Does the use of CBCT in endodontics have an influence on clinical decision-making? Arvind Sharma presents the first part of a structured critical review to evaluate this question
Imaging is essential in endodontics. Traditionally, X-rays (radiographs) have been used and more recently cone beam computed tomography (CBCT) is used to give the clinician more detailed tooth information as part of a clinical examination.
Radiographs have been an invaluable tool in the dentist’s armamentarium in the diagnosis and management of dental problems, (Grondahl and Huumonen, 2004), since their introduction in 1865. Radiographs may be taken as single parallel images or two images applying the parallax technique. Radiographs fundamentally represent a two-dimensional representation of a three-dimensional spatial relationship. The shortcomings and limitations of radiographs are; a degree of magnification – 5 per cent or more (Voorde and Bjorndahl, 1969), superimposition, geometric distortion and lack standardization or reproducibility.
Aria et al 1999 and Mozzo et al, 1998 independently developed a new tomographic scanner known as CBCT and this was specifically for maxillofacial and dental use. CBCT (Fig 1) is a modern three-dimensional imaging system which produces high-quality images using relatively low doses of radiation (see Table 1).
TABLE 1: Comparisons of scans reproduced from Essentials of Dental Radiography and Radiology, 4th edition 2007
CBCT differs from ‘medical’ multi-slice CT (MSCT), as the whole volume of data is acquired in a single sweep with rotations varying between 180-360 degrees. The scanning time is reduced, typically 10-20 seconds, and radiation dose to the patient is less since the cone shaped (not fan shaped as MSCT) beam is pulsed, reducing exposure times to only 3.5 seconds. Approximately 580 images are produced and the field of view (FOV) can be as small as 40mm x 40mm, which can be useful in endodontics (SEDENTEXCT 2012) (Fig 2).
FIG 1: An Accuitomo small volume CBCT scanning machine (Image reproduced from J.Morita USA Inc)
Application of CBCT in endodontics
Limited volume (small FOV) CBCT scanners capture small volumes of data that can include just two or three individual teeth. CBCT allows the operator to view data in three planes: sagittal, axial and coronal (Fig 3). As all the information is obtained in a single rotation, it is very important that the patient is stationary throughout the exposure.
Spatial resolution is a drawback with CBCT since there is only approximately a tenth of the resolution that is currently available with digital and conventional radiographic films. “Increased resolution usually comes at the expense of an increased dose to the patient, as a result of longer exposure times to acquire more 2D projections to a more detailed reconstruction,” (Christiansen et al 2009).
Another limitation of CBCT scans are their vulnerability to beam hardening and streak artefact, which can reduce the image quality even further by producing dark bands or streaks in the image.
FIG 2: Basic concept of CBCT
FIG 3: CBCT image planes
Notwithstanding the above limitations, there are a number of applications for CBCT in endodontics which may overcome the limitations of conventional and digital radiographs and ultimately improve patient management. CBCT with a limited FOV may be considered in the below situations as recommended by the European Society of Endodontology (ESE) position statement 2014:
The use of CBCT in endodontics:
- Diagnosis of radiographic signs of periapical pathosis when there are contradictory (non-specific) signs and/
- Confirmation of non-odontogenic causes of pathosis
- Assessment and/or management of complex dento-alveolar trauma, which may not be readily evaluated form conventional radiographic views
- Appreciation of extremely complex root canal systems prior to endodontic management
- Assessment of extremely complex root canal anatomy in teeth planned for non-surgical endodontic re-treatment
- Assessment of endodontic treatment complications (for example, [post] perforations) for treatment planning purposes when existing conventional radiographic views have yielded insufficient information
- Assessment and/or management of root resorption
- Pre-surgical assessment prior to complex peri-radicular surgery.
As stated by Rosen et al 2015: “A web-based survey emailed to 3,844 active members of the American Association of Endodontists in the United States and Canada reported a significant increase in the use of cone-beam computed tomographic (CBCT) imaging; 34.2 per cent of 1,369 respondents indicated that they were using CBCT imaging for diagnosis and treatment planning purposes,” (Dailey et al 2010).
