Practice Guidelines for CBCT with Markers
The available evidence does not provide specific practice guidelines for the use of markers during CBCT scanning in orthodontic or dental procedures, though markers can be incorporated into radiographic surgical stents to provide important information about bone position and implant placement 1.
Current Evidence on Markers in CBCT
The primary literature on markers in CBCT focuses on implant dentistry rather than general orthodontic applications. A technical overview describes that radiographic surgical stents with markers can be used during CBCT to help determine bone position and guide implant and restoration placement 1. This technique allows various marker positions to be quickly placed and removed, and permits adaptation of current prostheses to act as surgical stents during CBCT imaging 1.
General CBCT Guidelines Relevant to Marker Use
While specific marker protocols are not established in orthodontic guidelines, the following principles apply when considering CBCT with any additional devices:
Radiation Protection Principles
- Limit the field of view (FOV) to the smallest area necessary when using CBCT, as this is the most effective way to reduce radiation exposure 2.
- When two radiographic techniques yield comparable diagnostic information, always choose the technique with the lowest radiation exposure 2.
- Modern techniques exist to limit exposure areas by covering the cranial base and thyroid gland with protective elements 2.
CBCT Justification Framework
CBCT should only be used when conventional 2D radiography fails to provide adequate diagnostic information 2. The Dutch Association of Orthodontists (via Radiologia Medica guidelines) emphasizes that CBCT is justified only when it positively affects treatment options or provides treatment optimization 2.
Specific CBCT Indications (Without Markers)
- Consider CBCT for detecting and evaluating root resorptions caused by impacted canines only when other radiographs are insufficient and there is doubt about the prognosis of potentially resorbed teeth 2.
- Consider CBCT for localizing impacted canines only when other available radiographs do not provide sufficient information 2.
- Do not use CBCT for detecting or evaluating orthodontically-induced external apical root resorption (EARR), as it has no added value compared to panoramic radiography 2.
- Do not use CBCT for inter-radicular miniscrew placements, as it has no added value compared to periapical radiography 2.
Common Pitfalls
- Avoid using CBCT as a routine diagnostic tool without specific clinical justification, as this unnecessarily increases radiation exposure 3.
- The American College of Radiology advises against relying solely on panoramic radiography for root resorption assessment, as it underestimates both presence and severity with a false negative rate of 70% 3.
- Do not order CBCT before exhausting conventional 2D imaging options (panoramic, periapical, or lateral cephalometric radiographs) 3.
Practical Considerations for Marker Use
When markers are used in CBCT (primarily for implant planning):
- The technique allows current prostheses to be adapted as surgical stents during CBCT scanning 1.
- Markers should be radiopaque and clearly distinguishable from surrounding anatomical structures 1.
- The FOV should be optimized to the smallest size that encompasses all relevant structures, including any markers being used 4.
Evidence Limitations
The orthodontic radiology guidelines acknowledge that most evidence regarding CBCT use is graded as "very low" quality, and considerations by expert taskforces played a significant role in formulating recommendations 2. There remains uncertainty about when CBCT has clear advantages over conventional 2D radiographs, and more high-quality research is needed 2.