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Engine‐Driven Preparation Of Curved Root Canals: Measuring Cyclic Fatigue And Other Physical Parameters *
Author(s) -
Peters Ove A.,
Kappeler Stefan,
Bucher Willi,
Barbakow Fred
Publication year - 2002
Publication title -
australian endodontic journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.703
H-Index - 34
eISSN - 1747-4477
pISSN - 1329-1947
DOI - 10.1111/j.1747-4477.2002.tb00361.x
Subject(s) - fracture (geology) , cyclic stress , torque , root canal , radius , root (linguistics) , dental instruments , materials science , curvature , orthodontics , structural engineering , computer science , engineering , mathematics , composite material , geometry , physics , medicine , linguistics , philosophy , computer security , thermodynamics
An increasing number of engine‐driven rotary systems are marketed to shape root canals. Although these systems may improve the quality of canal preparations, the risk for instrument fracture is also increased. Unfortunately, the stresses generated in rotary instruments when shaping curved root canals have not been adequately studied. Consequently, the aim of an ongoing project was to develop a measurement platform that could more accurately detail physical parameters generated in a simulated clinical situation. Such a platform was constructed by fitting a torque‐measuring device between the rotating endodontic instrument and the motor driving it. Apically directed force and instrument insertion depth were also recorded. Additional devices were constructed to assess cyclic fatigue and static fracture loads. The current pilot study evaluated GT rotary instruments during the shaping of curved canals in plastic blocks as well as “ISO 3630–1 torque to fracture” and number of rotations required for fatigue fracture. Results indicated that torques in excess of 40Nmm were generated by rotary GT‐Files, a significantly higher figure than static fracture loads (less than 13Nmm for the size 20. 12 GT‐File). Furthermore, the number of rotations needed to shape simulated canals with a 5 mm radius of curvature in plastic blocks was 10 times lower than the number of rotations needed to fracture instruments in a “cyclic fatigue test”. Apical forces were always greater than IN, and in some specimens, scores of 8N or more were recorded. Further studies are required using extracted natural teeth, with their wide anatomical variation, in order to reduce the incidence of fracture of rotary instruments. In this way, the clinical potential of engine‐driven rotary instruments to safely prepare curved canals can be fully appreciated.