To determine whether ledging, zipping, and perforation occur more frequently in curved canals using crown down pressureless technique vs. traditional filing.
- n=40 single canal extracted human teeth with apical curvature 10-35 deg.
- mounted in typodont, half instrumented with crown-down technique and half using traditional hand filing.
- 5 similar uninstrumented teeth served as controls.
- injected xantopren blue impression material into root canal systems under vacuum and teeth cleared.
- 5 different evaluators (4 endos, 1 GP) gave an overal rating of quality
- significant difference only in overall rating.
- crown down technique received more excellent ratings and was deemed an effective method for instrumenting curved canals (P= .02)
Crown down instrumentation may allow easier preparation of curved canals.