CANAL OBTURATION TECHNIQUES

CANAL OBTURATION TECHNIQUES:

Definition :

Sealing the root canal system involves isolating the main canal, secondary or accessory lateral canals from the rest of the body to maintain the result obtained by the root canal preparation.

Goals :
1. A watertight obturation prevents the risk of endodontic infections or reinfections due to the rise of serosity into the canal from the periapex.
2. The technical objective: consists of filling the entire endodontium as completely as possible with an obturation system capable of sealing the main and secondary canals.

The hermeticity of the seal is the only thing capable of ensuring:

Biological healing of the apex.
Prevention of periapical lesions or their recurrences.
Remote microbial swarming.
The sustainability of endodontic treatment.

Criteria to observe when closing a canal:
- A canal is considered suitable for occlusion under the following conditions:
- Tooth asymptomatic on percussion.
- No bad smell in the canal.
- No periapical sensitivity.
- A perfectly dry canal.
- Negative culture.
Root canal filling techniques:

4.1. Filling with paste alone: filling with LENTULO:

It was in 1923 that HOUSSET recommended the use of a drill mounted on a lathe and rotating in reverse to close a channel.
In 1928, LENTULO, inspired by HOUSSET, designed the “rotary dough filler” made up of a flexible spiral steel wire mounted on a mandrel and used on a contra-angle.
This instrument is called “LENTULO” and exists in different diameters and different lengths: 21, 25 and 29 mm.

fig: LENTULO dough stuffing.

The obturation technique consists of:

Choose the LENTULO according to the diameter and length of the canal.
Adjust the rotation speed: use a low speed.
Check direction of rotation: conventional direction of rotation.
Load the instrument with dough.
Insert it while stopped at the channel level up to 0.5 mm below the end of the chosen working length.
Operate the instrument and remove it while it is rotating.
Repeat the operation 2 or 3 times.
Control X-ray.

CANAL OBTURATION TECHNIQUES

4.2 The single-cone technique:

It is a technique using a root canal paste inserted using a rotating LENTULO paste pack with the addition of a gutta percha cone.
Materials:
- Pastry stuffer
- Standardized gutta percha cones.

CANAL OBTURATION TECHNIQUES

Root canal filling paste with vaseline consistency.
A channel plugger.
Technique:
- Choice of master cone: must reach the apical limit of the preparation.
- Placement of the root canal filling paste: same method as the previous technique.
- Placement of the gutta cone: using a red-hot instrument, the cone is cut at the entrance to the canal; with the plugger, axial pressure is exerted to compact the cone.
- X-ray control.
Indications: can be used regardless of the preparation technique chosen.

Advantage :
- Quick, simple technique allowing respect for canal anatomy.
Disadvantages:
- The apical seal obtained is inferior to that achieved by gutta percha condensation methods.

4.3 Root canal obturation with semi-solid materials: gutta percha.

There are several techniques:

Cold lateral condensation.
Hot vertical condensation or SCHILDER technique.
MAC SPADDEN thermomechanical or technical condensation.
Recent techniques:

4.3.1 Lateral condensation: Instrumentation used:

Gutta percha cones.
Spreaders:

CANAL OBTURATION TECHNIQUES

A pair of fine scissors.
A root canal sealing cement.

The technique:

Choosing the main cone or master cone:
Cut it 1mm from the end of the preparation.
Test the master cone in the canal:
Radiological verification of the position of the master cone.
Prepare the sealing paste on a glass plate using a spatula.
Brush the walls of the canal either using a LENTULO or a skewer coated with paste.
Coat the master cone with sealing cement and position it correctly in the canal.

Choose a Spreader, dip it in zinc oxide powder and insert next to the main cone up to the working length minus 2mm.
A vertical pushing action combined with lateral pressure is then exerted.
This action aims to move the main cone towards the apical limit and to mold it against the side wall thus creating the necessary space for the introduction of the other cones.

CANAL OBTURATION TECHNIQUES

An accessory cone coated with sealing cement is then introduced and molded with the Spreader.
The operation is repeated until the Spreader only penetrates the canal 3 or 4 mm from the canal orifice.
A final accessory cone is then inserted and the entire set of cone ends is sectioned using a red-hot instrument.

CANAL OBTURATION TECHNIQUES

4.3.2 Vertical condensation of hot perch gutta or SCHILDER technique:
it is carried out in two phases:

Downward phase:

Obturation of accessory canals over the entire canal height.

Recovery phase:

Fill the coronal 2/3 of the canal.

Sterile materials and specific materials:
– Non-standardized gutta-percha cones.

Vertical compaction crushers or pluggers.
Gutta heater or Heat carrier.
Container containing zinc oxide powder.
Sterile compresses.

fig: Schilder’s rammers.

The technique:

1. Selection of vertical rammers:

3 vertical rammers of decreasing diameter
Setting up stop on each plugger

2. Choosing and trying on the MC:

Choice of master cone.
Visual inspection: apical limit at LT -1 mm.
Touch and X-ray control.

3. Descending phase:

Drying the canal.
Brush the canal walls with sealing cement at LT –2mm.
master cone coated with sealing cement brought to LT –1 mm
Heat carier cuts the cone at the entrance of the channel.
Vertical condensation with the 1st ^rammer .
Heat carrier brought to red condenses on 2 to 3mm.
Alternating heating/compaction.
Apical plug moved to the desired apical seal 1/3 apical.
Obturation of accessory canals on the coronal 2/3

4. Ascent phase:

Fill the coronal part of the canal left empty,
Cone identical to the master cone cut into fragments of 3 to 5 mm excluding the apical part.
Preheat the gutta at the bottom of the canal.
Vertical compaction. Renewal of the operation with rammers of increasing diameter
Radiographic control: homogeneity of the obturation.

