Results from this study suggest that mushroom archwires may provide better mechanics for movement of teeth in the anterior segment when using a round archwire; however, only biomechanical data was considered in this study and there are many factors that need to be considered in treatment planning.
Objective
To compare the biomechanics of straight labial, straight lingual, and mushroom lingual archwire systems when used in posterior arch expansion.
Materials and Methods
An electro-mechanical orthodontic simulator allowing for buccal–lingual and vertical displacements of individual teeth and three-dimensional force/moment measurements was instrumented with anatomically shaped teeth for the maxillary arch. In-Ovation L brackets were bonded to lingual surfaces, and Carriere SLX brackets were bonded to labial surfaces to ensure consistency of slot dimensions. Titanium molybdenum archwires were bent to an ideal arch form, and the teeth on the orthodontic simulator were set to a passive position. Posterior teeth from the canine to second molar were moved lingually to replicate a constricted arch. From the constricted position, the posterior teeth were simultaneously moved until the expansive force decreased below 0.2 N. Initial force/moment systems and the amount of predicted expansion were compared for posterior teeth at a significance level of α = 0.05.
Results
Archwire type affected both the expected expansion and initial force/moment systems produced in the constricted position. In general, the lingual systems produced the most expansion. The archwire systems were not able to return the teeth to their ideal position, with the closest system reaching 41% of the intended expansion.
Conclusions
In general, lingual systems were able to produce greater expansion in the posterior regions when compared with labial systems. However, less than half of the intended arch expansion was achieved with all systems tested.
Abstract:In this study, we conducted a worst-case risk assessment for children's health from ingestion exposure to water sources in two densely populated counties of the Piedmont province of New Jersey-Hunterdon and Mercer counties. Carcinogenic and non-carcinogenic health risk estimates for 19 contaminants, representing 3 different chemical classes-organic, inorganic and contaminants of emerging concern (CEC), for which environmental monitoring data are available-were generated. The three exposure scenarios examined were: (1) ingestion exposure to untreated groundwater from contaminated private wells; (2) recreational exposure through incidental ingestion of water from the Delaware River; and (3) ingestion exposure through fish consumption sourced from the Delaware River. The total health hazard posed by each contaminant across all the three exposure scenarios was compared to prioritize contaminants based on health risk potential. As a result of this analysis, arsenic and trichloroethylene in private well water were identified as key drivers of health risk and, hence, are proposed as the contaminants of primary concern for the target population. Significantly high total excess cancer risk of 2.13 × 10 −3 from arsenic exposure was estimated, highlighting the need for testing and treating water sources as well as setting a framework for more detailed work in the future.
Basic health and infection control measures are the main methods of protection against COVID-19. Patients are well informed about how practitioners should be conducting themselves, however, they may lose trust in clinicians who fail to demonstrate, and promote those same basic prevention measures. The broader COVID-19 strategy has included the rapid development and deployment of swabs and antibody tests. Flaws in testing fail to offer assurances due to false negatives while even true positives cannot guarantee future immunity as there is uncertainty regarding long-term antibody response. An understanding of human factors and an appreciation of the limitations of available tests could offer healthcare staff mechanisms to encourage safety.
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