Microbial colonisation associated with conventional and self-ligating brackets: a systematic review

Background: Decalcification and gingivitis caused by plaque accumulation around brackets are common iatrogenic effects of fixed appliances. The influence of conventional versus self-ligating bracket design on microbial colonisation is unknown. Objective: To assess the levels of microbial colonisation associated with conventional and self-ligating brackets. Search sources: Three databases were searched for publications from 2009 to 2021. Data selection: Randomised controlled trials comparing levels of microbial colonisation before and during treatment with conventional and self-ligating brackets were assessed independently and in duplicate. Data extraction: Data were extracted independently by two authors from the studies that fulfilled the inclusion criteria. Risk of bias assessments were made using the revised Cochrane risk of bias tool for randomized trials. The quality of the included studies was assessed using the Critical Appraisal Skills Programme Checklist. Results: A total of 11 randomised controlled trials were included in this systematic review. Six of the studies were found to be at low risk of bias and five presented with some concerns. The studies were considered moderate to high quality. Five trials reported no statistically significant difference in microbial colonisation between bracket types. The remaining studies showed mixed results, with some reporting increased colonisation of conventional brackets and others increased colonisation of self-ligating brackets. The heterogeneity of study methods and outcomes precluded meta-analysis. Conclusion: Of the 11 studies included in this systematic review, five found no differences in colonisation between conventional and self-ligating brackets. The remaining studies showed mixed results. The evidence is inconclusive regarding the association between bracket design and levels of microbial colonisation.

Fatigue Life Prediction of Aircraft Engine Bracket

The purpose of this project is to optimize the design, dimensions along with changing in material of the bracket structure to ensure the structural fatigue life increase along with reduction in stress and displacement of the component. Optimization study of components gives a great opportunity for material saving which leads to save cost and man power. The major bracket design parameters were explained in detail and the bracket configuration has been described. Different types of loads acting on the aircrafts bracket are determined and the moments, displacements, etc., are also determined. The bracket structure was also explained and functions of each component and their arrangement are also studied. The methodology of finite element method and the detailed description about various FEM tools have been studied and implemented in this work. The procedure of finite element method was followed to analyse the model. The analysing part of this project is done using CAE tool package and the results were discussed. In this Project, we designed Aircraft engine bracket using CATIA V5 and carried out linear static analysis using MSC Software. For Pre-Processing used MSC PATRAN and MSC NASTRAN for solving followed by Fatigue calculations.

Students’ Exploration Strategies in a Sustainability-Focused Structural Optimization Task

This paper examines students’ design exploration strategies in a sustainability-focused structural optimization task. The task was set up as a two-criteria optimization problem with the goal of simultaneously minimizing the weight and an environmental indicator for a pedal bracket design. Forty-two students in an undergraduate computer-aided design class solved this task as a week-long, take-home assignment. Our analysis shows the number of design iterations and the number of failed iterations were significant factors in determining overall performance on the task. We also found that the final shape, the number of material changes, and experiencing conflict in the objective functions between iterations, did not significantly affect task performance. Based on these findings, we discuss implications for computer-aided optimization tools in sustainable product design.