In this study tools were developed to test and compare levelling archwires that the manufacturers claim to have superelastic properties. As the classic spring model and Hook's law cannot be applied, new parameters had to be found. It could be shown that three parameters are necessary to describe a superelastic archwire adequately: the distinctiveness of the pseudo-elastic plateau, the deflection at the beginning of the plateau, and the force level of the plateau. The results showed that many materials either did not show any pseudoelastic properties at all or that the wire parameters were such that they did not give any advantage over conventional work hardened NiTi materials. In many archwires the beginning of the plateau and thereby the desired characteristics began only when the archwire was displaced 1 mm or more. For many archwires the force level of this plateau also proved to be rather high with values often above 500 g.

Bonded retainers have become a very important retention appliance in orthodontic treatment. They are popular because they are considered reliable, independent of patient cooperation, highly efficient, easy to fabricate, and almost invisible. Of these traits, reliability is the subject of this clinical study. A total of 549 patients with retainers were analyzed with regard to wearing time, extension of the retainer, mean time between failures, operator, and age of patient. The average frequency of breakage or loss was 0.55 per retainer per year. This frequency was dependent primarily on the operator who bonded the retainer and on the extent of the retainer. If the upper canines were involved, reliability was lower. The majority of failures occurred during the first 3 to 6 months. The study showed that bonded retainers represent a highly efficient and reliable retention appliance suited to long-term use.

No abstract

An adequate analysis of the skeletal pattern is essential since a considerable amount of dental compensation can mask the severity of a malocclusion. Disagreement prevails over the standards that should be used to judge the individual values. The paper describes a method of analyzing the skeletal pattern of a patient on an individualized basis. Rather than relating the individual cephalometric values to population means the method employs standards derived from the individual facial type (floating norms). The associations between the basic cephalometric variables can be derived from a box-like graphical representation that is based on the correlations between the different variables. It is thereby an improvement of the 'box' that has been used in the Bergen Technique.

Laudatio Professor Dr. Asbj0rn zum 65. Geburtstag Hasund ,,Wissenschat't kennt keine Grenzen!" So k6nnte das Leitmotiv lauten, das Prof. AsbjOrn Hasund ffir ein nahezu 40j~ihriges Berufsleben gew~hlt hat. Bedingt dutch seine internationale Ausbildung in Oslo, Chicago und Seattle sowie seine unz~hligen Gastvortr~ige, Kurse und Seminare, reichen seine Kontakte rund um die Welt, von Thailand bis in die USA. Besonders zu nennen sind hier auch die Verbindungen in den ehemaligen Ostblock. Sc,hon lange vor dem Fall des eisernen Vorhangs hielt Prof. Hasund Vom-age und Kurse, in denen er unter anderem in der DDR, Ungarn~ der Tschechoslowakei und UdSSR modeme Aspekte der Kieferorthop~idie vermittelte.