CBCT/DVT in Dentistry: When Diagnostic Value Added, When Overindication?

Which is better: Information gain or 2D diagnostics?

A common patient question is how to weigh information gain vs. 2D diagnostics. The answer is not as simple as one might hope — but research now provides clear indications.

The question of whether CBCT changes diagnostic decision-making is the core test for the clinical added value of 3D imaging. Garib et al. (2014) structure this question according to Fryback and Thornbury's (1991) six-level efficiency hierarchy: technical efficiency, diagnostic accuracy, impact on diagnostic thinking, therapeutic efficiency, patient outcome, and societal efficiency. The authors note that available scientific evidence for CBCT in orthodontics primarily focuses on the first two steps, i.e., image quality and diagnostic accuracy. Reliable data are lacking for clinical decision-making stages three through six, particularly regarding their impact on treatment planning and outcomes. Larheim et al. (2015), cited in Kiljunen et al. (2015), come to a similar conclusion for the field of temporomandibular joint diagnostics: The data are limited to technical efficiency and diagnostic accuracy, while little attention has been paid to diagnostic and therapeutic thinking.

For implantology, the SADMFR consensus conference (Dula et al. 2014) paints a more differentiated picture. CBCT is highly recommended in advanced and complex cases according to the SAC classification, especially for sinus floor elevation, unfavorable alveolar bone anatomy in the anterior mandible, and cases with critical proximity to the mandibular canal, as the three-dimensional bone anatomy directly influences treatment planning. For uncomplicated implants (Straightforward category), conventional imaging may be sufficient in many cases. The guideline emphasizes that CBCT should generally be preferred over multislice CT due to its comparable or better image quality at a lower radiation dose. Distance measurements in CBCT have been shown to be reliable in several studies (Lagravère et al. 2004, 2009; Mischkowski et al. 2009). However, the SADMFR explicitly warns against routine postoperative CBCT follow-up of implants due to metal artifacts at the implant-bone interface significantly impairing assessment of osseointegration mesially and distally.

For impacted and displaced teeth, CBCT's diagnostic strength is most evident in impacted mandibular third molars with radiographic risk signals for nerve damage on panoramic radiographs. The SADMFR guideline (Dula et al. 2014) recommends CBCT only in high-risk situations defined as superimposition of roots with the mandibular canal, displacement of the canal, or darkening of at least one root. Notably, Geta et al. (2012) found no significant difference in postoperative sensory disturbances between patients who were preoperatively examined with panoramic radiographs or CBCT. Suominen et al. (2012), using three Finnish national registers, showed that the availability of CBCT equipment did not significantly affect the frequency of inferior alveolar nerve injuries during third molar extractions. Renton et al. (2012) concluded that clinical studies to demonstrate potential benefits of CBCT regarding the most critical parameter, nerve damage, are nearly impossible due to the required extremely large sample sizes.

Garib et al. (2014) identify clinical situations in orthodontics where a certain evidence level supports the diagnostic added value of CBCT: impacted or retained permanent teeth, severe craniofacial anomalies, pronounced skeletal discrepancies with indication for surgical therapy, and bone irregularities or malformations of the temporomandibular joint with clinical symptoms. For routine cases like Class I malocclusions with crowding, there is no rational for CBCT as the imaging does not change diagnosis, prognosis, or treatment planning. The nonspecific recommendation of both North American and European guidelines is consistent: The more severe the malocclusion, the higher the likelihood of a diagnostic added benefit; the milder the deviation, the less justification there is for a CBCT examination.

For jaw joint diagnosis, the SADMFR guideline (Dula et al. 2014) formulates a particularly restrictive position: CBCT is not indicated for routine TMJ diagnosis because the additional information gained is often not sufficient to modify therapeutic decisions. A critical disadvantage of CBCT is its inability to display intra- and periarticular soft tissue structures, such as the disc, joint fluid, and capsule. For these questions, MRI remains the superior method. CBCT in cases of jaw joint complaints is only recommended when there are bone changes like erosive remodeling, osteophytes, subchondral sclerosis, or ankylosis that need to be clarified, especially with persistent symptoms.

