In-vitro-Untersuchung zur Prozessoptimierung bei Herstellung und adhäsiver Befestigung von 3-3-Retainern mit Hilfe einer Neodym-Magnetkette

Abstract

Background and objective: Since the development of 3-3-retainers different technologies have been designed in the attempt to optimize the process of the adhesive fixation in the patient's mouth. The aim of this study was to compare 3-3-retainers produced with a resin positioning aid as opposed to retainers made with a newly developed neodymium-iron-boron magnet chain. The expenditure of time needed for both, the production and the bonding process as well as the accuracy of fit of the completed 3-3 retainers were measured and examined in contrast. The influence of different types of dental wire on the duration of the production and adhesion procedures as well as on the accuracy of fit of the final product were also taken into account. Materials and methods: After the production and duplication of plaster models of the mandible and their separation into two groups (Irregularity Index for Little 0-1 and 4-10), the 3-3-retainers were manufactured by a dental technician of the University of Göttingen using two different production methods and two wire qualities (15er and 18er Dentaflex). The production time was measured and recorded. The finished models were mounted into clinical simulation units. Then, the adhesive fixation of 3-3-retainers was performed by a specialist in orthodontics, using either a resin-positioning aid or a neodymium magnet chain. The time required for bonding was measured and documented. Subsequently, the front-canine-segment was cut out of the model and then trimmed horizontally and in parallel up to the level of the retainer wire. Finally, each thus processed model was scanned and all of the areas as well as the vertical distances between teeth and retainer were measured. Results: Both the manufacturing and the fixation procedures were shown to be significantly improved by the use of the neodymium magnet chain as opposed to the application aid. The production of the 3-3 retainers was faster by 1.89 minutes, while the bonding process was accelerated by about 0.93 minutes. In both groups, the retainers that were adhered using the magnetic chain produced significantly smaller distances between the archwire and the dental arch. The wire type had no significant effect on the duration of the production, the fixation time or on the fit of the retainer. Conclusion: The expenditure of time needed by the dentist to both make and adhere a 3-3 retainer as well as the accuracy of its fit can be optimized by using the neodymium magnet chain. The magnetic chain provides a faster, simpler, clearer and therefore cost-effective technique for manufacturing and installing 3-3 dental retainers.