Resumen

CASTRO GUEVARA, Nancy Esperanza; MUNOZ DURAN, Joao Víctor; LOPEZ PEREZ, Luis Alberto  y  INFANTE CONTRERAS, Clementina. IN VITRO EVALUATION OF THE EFFECT OF HYDROFLUORIC ACID ONCENTRATION AND APPLICATION TIME ON ADHESION TO LITHIUM DISILICATE. Rev Fac Odontol Univ Antioq [online]. 2015, vol.26, n.2, pp.292-313. ISSN 0121-246X.

INTRODUCTION: the studies on morphological variations of craniofacial components to classify skeletal relationships have traditionally included univariate and multivariate analysis using variables such as distances, angles, and reference planes. However, these methods fail to explain general changes in shape and provide partial localized descriptions of these relationships. Whereas methods using two- or threedimensional (2D or 3D) Geometric Morphometrics (GM) allow a detailed understanding and a more sensitive test of variables. The objective of this study was to identify morphological pattern variations of the Overall Craniofacial Structure (OCS) in skeletal relationships I, II, and III using GM-2D. METHODS:this was a prospective study using non-probability sampling. It implied taking 272 lateral radiographs of the head of Colombian individuals (140 males/132 females) aged 17 to 25 years, determining intra-examiner error and using F-ANOVA as statistic test. Generalized Procrustes Analysis (GPA) was conducted as well as atypical data detection by Adaptive Quantile. Size variation was analyzed by the Kruskal-Wallis test considering Centroid Size matrix (CS) and conformational differences were analyzed with MANOVA. Craniofacial patterns were identified by Principal Components Analysis (PCA) and K-means/cluster. RESULTS: the OCS showed conformational differences and a good classification capacity of 89% (Class I), 89% (Class II), and 91% (Class III). Four craniofacial patterns were identified; three of them showed typical skeletal relationships and the other pointed out to a new Class I/II combined group. CONCLUSIONS:the morphological differences in the four identified patterns were evident; GM allowed an explanatory display of morphological variation patterns, identifying actual sites where changes in size and shape take place.

Palabras clave : geometric morphometrics; anatomical landmark; principal component analysis; Procrustes analysis; morphology; biometrics; discriminant analysis; cephalometrics; cluster analysis.

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