the responsibility = the referrers
§ For your patients the responsibility = you

• Complete in the patient’s written notes only

Question 6

what are the sites for caries

Answer 6

• Pit and fissure
○ Occlusal
§ Premolars and molars
○ Buccal - may be confused radiographically with occlusal
§ Lower first molar has a little pit on this surface

• Smooth surface
○ Interproximal
§ Difficult to detect clinically
○ Lingual - may be confused radiographically with occlusal and buccal
§ Poor caries control
○ Root - may be confused with cervical burnout
§ Cervical burnout is a radiographical phenomenon

• Secondary / recurrent
○ Under restorations
○ Always check the edges for radiolucency - will either suggest caries has been left behind or there is new caries due to a leakage at the margins

Question 7

what are the methods of caries diagnosis

Answer 7

• Visual - look at the teeth:
○ Wet
○ Dry
○ Good for smooth surfaces (apart from interproximal) and occlusal surfaces

• Radiography
○ Film
○ Digital
○ Either way for the technique for producing the radiographs is similar

• Elective temporary tooth separation
○ Use of special rubber bands to force teeth slightly apart which then gives you access to a surface which was previously inaccessible

• Fibreoptic transillumination
○ Use of light

• Electrical methods
• Laser fluorescence
• Calcivis - detects calcium ion loss from demineralising tooth surfaces

Question 8

why do we often take panoramic instead of bitewings for children

Answer 8

often take panoramic radiographs as children can find it difficult to have bitewings done

Question 9

what is cervical burnout

Answer 9

Phenomenon caused by relative lower X-ray absorption on the mesial or distal aspect of teeth, between the edge of the enamel and the adjacent crest of the alveolar ridge
Because of the relative diminished X-ray absorption, these areas appear relatively radiolucent with ill-defined margins
Cervical burnout may mimic root surface caries

Exposure dependent

Question 10

what is the difference between cervical burnout and root caries

Answer 10

Difference is that root caries should be able to be identified clinically - either by feeling with an instrument or with the use of floss whether it is a sound tooth or a caries affected tooth

Question 11

on what teeth is cervical burnout mostly seen

Answer 11

premolars and molars

Question 12

what dimension of the teeth is variable

Answer 12

Bucco-lingual dimension of teeth variable

Question 13

what happens when the x-ray photon hits the tooth straight

Answer 13

So when the x-ray photon hits the tooth straight it has to pass through the enamel, then dentine, then pulp then back through the dentine and enamel on the other side so it has to pass through a lot of hard tissue in the middle of the tooth (this is seen in one of the molars and the premolar)

Question 14

what happens when the x-ray photon passes through the edges of the tooth

Answer 14

However the second arrow passes through the edges of the tooth so the total thickness is less and the thickness of the different constituents will also be less [and as it is right at the edge it may just be passing through enamel and no dentine at all]

Question 15

what creates the radiolucency

Answer 15

There is different amounts of x-ray energy getting through at the different points
The radiation that gets through creates the radiolucency

Question 16

what are the selection criteria recommendations for periodontal assessment

Answer 16

• Radiography secondary to clinical examination and full mouth periodontal assessment

• Pocketing 4-5mm
○ horizontal bitewings
○ Long axis of image receptor is running horizontally - this is the standard

• Pocketing =/>6mm
○ vertical bitewings and periapical if bone not shown
○ Different holder and the long axis goes vertically
○ Not very commonly requested

• Irregular bone levels
○ may supplement with periapical
○ If needing to see bone and know you won’t pick it up with bitewings

• Panoramic useful for overview of all teeth, supplemented by periapical if needed, or full periapical
• Periapical for suspected perio / endo lesions

Question 17

for periodontal radiography if panoramic what should you choose

Answer 17

If panoramic choose orthogonal projection (P4)

Question 18

what is crucial in periodontal radiography

Answer 18

• Beam angulation crucial
• Horizontal angle 90˚ to line of arch
• Avoids overlaps of adjacent teeth
• The angle that the beam makes with the teeth coming in at 90˚
• Overlap means we cannot see the bone level between the teeth either

• Vertical angle 90˚to long axis of tooth
- In some situations where you pick up an isolated pocket clinically and if it is just rom one aspect of the tooth, the bone else where is good, can just put a GP point into that pocket and the tip of it will show you were the base of that pocket is

Question 19

what can be difficult to show in periodontal radiography

Answer 19

Pockets may be difficult to show - consider GP point

Clinical pocket depth examination crucial