Objective: The aim of this article is to investigate, study, and summarize cone beam computed tomography (CBCT)-related guidelines offered by relevant organizations and associations within North America to provide the dental practitioner a clearer direction on the practice of CBCT-related procedures in North America. Data sources: Scientific databases including PubMed, Science Direct, Scopus, MedLine, and Web of Science were used for the search of relevant literature on the CBCT guidelines developed in North America. In addition, the World Wide Web was searched for comparative CBCT guidelines nationally or internationally using the same search strategies.
Conclusion: In 1999, the American Dental Association (ADA) recognized Oral and Maxillofacial Radiology as the ninth dental specialty in the United States. The American Academy of Oral and Maxillofacial Radiology (AAOMR) issued their first statement on the use of CBCT in 2008. There have since been several statements issued, independently or jointly with other specialty organizations, related to the use and interpretation of the CBCT volumes. The guidelines identified Oral and Maxillofacial Radiologists (OMR) as providers of interpretative services, portrayed as key players in the dissemination of information related to CBCT, implementation of CBCT-related services and radiation protection, as well as interpretation assistance for CBCT volumes, especially medium to large volumes covering anatomical areas of head and neck, considered beyond the scope of a general dentist. Regulations concerning radiation-producing devices are promulgated through state health codes and practice acts. Selection criteria and interpretation of imaging studies are left to the clinician’s choice and abilities (Quintessence Int 2019; (50); 2; 136-145).
Authors: Irene H. Kim, Steven R. Singer and Mel Mupparapu
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Medical computed tomography (CT) was first developed by Sir Godfrey Hounsfield in 1967, and since then many advancements have been made involving detectors, beam source, and movement patterns of the detectors and beam sources.1 Conventional multi-detector computed tomography (MDCT) scanners are too large and expensive for maxillofacial and dental use.2 Cone beam computed tomography (CBCT) became available for dental and maxillofacial imaging in the United States at the beginning of the new millennium. It was first introduced in Europe in 1996 and in the United States in 2001. The only recommendations for oral and maxillofacial imaging that existed at that time were issued by the American Dental Association Council on Scientific Affairs and the US Department of Health and Human Services. Named as dental radiography guidelines, they did not cover advanced imaging protocols such as CBCT.3
First Integration of CBCT into dental practice
Cone beam computed tomography was quickly integrated into dental practice as clinicians started using the technology for skeletal imaging of jaws for a variety of diagnostic and treatment-related tasks.4 By 1998, Mozzo et al5 had laid the foundation for the new revolution in three-dimensional (3D) imaging by describing how a volumetric CT machine would be useful for dental imaging. For decades clinicians relied on standard two-dimensional (2D) images that offered little useful information about the z-axis (depth of the anatomical volume). CBCT technology offered a low-dose, high-resolution digital technology providing high-quality and dimensionally accurate imaging for all three reference planes. Oral and maxillofacial surgeons, long users of MDCT technology to visualize the 3D soft and hard tissue structures of the orofacial region, were now able to use CBCT to acquire 3D imaging at significantly lower radiation doses. CBCT also proved to be very useful in pre-implant imaging. In specialties such as endodontics or periodontics, small volume CBCT imaging using pixels as small as 60 to 70 µm could be used to view periodontal ligament space, furcation defects, root anatomy, fractures, and complex pulp pathways that otherwise would be difficult using 2D imaging alone.6 In pediatric dentistry, the field of view (FOV) could be tailored in CBCT to suit the imaging needs of children and adolescents, reducing the effective dose when compared to that of MDCT examinations. Collectively, we have an obligation to our patients to reduce the dose to as low as reasonably achievable (ALARA).7 In the years since its introduction, CBCT technology has advanced due to research and development by the manufacturers of CBCT machines and the competition among them. Better education of dentists, modern flat panel detectors, individualized scanning protocols (selection criteria), and faster scan times all contribute to further reducing the radiation dose.8
The first CBCT guidelines
The first cone beam computed tomography guideline from organized dentistry in North America came in the form of an executive opinion of the American Academy of Oral and Maxillofacial Radiology (AAOMR).9 This was followed up by statements addressing CBCT use in various dental specialties, including periodontics, endodontics, and orthodontics, CBCT use in dental implants, and a position statement issued by the American Dental Association Scientific Council.10-16 In Europe, parallel development of guidelines took place somewhat earlier than in North America, and the European Commission issued evidence-based CBCT guidelines known as the SEDENTEXCT (Safety and Efficacy of a New and Emerging Dental X-Ray Modality) project.17 National guidance on CBCT has been documented in the United Kingdom, Germany, Norway, Belgium, and Denmark.17 The time frame for these various statements and guidelines in North America is presented in Fig 1.
English language medical and dental literature that was relevant and most recent was reviewed for this study. Scientific databases including PubMed, Science Direct, Scopus, MedLine, and Web of Science were used for the search of relevant literature on the cone beam computed tomography guidelines pertaining to North America.
