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The authors compare the cleaning effect of various root canal preparation techniques (hand as well as power driven preparation). Two hand techniques (circumferential filing and balanced force technique) and two power driven techniques (the rotary system Wizard CD Plus, Medin, CR, and oscillating NiTi instruments AET Endo-EZE, Ultradent, USA) were used. The preparation was provided under standard conditions (lubrication with the EDTA gel, rinsing with 2% NaOCl). After the preparation the specimen were split longitudinaly and observed in SEM using the three step scala of the cleanliness of the root canal walls. Part of the specimen was split transversaly and observed macroscopically with magnification 5x. The time of the preparation (circumferential filing and rotary preparation) was comapred using the clear resin blocks. The cleanliness of the root canal walls after the hand preparation techniques was comparable to that after the rotary preparation. The preparation using the oscillating instruments (AET Endo -EZE) showed more smear layer and debris in comparsion to the others methods. In all cases the unprepared areas were found. The preparation with the rotary instruments was less time consuming in compasrion to the circumferential filing.

Introduction: The effort to exclude metals from stomatological treatment follows to continuing effort for development of new materials or application of materials from other branches. The fiber-reinforced composites have been used in dental medicine since the end of 80ies. They are composed from glass fibers embedded in a resin matrix. For splinting the materials have been used in the form of strips which toughen during the application. Care report: The authors planned the magnetic resonance imaging of the head in the orthodontic patient for suspected neurological illness. In view of the character of the disease the physician was asked to finish the orthodontic examination as soon as possible and to dismantle the fixed orthodontic apparatus.As a retention device the authors made use of a strip from FRC material, which was not contraindicated for MR imaging in contrast to the conventional steel wire. Conclusion: With growing requirements to esthetic outcome the development of non-metal technologies has been increasing. The application of FRC materials for retention after orthodontic therapy has been gaining importance. In case of MR imaging of the head is the use of non-metal materials of cardinal importance.