A geometric morphometric approach to the study of variation of shovel-shaped incisors

International audienc

A geometric morphometric approach to the study of variation of shovel-shaped incisors

Objectives: The scoring and analysis of dental nonmetric traits are predominantly accomplished by using the Arizona State University Dental Anthropology System (ASUDAS), a standard protocol based on strict definitions and three‐dimensional dental plaques. However, visual scoring, even when controlled by strict definitions of features, visual reference, and the experience of the observer, includes an unavoidable part of subjectivity. In this methodological contribution, we propose a new quantitative geometric morphometric approach to quickly and efficiently assess the variation of shoveling in modern human maxillary central incisors (UI1). Materials and methods: We analyzed 87 modern human UI1s by means of virtual imaging and the ASU‐UI1 dental plaque grades using geometric morphometrics by placing semilandmarks on the labial crown aspect. The modern human sample was composed of individuals from Europe, Africa, and Asia and included representatives of all seven grades defined by the ASUDAS method. Results: Our results highlighted some limitations in the use of the current UI1 ASUDAS plaque, indicating that it did not necessarily represent an objective gradient of expression of a nonmetric tooth feature. Rating of shoveling tended to be more prone to intra‐ and interobserver bias for the highest grades. In addition, our analyses suggest that the observers were strongly influenced by the depth of the lingual crown aspect when assessing the shoveling. Discussion: In this context, our results provide a reliable and reproducible framework reinforced by statistical results supporting the fact that open scale numerical measurements can complement the ASUDAS method

A geometric morphometric approach to the study of variation of shovel‐shaped incisors

Objectives : The scoring and analysis of dental nonmetric traits are predominantly accomplished by using the Arizona State University Dental Anthropology System (ASUDAS), a standard protocol based on strict definitions and three‐dimensional dental plaques. However, visual scoring, even when controlled by strict definitions of features, visual reference, and the experience of the observer, includes an unavoidable part of subjectivity. In this methodological contribution, we propose a new quantitative geometric morphometric approach to quickly and efficiently assess the variation of shoveling in modern human maxillary central incisors (UI1).; Materials and methods : We analyzed 87 modern human UI1s by means of virtual imaging and the ASU‐UI1 dental plaque grades using geometric morphometrics by placing semilandmarks on the labial crown aspect. The modern human sample was composed of individuals from Europe, Africa, and Asia and included representatives of all seven grades defined by the ASUDAS method.; Results : Our results highlighted some limitations in the use of the current UI1 ASUDAS plaque, indicating that it did not necessarily represent an objective gradient of expression of a nonmetric tooth feature. Rating of shoveling tended to be more prone to intra‐ and interobserver bias for the highest grades. In addition, our analyses suggest that the observers were strongly influenced by the depth of the lingual crown aspect when assessing the shoveling.; Discussion : In this context, our results provide a reliable and reproducible framework reinforced by statistical results supporting the fact that open scale numerical measurements can complement the ASUDAS method.Facultad de Ciencias Naturales y MuseoConsejo Nacional de Investigaciones Científicas y Técnica

Machine Learning Analysis of the Anatomical Parameters of the Upper Airway Morphology: A Retrospective Study from Cone-Beam CT Examinations in a French Population

The objective of this study is to assess, using cone-beam CT (CBCT) examinations, the correlation between hard and soft anatomical parameters and their impact on the characteristics of the upper airway using symbolic regression as a machine learning strategy. Methods: On each CBCT, the upper airway was segmented, and 24 anatomical landmarks were positioned to obtain six angles and 19 distances. Some anatomical landmarks were related to soft tissues and others were related to hard tissues. To explore which variables were the most influential to explain the morphology of the upper airway, principal component and symbolic regression analyses were conducted. Results: In total, 60 CBCT were analyzed from subjects with a mean age of 39.5 ± 13.5 years. The intra-observer reproducibility for each variable was between good and excellent. The horizontal soft palate measure mostly contributed to the reduction of the airway volume and minimal section area with a variable importance of around 50%. The tongue and the position of the hyoid bone were also linked to the upper airway morphology. For hard anatomical structures, the anteroposterior position of the mandible and the maxilla had some influence. Conclusions: Although the volume of the airway is not accessible on all CBCT scans performed by dental practitioners, this study demonstrates that a small number of anatomical elements may be markers of the reduction of the upper airway with, potentially, an increased risk of obstructive sleep apnea. This could help the dentist refer the patient to a suitable physician