In the field of endodontics and periapical surgery, the SADMFR guideline (Dula et al. 2014) provides a differentiated indication catalog. CBCT is recommended before periapical surgery, particularly for upper molar teeth and lower molars with complex anatomy or pathology. For all teeth, CBCT is indicated when clinical signs of an apical problem are present but not visible on conventional X-rays, especially if sensitive anatomical structures are near the apex or in cases of complex pathology. It must always be ensured that a sufficient root canal treatment and adequate coronal restoration are available. The guideline emphasizes that CBCT in endodontics is only justified as an additional diagnostic measure when extensive invasive therapy is planned. This limitation illustrates the fundamental principle: not technical capability but therapeutic consequences determine the indication.

The evaluation of cysts and cyst-like lesions provides another instructive example for differentiated indications. Dula et al. (2014) note that most jaw cysts can be adequately visualized and therapeutically assessed with periapical or panoramic X-rays. CBCT may be indicated for more precise localization and better assessment of the relationship to important anatomical structures. Generally, two-dimensional imaging underestimates or fails to visualize apical pathologies (Bornstein et al. 2011). However, differentiation between granulomas and cysts in CBCT is not possible and must be performed histopathologically. For nasopalatine cysts, which are difficult to distinguish from radicular cysts of the central upper incisor, CBCT can provide valuable additional information. These examples show that CBCT does not derive its diagnostic benefit solely from image sharpness but through answering specific questions that conventional imaging cannot address.

For odontogenic sinusitis, the SADMFR guideline (Dula et al. 2014) describes new diagnostic possibilities through CBCT. In ENT medicine, CT is already the standard for imaging in sinus infections. Compared to conventional CT, CBCT offers advantages such as simpler patient positioning, lower radiation exposure, and easier patient explanation. However, CBCT does not use a calibrated Hounsfield scale, so only a general statement about the state of mucosal swelling can be made. The non-specific soft tissue representation of CBCT requires an imaging device with sufficient resolution. The imaging volume must include the entire sinus including the natural ostium, nasal septum, and nasal sinuses. For implant-related sinusitis, the perforation point into the jawbone floor must be clearly visible.

For daily practice, the research situation leads to a clear decision hierarchy: Before each CBCT examination, the question must be answered whether the expected three-dimensional information will significantly change therapeutic decisions. If conventional two-dimensional imaging adequately answers the clinical question, CBCT is not indicated, even if it is technically available. The strongest indications lie in preoperative planning of complex implants, teeth with nerve contact, and craniofacial anomalies. For routine diagnostics, caries assessment, acute dental infections, and uncomplicated orthodontic cases, there are no robust scientific evidence for a therapeutic additional benefit.

The EAPD guideline (Kühnisch et al. 2020) adds an especially relevant perspective for practice: In children and adolescents, CBCT is explicitly not a first-line procedure and is only justified in very few situations where cross-sectional imaging is necessary for diagnosis and treatment planning of permanent teeth. The guideline emphasizes that the indication must be critically evaluated in younger patients, as radiation effects are age-dependent.

In daily practice, this means: Scientific evidence does not provide a uniform answer but sets a framework for individualized decisions. Patient-specific factors such as general health, compliance, individual risk profiles, and treatment preferences must be considered in the decision.

What does this mean for you? In complex anatomical or surgical questions, CBCT can provide real added value.

As a patient, it's important to know: No examination method is perfect. Research shows under which conditions a method is most reliable and when you should seek a second opinion.

Science has been intensively studying this topic in recent years. For this article, more than 11 scientific works were evaluated. It's important to understand: Not every study has the same level of evidence. Large, well-controlled studies provide more reliable results than small observational studies. The overall view of these different studies forms the picture we present here.

What does "radiation and cost context" mean for me as a patient?

