Apical third instrumentation of curved canals with K-type and canal master instruments.

Forty acrylic blocks with curved canals were divided into two groups of 20 each. One group had canals with 30-degree curvature and the other with 45-degree curvature. Each group was divided into two subgroups of 10 blocks each. One subgroup was instrumented with precurved Kerr files and the other was instrumented with Canal Master hand instruments. The efficiency of the two instruments for preparing the apical third of curved canals was compared. In plastic blocks, Canal Master caused less transportation and was more suitable for instrumenting the canals.