Implications of CBCT in endodontics
There are a number of implications of CBCT in its application in endodontics, some of which have been discussed earlier, such as radiation dose and treatment outcome.
CBCT still uses ionising radiation and is not without risk. Radiation dose and ‘stochastic effects’ are important considerations. As discussed earlier, CBCT does expose patients to an increased radiation dosage. The principles of ‘As Low As Reasonably Achievable’ (ALARA) should always be applied to limit patient dose.
Every radiation exposure a patient has must be justified and optimised ideally with strict selection criteria as stated by the FGDP guidelines, 2013. The FOV must be reported on in its entirety since the clinician has a legal obligation to read and comment on the whole view. This highlights the training the operator must undergo before taking scans and the clinician must engage the advice of a suitably qualified radiologist if further advice/information is sought (Brown et al 2014).
The cost of CBCT scanners must not be allowed to motivate clinicians to take scans without first justifying the exposure. Ethical scanning is paramount.
Another implication may be the potential removal of metallic coronal restorations to avoid ‘beam hardening’, which would increase procedural time and patient cost.
Wu et al 2009 recommended that: “The outcome of root canal treatment should be re-evaluated in the long term using CBCT and stricter evaluation criteria”, for the reasons as discussed earlier. This has led many researchers to argue and debate a very crucial question: What constitutes endodontic success? An asymptomatic patient or a ‘healed’ scan or periapical?
“This has a huge implication on clinical decision making and selection criteria when considering (re-) placing coronal restorations on teeth which have previously been endodontically treated and appear to have successfully healed on the radiograph,” (FGDP 2013).
Some have asked for more clarification from the European Society of Endoontology (ESE), which has recently published a position statement: ‘The use of CBCT in Endodontics’, in 2014. The guidelines advise that “every image involving ionizing radiation, including CBCT, must be justified and optimised. A record of the justification process must
“Clinical studies with a primary outcome measure of detecting the presence or absence of apical periodontitis and epidemiological studies assessing the prevalence of apical periodontitis in different populations may have to be re-evaluated,” (Ng 2010).
The question, therefore, may be posed as to how much relevance a CBCT has in clinical decision-making in endodontics? If a clinician has not obtained enough relevant information from a radiograph and has made the clinical judgement to expose the patient to a CBCT scan, does the information provided by the CBCT image have an effect on the clinician’s clinical management of that patient? Does the exposure of the patient to a CBCT image have a net positive benefit to the patient? Is this justified following the guidelines discussed earlier?
The scoping searches showed a number of papers important to this review in the existing literature:
- Balasundaram et al 2012. Comparison of Cone-Beam Computed Tomography and Periapical Radiography in Predicting Treatment Decision for Periapical Lesions: A Clinical Study.
- Cheung et al 2013. Agreement between periapical radiographs and cone-beam computed tomography for assessment of periapical status of root filled molar teeth.
- Mota de Almeida et al 2014. The impact of CBCT on the choice of endodontic diagnosis.
- Estrela et al 2014. Characterization of successful root canal treatment.
- Mota de Almeida et al 2014. The effect of CBCT on therapeutic decision-making in endodontics.
- Rosen et al 2015. The diagnostic efficacy of CBCT in endodontics: A systematic review and analysis by a Hierarchical Model of Efficacy.
- Ee et al 2014. Comparison of endodontic diagnosis and treatment planning decisions using CBCT vs periapical rads.
- Hashem et al 2015. Clinical and radiographic assessment of the efficacy of calcium silicate indirect pulp capping: a randomised controlled clinical trial.
- SEDENTEXCT Project. Radiation Protection 172. Evidence-Based Guidelines on Cone Beam CT for Dental and Maxillofacial Radiology [Internet]. 2011 [cited 2012 Dec 10]. Available at: http://www.sedentexct.eu/content/guidelines-cbctdental-and-maxillofacial-radiology. Accessed August 6, 2012.
