Applications of Cone Beam Computed Tomography in Orthodontics: A Review

Comparison of the accuracy of 2D and 3D cephalometry: a systematic review and meta-analysis

Objectives

To compare the measurement of cephalometric parameters using 3D images obtained from CBCT to 2D images obtained from a conventional cephalogram.

Methods

An electronic literature search was conducted using PubMed, Embase, Web of Science, CNKI, CENTRAL, and the grey literature database of SIGLE (up to May 2021). The selection of the eligible studies, data extraction, and an evaluation for possible risk of bias (Quality Assessment of Measurement Accuracy Studies tool) were performed independently by two authors. Inconsistencies were judged by a third author. Statistical pooling, subgroup analysis, a sensitivity analysis and an evaluation of publication bias were performed using Comprehensive Meta-Analysis (version 2.2.064, Biostat, Englewood, NJ).

Results

A total of eight articles were eligible for final meta-analysis. The differences in two of the skeletal measurement parameters [Ar(Co)-Gn, Me-Go] and one of the dental measurement parameters (U1-L1) were found to be statistically significant when using CBCT and conventional cephalograms (P = 0.000, P = 0.004, P = 0.000, respectively).

Conclusions

CBCT can be used as a supplementary option to support conventional cephalometric measurements. In clinical situations in which three-dimensional information is required, patients can benefit from CBCT analysis to improve diagnosis and treatment planning.

Modern 3D cephalometry in pediatric orthodontics-downsizing the FOV and development of a new 3D cephalometric analysis within a minimized large FOV for dose reduction

OBJECTIVES

Dose reduction achieved by downsizing the field of view (FOV) in CBCT scans has brought no benefit for pediatric orthodontics, until now. Standard 2D or 3D full-size cephalometric analyses require large FOVs and high effective doses. The aim of this study was to compare a new 3D reduced-FOV analysis using the Frankfurt horizontal (FH) plane as reference plane with a conventional full-size analysis using the Sella-Nasion (S-N) plane as reference plane.

MATERIALS AND METHODS

Thirty-eight CBCT data sets were evaluated using full- and reduced-FOV analysis. The measurements of a total of 20 skeletal and dental standard 3D full-size variables were compared with the measurements of 22 corresponding 3D reduced-FOV variables. Statistical analysis was performed to prove mathematic relation between standard and alternative variables. Regression analyses were carried out.

RESULTS

Coefficients of determination (R²) between 0.15 and 0.95 (p < 0.001-0.055) were described. All variables showed obvious relations of different strength except for SNA and its alternative Po_R-Or_R-A (°) (R² = 0.15, p = 0.055), but a second variable Ba_A (mm) showed stronger relation (R² = 0.28, p = 0.003).

CONCLUSIONS

All standard variables related to the reference plane S-N could be described with alternative variables related to the FH. Further research should define more reliable landmarks for coordinate systems and reference points.

CLINICAL RELEVANCE

Minimized large FOVs meet the demand of 3D cephalometric analyses and enable the application of CBCT scans in pediatric orthodontic patients in many specific indications. Dose reduction is accompanied by increasing access to all the advantages of 3D imaging over 2D imaging.

Cone-Beam Computed Tomography in Orthodontics

Unlike patients receiving implants or endodontic treatment, most orthodontic patients are children who are particularly sensitive to ionizing radiation. Cone-beam computed tomography (CBCT) carries risks and benefits in orthodontics. The principal risks and limitations include ionizing radiation, the presence of artifacts, higher cost, limited accessibility, and the need for additional training. However, this imaging modality has several recognized indications in orthodontics, such as the assessment of impacted and ectopic teeth, assessment of pharyngeal airway, assessment of mini-implant sites, evaluation of craniofacial abnormalities, evaluation of sinus anatomy or pathology, evaluation of root resorption, evaluation of the cortical bone plate, and orthognathic surgery planning and evaluation. CBCT is particularly justified when it brings a benefit to the patient or changes the outcome of the treatment when compared with conventional imaging techniques. Therefore, CBCT should be considered for clinical orthodontics for selected patients. Prescription of CBCT requires judicious and sound clinical judgment. The central question of this narrative review article is: when does CBCT add value to the practice of orthodontics? To answer this question, this article presents discussion on radiation dosage of CBCT and other imaging techniques used in orthodontics, limitations of CBCT in orthodontics, justifying the use of CBCT in orthodontics, and the benefits and evidence-based indications of CBCT in orthodontics. This review summarizes the central themes and topics in the literature regarding CBCT in orthodontics and presents ten orthodontic cases in which CBCT proved to be valuable.