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This ex-vivo study investigated the effect that repeated bracket displacement has on sliding friction and the magnitude of bracket displacement, and hence tooth movement, required to release bracket/archwire binding. The design consisted of an ex-vivo laboratory study. A jig was designed that allowed repeated displacement of a bracket to occur, while the resistance to sliding (friction) was measured using an Instron universal testing machine. One type of stainless steel bracket was used in conjunction with four archwire types (0.016-inch stainless steel, 0.019 x 0.025-inch stainless steel, 0.021 x 0.025-inch stainless steel, 0.019 x 0.025-inch beta-titanium) and four magnitudes of displacement. Repeated bracket displacement has a significant effect on the sliding resistance at the bracket/archwire interface (P < 0.001). The reduction in sliding resistance noted with displacement depended on the archwire. Over the range of displacements tested, there was an 85 and 80 per cent reduction associated with 0.021 x 0.025-inch and 0.019 x 0.025-inch stainless steel, respectively. For 0.019 x 0.025-inch beta-titanium and 0.016-inch stainless steel, these reductions were 27 and 19 per cent, respectively. The importance of true friction, given the likelihood of bracket and/or archwire displacements in vivo, may be lessened.

The DentEd Thematic Network Project employed a process of schools visits, plenary meetings and the use of an interactive web site to help reach consensus on innovations, best practices and significant divergence in standards in dental education in Europe. This process has proven an effective method of improving communication and of increasing the understanding of diversity in a wide range of educational methods. It also emphasised the importance of continuing quality improvement and outcome analysis of the clinical competence of graduates from European dental schools. It is important to emphasise that schools visited are likely to reflect those with an open and flexible attitude to educational reform and development and perhaps they were not representative of those schools that would benefit most from a self-assessment followed by peer review. On completion of the DentEd Thematic Network Project (TNP) the European Union's Directorate for Education and Culture approved a new three-year DentEdEvolves TNP and the consortium has recently submitted a major proposal in the EU's eLearning initiative on the basis of the success of this collaboration. This has extended to include 75% of dental schools from North America and plans for extension to South-east Asia will bring a major meeting to Singapore in April 2002.

The object of the study was to investigate the behavioural characteristics of orthodontic elastomeric modules with regard to their effect on frictional resistance and their failure load forces, and involved the use of an experimental laboratory-based study. Six cohorts were assembled employing five types of module and two bracket types. Straight lengths of 0.018 x 0.025-inch stainless steel were pulled through the ligated brackets and frictional resistance was measured using an Instron universal testing machine. Recordings were repeated over a 4-week period, during which time the cohorts were placed in a simulated oral environment. Failure load forces of new and used modules were also recorded, and frictional resistance and failure load forces. Analysis of variance revealed that the Minitwin cohort exhibited significantly higher frictional resistance and that the clear modules demonstrated the lowest levels of friction. Time soaked in a simulated oral environment had a variable effect on frictional resistance. A wide range of failure load forces was seen for the five types of module and all types showed a reduction in failure load force following their soaking in the simulated oral environment. There was variation in performance of the different modules both in friction testing and failure load testing.