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Longitudinal Photogrammetric Analysis of Soft Tissue Facial Changes: A Systematic Review of the Literature and a Summary of Recommendations

Wen, Yi Feng BDS*; Wong, Hai Ming DDS, PhD*; McGrath, Colman P. BDentSc, PhD

doi: 10.1097/SCS.0000000000001909
Original Articles

Human faces are under a constant state of change throughout the entirety of one's lifetime. Photogrammetry has been advocated for use in large epidemiological studies investigating facial characteristics. This study aimed to review existing longitudinal photogrammetric studies in terms of the measurements selected and the observed facial changes overtime. A comprehensive literature search was performed in 4 databases, PubMed, ISI Web of Science, EMBASE, and Scopus, which was supplemented by hand search. No limitations were set as to the language, dates, or status of publication. The records were assessed for the eligibility and rated for the risk of bias by 2 independent reviewers. Data regarding study characteristics, measurements selected and the outcomes reported, were extracted for analysis. An initial search identified 5127 studies. After 2 rounds of study screening, 6 eligible studies informed this review. The risk of bias of the studies ranged from 41.7% to 80.8%. Only 1 study performed sample size calculation, and only 17% of the studies had a sample size of over 30 subjects. Confidence interval was reported by none of the studies. The facial features assessed varied among the studies, and some studies focused on only specific regions of the face. Photogrammetry has been used by a limited number of studies in the analysis of longitudinal soft tissue facial changes. Moreover, these studies are heterogeneous with respect to their levels of risk of bias and the facial features assessed. Recommendations are provided to improve the qualities of future photogrammetric studies.

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*Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, 2/F Prince Philip Dental Hospital

Periodotology and Public Health, Faculty of Dentistry, The University of Hong Kong, 3/F Prince Philip Dental Hospital, Hong Kong, China.

Address correspondence and reprint requests to Hai Ming Wong, Clinical Associate Professor, Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, 2/F Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong, China; e-mail:

Received 29 January, 2015

Accepted 22 March, 2015

The work described in this paper was fully supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. 781112).

The authors report no conflicts of interest.

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© 2015 by Mutaz B. Habal, MD.