Descriptions of Protocols and Terminology

Rake & Cutting Angle:
If the file is sectioned perpendicular to its long axis, the rake angle (cutting angle) is the angle formed by the leading edge and the radius of the file inscribed in its circle of rotation. While using the radius as the line of reference, if the leading edge is in front of the perpendicular radius, it is referred to as a negative (scraping) cutting angle and is measured as the angle formed by the leading edge and radius. If the leading edge is behind the radius, it is referred to as a positive cutting angle.

Negative Angle

X-Section with Negative Angle

X-Section with Positive Angle

X-Section with Positive Angle

 

 

 

 

 

 

 


 

Circumference Area & Core Area:
The circumference area (A=3.14r²), inscribed by the rotation a file, is determined by defining r as the distance from the file’s central axis of rotation to the file’s outer most boundary. The core area of the file (A=3.14r²) is the cylindrical center area of the file having its circumference outlined and bordered by the depth of its flutes. It should be noted that there are instances when the central axis of rotation is separate from the file core’s center.

File with symmetrical X-section

File with Symmetrical X-Section

File with Asymmetrical X-Section

File with Asymmetrical X-Section

Circumference&AreaKey

 

 

 

 

 

 


 

FLUTES & SPIRALS:
The flute of the file is the groove in the working surface used to collect soft tissue and dentine chips removed from the wall of the canal. The surface having the greatest diameter that follows the groove (defined as where the flutes intersect), as it rotates, forms the leading (cutting) edge. The number of spirals that a file has in its working surface can be calculated by dividing the number of flutes on the working surface by the number of flutes in  x-section.

Sides of X-Section Point to Corresponding Flutes

Sides of X-Section Point to Corresponding Flutes

 

 

 

 

 

 

 

 

 


 

HELIX ANGLE:
The helix angle is the angle the blade makes as it intersects with central longitudinal axis of the file.

Helix Angle

Helix Angle

 

 

 

 


 

DEBRIS REMOVING AREA:
The debris removing area is the total flute space represented as a percentage of the circle area that inscribes the file.

DebrisRemovalArea

 

 

 

 


 

DEFLECTION & DEFORMATION:
Deflection is measured as the file is lowered 5mm onto a 60 degree incline. If the file remains bent as it is lifted from the incline, the angle of the bend is measured as plastic deformation.

Deflection

 

 

 

 

 

 

 


 

ROTATION TO FAILURE:
To determine rotation to failure, 3mm of the tip end of a file is locked into place before rotating its handle end continuously until it breaks. The degree of total rotation is measured at the point where the file fails.


 

PEAK TORQUE AT FAILURE:
Peak torque at failure describes the maximum torque the file undergoes as it is rotated to failure.


 

 

 

One thought on “Descriptions of Protocols and Terminology

  1. hi from Cairo
    as a prof of endodontics at Faculty of Oral and Dental Medicine, Cairo university a former graduate student at university of indiana (1965-1967) i did supervised MSD and PHD TH
    THESIS TITELS
    1. Effect of novel hand stainless steel file vs rotary nickel titanium instruments and modified instrumentation technique on shaping of root canal space 2013
    ARTICLE FROM TH PUBLISHED IN Engineering Failure Analysis 18 (7), 1775-1783
    Correlating cutting efficiency and debris retention of endodontic files to their design features using AutoCAD measurements M Kataya, S Ibrahim, GEH Eid, I El-Mahallawi
    3. Implication of Autoclave Sterilization on Topographic Surface Changes, Cutting Efficiency and Instrument Failure of New Nickel Titanium Rotary Instruments MSD 2013
    4. Assessment of distortion and separation of new rotary ni-ti files under clinical standardized simulated a new method 2010
    5. Shaping ability . centering ability and cutting efficiency in curved root canals using s5 endo-files 2010
    6. Efficiency of nickel titanium rotary instruments in shaping curved root canals. 2006
    9. Apical third preparation of curved root canals of molars using nickel titanium and stainless steel hand file. 2004
    10. Efficiency of nickel titanium rotary instruments in shaping curved root canals.2003
    11. Effect of two new automated systems on cleanliness of root canals. An in-vitro study. 2003
    Access cavity and canal orifices location on the occlusal surface in maxillary and mandibular first molars: in vitro study 2003
    13. Digital radiographic analysis of the remaining dentin thickness in mesio-buccal roots after flaring.2003
    7. Effect of two new automated systems on cleanliness of root canals. An in-vitro study.1999
    8. Efficiency of nickel titanium rotary instruments in shaping curved root canals.1997
    I think i will benefit a lot
    good luck

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