In which circumstances is CBCT generally indicated over 2D radiographs in dental practice?

• A. When 3D diagnostic information is essential for treatment planning, such as implants, impacted teeth, or pathology.
• B. For routine screening of caries or periodontal disease with no additional information needed.
• C. Because CBCT is cheaper and faster than conventional 2D radiographs.
• D. Whenever the patient requests CBCT, regardless of clinical need.

Answer: (A)

Three-dimensional imaging is indicated when the treatment plan depends on spatial relationships that cannot be reliably assessed on 2D radiographs. CBCT provides true 3D views of bone, teeth, and surrounding anatomy, allowing precise assessment of bone height and width, root morphology, canal anatomy, and proximity to critical structures like the inferior alveolar nerve or maxillary sinus. This makes it especially valuable for implant planning, where you need to simulate implant position, evaluate available bone, and avoid vital structures; for impacted teeth, where exact location, angulation, and relation to adjacent roots and structures must be understood; and for evaluating pathology or lesions where extent, borders, and effects on surrounding bone are better characterized in three dimensions.

In contrast, routine screening for caries or periodontal disease typically does not require 3D information, and 2D radiographs suffice for those purposes. CBCT generally involves higher radiation dose and, in most settings, higher cost and longer imaging times, so it should be used only when the additional 3D information will meaningfully influence diagnosis or treatment. Patient requests alone do not justify its use; justification should be based on clinical need and adherence to ALARA.