There was a high variation in the prevalence of hypodontia between the studies. African populations were found to have a higher risk for tooth agenesis and there was an increased risk for females to have hypodontia than males.
Background Dental education involves teaching and assessing the acquisition of verifiable domains that require superior psychomotor, communication, and cognitive skills. Evolving technologies and methods of assessment could enhance student learning environment and improve tutor assessment experience. Objective The aim of this study was to introduce the application of a comprehensive high-stakes online exam to final-year dental students during the COVID-19 pandemic and evaluate its effectiveness. Design A high-stakes exam was introduced and implemented online to the final-year dental students prior to their graduation. The exam consisted of four components: MEQs, MCQs, OSCE and an oral exam. The exam and invigilation were conducted using Blackboard and MS Teams programs. Stakeholders’ views of the exam were obtained using two tailored surveys, one for students and another for faculty; both included closed- and open-ended questions. Results The exam was run successfully without untoward events. Both students and staff were satisfied with the online exam with the latter being more satisfied than the former. Students with previous experience in online learning system were more satisfied with the online exam compared with those with less experience ( p < 0.05). The main issues raised by students’ satisfaction with the exam were: inadequacy of time for the MEQ part, prevention of back tracking in the MCQ part and minor technological issues, whereas those raised by faculty members were increased time required to complete the exam setup and grading compared to the paper-based exam and minor technological issues. Conclusions A newly introduced, multi-format, online high-stakes exam was implemented successfully to final-year dental students with minor technological issues and good satisfaction by students and staff alike.
The pgsA null Escherichia coli strain, UE54, lacks the major anionic phospholipids phosphatidylglycerol and cardiolipin. Despite these alterations the strain exhibits relatively normal cell division. Analysis of the UE54 phospholipids using negativeion electrospray ionization mass spectrometry resulted in identification of a new anionic phospholipid, N-acylphosphatidylethanolamine. Staining with the fluorescent dye 10-N-nonyl acridine orange revealed anionic phospholipid membrane domains at the septal and polar regions. Making UE54 null in minCDE resulted in budding off of minicells from polar domains. Analysis of lipid composition by mass spectrometry revealed that minicells relative to parent cells were significantly enriched in phosphatidic acid and N-acylphosphatidylethanolamine. Thus despite the absence of cardiolipin, which forms membrane domains at the cell pole and division sites in wildtype cells, the mutant cells still maintain polar/septal localization of anionic phospholipids. These three anionic phospholipids share common physical properties that favor polar/septal domain formation. The findings support the proposed role for anionic phospholipids in organizing amphitropic cell division proteins at specific sites on the membrane surface.A unique lipid composition and lipid-protein interactions appear to exist at the transient membrane domain that defines the division site in bacterial cells (1). Using the cardiolipin (CL) 4 -specific fluorescent dye 10-N-nonyl acridine orange (NAO), we previously found CL-enriched membrane domains located at cell poles and near potential division sites in Escherichia coli (2). Subsequently others reported similar CL domains in Bacillus subtilis (3) and Pseudomonas putida (4). In addition, cell pole and division site enrichment in CL in E. coli was confirmed by lipid analysis of minicells spontaneously budded off from the cell poles of a ⌬minCDE mutant (5). We suggested that formation of CL domains at cell pole/division sites plays an important role in selection and recognition of the division site by amphitropic cell cycle and cell division proteins, such as DnaA (initiation of DNA replication at oriC), MinD (a part of MinCDE system preventing positioning of the divisome at cell poles in E. coli), and FtsA (bacterial actin, which is a linker protein for cytoskeletal protein FtsZ (bacterial tubulin), responsible for targeting the Z-ring to the mid-cell membrane domain). They interact directly with membrane phospholipids through specific amphipathic motifs enriched in basic amino acids, which confers the preference for anionic lipids (for references see Ref. 1). In E. coli the ATP-bound form of MinD recruits an inhibitor of Z-ring formation, MinC, to the membrane, whereas the topological regulator, MinE, induces hydrolysis of ATP bound to MinD resulting in release of MinD, and consequently MinC, from the membrane into the cytoplasm. As a result, all three proteins oscillate between the cell poles maintaining the maximum concentration of the inhibitor MinC at the cell p...
ObjectivesThe purpose of the present study was to investigate factors affecting the formation, severity and location of white spot lesions in patients completing fixed appliance therapy.Material and MethodsA total of 45 patients (19 males and 26 females, mean age 15.81 years, standard deviation 2.89 years) attending consecutively Aberdeen Dental Hospital (ADH) between January and June 2013 to have their fixed appliances removed were given a questionnaire to elicit information regarding their dental care and diet. They were then examined clinically as well as their pre-treatment photographs to record treatment data and white spot lesion (WSL) location and severity using a modified version of Universal Visual Scale for Smooth Surfaces (UniViSS Smooth). Absolute risk (AR) and risk ratios (RR) were also calculated.ResultsThe incidence of at least one WSL observed in patients was 42%, with males displaying a higher incidence than females. The highest incidence of WSLs was recorded on the maxillary canines and lateral incisors, and on the maxillary and mandibular premolars and first molars. The gingival areas of the maxillary and mandibular teeth were the most affected surfaces. Significant (P < 0.05) relationships were found between the presence of WSLs and the following factors: poor oral hygiene (OH), males, increased treatment length, lack of use of fluoride supplements, use of carbonated soft drinks and/or fruit juices and the use of sugary foods. Poor OH posed the highest risk of developing WSL (RR = 8.55).Conclusions42% of patients have developed white spot lesions during fixed appliance therapy. Various contributing risk factors were identified with the greatest risk posed by a poor oral hygiene.
A multifactorial model based on an underlying continuous distribution of tooth size, with thresholds determining hypodontia and supernumeraries, has been proposed [1]. Our aim is to investigate this model by comparing tooth morphology of affected patients and their first degree relatives with normal controls. An image analysis system [2] was used to measure teeth on study models of controls, patients with hypodontia of varying degrees and location, first-degree relatives of hypodontia index cases, and patients with supernumerary teeth in the maxillary incisor region. Mesio-distal crown size in hypodontia patients was smaller than controls, and this difference was significant for all tooth types. There was a general pattern: the more severe the hypodontia, the smaller the size of the tooth formed. Patients with supernumerary teeth had permanent maxillary central and lateral incisors and canines that were significantly larger in mesio-distal width than controls. The maxillary central incisors also differed in taper in supernumerary patients compared to controls. Hypodontia prevalence was higher in first-degree relatives (22%) of hypodontia index cases than in the general population (4.4%), and unaffected relatives had smaller teeth than controls. Thus, there were generalized and localized effects within the dentition, and these findings are compatible with the statistical expectations of the proposed multifactorial model.
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