CBCT Reading in Ortho Flashcards
What triggers the need for a CBCT examination
Need to know dento-facial anatomy that is not visible from clinical examination and 2D X-ray examination in order to drive better decisions
What are some -ves of CBCT
Increased radiation (Esp for kids)
Expensive
What are the radiation dosage issues in the use of CBCT
7
- Radiation damages tissues
- X-rays are a type of EM radiation
- Radiation is a carcinogen
- Stochastic effects - no threshold radiation dose below which they will not occur
- Deterministic effects - no damage until threshold radiation is reached
- Children are more radiosensitive than adults (risk x3 for <10)
- X-ray effects are cumulative
10x more likely to get cancer than from DPT
ALARA
What are the different Field of Views (FOV) of CBCTs
cm is of spherical volume diameter or cylinger height
Large FOV (>15cm):
- TMJ, quantitative ceph and/or airway assessment
- Orthognathic jaw surgery
Medium FOV (10-15cm)
- 1-2 dental arches
Small FOV (<10cm)
- Few teeth, a quad, up to 2 dental arches
What are the British Orthodontic Society’s and Prof Foong’sindications for CBCT
- Highly selected cases where conventional radiography cannot supply satisfactory diagnostic information
- Cleft palate case
- Assessment of unerupted tooth position, particularly where resorption is a concern
- Identification of root resorption caused by unerupted teeth (upper laterals)
- Orthognathic surgery planning
Prof Foong’s:
1. Bone thickness surrounding teeth
2. Tooth impaction and possibility of root resorption and/or ankylosis