Scoping searches to formulate an idea of the current state of knowledge of the topic literature showed limited studies in this area. Studies that were found appear mainly to be in-vitro with few in vivo studies. This, of course, highlights the justification of performing in vivo studies in humans where ethical issues are paramount in the 21st century. Scoping searches were performed using the PROSPERO, PubMed and Google Scholar databases. Scoping searches also identified a number of well-published authors who appear to be leaders in the field of CBCT: S Patel, C Durack, F Abella, M Roig, H Shemesh, P Lambrechts and K Lemberg.
CBCT can overcome some of the limitations of intra-oral radiographs, which are the primary imaging method in endodontics (Lofthag-Hansen et al, 2007 and Scarfe et al, 2009).Therefore, the usefulness of CBCT imaging can no longer be disputed, since they can complement radiographs. It is an important imaging tool in contemporary endodontics and “has been shown to be superior to conventional periapical and panoramic radiography in its accuracy and sensitivity in detecting endodontic related pathology” (Stavropoulos and Wenzel, 2007, Tsai et al, 2012, Liang et al, 2014).
As scanners become more affordable and radiation dose to the patient possibly reducing, more endodontic disease may be detected in the future, which inevitably means better patient management. However, Pope et al 2014 have discussed that more sensitive technology may cause over-diagnosis, which could potentially harm
Presently, academic opinion (ESE position statement, 2014) advises that “CBCT should only be considered in situations where diagnostic information from clinical examination and conventional radiographs does not yield an adequate amount of information to allow appropriate management of the patient. A case-by-case approach is recommended and a CBCT scan should have a net benefit to the management of a patient’s endodontic problem”.
Clinical decision-making in endodontics
Clinical decision-making in endodontics is a process which involves the clinician’s diagnostic skills and the patient’s presenting signs and symptoms. It is a conclusion reached only after assessment of signs, symptoms, examination, special tests, consideration of expected outcome and, most importantly, the patient’s wishes. Therefore, “decision-making depends on the skill and experience of the clinician and the treatment options available which is termed as evidence-based practice” (Sackett et al, 1996).
However, “the needs and preferences of the patient are what drives the treatment decision since only the patient is truly the expert as to how he/she feels about maintaining a tooth, what symptoms are tolerable, what risks are worth taking and of course what costs are acceptable” (Bergenholtz and Kvist, 2014). Therefore, a patient-centred outcome is ideal. “Diagnosis is seen as only one part of the medical decision process” (Ledley and Lusted, 1959). Once a clinical decision has been reached, only then should treatment be executed with the patient’s informed consent.
TABLE 2: A Hierarchical Model of Efficacy: Typical Measures of Analysis (Fryback and Thornbury 1991)
Radiographs have been used as an imaging tool to base clinical decisions on and Strindberg developed a system in 1956. His system was based on biology and can be perceived as being dogmatic and inflexible. In the Strindberg system, a normal periradicular situation on periapical image with no patient symptoms was identified as endodontic success and a periradicular lesion apparent on a periapical radiograph was identified as endodontic failure. This has been discussed by Kvist 1994 and in a series of papers (Papers I-V, 1998, 1999 and 2000) where he proposed an alternative theory based on Praxis Concept (Jensen 1985). Praxis, which is Greek for process, is the process by which a theory or skill is enacted, embodied or realised. This theory states that personal values influence endodontic treatment and that clinicians use ‘cut-off’ points in their decision-making process.
Fryback and Thornbury (1991) have discussed the assessment of the contribution of diagnostic imaging to the patient management process in their seminal paper, The Efficacy of Diagnostic Imaging. In their study, they propose a ‘Hierarchical Model of Efficacy’, which is an organising structure for appraisal of the literature on the efficacy of imaging. There are six levels as listed in Figure 4:
- Technical quality of image
- Diagnostic accuracy, sensitivity and specificity of image interpretation
- Change in clinician’s diagnostic thinking?
- Effect on patient management
- Effect on patient outcomes
- Societal costs and benefits of a diagnostic imaging technology.
