What do we (do not) know about the use of cone beam computed tomography in endodontics? A thematic series with a call for scientific evidence

The introduction of cone beam computed tomography (CBCT) imaging had significant effects on the daily practice of endodontics (Rosen et al. 2017; Rosen et al. 2015; Kumar et al. 2015; AAE and AAOMR Joint Position Statement 2015; AAOMR and AAE 2010). It is generally accepted that CBCT should not be used routinely in endodontics due to its excessive radiation dose compared to intraoral radiography (Rosen et al. 2015; AAE and AAOMR Joint Position Statement 2015; AAOMR and AAE 2010; Patel et al. 2015). However, it seems that CBCT use expended to almost every daily endodontic procedure (Rosen et al. 2017; Metska et al. 2014; Liang et al. 2013; Jeger et al. 2012; Janner et al. 2011; Ustun et al. 2016). This increased usage of CBCT in endodontic practices raises questions regarding what do we actually know about the benefits and risks of CBCT use for endodontic proposes. In this thematic series, we call for manuscripts that discuss different aspects of the use of CBCT in endodontics.

The benefit of a diagnostic imaging should be estimated by its diagnostic efficacy that is “the probability of benefit to individuals from a system or test under ideal conditions of use” (Rosen et al. 2015; Krupinski and Jiang 2008). A common misunderstanding is that a “good” diagnostic efficacy means providing remarkable images of sufficient quality (Rosen et al. 2017; EUROPEAN-COMMISSION 2012; Fryback and Thornbury 1991). The basis for this misunderstanding relies in the disregard of the wider clinical context (Rosen et al. 2017). For example, disregarding additional valuable diagnostic information that may have already been acquired before the endodontic procedure (e.g., by previous intraoral radiographs together with a meticulous clinical examination (AAOMR and AAE 2010; ADA 2012; Carrotte 2004; Ee et al. 2014; Mota de Almeida et al. 2015)) or during the procedure (e.g., by the use of magnification and illumination devices to asses complex anatomy (Weinstein et al. 2010; Del Fabbro et al. 2015). This preoperative and intra-operative acquired information may provide all the necessary information to support the practitioner’s clinical decision making and therefore may lead to the conclusion that CBCT is not necessary (Rosen et al. 2017). In addition, there is fundamental question of what would be the ultimate benefit of this information, if attained by the CBCT?

In order to assess the ultimate benefit of an imaging modality, Fryback and Thornbury (1991) developed a diagnostic efficacy hierarchical model (Rosen et al. 2015). It includes several levels of imaging efficacy that for simplicity can be categorized into: technical efficacy (considered as the inferior levels and assess the technical quality of the images or the diagnostic accuracy associated with interpretation of the images) and to clinical efficacy (considered as the superior levels and asses the efficacy of the evaluated imaging modality to support the practitioner’s clinical decision making and to improve treatment outcomes) (Rosen et al. 2017; Rosen et al. 2015; Fryback and Thornbury 1991; Matzen and Wenzel 2014). This model has been used in recent years also in dental research to evaluate the diagnostic efficacies of CBCT (Rosen et al. 2017; Rosen et al. 2015; EUROPEAN-COMMISSION 2012; Pittayapat et al. 2014; Kim et al. 2011; Kaeppler et al. 2013). In endodontics, a recent systematic review of the literature (Rosen et al. 2015) used this model to evaluate the endodontic literature (Fryback and Thornbury 1991), and concluded that the expected ultimate benefit of CBCT to the endodontic patient is yet unclear, and is mainly limited to its technical and diagnostic accuracy efficacies, and thus, recommended a cautious and rational approach when considering CBCT for endodontic purposes (Rosen et al. 2015). These conclusions are in accordance with other recently published articles in endodontics (Kruse et al. 2015) and in other disciplines of dentistry (Rosen et al. 2017; EUROPEAN-COMMISSION 2012; Matzen and Wenzel 2014; Pittayapat et al. 2014; Kim et al. 2011).

It is therefore evident that the current literature assessing the benefit of CBCT to the endodontic patient is mainly limited to its technical efficacy (i.e., an inferior level of efficacy) and provides little information about its clinical efficacy (Rosen et al. 2017). Thus, the question regarding what is the ultimate benefit of CBCT to the endodontic patient remains un-answered.

