IADR Abstract Archives
Size and Shape of the Mandible in Different Vertical Facial Patterns
Objectives: To determine whether the morphology of the mandible (size and shape) differs among adult subjects with different vertical facial patterns.
Methods: A sample of 187 white adults (92 males, 95 females; age range, 20–30 years; mean age, 25.6 ± 4.2 years) from Granada (southern Spain) were randomly selected and grouped according to the standard cephalometric criteria of vertical facial patterns (mesofacial, FMA angle between 20° and 28°, n=97, dolichofacial, FMA angle >28°; n=49, and brachyfacial, FMA angle <20°; n=41). Geometric morphometrics were used to analyse the size (centroid size) and shape (principal components analysis, mean shape comparisons) of the mandible.
Results: Mean size comparisons indicated no size differences among different vertical facial patterns. Quantitative analyses of mean shape showed significant differences in the shape of the mandible between all vertical patterns (Procrustes distances between means: Dolichofacial vs. brachyfacial = 0.626, p<0.001; dolichofacial vs. mesofacial = 0.0312, p<0.001; brachyfacial vs. mesofacial = 0.035, p<0.001). The greatest differences were found between dolicho- and brachyfacial mandibles. Due to its specific shape configuration, dolichofacial mandibles are less pronounced antero-posteriorly. This configuration, together with its smaller size, contributes to a more retrognathic profile, and brachyfacial mandibles are vice versa.
Conclusions: No differences were found in the size of the mandible between meso-, dolicho- , and brachyfacial patterns. Shape evaluation of the mandible revealed specific and significantly different shape characteristics associated with every vertical facial pattern.
Methods: A sample of 187 white adults (92 males, 95 females; age range, 20–30 years; mean age, 25.6 ± 4.2 years) from Granada (southern Spain) were randomly selected and grouped according to the standard cephalometric criteria of vertical facial patterns (mesofacial, FMA angle between 20° and 28°, n=97, dolichofacial, FMA angle >28°; n=49, and brachyfacial, FMA angle <20°; n=41). Geometric morphometrics were used to analyse the size (centroid size) and shape (principal components analysis, mean shape comparisons) of the mandible.
Results: Mean size comparisons indicated no size differences among different vertical facial patterns. Quantitative analyses of mean shape showed significant differences in the shape of the mandible between all vertical patterns (Procrustes distances between means: Dolichofacial vs. brachyfacial = 0.626, p<0.001; dolichofacial vs. mesofacial = 0.0312, p<0.001; brachyfacial vs. mesofacial = 0.035, p<0.001). The greatest differences were found between dolicho- and brachyfacial mandibles. Due to its specific shape configuration, dolichofacial mandibles are less pronounced antero-posteriorly. This configuration, together with its smaller size, contributes to a more retrognathic profile, and brachyfacial mandibles are vice versa.
Conclusions: No differences were found in the size of the mandible between meso-, dolicho- , and brachyfacial patterns. Shape evaluation of the mandible revealed specific and significantly different shape characteristics associated with every vertical facial pattern.