According to Fryback and Thornbury (1991), with level three “the imaging information may change the differential diagnosis, strengthen an existing hypothesis, or simply reassure the physician”. With level four, ‘Therapeutic Efficacy’, “an imaging examination result may influence the physician’s diagnostic thinking and yet have no impact on patient treatment”. With level five, ‘Patient Outcome Efficacy’, “is concerned with whether there is measurable effect of the image on the outcome experienced by the patient” since the ultimate goal of dental care is to improve, or return to normal, the health of the patient.
Therefore, this structured critical review will focus on levels three, four and five in the ‘Hierarchical Model’ (Table 2) since the question posed is the use of an imaging modality (CBCT) and how it influences clinical decision-making in endodontics.
So, with regards to the use of CBCT in clinical decision-making in endodontics, what does the current literature say? Evidence appears to be sparse. Mota de Almeida et al (2014) have concluded that “CBCT has a substantial impact on diagnostic thinking in endodontics when used in accordance with the European Commission guidelines”. In their clinical study, Balsundaram et al (2012) concluded that “Lesion size and choice of treatment of periapical lesions based on CBCT radiographs do not change significantly from those made on the basis of 2D radiographs”. Cheung et al (2013), concluded that “there were substantial disagreements between PA and CBCT for assessing the periapical status of molar teeth, especially for the maxillary arch”.
It is clear that there is not an agreement of opinion and whether there is a clear benefit to the clinician and to the patient in taking a CBCT scan. An investigation of available evidence as it relates to levels three, four and five, may clarify the role of CBCT in endodontic decision-making.
The research question for this study: Does CBCT influence clinical decision making in endodontics?, arose from the author’s interest in the imaging modalities used in endodontics. In the author’s almost 20 years clinical experience, it has been noted that many Scottish patients wish to keep their teeth and avoid extractions. People’s attitudes to dentistry, which may be media and culturally led, appear to be changing. The limitations within the National Health Service (NHS) in Scotland, may have led patients to look at private options to restore their teeth with a view to avoiding costly dental implants.
In the author’s opinion, root canal treatments are being considered more by patients, not only on the NHS but also privately. The author has found that since patient expectations are sometimes high, the diagnostic process must give the clinician and patient as much information as possible so the patient is able to make the correct informed decision. CBCT may offer more information, as discussed earlier, but does this information make a difference in the decision-making process? CBCT, being a relatively new and exciting diagnostic tool in endodontics, is used by some general dental practitioners and specialists in the UK but its use should be only when radiographs do not prove diagnostically beneficial. The question arises, when is this?
As discussed earlier, ESE guidelines are quite specific. CBCT should not be taken routinely in the diagnostic process but only when there is a net benefit to the patient. Clinically, a patient may present to a clinician with symptoms which cannot be diagnosed either upon clinical examination or with a radiograph. In this scenario is a CBCT useful?
The aim of this study is to perform a structured critical review on the current published research and to draw a conclusion as to the influence of CBCT in clinical decision making in endodontics.
The objectives of this review are based on nine basic steps, as suggested by Boland et al (2014):
- Performing scoping searches, identifying the review question and writing the protocol
- Literature searching including the search strategy
- Screening titles and abstracts
- Obtaining papers
- Selecting full-text papers
- Quality assessment
- Data extraction
- Analysis and synthesis
- Writing up and editing.
About the author
Arvind Sharma, BDS(Dund), MSc(Endo), MJDFRCS(Eng), MFDSRCPS(Glas), work in practice limited to endodontics and takes referrals at New Life Teeth in Edinburgh and Philip Friel Advanced Dentistry in Glasgow.
This article is based on the submitted dissertation in partial fulfilment of the requirements for the Degree of Master of Science in Endodontology, 2016. The author appreciates that much of the in-depth analysis has been omitted for the purposes of the current publication and readers are welcome to contact the author for more detail if they so wish – visit asendodontics.com for info.
References will be provided in full in the second part of the article, which will be published in the next issue of Scottish Dental.
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