ENDODONTIC INSTRUMENTATION

ENDODONTIC INSTRUMENTATION:

1. Introduction :

Endodontics is one of the dental disciplines where instrumentation is very varied and omnipresent. There is currently a very wide variety of instruments on the market, made of stainless steel or nickel-titanium, used with manual and/or mechanized techniques called assisted.

2. Endodontic instrumentation:

The material needed for endodontic treatment:

1. Instruments for preparation of the endodontic access cavity:

Rhein probe

Probe number 17

Turbine cutters: ball cutters + the Bâtt cutter.

ENDODONTIC INSTRUMENTATION

2. Materials needed for root canal preparation:

• Sterile endodontic instruments stored in a Pulpotomy box.
• Clean grip or a transfer sponge.

• Endodontic syringes or micropipettes for irrigation.

ENDODONTIC INSTRUMENTATION

• Bucket for irrigation solution.

3. Materials needed for root canal filling:

• Absorbent paper cones: for drying the canals.

• Stuff lentulo paste.

• Root canal filling paste.
• Gutta percha cones.

ENDODONTIC INSTRUMENTATION

3. Root canal preparation instrumentation: 
4. Alloys used in the manufacture of endodontic instruments:

Endodontic instruments are made either of stainless steel or of a shape memory alloy based on nickel and titanium.

1. Stainless steel alloys: stainless steels are groups of iron-based metals containing at least 10% Chromium, the presence of Chromium as an addition element allows the creation of an invisible barrier which protects the iron against most corrosion.
2. Nickel-Titanium alloys: Nickel-Titanium is part of the shape memory family, composition in %: approximately 44% titanium and 56% nickel.

• Properties of Nickel-Titanium: Ni-Ti has two important properties: shape memory and superplasticity.
  • Superplasticity: Ni-Ti allows it to return to its initial shape without undergoing any deformation (temporary deformation), unlike steel (permanent deformation).
  • Flexibility  : is the ability of a file subjected to stress (canal curvature) to deform reversibly, the elastic modulus of the alloy is 4 times lower than that of stainless steel (the NiTi instrument is 4 times more flexible than the steel instrument).

2. Manual instrumentation (steel): Manual endodontic instrumentation is the oldest technique of root canal preparation, the need for harmonization of instrumentation. This resulted in the first instrumental standardization in 1976. 
3. Profile of a manual endo instrument:

ENDODONTIC INSTRUMENTATION

It consists of:

• A handle: color code + number + symbol.
• A rod: determines the overall length of the instrument.
• An active blade: its length is fixed = 16mm.

2.  ISO standard and instrument dimensions:

• The majority of endo instrumentation meets the ISO standard, to establish this standard the International Standards Organization (ISO) worked in collaboration with the World Dental Federation and the ADA.
• They impose the metal to be used: stainless steel; but also a certain number of parameters such as dimensions , color code and a fixed conicity of 2%.
• The dimension: the length of the “rod – active blade” assembly can be 19mm, 21mm, 25mm, 27mm or even 31mm; the active blade = 16mm.
• Diameters: are displayed in hundredths of a millimeter, they vary from 6/100 mm to 140/100 mm, the diameter gives the instrument its number.
• the ISO color code:

ENDODONTIC INSTRUMENTATION

3. Main reference manual instruments:

These are mainly the K and H files and the pins

• Kerr’s K file:

• Root canal shaping instrument. 
• Twisted from a square section blank.
• Square symbol.
• The pitch of these instruments remains short so it has a large number of turns.
• Mode of action by traction or a back and forth movement. 
• The Hedstrom H file or scraper:

• Very sharp root canal shaping instrument.
• Machined from a round section blank.
• Round symbol. 
• Mode of action: by traction back and forth movement only.
• Profile: truncated cone with apical point.
• It is mainly used for canal widening after using the K file of the same number.
• The pin:

• Endodontic instrument twisted from a triangular section blank. 
• Low number of turns.
• Symbol: triangle.
• Mode of action: by rotation, a ¼ turn plus withdrawal   

ENDODONTIC INSTRUMENTATION

3. Mechanized instrumentation: Mechanized endodontic instrumentation uses motorized assistance (contra-angle), which allows the rotational movement of steel or Ni Ti instruments at variable speeds.
   1. Steel rotating instruments: 

This category of instruments is mainly represented by drills. They are intended for widening the coronal part of the canal, in order to straighten the curvatures, eliminate interferences on the instruments and thus promote instrumental access to the apical 1/3 without complications.

The most widespread forests remain the Gates Glidden Forests and the Largo Forests.

The use of drills must always remain limited to the straight portion of the canals. The risk of perforation becomes major if they are used to cross a canal curvature or for a lateral cutting action, these instruments are increasingly giving way to those in Ni Ti.

ENDODONTIC INSTRUMENTATION

Fig: Largo drills. Fig: Gates Glidden drills.

2. Continuously rotating NiTi endodontic instruments:

The use of Ni-Ti endodontic instruments in continuous rotation has undoubtedly allowed an improvement in the quality of preparations, an easier approach to complex cases, better ergonomics and fewer per- and post-operative complications. There are several reasons for this:

• the superelasticity of Ni-Ti promotes respect for the canal anatomy during preparation and helps maintain apical constriction by minimizing flaring phenomena and/or transport of the apical foramen.

