Join me for a summary of CBCT use inorthodontics, where I look into the current risk of cancer with CBCT use, the differenceit can make to treatment planning, and the 3 most common incidental findingsorthodontists should be aware of. This was one my highlight lectures from lastyears British Orthodontic Conference by Consultant Dental Radiologist, SimonHarvey.
How much radiation comes from dentalCBCT, medicine?
Effective dose of modern machines:
· Dose from full DPT with adigital system = 20-25µSv
· KAVO, MoritaX800 4 x 4cm =16uSv
· FDA values of CT scans acrossthe boy from Lubar 1500uSv – Heart 16000uSv
FACT 1 – effective dose in dental imagingare far below the rest of medicine
Background radiation
· Terrestrial radiation
· Cosmic radiation
o Flight London – New York 56uSv– cancer UK ‘does not effect risk of cancer, even for frequent flyers’, 4uSvper hour
o Pilots do not have an increasedrisk of cancer
UK 3000 uSv annually
FACT 2 – EFFECTIVE DOSES IN DENTAL IMAGINGARE FAR BELOW THE NATURAL BACKGROUND RADIATION
American Association of Physicist inMedicine AAPM
“evidence supporting increased cancerincidence or mortality from radiation doeses below 100mSv is inconclusive” –cancer incidence and mortality from the use of diagnostic imaging are highlyspeculative, discourage these prediction of hypothetical harm
FACT 3 EFFECTIVE DOSES IN DENTAL IMAGINGARE SO LOW, THEY DO NOT CAUSE CANCER
Clinicians improved confidence andconsistency in treatment planning decisions.
Impacted canine:
· 3 radiographs - namely occlusal view, opg , periapical = still not confident about prognosis.
· CBCT = clear follicle and impactedcanine proximity to adjacent tooth, = easily make up the decision estimatingprognosis
o 22%-44% change of plans Hodges 2013 Stoustrup 2024 change in treatment plans ofimpacted teeth. The majority related to change in planning, with approximately10-20% a change in exposure Vs extraction. Keener 2023
· Cleft – quantification of bonedefect volume for grafting and localisation of ectopic teeth
· Surgery – location of importantanatomical structures
3 Commonincidental findings for orthodontists
· Dense bone island-
o Radiopacity with no radiolucenthalo
o Mandibular premolar region
o Harmless, may resorb roots ifcontact it
· Sinus mucosal thickening
o Antrum floor intact
o Only concern if 5mm+
· Trabecular pattern
o Around inferior dento-alveolarcanal
o No corticated boarder
o normal in children, technicalreason is physiologic response as more RBC’s are developing surrounding thatarea.
Pregnant women –yes as not irridating pelvic reason, CBCT beam is horizontal so no risk
Conclusion
1. CBCT superior for resorption,material change to treatment plans and improve confidence of the orthodontists
2. No recommendation for takingfull mouth CBCT instead of DPT ahead of starting every orthodontic treatment asroutine and x rays should never go hand in hand
3. Small volume CBCT does is solow it doesn’t cause cancer
