F.L.G. Calberson, C.A.J.G. Deroose, G.M.G. Hommez, H. Raes and R.J.G. DeMoorDepartment of Operative Dentistry and Endodontology, Dental School, Ghent University Hospital, Ghent University, Gent, Belgium.
Department of Biology, Ghent University, Gent, Belgium.Introduction.
The objectives of root canal instrumentation are to clean and shape the canal system(Schilder1974).The ideal preparation for the root canal is a funnel shaped form with the smallest diameter at the apex and the widest diameter at the or ice (Schilder 1974). This is not an easy task in teeth with curved canals and in teeth with complex root canal anatomy.
The funnel shaped form can be achieved either by hand or by mechanical preparation. This optimal shape can be easily provided in straight canals, however, in narrow and curved canals aberrations, such as ledging, zipping, danger zones and canal transportation appear because larger instruments tend to straighten the canal (Esposito & Cunningham1995, Glosson et al.1995).
More flexible files made of nickel-titanium have been effective in minimizing complications in narrow and curved canal preparation (Wu&Wesselink1995,Zmener & Banegas 1996, Thompson & Dummer 1997). In this respect, it has been shown that nickel-titanium instruments have several advantages over stainless steel files such as agreater flexibility due to super elasticity, a shape memory effect and a better resistance to torsional fracture (Walia et al.1988).
Rotary nickel-titanium instruments for the mechanical preparation of root canals are available in various designs. At this time, there is little information available on the shaping ability of GT Rotary Files (Kum et al. 2000). The aim of the present study was, therefore, to investigate the shaping ability of the GT Rotary File System (Dentsply Maillefer, Ballaigues, Switzerland) during preparation in simulated root canals and to record the aberrations that appeared. In this respect, root canals with 408 and 608 curves were produced. The shaping ability of nickel-titanium instruments in canals with a 608 curve has not yet been investigated.