All articles were reviewed by at least two authors and duplicates removed from the overall list. Each article was reviewed and discussed by the authors and relevant details were extracted to tables (Tables 1 to 8). Based on the eight selected articles,9-16 this study investigated the literature for guidelines and position papers since cone beam computed tomography was introduced to the US market in 2001. The guidelines, principles, and position statements on the use of CBCT in the dental profession studied were limited to organizations and associations within North America. The dental organizations involved in publishing statements included the AAOMR, the American Dental Association (ADA), the American Academy of Oral and Maxillofacial Pathology (AAOMP), the American Academy of Pediatric Dentistry (AAPD), the American Association of Endodontists (AAE), the American Association of Oral and Maxillofacial Surgeons (AAOMS), the American Association of Orthodontists (AAO), and the American Academy of Periodontology (AAP). The non-dental organizations included the American Association of Physicists in Medicine (AAPM), the Conference of Radiation Control Program Directors (CRCPD), the National Council on Radiation Protection and Measurements (NCRP), and the United States Food and Drug Administration (FDA). The history of the guidelines and statements were studied, reviewed, and summarized.
Review and discussion
Since the introduction of cone beam computed tomography technology to the profession at the turn of the new millennium, there has been a marked increase in the use of CBCT. The North American CBCT dental imaging market is expected to reach USD 360.44 million in the year 2023, up from USD 172.31 million in 2016. The market is expected to grow at a compound annual growth rate (CAGR) of 11.1% for the forecasted period.18 This is a clear indicator of the growth of the use of CBCT among dentists in North America. Although education and training are key pieces for the appropriate use of CBCT technology, development and regulation of clinical guidelines are even more important for radiation dose reduction and patient safety. Commercialization and excessive use of CBCT imaging should be avoided, especially when not indicated.
The Executive Council of the AAOMR published an executive opinion statement performing and interpreting diagnostic CBCT in 2008.9 Their opinion document outlined recommendations based on CBCT use, practitioner responsibilities, documentation, and radiation safety and quality assurance. A summary of the guidelines is presented in Table 1. The goal of the executive statement was to help dental practitioners provide the best CBCT imaging to their patients based on radiographic selection criteria, dose, technique, and diagnostic or treatment needs.
In 2011, the AAOMR and the AAE issued a joint position statement on the use of CBCT in endodontics.10 The joint statement, summarized in Table 2, provided guidelines based on volume, dose consideration, patient selection criteria, patient consent, interpretation, and protection of patients and office personnel. The statement also recommended that the use of CBCT in endodontics be limited to certain complex conditions (Table 3).
CBCT in dental implantology
In 2012, the AAOMR addressed the use of cone beam computed tomography in dental implantology with a position statement on radiographic selection criteria, with an emphasis on CBCT for dental implants.11 These recommendations were evidence-based on peer-reviewed research, as well as consensus. They offered guidelines and advice on the use of CBCT, as well as other planar modalities such as intraoral, panoramic, and cephalometric imaging. Clinical considerations on selection criteria, radiation dose considerations, and principles of imaging for dental implantology were also discussed in the position paper. A summary of the AAOMR recommendations for CBCT is presented in Table 4. In summary, it was recommended to perform cross-sectional imaging in the preoperative diagnostic phase. CBCT imaging would remain the method of choice, as it provides the most diagnostic information at an acceptable radiation dose risk. Postoperative implants may be monitored with periapical and, in some cases, panoramic imaging. Practitioners should always clinically justify the use of CBCT (as well as all imaging modalities) and properly maintain all equipment to minimize radiation exposure to the patient. The report added that all CBCT volumes should also be systematically reviewed for any abnormalities and a report generated for all CBCT examinations.
Advisory statement on the use of CBCT in dentistry
In 2012, the ADA Council on Scientific Affairs issued an advisory statement on the use of cone beam computed tomography in dentistry.12 The council reviewed the current research literature, and also received input from various stakeholder organizations. These organizations included dental associations such as the AAOMR, the AAOMP, the AAPD, the AAE, the AAOMS, and the AAO. In addition to these dental organizations, the AAPM, the CRCPD, the NCRP, and the United States FDA were also included. This collaborative effort resulted in the Council recommending adherence to principles for the safe use of dental and maxillofacial CBCT. The results are summarized in Table 5. In summary, the council recommended that CBCT use for dental and maxillofacial imaging should be based on sound professional judgment, including weighing patient risk against potential benefits, using the ALARA principle to protect the patient and staff, justifying the use of CBCT for diagnosis using all precautions such as protective aprons and collars when possible, and optimizing technical factors such as the smallest FOV for diagnosis. The council also stressed the importance of proper CBCT education and training for all staff and clinicians, as well as proper maintenance and evaluation of the CBCT equipment.
Clinical recommendations for the use of CBCT in orthodontics
In 2013, the AAOMR published a position statement on clinical recommendations for the use of cone beam computed tomography in orthodontics.13 A panel of board-certified orthodontists and oral and maxillofacial radiologists convened to reach a consensus on all aspects of the use of CBCT in orthodontic practice, based on a review of the literature on clinical efficacy and radiation dose. The clinical recommendations are summarized in Table 6. The panel agreed with the principles put forth by the ADA Scientific Council in 2012. It was concluded that the use of CBCT in orthodontics should be determined individually based on clinical presentation, assessment of radiation dose risk, and minimizing patient exposure. In addition, the orthodontist should maintain professional competency in performing and interpreting CBCT studies through continuing education courses.
