Accuracy and precision of a 3D anthropometric facial analysis with and without landmark labeling before image acquisition

Objective: To determine the influence of landmark labeling on the accuracy and precision of an indirect facial anthropometric technique. Materials and Methods: Eighteen standard linear craniofacial measurements were obtained from 10 adults using the 3dMDface system, with landmarks labeled (Labeled-3D) and without landmarks labeled (Unlabeled-3D) before image acquisition, and these were compared with direct anthropometry (Caliper). Images were acquired twice in two different sessions 1 week apart (T1 and T2). Accuracy and precision were determined by comparing mean measurement values and absolute differences between the three methods. Results: Mean measurements derived from three-dimensional (3D) images and direct anthropologic measurements were mostly similar. However, statistically significant differences (P <.01) were noted for seven measurements in Labeled-3D and six measurements in Unlabeled-3D. The magnitudes of these differences were clinically insignificant (<2 mm). In terms of precision, results demonstrated good reproducibility for both methods, with a tendency toward more precise values in Labeled-3D, when compared with the other two techniques (P <.05). We found that Labeled-3D provided the most precise values, Unlabeled-3D produced less precise measurements, and Caliper was the least capable of generating precise values. Conclusions: Overall, soft tissue facial measurement with the 3dMDface system demonstrated similar accuracy and precision with traditional anthropometry, regardless of landmarking before image acquisition. Larger disagreements were found regarding measurements involving ears and soft tissue landmarks without distinct edges. The 3dMDface system demonstrated a high level of precision, especially when facial landmarks were labeled.