The aim of this systematic review was to identify studies that assessed the accuracy of linear measurements of bone dimensions related to implant dentistry using CBCT. For inclusion, the studies could be designed as ex vivo or in vivo investigations, but were only included when the linear values from CBCTs were also compared to a control, which could be considered as the gold standard. The review was performed using the PICOs framework, where intervention was described as the use of CBCT for the purpose of determining outcomes associated with the accuracy and reliability (repeatability/reproducibility) of linear measurements.
There was great variability in the methodology of the included studies as well as the extracted data; thus, a direct comparison of the available evidence was not possible. The data were therefore compared using descriptive modalities, and no meta-analysis was performed.
The present systematic review identifies, reviews, analyses, and summarizes available evidence on the accuracy of linear measurements when using CBCT imaging specifically in the field of implant dentistry. The primary outcome of this systematic review was demonstration of the accuracy of linear CBCT measurements of alveolar bone at edentulous sites or anatomical structures related to implant dentistry.
The secondary outcomes of this review were as follows:
- Demonstration of reliability (repeatability within one observer / reproducibility between different observers) of linear measurements from CBCTs.
- Assessing the potential impact of imaging factors such as voxel size, FOV, rotational arc, and software package used on the accuracy of linear measurements in CBCTs.
From 2516 titles retrieved initially, a total of 22 studies were included for the final analysis. Of those, two were clinical and 20 were ex vivo investigations.
- With regard to implant treatment planning, CBCT provides crosssectional images that demonstrate high accuracy and reliability for linear bone measurements with a relatively low radiation dose according to As Low As Diagnostically Acceptable (ALADA) guidelines.
This statement is based on a total of 19 studies: one clinical, five cadavers, and 13 dry jaws/skulls studies.
- The actual linear dimensions taken from CBCT scans can be over- or underestimated, and the range of error can exceed 1 mm in selected cases.
This statement is based on a total of six studies: two clinical, two cadavers, and two dry skull studies.
- A smaller voxel size resulting in a higher resolution does not lead to a higher accuracy of linear measurements on CBCTs for bone dimensions at edentulous sites.
This statement is based on a total of four studies: one cadaver, and three dry skull/jaws studies.
- The size of the field of view and partial rotations (180° vs. 360°) do not adversely affect linear measurements.
This statement is based on one cadaver study (addressing the FOV) and one dry mandibles’ study (addressing the impact of rotation).
- Reported accuracy is independent of the software package used.
This statement is based on one study (dry mandibles).
- CBCTs should be considered the imaging tool of choice for three-dimensional (3D) dental implant site assessment.
- Based on consensus statement 2, a minimal safety margin of 2 mm to relevant adjacent anatomic structures should be considered.
- Smaller voxel sizes do not result in increased accuracy of linear measurements on CBCT scans. A voxel size of 0.3–0.4 mm3, the smallest FOV, and if possible partial rotations should be used for preoperative implant treatment planning in order to reduce radiation dose exposure: this should result in similar image quality as scans comprised of smaller voxel size or larger FOV.