Tooth transposition prevalence and type among sub-Saharan Africans

Objectives: Although rare, tooth transposition—an exchange in location of two teeth—is a frequent topic of study. Clinical and, to a much lesser extent, dental anthropological research have focused predominantly on prevalence (0.03%‐0.74% in several world populations) and case studies, albeit on a restricted spatiotemporal scale. Many regions have received little attention, including sub‐Saharan Africa, while premodern data are few. Here, the aim is to supplement both fields of dental research by reviewing previous publications, and newly reporting transposition rates, types, and co‐occurring abnormalities in time‐successive samples across the subcontinent. Methods: Dental data in 51 sub‐Saharan samples (>2500 individuals) dating >10 000 BC to 20th century were recorded. Of these, 36 are of modern and 15 premodern age, comprising males and females ≥12‐years of age. Transposition presence, quadrant, and type were tabulated, cases described, and prevalence presented. In the latter case, Poisson 95% confidence intervals were calculated to better discern true population rates at various geographic levels. Results: Overall, six of 1886 modern individuals (0.32%) and one of premodern age evidence Mx.C.P1, an exchange of the maxillary canine and first premolar. Various associated dental abnormalities are also evident, including retained deciduous teeth, reduced permanent crowns, and agenesis. Conclusions: This study provides additional insight into the geographic distribution, features, and time depth of transposition, along with hints supporting a genetic etiology and, potentially, some indications of diachronic change from an initial Mx.C.P1 to several types more recently based on premodern evidence. It is of clinical concern today, but is not just a modern anomaly

Evaluation of facial soft tissue parameters for Palestinians using Holdaway analysis

OBJECTIVE: The aims of this study were to evaluate soft-tissue measurements for a Palestinian sample population with normal occlusion by Holdaway’s analysis, and to check the applicability of Holdaway values to the Palestinian population. Normal Holdaway values for Palestinians will be established if their parameters do not match those of Holdaway. MATERIAL AND METHODS: Cephalometric radiographs of 93 Palestinian university students with normal occlusion (63 women, mean age: 20.1 ± 2.1 years; 30 men, mean age: 20.2 ± 2.4 years) were traced and evaluated. Cephalometric landmarks were located according to Holdaway analysis. Ten linear and two angular measurements were produced on each radiograph. RESULTS: The soft-tissue measurements for the Palestinians were similar to the Holdaway norms, except for the soft-tissue convexity angle and soft-tissue chin thickness, which were larger than the Holdaway averages. The Palestinian sample had a narrower range for normal nose prominence, as well as thicker lips, deeper superior and inferior sulci, and thicker soft-tissue chins than the Holdaway values. CONCLUSIONS: We determined normal values for the Holdaway soft-tissue analysis for Palestinians, which are appropriate for use in orthodontic practices in these territories

Massive Numbers, Diverse Learning

MOOCs provide education for millions of people worldwide. Though it is not clear whether everyone can learn in a MOOC. Building on the typology of MOOC participants introduced is in Chap. 3, and we explore the claim that MOOCs are for everyone. We trace the different reasons people participate in MOOCs and the ways they learn. MOOCs tend to be designed for people who are already able to learn as active, autonomous learners. Those with low confidence may be inactive. However, even learners who are confident and able to regulate their learning experience difficulties if they don’t comply with the expectations of the course designers or their peers. For example, if a learner chooses to learn by observing others, rather than contributing, this behaviour can be perceived negatively by tutors and by peers. This indicates that MOOCs sustain the traditional hierarchy between the educators (those that create MOOCs and technology systems) and the learners (those who use these courses and systems). Although this hierarchy is not always visible, since it is embedded within the algorithms and analytics that power MOOC tools and platforms