ENDODONTIC INSTRUMENTATION

INGLE & LEVINE RECOMMENDATION
1. Instruments shall be numbered from 10 to 100,
  1. the numbers to advance by 5 units to size 60, then by 10 points to size 100.
2. Each number shall be representative of the diameter of the instrument in hundredths of a millimeter at the tip.
3. • Working blade (flutes) begin at the tip designated as DO (diameter at tip) and shall extend exactly 16 mm Up the shaft, terminating at D16 (Diameter at 16mm).
4. DO is also termed as cross section diameter at the 1st rake angle of any file
5. The diameter at D16 shall be 32/100 or 0.32mm greater than that of DO.
6. This sizing ensures a constant increase in taper of 0.02mm per mm for every instrument regardless of size.
7. The tip at the angle of instrument should be 75+15°.
Hand files
1. Kfile
  1. file is manufactured from a square blank.
  2. Files are manufactured with tighter flutes,
  3. K-files have 11/2 to 21/2 cutting edges per mm of their working end
  4. The angle of flutes to long axis is about 20-40°
  5. The risk of torsional fracture is less for K-files than for reamers.
  6. These are the first instruments used to extirpate pulp.
  7. Ultra or endosonics uses K-file.
2. Hfile
  1. Hedstroem files are made from a round blank to produce spiral flutes.
  2. They show higher cutting efficiency than K-instruments, but is more prone to fracture.
  3. Hedstroem file is the endodontic instrument with maximum cutting efficiency.
  4. The angle between cutting edge and long axis of the instrument is about 60 - 65°.
    1. they are designed primarily for a linear filling motion.
  5. Due to positive rake angle, they cut in one direction only.
3. Reamer
  1. traditional reamer is manufactured from a triangular blank,
  2. reamers are manufactured with looser flutes.
  3. Triangular blanked instruments cut more effectively but are less resistant to fracture
  4. reamers are used with a pushing rotating motion (torque) whereas files are used with a rasping or pulling motion.
  5. Angle of the blade to the long axis of K-reamer is about 10-30°.
    1. these instruments are primarily designed to be used in rotary reaming motion.
4. K Flex Files
  1. Cross section is rhombus or diamond shaped.
    1. The rhomboidal blank produces alternating high and low flutes that are supposed to make the instrument
  2. more efficient in removal of debris.
  3. They have better cutting ability and flexibility than the files with square cross section.
  4. The instrument is fabricated of V-4 steel.
5. Uni files
  1. Mc-Spadden modified the traditional Hedstroem file, which were marketed as Burns unifile.
  2. The blades present a S-shape or double-helix design rather than the single helix teardrop cross-sectional shape of the hedstroem file.
  3. The unifile has two continuous cutting edges
  4. It is claimed that the unifile can be used for cutting in both a filling and a reaming action, hence, referred to as a universal instrument.
  5. Unifiles are less subject to fracture, but are less efficient. Unifiles are stiff in coronal and middle thirds, but bends in apical 1/3rd.
6. Color Coding
Ni-Ti Files
1. Composition
  1. Nickel 54%
  2. Titanium 44%
  3. Cobalt -.0.2%
    1. reduces transition temperature
  4. Borax
    1. added to improve surface hardness
2. Advances
  1. R-Phase
    1. Rhombohedral phase is intermediate phase that can form during transformation from AR- Phase
    2. Austenite
      1. On cooling
      2. Martensite
    3. Martensite
      1. On heating
      2. Austenite
    4. Ni-Ti instruments manufactured in R-phase shows high flexibility and shape memory.
      1. Eg:- Twisted files
  2. Controlled Memory Files
    1. Special thermomechanical process that control memory of Ni-Ti Extremely flexible but without shape memory
    2. The instruments does not come to its original shape in the canal or on withdrawal After autoclaving the shape reverts back to original
      1. Eg: Hyfile X CM
  3. M-wire
    1. Thermomechanical process thereby leading to increased superelasticity which decreases cyclic fatigue and instrument fracture.
    2. Eg: - Protaper Next -
    3. Profile vortex
    4. - GT series X
3. PROPERTIES
  1. At high temperatures, it exists a body centered cubic (BCC) lattice, referred to as autestentic phase, which is stable and stronger.
    1. On cooling, this phase transfers to close packed hexagonal, weak phase known as martensitic phase.
  2. Ni - Ti alloys also undergo a stress-induced martensitic transformation from austenite form.
    1. On release of stress, the structure reverts back to austenite.
  3. This transformation results in two unique features of clinical relevance.
    1. Shape memory
    2. Super elasticity
  4. • This super elastic behaviour of Ni-Ti occurs over a limited range with an optimum of 37°C.
  5. NiTi files suffer no permanent deformation when being used in curved canals, whereas steel instruments undergo permanent deformation.
  6. • The main disadvantage of Nitinol is that its cutting efficiency is only 60% than that of matching stainless steel file.
FEATURES OF ROTARY INSTRUMENTS
1. Taper
  1. Taper is described as the amount of file diameter increase per millimeter along the working surface from the tip toward the file handle.
2. HELICAL ANGLE
  1. It is the angle formed between the blade and the long axes of the instrument.
  2. Variable helical angles (HA) are important aid to moving debris up and out of the canal
3. Rake angle
  1. rake angle (RA) is the angle formed by the leading edge and the surface to be cut. The RA can be negative, neutral or positive
4. pitch
  1. Pitch is the distance between a point on the leading edge and the corresponding point on the adjacent leading edge.
5. cutting edge
  1. surface with the greatest diameter that follows the groove (where the flute and land intersect).
ISO GROUPING
1. Group I: Hand use only 1
  1. Files
    1. K-type
    2. H-type
  2. Broaches
  3. Pluggers
  4. Spreaders
2. Group - II
  1. Same as group I instruments but made to be attached to a hand piece.
3. Group - III:
  1. i) Engine driven latch type drills or reamers
    1. Gates - Glidden (G-type)
      1. USES
      2. Preparing the coronal two thirds of molars canals.
      3. Removing gutta-percha from the canal during post space preparation or during retreatment.
      4. Widen the canal when an instrument has fractured within it
    2. Peeso reamers (P-type)
      1. USES
      2. Removing gutta-percha from the canal during post space preparation or during retreatment.
    3. M-type reamers
    4. Kurer root facer
  2. ii) Rotary canal instruments
    1. Profile
    2. Light speed
    3. POW-R
    4. HERO-642
4. d) Group IV: (Root canal points)
  1. Guttapercha
  2. Silver points
  3. Paper points
Grossman's Classification
1. Exploring instruments:
  1. Smooth broaches
  2. endodontic explorer.
2. Debridement (Extirpating instruments)
  1. Eg: Barbed broaches.
3. Shaping (Enlarging) instruments.
  1. Eg. Reamers
  2. Files
4. • Obturating instruments
  1. Eg: Pluggers
  2. spreaders
  3. lentulospirals