title: Longitudinal Photogrammetric Analysis of Soft Tissue Facial Changes: A Systematic Review of the Literature and a Summary of Recommendations.
abstract: 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.
authors.affiliation: *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.
authors.forename: Yi Feng
authors.initials: YF
authors.lastname: Wen
authors.forename: Hai Ming
authors.initials: HM
authors.lastname: Wong
authors.forename: Colman P
authors.initials: CP
authors.lastname: McGrath
mesh_terms: D015982:Bias; D002508:Cephalometry / Q000706:statistics & numerical data; D005145:Face / Q000033:anatomy & histology*; D006801:Humans; D008137:Longitudinal Studies; D008445:Maxillofacial Development / Q000502:physiology; D010780:Photogrammetry / Q000706:statistics & numerical data*