The standardized-taper root canal preparation--Part 1. Concepts for variably tapered shaping instruments.

AIM: To introduce the concept of variable taper instruments for predictable and ergonomic root canal preparation, and demonstrate the design features of Greater Taper files.
SUMMARY: Optimal root canal shaping is difficult to practice and teach with traditional instruments. Instrument sequences are complex, with up to 18 instruments and 63 procedural stages, providing almost limitless scope for poor results and iatrogenic error. In the first of six articles, Dr Buchanan describes the Variable Taper concept, which grew from such frustrations, and represents a new concept in file design. Milled from NiTi alloys in tapers of 0.06, 0.08, 0.10 and 0.12 mm mm-1, with accessory files for wide canals, their design embodies the key shaping features of adequate coronal enlargement, full deep shape, and predictable apical resistance form case after case. The ease and simplicity of their use is described, and enhanced cleaning and obturation outcomes discussed in relation to their unique design features. KEY LEARNING POINTS: Canal preparation is difficult to practice and teach with traditional K-files and Gates Glidden drills. Variable Taper files are designed to offer the optimal preparation features of adequate (not excessive) coronal enlargement, full deep shape, and apical resistance form in a simple instrument sequence. Variable Taper technique is simple to master, and offers predictable cleaning and obturation outcomes, even in inexperienced hands.