Assessment modalities of non-ionizing three-dimensional images for the quantification of facial morphology, symmetry, and appearance in cleft lip and palate: a systematic review

The use non-ionizing three-dimensional (3D) imaging in cleft lip and palate is an emerging field, but properly designed methods for the assessment of these images are not well established. Therefore, the aim of this study was to review the current literature on the modalities of assessment of non-ionizing 3D images for the quantification of facial morphology, symmetry, and appearance in cleft lip and palate, and to assess the method error of these modalities. A systematic literature search was conducted using MEDLINE (PubMed), Cochrane Central Register of Controlled Trials, Web of Science, and Embase. Cross-sectional studies with prospective or retrospective data collection, using non-ionizing 3D imaging, with a subjective or objective outcome assessment and including at least 10 cleft lip and/or palate patients were considered eligible. Overall, 1767 unique studies were identified and 33 met the inclusion criteria. The images were objectively assessed using elementary measurements and comprehensive statistical methods for superimposition, shape description, and structuring. Subjective assessment was performed using a Likert-type scale or visual analogue scale. It can be concluded that non-ionizing 3D images are widely used in cleft research, but 3D analysis of the images is often methodologically suboptimal. Researchers must fully utilize the content of 3D images to quantify morphology, symmetry, and appearance.