• The increased conicity of the instrument allows for optimal corono-apical preparation on both mechanical (better trimming and improved evacuation of debris) and chemical (easier and deeper irrigation) levels.
• Improved coronal evacuation and reduced extrusion at the periapical level reduce the risk of peri- and postoperative complications
• the reduced number of instruments, the well-established sequences, the use of assistance (mechanization of the technique) and the speed of execution make the preparation more ergonomic and less tiring than with manual instrumentation, both for the patient and for the practitioner.

1. Precautions for clinical use:

The clinical use of Ni-Ti endodontic systems requires a number of precautions:

• the analysis of the preoperative intraoral radiograph must be as precise as possible in order to guide the clinician towards an optimal choice of instrumentation and sequence based on the difficulties to be anticipated;

• the protocol recommended by the manufacturer must be scrupulously followed. In particular, the indicated rotation speed must be kept constant throughout the preparation.

• The preparation must be carried out by a back and forth movement of low amplitude, without excessive pressure and under permanent and adequate irrigation, associating an irrigant (sodium hypochlorite).

2. Various mechanized systems:

There are many mechanized Ni-Ti root canal preparation systems, for example: profile, Hero 642, protaper, CMA…..

ENDODONTIC INSTRUMENTATION

3. Geometric characteristics:

Mechanized Ni-Ti instruments have many geometric parameters, among which the main ones are: length , diameter , conicity and section , which allow them to be characterized. 

• The classic lengths offered by manufacturers are generally 21mm, 25mm, 29mm and 31mm .
•  The diameters vary from 0.20 mm to 0.60 mm .
•  The tapers vary from one system to another, from 2% to 12% , or even up to 19% for short instruments dedicated to coronal opening. The same sequence generally has instruments with several tapers.
•  the section, it is also very variable and generally symmetrical (triangular, triple helical, pentagonal, etc.). 
• However, some systems have instruments with a non-symmetrical section. This would promote cutting efficiency, centering and debris evacuation (example: the revo S system).

4. Presentation of some instruments of the initial mechanized negotiation,  
   1. Path Files:

• The first system proposed by the company Dentsply Maillefer in 2009  
• Three square section NITI files with a taper of 0.02.
• Available in three lengths: 21mm, 25mm and 31mm. Advantage:
• Less canal deviation;
• Better centering of the instrument on the canal trajectory;
• Less apical extrusion of debris;
• Less post-operative pain.

ENDODONTIC INSTRUMENTATION

2.  Glide path systems with a single instrument:

1. The ProGlider (Dentsply-Maillefer): unique instrument in Mwire (heat treatment of the alloy (NiTi) involves an internal modification of the structure, giving it on the one hand modifications of their mechanical properties, and on the other hand a change of color). 

• Available in sterile blister pack in three lengths: 21, 25 and 31 mm with a short handle length of 11 mm;
• Unique instrument;
• Good flexibility;
• Increased fatigue resistance compared to conventional NiTi alloy;
• Good cutting efficiency;
• Features a progressive taper ranging from 2% to 8% on an 18mm active blade;
• Its cross section is square with a semi-active tip of 0.16mm diameter;

2. The R-Pilot: machined in MWire

• S-shaped section (same as Reciproc)
• Excellent cutting efficiency;
• Constant taper of 4% with a tip diameter of 0.125 mm;
• Available in lengths of 21, 25 and 31 mm;

ENDODONTIC INSTRUMENTATION

5. Presentation of some canal shaping instruments:
   1. The ProFile system (Dentsplys-Maillefer):

One of the first systems on the market, it is composed of: ProFile° OS intended for coronal opening, ProFiles° in 6% taper, in 4% taper and in 2% taper. The section of the instruments is U-shaped.

2. The HERO 642 (Micro Mēga) system: 

The instrument profile is helical, with 3 cutting angles and a large central blade. It has 9 main instruments: instruments with diameters of 20, 25 and 30, each available in 6%, 4% and 2% taper, supplemented by 2% instruments in diameters of 35, 40 and 45.

3. The Revo S (Micro Mega) system:

It is composed of a basic sequence of three instruments

 (SC1, SC2 and SU) and three apical widening instruments. The basic sequence allows an apical finish with the SU, an instrument with a diameter of 25 and a 6% taper. 

4. The ProTaper Universal system (Dentsply-Maillefer):

The complete system includes 8 instruments:

 The Shaping Files, 3 in number (SX for the relocation of the canal entrances, then S1 and S2), have an increasing variable conicity and are intended for the opening of the canal trajectory.

The five Finishing Files are intended for apical finishing and have decreasing variable tapers with a significant taper over the first 3 apical millimeters.

5. The One Shape (Micro-mega) concept: 

It is a single-instrument, single-use  root canal shaping concept used in continuous rotation.

The One Shape instrument is a NiTi instrument with an apical diameter of 25/ ^100th , a constant taper of 6%, available in three lengths: 21, 25 and 29mm. 

Conclusion :

If the advent of continuous rotation assisted preparation techniques revolutionized the practice of endodontics in the 1990s, new materials and/or future innovative technologies could maintain, or even accelerate, this favorable development and contribute to improving the image of this discipline among practitioners and patients.

ENDODONTIC INSTRUMENTATION

  Untreated cavities can reach the nerve of the tooth.
Porcelain veneers restore a bright smile.
Misaligned teeth can cause headaches.
Preventative dental care avoids costly treatments.
Baby teeth serve as a guide for permanent teeth.
Fluoride mouthwash strengthens tooth enamel.
An annual checkup helps monitor oral health.
 

ENDODONTIC INSTRUMENTATION