Patency file and apical transportation: an in vitro study.

The purpose of this study was to evaluate the transportation produced at the apical foramen by the use of stainless steel and nickel-titanium K-files #10, #15, #20, and #25 as a patency file. Thirty human maxillary lateral incisors were transversally cut at 4 mm from the apex and mounted in square pieces of silicone with special marks to ensure repositioning of the specimens. The specimens were randomly divided in two equal groups of 15.