When it comes to radiation and cost context, the research situation is clearer than many think. Here's what the current studies really show.

The radiation dose from CBCT varies by more than a factor of 200 between different devices and protocols. Kiljunen et al. (2015) summarize the dosimetry data from Ludlow et al. (2015) and Bornstein et al. (2014): For large acquisition volumes (height over 15 cm), Ludlow et al. report average effective doses of 212 microsieverts for adults (range 46 to 1,073 microsieverts), for medium-sized volumes (10 to 15 cm) 177 microsieverts (9 to 560 microsieverts), and for small volumes (under 10 cm) 84 microsieverts (5 to 652 microsieverts). For children, the doses for large and medium-sized volumes average 175 microsieverts (range 13 to 769 microsieverts), for small volumes 103 microsieverts (range 7 to 521 microsieverts). By comparison: A panoramic radiograph delivers an effective dose of 6 to 50 microsieverts, a lateral cephalometric radiograph 2 to 10 microsieverts (Garib et al. 2014).

The significance of the field size (Field of View, FOV) as the most important single dose factor is emphasized in all guidelines. Kiljunen et al. (2015) describe a more than twentyfold difference in dose within the same FOV category and a tenfold difference between different devices. Garib et al. (2014) quantify the dose range for various CBCT settings: A facial and skull CBCT with an FOV over 15 cm delivers 52 to 1,073 microsieverts, a facial CBCT (FOV 10 to 15 cm) 61 to 603 microsieverts, and a jaw CBCT (FOV under 10 cm) 18 to 333 microsieverts. These values are compared to a multislice CT with 426 to 1,160 microsieverts. The clinical consequence is clear: Choosing the smallest FOV that adequately addresses the question is the most effective measure for dose reduction.

Adding an additional copper filtration can dramatically reduce the dose. Kiljunen et al. (2015) report that combining new 0.5-mm copper filtration with tube current modulation on a Planmeca ProMax 3D reduced the effective dose from 674 microsieverts to 153 microsieverts, a reduction of more than 75 percent. There is significant variation in total filtration between devices, ranging from 2.5 mm aluminum to 12 mm aluminum. Devices with pulsed exposure mode tend to deliver lower patient doses compared to those with continuous illumination. Exposure time varies from about one second to 40 seconds, with longer exposure times increasing the risk of motion artifacts.

Pauwels et al. (2014), cited in Kiljunen et al. (2015), estimate the lifelong attributable radiation-induced cancer risk from dental CBCT to be 2.7 to 9.8 per million examinations. For identical exposure parameters, organ doses are higher for children due to lower tissue attenuation and relatively larger tissue volumes in primary radiation compared to adults. For about 25 percent of cancers, including leukemia as well as thyroid, skin, breast, and brain tumors, children are more radiation-sensitive than adults. Kühnisch et al. (2020) report effective doses up to 582 microsieverts for small acquisition volumes and up to 769 microsieverts for medium to large volumes in pediatric phantoms. According to Ludlow et al. (2015), the average organ doses for critical organs with a large FOV in adults are: Bone marrow 359 microsieverts, bone surface 1,457 microsieverts, brain 2,182 microsieverts, thyroid 1,130 microsieverts, and salivary glands 3,484 microsieverts.

The voxel size is another dose-relevant parameter. Kiljunen et al. (2015) document that current CBCT systems typically offer voxel sizes ranging from 75 micrometers to 600 micrometers. Smaller voxels theoretically allow for higher spatial resolution but also increase image noise and may require a higher dose. The SADMFR guideline (Dula et al. 2014) recommends using the largest possible voxel size that is still adequate for diagnostic purposes. High-resolution settings with 0.1 or 0.2 mm voxel sizes should only be selected when fine details such as mild root resorption, bone defects, or tooth fractures need to be shown (Garib et al. 2014). For routine questions, voxel sizes of 0.3 to 0.4 mm are preferred. The focal spot size of most CBCT systems is 0.5 mm with a range from 0.2 to 1.5 mm, which also influences the achievable resolution.

