Shaping ability and safety of five different rotary nickel-titanium instruments compared with stainless steel hand instrumentation in simulated curved root canals - Schirrmeister, J F; Strohl, C; Altenburger, M J; Wrbas, K T; Hellwig, E (Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 2006)