Clinical
Dr Maria Jennings BDS MSc examines the developments in rotary endodontic systems, from their early days to the present day
century The turn of the
E
ndodontic instrumen- tation has been vastly changed in the past decade due to the introduction of rotary
files manufactured from Nickel- Titanium (NiTi). This material, discovered by a scientist in a US Navy laboratory, has trans- formed the mechanics of canal preparation. Now, every manufacturer has
introduced NiTi rotary endodontic filing systems, with claims of better, faster preparations, fewer files etc., such that it is difficult to keep up with the latest develop- ments. The change in technology and introduction of newer systems is happening so quickly that claims being made are often not backed up with scientific studies. By the time the instruments have
been subjected to independent evaluation, the design or material has been changed or the manufac- turer has been taken over by a rival company. Part one of this article will attempt to describe the evolution of files, and part two will describe the most common rotary endodontic preparation systems now available.
History of endodontic files In ı883, Edward Maynard developed a barbed broach for removing the pulp from teeth and later made reamers by twisting piano wire filed to a sharp point. In ı889, William Rollings invented a root canal drill which he attached to a motor rotating at ı00rpm, so rotary endodontic files are nothing new! ISO specifications for endodontic instruments were not standardised until ı974 with hand files in either 2ımm, 25mm or 3ımm lengths, with a ı6mm cutting surface which increased in taper from the tip to the end of the cutting surface by 2 per cent. The size was determined by the diameter of the tip measured in 0.0ımms initially from ı0 (0.ımm) to ı00 (ı.0mm) Sizes 06 and 08 were added later. The instrument sizes were colour coded with all manu- facturers having much the same array of stainless steel hand instru- ments. These were reamers, K-files or Hedstrom files and the variations were mainly confined to the shape of the cross-section of the file. The most commonly used mechanical rotary
Continued » Ireland’s Dental magazine 25
Above: Fig 1. Hedstrom files
Fig 2 Gates Glidden drill Fig 3 Flexibility of NiTi file
Fig 4 Cross-sections of NiTi files
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