A geometric morphometric approach to the study of variation of shovel‐shaped incisors

OBJECTIVES : The scoring and analysis of dental nonmetric traits are predominantly accomplished by using the Arizona State University Dental Anthropology System (ASUDAS), a standard protocol based on strict definitions and three‐dimensional dental plaques. However, visual scoring, even when controlled by strict definitions of features, visual reference, and the experience of the observer, includes an unavoidable part of subjectivity. In this methodological contribution, we propose a new quantitative geometric morphometric approach to quickly and efficiently assess the variation of shoveling in modern human maxillary central incisors (UI1). MATERIALS AND METHODS : We analyzed 87 modern human UI1s by means of virtual imaging and the ASU‐UI1 dental plaque grades using geometric morphometrics by placing semilandmarks on the labial crown aspect. The modern human sample was composed of individuals from Europe, Africa, and Asia and included representatives of all seven grades defined by the ASUDAS method. RESULTS : Our results highlighted some limitations in the use of the current UI1 ASUDAS plaque, indicating that it did not necessarily represent an objective gradient of expression of a nonmetric tooth feature. Rating of shoveling tended to be more prone to intra‐ and interobserver bias for the highest grades. In addition, our analyses suggest that the observers were strongly influenced by the depth of the lingual crown aspect when assessing the shoveling. DISCUSSION : In this context, our results provide a reliable and reproducible framework reinforced by statistical results supporting the fact that open scale numerical measurements can complement the ASUDAS method.Supplementary material: Table S1 Supporting Information Table 1. Visual scoring performed by two independent observers (intra‐ and interobserver tests). SSc: Statistical Scoring; VS1T1: Visual scoring Observer 1 Test 1; VS1T2: Visual scoring Observer 1 Test 2; VS2: Visual scoring Observer 2. In some cases, the observers gave an intermediate rating (0_1 meaning a category between ASUDAS references 0 & 1). Table S2: Supporting Information Table 2. Definition of UI1 shoveling grades (Scott et al., 2018; Scott & Irish, 2017; Turner et al., 1991). Table S3: Supporting Information Table 3. Correlations between various measurements obtained from the coordinates of the 7 ASUDAS reference casts. The ASUDAS category values were also compared against these metrics. Table S4: Supporting Information Table 4. Correlations between various measurements obtained from the coordinates of all French samples (both contemporary and medieval). Maximum depth and hollow area are the directly measured metrics based on the non‐Procrustes alignment method. Principal components were obtained from both Procrustes and non‐Procrustes methods. Only PC1 is presented here for simplicity. Shades of color represent the degree of correlation, with darker green corresponding to the highest degrees and white to the lowest degree. Table S5: Supporting Information Table 5. Correlations of rater‐assigned ASUDAS categories with various measurements obtained from the coordinates of all French samples. Figure S1 Supporting Information Figure 1. Principal Component loadings represented as PC shape changes. Results are shown here for non‐Procrustes PCs; the plots for Procrustes PCs are very similar. The axes are same as in Figure 2. The black line, showing the shape for ASUDAS reference cast category 3, indicates the baseline in all figures. The thick colored curve in each figure represents a + 1 unit shift toward the direction of the PC from the baseline. Thin dotted lines join the coordinate of each of the 100 points before and after the shift, thus representing the amount and direction of shift for each point.Toulouse Dental Faculty (PLTRO); Midi‐ Pyrenées Region; Université Toulouse III–Paul Sabatier; CHU de Toulouse; Université de Toulouse; French CNRS; Arizona State Universityhttps://wileyonlinelibrary.com/journal/ajpahj2020Anatom

Bulletin Bibliographique

À tous les lecteurs et collaborateurs du Bulletin Bibliographique des ASSR Pour la première fois cette année nous mettons en ligne les comptes-rendus sur note site Revues.org au rythme semestriel (juin / décembre) qui est celui des échéances du Bulletin Bibliographique. La totalité des recensions de l'année 2009 sera publiée dans notre numéro 148 (octobre-décembre)