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Reliability and Reproducibility of Landmarks on Three-Dimensional Soft-Tissue Cephalometrics Using Different Placement Methods

Lin, Han B.S.; Zhu, Ping M.D.; Lin, Yi B.S.; Zheng, Yuxi B.S.; Xu, Yue M.D., Ph.D.

Plastic & Reconstructive Surgery: July 2014 - Volume 134 - Issue 1 - p 102e–110e
doi: 10.1097/PRS.0000000000000279
Reconstructive: Head and Neck: Original Articles

Background: Affixing markers on the face in vivo with an optical surface imaging system and placing landmarks on a computed tomographic reconstructive facial model represent two helpful approaches prevailing in three-dimensional cephalometric analysis of facial aesthetics. In this study, the authors determine the suitability of these methods for soft-tissue evaluation along with the reproducibility and reliability of landmark placement.

Methods: Thirty-seven soft-tissue landmarks were investigated in 35 normal healthy volunteers who underwent cephalometric analysis by direct and indirect placement methods. Two operators performed the analysis twice for each method at a 1-week interval. Landmark positions were measured on the three-dimensional coordinates, and data were standardized and converted into landmark placement errors for the estimation, by two-way random intraclass correlation coefficients.

Results: Using the direct method, 86.5 percent of the landmarks had a higher intraclass correlation coefficient than 0.75, and 67.6 percent were higher than 0.90. The authors found that 75.7 percent were higher than 0.75 and 43.2 percent were higher than 0.90 with the indirect method. Both methods showed good reliability in identifying midline-related structures, although the correlations of markers surrounding eyelashes and lips were better using the direct method. The direct method had a significantly smaller landmark placement error and better reproducibility than that identified indirectly (p < 0.05).

Conclusions: When evaluating well-defined contours and the natural texture of the face, the direct placement method shows better accuracy than the indirect method. The three-dimensional evaluation emphasizes the eye, lip, and some structures more laterally, therefore providing comprehensive analysis for clinical diagnosis.

CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, II.

Guangdong, People’s Republic of China; and Cleveland, Ohio

From the Department of Orthodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology; and Case Western Reserve University.

Received for publication September 4, 2013; accepted December 12, 2013.

The first two authors contributed equally to this work and should be considered co–first authors.

Disclosure: The authors have no financial interest in any of the products or devices mentioned in this article.

Yue Xu, M.D., Ph.D., Guanghua School of Stomatology, Sun Yat-sen University, Lingyuan Xilu No.56, Guangzhou 510055, People’s Republic of China, kou9315@hotmail.com

©2014American Society of Plastic Surgeons