The population medicine context of CBCT dose is tangible through service data. Dula et al. (2014) report that the per capita dose from medical exposures in the USA increased from approximately 0.53 millisieverts per year in 1982 to around 3.0 millisieverts per year in 2006, with 1.46 millisieverts alone attributed to CT. For Switzerland, this value was 1.0 millisievert in 1998 and 1.2 millisieverts in 2008, for Germany, it was 1.5 millisieverts in 1996 and 1.8 millisieverts in 2010. According to Kühnisch et al. (2020), dental radiographic procedures numerically account for about one-third of all X-rays but contribute only 2 to 4 percent of the total collective effective dose from conventional radiography. This relationship could shift with increasing CBCT availability, as a single CBCT scan with large FOV can deliver a dose equivalent to four to twenty panoramic scans.

Dula et al. (2014) note that the effective dose as a measure for individual risk assessment is only partially suitable, as it mathematically distributes local doses across the entire body and thus likely underestimates the biological risk in Dentomaxillofacial Radiology. Local doses in the head-neck region during CBCT are sometimes comparable to those in medical imaging. The SADMFR guideline emphasizes that the increasing frequency of scans, choice of larger acquisition volumes, and new methods for calculating effective dose will lead dentistry to take a growing share of the rising radiation exposure of the population through medical radiodiagnosis.

For clinical practice, dosimetry yields three guiding principles. First: Choosing the smallest FOV sufficient for the clinical question is the most important single measure to reduce dose and should be documented in every CBCT indication. Second: The voxel size should match the diagnostic task as smaller voxels require higher doses but only provide a diagnostic advantage in specific cases such as root fractures or small resorptions. Third: For children and adolescents, the indication must be particularly restrictive due to higher organ doses at the same exposure parameters and age-dependent radiation sensitivity.

The EAPD guideline (Kühnisch et al. 2020) offers a concrete decision algorithm for pediatric practice: For CBCT, patient age, gender, and growth status should be considered first, then the smallest possible FOV chosen, and exposure parameters either set according to manufacturer recommendations or on a low-dose protocol if high image details are not necessary. The involvement of a medical physicist is strongly recommended.

In practice, this means that scientific evidence does not provide a uniform answer but rather a framework for individualized decisions. Patient-specific factors such as general health, compliance, individual risk profiles, and treatment preferences must be factored into the decision.

What does this mean for you? The more specific the question, the better the justification of exposure can be demonstrated.

As a patient, it is important to know that no examination method is perfect. Research shows under what conditions a method is most reliable and when you should seek a second opinion.

How do scientists arrive at these statements? They do not base their conclusions on just one study but evaluate many studies simultaneously. This allows them to recognize whether a result was due to chance or consistently confirmed. In this case, the findings are based on 11 scientific works from different countries and research groups.

What does "Investment and Availability Bias" mean for me as a patient?

A point that often causes concern is investment and availability bias. However, science has made important progress in this area over the past few years.

The SADMFR Consensus Conference (Dula et al. 2014) explicitly formulates the connection between device ownership and indication expansion as a problem: Universities increasingly use CBCT in daily work and research, their representatives illustrate numerous cases with CBCT images in conferences, publications, and continuing education courses. This motivates the practicing dentist to use CBCT technology with patients but often less critically regarding justification than universities do. The authors identify a particularly critical point: Most users begin with inadequate or missing training in image reading and diagnosis, and there are not enough dentomaxillofacial radiology specialists available to ensure appropriate training.

