Wurzelkanalaufbereitung mit rotierenden Ni-Ti FlexMaster® und MFile® Instrumenten,eine Vergleichsstudie

Aim: To compare two Ni-Ti rotary root canal systems FlexMaster [FM] and MFile [MF]. Methodology: 2 x 70 (= 140) artificial root canals were prepared to ISO #35. Fracture rate, preparation time and changes to the root canal geometry were recorded. Results: In none of the evaluated root canals were zip or ledge configurations observed. The use of FM instruments caused statistically less elbows in the canals compared to MF instruments (p < 0,01%). FM instruments transportated canals at point 7 mm from the apex significantly more than MF instruments (p < 0,001%). Correct preparation length was achieved with both systems. The mean time of preparation of a root canal was significantly less with the MF system (p < 0,001%). The registered fracture rate was zero with FM, with MF it was 25.7% between the 2nd and the 7th treatment (p < 0,001%). Torsion was observed in more than 50% of MFiles that preparated the medial and the apical third of the canal. FM instruments showed no torsion Conclusions: Repeated usage of MF instruments in curved canals is not recommended due to high rate of fracture and torsion. One time usage is to be preferred. Reducing the number of instruments from 9 (FM) to 4 (MF) increases mechanical stress of the files. Instruments with shorter working parts remove less material from the inner curvature and cause less transportation. Prior to clinical usage more investigations at extracted molars are needed