In addition to the data on the endodontically involved tooth, CBCT scans also include additional adjacent areas that are usually not evident in routine intraoral radiographs (Kumar et al. 2015). The practitioner is required to examine the entire region that appears in the CBCT scan and report on any suspected abnormalities or pathologies (Rosen et al. 2017; Kumar et al. 2015; EUROPEAN-COMMISSION 2012; ADA 2012; Brown et al. 2014). The daily use of CBCT by endodontic practitioners therefore raises concerns regarding the necessary training and experience required by the practitioner in order to efficiently evaluate the CBCT scans (Rosen et al. 2017; AAOMR and AAE 2010; Patel et al. 2015; ADA 2012; Brown et al. 2014). This diagnostic challenge may require comprehensive knowledge regarding the radiographic features of the head and neck anatomy and pathology that may be beyond the endodontic practitioner experiences (Brown et al. 2014), thus subjecting the patient to risks of undiagnosed pathologies and the practitioner to an ensuing medico-legal liability risk (Rosen et al. 2017; Brown et al. 2014; Friedland 2009; Givol et al. 2010).

CBCT yields a higher radiation dose than traditional intraoral radiography (ADA 2012). CBCTs use X-ray ionizing radiation (Rosen et al. 2017; EUROPEAN-COMMISSION 2012; Bornstein et al. 2014; Brenner and Hall 2007) that potentially may harm the DNA leading to an ensuing risk of malignancy (EUROPEAN-COMMISSION 2012). These potential harmful effects are unpredictable, and therefore, every exposure to X-rays should be considered as dangerous (Rosen et al. 2017; Rosen et al. 2015; Patel et al. 2015; EUROPEAN-COMMISSION 2012; ADA 2012; Patel 2009; Patel et al. 2009). In addition, the risks may be significantly higher in children (EUROPEAN-COMMISSION 2012). Thus, strict considerations should be weighted prior to the use of CBCT, especially in children (Rosen et al. 2017; Pauwels et al. 2014; Petersen et al. 2015; Wu et al. 2015). The effective dose of CBCT scans is unpredictable and varies significantly depending on the field of view (FOV), the scanner type, and on many other acquisition parameters (Rosen et al. 2017; Patel et al. 2015; EUROPEAN-COMMISSION 2012; Ludlow et al. 2015).

Thus, a careful and rational CBCT use should be based on a modern “better safe than sorry” preventive approach. This preventive approach advocates that preventive actions should be taken in order to disable potential harmful effect even when it is not certain to occur (Rosen et al. 2017; Rosen et al. 2015; AAOMR and AAE 2010; European-Environment-Agency 2001; Kheifets et al. 2001). In the context of CBCT use, the application of this preventive approach may be challenging since the immediate profit from the use of CBCT may seem significant (Rosen et al. 2015; AAOMR and AAE 2010; Berman and Hartwell 2006), and conversely, the harmful effects of the CBCT radiation exposure may not be obvious until years after the actual exposure (Rosen et al. 2017; Rosen et al. 2015; AAOMR and AAE 2010; Patel et al. 2015; Brenner and Hall 2007; Pauwels et al. 2014; Petersen et al. 2015; Wu et al. 2015; European-Environment-Agency 2001; Kheifets et al. 2001; Berrington de Gonzalez et al. 2009).

Recent guidelines published regarding the use of cone beam computed tomography in Endodontics–2015/2016 Update AAE/AAOMR Joint Position Statement recommended periapical imaging be used for the evaluation of healing after nonsurgical and surgical endodontic treatment in the absence of clinical signs or symptoms. However, in the absence of clinical signs or symptoms, if limited FOV CBCT was the imaging modality of choice at the time of evaluation and treatment, CBCT was advised for the follow-up assessment. This recommendation was based on evidence that generally CBCT performed better for accurate diagnosis of complete and uneventful healing when compared with intraoral imaging (American Association of Endodontists. AAE and AAOMR joint position statement:use of cone beam computed tomography in endodontics-2015/2016 update. Available at: http://www.aae.org/uploadedfiles/clinical_resources/guidelines_and_position_statements/conebeamstatement.pdf. Accessed 9 May 2017).

It may be concluded that the current literature, including recently published articles, raise substantial concerns regarding the long-term health risk associated with the use of CBCT in dentistry, advocating further research and a rational and cautious use of CBCT for endodontic proposes (Rosen et al. 2017; Pauwels et al. 2014; Petersen et al. 2015; Wu et al. 2015).

To-date, key questions regarding many aspects of the use of CBCT in endodontics still await to be answered, such as: what are the expected ultimate benefits of CBCT to the endodontic patient? What is the necessary training required by the practitioners in order to efficiently evaluate the CBCT scans? What are the potential and actual long-term radiation risks of CBCT scans? How these expected benefits and risks should be implemented as part of a cautious and rational clinical approach? (Rosen et al. 2017). Therefore, the scientific community is obligated to perform additional studies to elucidate these crucial matters, and endodontic practitioners must stay scientifically updated with the extensive ongoing research of the CBCT technology (Rosen et al. 2017; Rosen et al. 2015; ADA 2012).