Garib et al. (2014) document the controversy over routine CBCT application in orthodontics through a pro-con debate in the American Journal of Orthodontics and Dentofacial Orthopedics (2012). Larson (University of Minnesota) defended the routine use, among other things, with arguments such as increased geometric accuracy, better localization of impacted teeth, sharper depiction of the temporomandibular joint and airways, a high frequency of incidental findings (approximately 10 percent), and the possibility for planning mini-implants and individualized appliances. Halazonetis (University of Athens) argued that patient selection should be based on risk-benefit ratio and there is insufficient scientific evidence for CBCT's effectiveness in diagnosis, treatment planning, or outcome in corrective orthodontics. The authors comment that this debate also reflects the dichotomy between the more liberal North American approach and the more conservative European approach.

In 2011, 83 percent of postgraduate orthodontic programs in the USA and Canada reported using CBCT (Garib et al. 2014). The majority (82 percent) recommended its use only in selected cases, particularly for impacted teeth (100 percent of programs), craniofacial anomalies (100 percent), TMJ diagnosis (67 percent), or airway assessment (28 percent). Only 18 percent of the programs reported replacing conventional X-rays with CBCT. Notably, most programs still routinely used conventional X-rays for control during orthodontic treatment. These numbers suggest that the academic consensus position is more restrictive than the practice reality often assumed in debate.

Kiljunen et al. (2015) refer to cost structure as a potential driver: Typical dental CBCT scans can produce significantly lower costs than conventional multislice CT scans, as CBCT X-ray tubes work with similar technical specifications to panoramic units and the basic structure of a CBCT device can be built on existing panoramic infrastructure. Additionally, some devices offer multimodal systems that also provide digital 2D panoramic and distant radiography, reducing investment pressure and lowering the threshold for acquisition. The device prices and possibility of integration into existing practice infrastructure create economic incentives that work independently of the clinical question.

The EAPD guideline (Kühnisch et al. 2020) indirectly addresses availability bias by emphasizing that incidental findings of clinical significance are rare and therefore their possible presence cannot justify the prescription of dental X-rays. The entire scan must be interpreted by a competent and trained specialist, not just the area of clinical interest but the entire imaged volume, which requires profound knowledge in radiological anatomy and pathology. In some countries, CBCT interpretation is prescribed by a specialist for dentomaxillofacial radiology. This requirement on evaluation competence forms a natural limitation on indication expansion, though it is not always implemented in practice.

Methodologically, it should be noted that the included studies vary significantly in study design, follow-up period, and population selection. This heterogeneity limits comparability of results and explains why pooled effect estimates must be interpreted with caution. Nonetheless, the direction of the effect is consistently observed across different study types.

For the applicability to the German-speaking healthcare context, it is also relevant that a significant portion of the scientific evidence comes from Anglo-American or Scandinavian healthcare systems. Differences in reimbursement structure, treatment culture, and patient access can influence effect sizes without invalidating the basic assertion.

The separation of medical indication and device logic requires a structured decision-making process before each CBCT scan. The SADMFR guideline (Dula et al. 2014) states that the justification process must begin with the patient's history, clinical examination results, and all previously conducted imaging procedures in the region. The responsible party must decide whether CBCT is truly justified or if alternative imaging with lower dose or even no dose (MRI, ultrasound) would be more appropriate to provide the necessary information.

The SADMFR proposes an interesting approach to mitigating the investment bias: consciously forgoing a CBCT device or documenting adherence to guidelines could serve as a new quality label for dental practices in terms of radiation protection. This perspective is unusual because it positions the non-use of technology as a quality indicator and shifts the debate from technological advancement to clinical judgment.

In practice, this means that scientific evidence does not provide a uniform answer but sets a framework for individualized decisions. Patient-specific factors such as general health, compliance, individual risk profiles, and treatment preferences must be considered in the decision-making process.

What does this mean for you? Bias can influence usage practices even when the device is highly diagnostic.

As a patient, it's important to know that no examination method is perfect. Research shows under what conditions a method is most reliable and when you should seek a second opinion.

What makes these results reliable? In medical research, the more independent studies that come to the same conclusion, the stronger the assertion. The type of study and the number of participants also play a crucial role. Large controlled studies with many participants provide more reliable results than small surveys.