Endodontic files and reamers

Endodontic files and reamers are surgical instruments used by dentists when performing root canal treatment. These tools are particularly used to clean and shape the root canal, with the concept being to perform complete chemomechanical debridement of the root canal to the length of the apical foramen.

Files are commonly made from metal; usually stainless steel or nickel titanium alloy. Files may be made from metal blanks that are twisted or machined to produce various sizes and tapers. Typical file lengths are 21mm, 25mm, 31mm. An ISO sizing system is used to describe the tip size of endodontic files. Files are usually colour-coded in an ISO colour system to aid the dentist. Typically steel files have 2% tapers, but in recent years Ni-Ti files with up to 12% tapers have been popularized.

Fracture of an endodontic file may cause the endodontic treatment to have a lower success rate. Fragments of files may be removed using a retrieval system, but this is very technically demanding, and many fragments are left in-situ without problems.

Today there are a number of rotary NiTi systems all prone to separation and cyclic fatigue. An alternative approach, 30° horizontal oscillations (reciprocation) has virtually eliminated concerns for breakage, while managing to fully shape canals without distortion. missing reference

Self-adjusting files is a general term for hollow, compressible files made of nickel-titanium that adapt three-dimensionally to the shape of a given root canal, including its cross section. The files are operated with vibratory in-and-out motion, with continuous irrigation of disinfectant delivered by a peristaltic pump through the hollow file. A uniform layer of dentin is removed from the whole circumference of the root canal, thus achieving the main goals of root canal treatment while preserving the remaining root dentin. The 3D scrubbing effect of the file, combined with the fresh irrigant, result in clean canals, which in turn facilitate better obturation. More effective disinfection of flat-oval root canals is another goal that is simultaneously attained.

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