An update of the AAE and AAOMR joint position statement was issued in 2015.14 It reiterates that CBCT should only be used when indicated by the patient’s complaint, history, and clinical findings, and that the smallest applicable FOV with the lowest radiation dose should be used. In addition, any questions regarding interpretation of the images should be referred to an oral and maxillofacial radiologist. The position paper outlined each recommendation and provided a rationale for each recommendation. Table 7 summarizes the updated recommendations of the AAE and AAOMR.
Taskforce to study the indications, safety and clinical patterns of CBCT
In 2016, a task force was appointed by the AAOMS to study the indications, safety, and clinical patterns of cone beam computed tomography in oral and maxillofacial surgery.15 A global study of the CBCT literature was performed and a national survey of academic thought leaders and practicing oral surgeons to determine how CBCT is used and adopted in academic and private practice settings. It was concluded that there is much confusion associated with the indications, authorizations, and payment policies of CBCT use. After reviewing the literature and survey results, the authors proposed an industry guideline to help reach a consensus on the clinical indications of CBCT, as well as offer guidance on third-party payment policies. Based on majority expert opinion, CBCT is usually indicated in oral and maxillofacial pathology, orthognathic surgery, maxillofacial trauma, foreign body evaluations, reconstructive surgery planning, supernumerary teeth, impacted teeth, dental implant evaluation, and sinus elevation planning. CBCT might be indicated in craniofacial surgery, maxillofacial infections, salivary gland pathology, temporomandibular joint evaluations, and facial pain.
In 2017, the AAP issued a best evidence consensus statement on selected oral applications for CBCT.16 The panel of experts addressed the application of CBCT in three specific clinical therapies: placement of implants, interdisciplinary dentofacial therapy involving orthodontic tooth movement in the management of malocclusion with associated risk to the supporting periodontal tissues, and management of periodontitis. A literature search was performed for each therapy, and the benefits, limitations, and risks were discussed by the panel. A summary of their consensus conclusions is presented in Table 8. The panel concluded that while there is a critical mass of evidence, there is not enough evidence to support periodontal clinical practice guidelines.
European evidence-based CBCT guidelines
SEDENTEXCT, the European evidence-based cone beam computed tomography guidelines, were initially developed in 2009 and led to the development of national guidelines within the European Union.17 A final guideline document that was based on a sound systematic review based on established methodology was developed and published in 2012. The project included dentists, dental radiologists, medical physicists, and other dental specialists, including oral and maxillofacial surgeons, orthodontists, periodontologists, and restorative dentists. The guidelines were essentially developed for dentists and all specialists using the technology in Europe. Although there are no definitive published numbers of actual users of CBCT in the United States, it is believed that general dentists comprise the majority of users. CBCT technology is currently used in various clinical radiographic tasks including endodontics, where higher resolutions are needed due to the nature of the diagnostic tasks involved.19 A survey conducted among endodontic practitioners who were members of the AAE in the United States revealed that about a third of those surveyed used CBCT technology in their practice.20
Cone beam computed tomographyguidelines in the United States were developed through cooperative efforts of the AAOMR and other US-based dental specialty groups. The guidelines are generally focused on the appropriate use of CBCT technology for diagnostic and treatment planning applications in both specialty care and general dental practice. The guidelines are also focused on the concept of ALARA and the recommendations are very specific to the situations in dental practice where the tasks on hand cannot be completed using 2D imaging alone. If a CBCT is indicated, the FOV selected is an important consideration to reduce to dose to the patient.
Summary of recommendations
The guidelines can be summarized for clinical care as below:
- CBCT is a new and emerging technology that has the potential for use and application in a variety of clinical tasks, both diagnostic and prognostic.
- 2D radiography or plain radiography is the first choice of imaging in many clinical scenarios, and CBCT should be used when 2D imaging alone cannot answer the question on hand. When using CBCT, published criteria should be used for selection of the appropriate FOV.
- A thorough clinical examination must precede the use of CBCT, as is the case with any other radiation-based examination. CBCT is a higher x-ray dose modality, and hence caution should be exercised while selecting the FOV to be scanned. Large FOV should not be used when a small or medium FOV can be adequate for the task.
- Pre-implant imaging using CBCT is more useful than post-implant imaging.
- The effective doses for dentoalveolar CBCT range from 11 to 674 µSv. The effective doses for craniofacial CBCT range from 30 to 1,073 µSv.
- CBCT is indicated in situations where a tooth is impacted, infected, or missing, and 2D radiography did not reveal the pathoses. Pre-implant planning, preoperative evaluation, postsurgical evaluation in a variety of oral surgical, periodontal, endodontic, restorative, and prosthodontic conditions can be performed using CBCT.
- Dose sparing techniques must be used in children and adolescents to minimize the effective doses using the ALARA principle.
Irene H. Kim, DMD, MPH/Steven R. Singer, DDS/Mel Mupparapu, DMD, MDS
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