Assessment of facial landmarks for bone asymmetry in geometric morphometric studies: A review
Abstract
Background
Anthropometrical points or landmarks are key for facial shape analysis using geometric morphometrics. In the early 1990s Fred Bookstein created a classification system with landmarks type 1., type 2., type 3. based on anatomical landmark homology. However, thirty years later, a uniform referece index of landmarks that can be used for assessing facial asymmetry still does not exist. The criteria for selecting landmark points are not fully defined, which makes classification of homology and and landmarks prone to arbitrary interpretations. A systematic review of literature indicates that authors of studies do not provide explanation for choosing exact points. Most of them also do not provide a clear definition of landmarks and landmarks classification according to homology.
Objective
The objective of this systematic review was to assess, in an evidence based manner, which landmarks inside the Bookstein groups of on facial hard tissues can be reccomended for facial asymmetry assessment using geometric mophometrics.
Search methods
An electronic search of 9 databases up to March 2020 by two reviewers was conducted to identify relevant articles.
Selection criteria
Prospective randomized, non-randomized controlled trials and cross sectional studies reporting on facial asymmetry using three-dimensional images and geometric morphometric methods. The reasons for assessing facial asymmetry were not considered.
Data collection and analysis
The 23 selected studies were categorized according to the number and specification of the research subjects, types of three-dimensional images, number of landmarks, and the craniofacial region of interest. All landmarks were extracted with the following data: name, abbreviation, and the author’s definition of the location.
Results
The craniofacial region is divided into neurobasic cranial part, ethmomaxillar part and the mandible. Assessment of neurobasic cranial asymmetry was conducted in 6 studies and 45 different landmarks were recorded, of which 11 were medial and 34 bilateral. Bregma and Lambda occur most frequently and according to homology both belong to type 1 landmarks.
Assessment of ethmomaxillary asymmetry was conducted in 21 studies and 68 different landmarks were recorded, of which 16 were medial and 52 bilateral. Nasion and Jugale occur most frequently and according to homology Nasion belongs to type 1 landmarks and Jugale to type 2 landmarks.
Conclusion
The selection and definition of craniofacial hard tissue landmarks is one of the most important tasks in the design of morphometric studies, and thus for the purpose of assessing facial asymmetry. The review provides an extensive cross-section of possible landmarks with the definition of the location as well as the possible location variation. The list of these landmarks should be observed through the classification of landmarks according to their homology, as well as possible variations of the classification.
References
2. Thiesen G, Gribel BF, Freitas MP. Facial asymmetry: a current review. Dental Press J Orthod. 2015;20(6):110-25.
3. Corruccini RS, Yap Potter RH. Genetic analysis of occlusal variation in twins. Am J Orthod. 1980;78:140-54.
4. Sahu A, Lall R, Nezam S, Singh R, Kumar SB, Ayub FB. Comparative Assessment of Facial Asymmetry in Malocclusion using Posteroanterior View. J Contemp Dent Pract. 2018;19(6):712-18.
5. Castelo PM, Pereira LJ, Andrade AS, Marquezin MC, Gavião MB. Evaluation of facial asymmetry and masticatory muscle thickness in children with normal occlusion and functional posterior crossbite. Minerva Stomatol. 2010;59(7-8):423-30.
6. Parsons PA. Fluctuating asymmetry: A biological monitor of enviromental and genomic stress. Hered. 1992;68:361-4.
7. Gangstead SW, Thornhill R. Individual differences in developmental precision and fluctuating asymmetry: a model and its implication. J Evol Biol. 1999;12:402-16.
8. Polak M. Developmental instability, causes and consequences. 1st ed. Oxford: Oxford University Press; 2003.
9. Bookstein FL. Morphometric tools for landmark data. 1st ed. Cambridge: Cambridge University Press; 1991.
10. Bookstein FL. Landmark methods for forms without landmarks: morphometrics of group differences in outline shape. Med Image Anal. 1997;1(3):225–43.
11. Liberati A, Altman DG, Tetzlaff J, Mulrow C, Getzsche PC, Ioannimid J, et al. The PRISMA statement for reporting systematic review and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. J Clin Epidemiol. 2009;62:1-34.
12. Higgins JPT, Green S, editors. Cochrane handbook for systematic review of interventions (version 5.1. 0, updated March 2011). The Cochrane Collaboration; 2011. Available at: www-cochrane-handbook.org.
13. Warmlander SKTS, Garvin H, Guyomarc’h P, Petaros A, Sholts SB. Landmark Typology in Applied Morphometrics Studies: What’s the Point?. Anat Rec. 2019;302:1144-53.
14. O’Higgins P. Quantitative approaches to the study of craniofacial growth and evolution: Advances in morphometric techniques. In: O’Higgins P, Cohn M. Development, growth, and evolution: Implications for the study of the hominid skeleton. London, UK: Academic Press; 2000.
15. Smith GR. Homology in morphometrics and phylogenetics. In: Rohlf FJ and Bookstein FL. Proceedings of the Michigan Morphometrics Workshop. Ann Arbor, MI: The University of Michigan Museum of Zoology; 1990.
16. Roth VL. On three-dimensional morphometrics, and on the identification of landmark points. In: Marcus L, Bello E, Valdecasas AG. Advances in morphometrics. Madrid, Spain: Museo Nacional de Ciencias Naturales; 1993.
17. Lele SR, Richtsmeier JT. An invariant approach to statistical analysis of shapes. 1 st edition. Boca Raton: Chapman & Hall/CRC; 2001.
18. Zelditch ML, Swiderski DL, Sheets HD. Geometric morphometrics for biologists: A primer. 2nd ed. New York: Elsevier Academic Press; 2012.
19. Shearer BM, Cooke SB, Halenar LB, Reber SL, Plummer JE et al. Evaluating causes of error in landmarkbased data collection using scanners. PLoS One. 2017;12:e0187452.
20. Ruskova H, Šarka B, Peterka M, Krajiček V, Veleminska J. 3-D shape analysis of palatal surface in patients with unilateral complete cleft lip and palate. J Craniomaxillofac Surg. 2014;42(5):140-7.
21. Senck S, Coquerelle M, Weber WG, Bebazzi S. Virtual reconstruction of very large skull defects featuring partly and completely missing midsagittal planes. Anat Rec. 2013;296:745-58.
22. Katsube M, Rolfe SM, Bortolussi SR, Yamaguchi Y, Richman JM et al. Analysis of facial skeletal asymmetry during foetal development using μCT imaging. Orthod Craniofac Res. 2019;22:199-206.
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