Sanket Nagarkar BDS, MPH
No high-quality evidence exists regarding the benefits of cone-beam computed tomography (CBCT) use in orthodontics, and its application can only be justified in some cases.
What are the applications of CBCT in orthodontics and what level of evidence is available to support the use of CBCT in orthodontic diagnosis and treatment planning?
The authors searched six electronic databases with no language restrictions for articles published between Jan. 1, 1966 and March 15, 2010 regarding CBCT use for orthodontic purposes. They also manually searched the reference lists of articles. Using a two-step screening process, two reviewers independently screened the retrieved publications that included all types of study designs except letters, reviews and case reports. The first step was to classify articles as included, excluded, or unclear by reviewing the title and abstract. The second step was a full-text review of the “included” or “unclear” articles, and any differences in opinion on inclusion were resolved by achieving consensus. They also independently assessed the methodological quality of included studies using a modified scoring system originally developed by Lagravere and colleagues(1) and rated studies according to the mean quality.
The authors included 50 studies in this review, which they segregated into seven topic areas with a mean methodological quality score of 53 percent (range 15 percent to 77 percent). The topic areas included use of CBCT for placement of temporary anchorage devices, combined orthodontic-surgical treatment, airway measurements, assessment of root resorption and tooth positioning, cleft lip and palate cases, differences between CBCT and conventional cephalometry, and “various other subjects” (incidental CBCT findings, quality of CBCT images, and the indications and justification for CBCT).
No high-quality evidence exists regarding the benefits of CBCT use in orthodontics, and its application can only be justified in some cases. Apart from studies regarding airway measurements, no other studies provided sound scientific data to suggest that CBCT may provide added diagnostic value beyond conventional two-dimensional (2-D) imaging modalities. The additional radiation exposure associated with CBCT should be weighed against possible benefits, which have not been supported in the literature. Further research is needed to elucidate the efficacy, efficiency and cost effectiveness of CBCT use in orthodontic diagnosis and treatment planning in terms of quantifiable effects of CBCT on treatment procedures, progression and outcomes.
Source of Funding:
No source of funding listed.
Importance and Context:
CBCT appears to be powerful imaging modality that provides three-dimensional oral and maxillofacial images with the potential aim of optimizing orthodontic diagnosis and treatment planning. However, the radiation exposure associated with CBCT is much higher compared to conventional orthodontic radiographs. Hence, this systematic review addresses an important question with high clinical relevance regarding the evidence supporting the use of CBCT in orthodontic diagnosis and treatment planning.
Strengths and Weaknesses of the Systematic Review:
This systematic review utilized a comprehensive search of multiple electronic databases with no language restrictions, clearly defined key words, and involved duplicate screening as well as quality assessment by independent reviewers. However, the authors started with several topic areas and did not search unpublished data sources (grey literature). Additionally, the authors incorrectly interpreted studies that retrospectively and randomly selected 2-D radiographs and/or CBCT images(2-5) as utilizing randomization, a term that actually refers to random assignment of study participants in a randomized trial.
The scale used to assess study quality had several issues and was originally developed for clinical trials(1) with limited applicability to the study designs included in this review. Additionally, other issues with the scale such as averaging scores into a summary percentage rather than performing a domain-based evaluation,(6) use of sample size as a determinant of study quality(7) and exclusion of "prospective study design” criterion would most likely estimate the study quality inaccurately and affect the conclusions.
Lastly, the Results section only included information on the methodological scores rather than actual results from studies. Though actual results were somewhat addressed in the Discussion section, the manner in which they were discussed is more consistent with a narrative review on a broad topic rather than a quality systematic review.
Strengths and Weaknesses of the Evidence:
The authors stated that the lowest level of study design eligible for inclusion in the review was a case series study with five or more patients. However, the review authors did not explicitly state the study designs of the included studies. Additionally, given the limitations of the quality assessment scale, it is difficult to accurately assess the quality of the evidence included in this review.
Implications for Dental Practice:
Despite several methodological limitations, this systematic review highlights the absence of high-quality evidence regarding CBCT use in orthodontics. Clinicians are thus strongly advised to consult previously published evidence-based guidelines(8) and exercise clinical judgment utilizing risk-benefit analysis regarding CBCT use for orthodontics.
1. Lagravere MO, Major PW, Flores-Mir C. Long-term skeletal changes with rapid maxillary expansion: a systematic review. Angle Orthod. Nov 2005;75(6):1046-52.
2. Gracco A, Luca L, Cozzani M, Siciliani G. Assessment of palatal bone thickness in adults with cone beam computerised tomography. Aust Orthod J. Nov 2007;23(2):109-13.
3. Cevidanes L, Oliveira AE, Motta A, Phillips C, Burke B, Tyndall D. Head orientation in CBCT-generated cephalograms. Angle Orthod. Sep 2009;79(5):971-7.
4. Chien PC, Parks ET, Eraso F, Hartsfield JK, Roberts WE, Ofner S. Comparison of reliability in anatomical landmark identification using two-dimensional digital cephalometrics and three-dimensional cone beam computed tomography in vivo. Dentomaxillofac Radiol. Jul 2009;38(5):262-73.
5. Tso HH, Lee JS, Huang JC, Maki K, Hatcher D, Miller AJ. Evaluation of the human airway using cone-beam computerized tomography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. Nov 2009;108(5):768-76.
6. Juni P, Witschi A, Bloch R, Egger M. The hazards of scoring the quality of clinical trials for meta-analysis. JAMA. Sep 15 1999;282(11):1054-60.
7. Higgins JPT, Green S, Cochrane Collaboration. Cochrane handbook for systematic reviews of interventions. Chichester, England; Hoboken, NJ: Wiley-Blackwell; 2008.
8. SEDENTEXCT project. Radiation protection: cone beam CT for dental and maxillofacial radiology. Evidence based guidelines 2011. http://www.sedentexct.eu/files/guidelines_final.pdf. Accessed August 21, 2012.