CANAL OBTURATION TECHNIQUES

4.3.3 MAC Spadden thermo-mechanical condensation technique:

Principle:

Thermomechanical condensation consists of the simultaneous introduction, thermoplasticization and compaction of gutta percha using a rotating instrument: the Mac Spadden compactor.

This instrument rotates clockwise, mounted on a contra-angle.
It has the profile of a Hedstrom H file with reverse screw pitch.
By rotating the instrument, a release of heat by friction occurs and causes a plasticization of the gutta.

Indications:

All cases where maximum condensation is desired.
When adaptation of the master cone to the apical part is impossible.
Teeth with internal resorption.

Technique:

Choose a compactor of a caliber immediately smaller than the caliber of the last instrument used for canal preparation.
Try it in the canal, making sure that it passes freely through the entire length of the preparation reduced by 1mm.
The location of this penetration length is marked on the instrument using an indelible felt-tip pen.
Choose a master cone in the same way as for the previous technique, coat its end with cement and seal it 1.5 mm from the apex.
Insert the compactor while stationary until it jams the cone against the walls to a height of 3 to 4 mm.
Operate the compactor for 1 to 2 seconds without pressure to soften the gutta percha.
To push in the material, use a gradual movement, applying a little pressure until the desired level is reached.
This apical pressure is necessary to compensate for the recoil movement caused by the plasticized gutta percha against the spirals of the instrument.
When you reach the mark on the instrument, the feeling of moving backwards develops.
At this point, leave the instrument rotating for 1 second then gradually remove it by rotating, the duration of the operation can range from 4 to 6 seconds.
Then seal the rest of the channel with a larger gauge compactor.

5. Root canal obturation: current techniques:

5.1. Microseal System:

Evolution of the Mc Spadden concept.
Combination of lateral compaction and the use of NiTi rammers and compactors → better passage of bends.

Specific materials and equipment:

Low viscosity gutta cones. Diam. 25 to 60 in 2% taper, diam. 25 in 4% taper.
Microseal low viscosity gutta cartridge.

CANAL OBTURATION TECHNIQUES

Microseal gutta warmer with Microseal cartridge syringe.

Manual or rotating Microseal spreader in NiTi, Diam 20 and 25 in 2% taper, diam 25 in 4% taper.
Microseal compactor in NiTi.

Contra-angle reducer and motor to obtain a speed of 340 rpm.
Large diameter vertical compaction crusher.

Technique:

Selection and adjustment of the master cone: tactile, visual and radio tests.
Sealing and compacting the master cone, coating the cone with sealing cement and introducing it into the canal up to the LT.
Lateral compaction of the master cone: using a manual or rotary NiTi Spreader (340 rpm).
Thermo-compaction:
- Preheating a Microseal cartridge
- Cover the NiTi condenser with a thin, uniform layer of low viscosity gutta taken from a preheated cartridge.

Insert into the space left empty by the lateral compaction up to LT – 2mm.
The rotation is initiated without exerting pressure in the apical direction.
Still rotating, the condenser will be brought back coronally after 2 seconds, resting on a canal wall.

NB: The speed and friction of the instrument cause the cone to heat up, the materials to mix and the gutta to be propelled throughout the canal system.

Remove excess.
Vertical compaction (Plugger).
Post-operative radio.

5.2. BEN JHONSON’s Thermafill System:
It is based on the use of preheated gutta percha:

Materials and equipment:

Verifier: manual instrument in NiTi with a 4% taper (diameter: from 20 to 90, its role: to gauge the diameter and the apical taper to allow the selection of the obturator.

Thermafill obturator: composed of a flexible, radiopaque plastic support coated with alpha phase gutta percha.

Thermaprep tank: allows uniform and controlled reheating of gutta percha.

Thermacut: completely smooth tungsten carbide ball end mill, allows the plastic shutter to be cut by thermomechanical reheating without risk of perforation.

CANAL OBTURATION TECHNIQUES

The technique:

The conicity of the preparation is checked using metal gauges: verifiers.
The thermafill caliber will be chosen according to the verifier caliber which generally corresponds to the diameter of the last preparation instrument used at the LT.
The LT is transferred to the “thermafill” shutter using a silicone stop.
The canal is dried and the coronal 2/3 are coated with a thin layer of sealing cement.
The thermafill is introduced into the “thermaprep” reheating tank.
The thermafill, whose gutta perche is at this stage warmed, is removed from the tank and inserted into the canal in a slow and continuous movement up to the LT.
After a short wait (2 minutes) during which the gutta percha is left to cool, the stake is cut at the entrance to the canal by the bur: “thermacut”.

Advantage :

Ease, efficiency and ergonomics.
This system meets the biological objectives of obturation by ensuring obturation of the canal system and good apical sealing.

Disadvantages:

The price of shutters and preheaters.

5.3. The system (B) or single wave centered vertical compaction technique:

Principle: Derived from the Schilder technique, the Buchanan system (B) is based on the use of a single instrument acting as a plugger and heater. This plugger is used to compact vertically and in a single downward wave, a gutta percha cone that has been previously adjusted. This downward wave results in the obturation of the canal system laterally and the creation of an apical plug. It is followed by an upward phase aimed at obturating the rest of the canal.
Technique:
- Adjusting the master cone.
- The choice of rammer: which will be used to heat and compact the gutta. The appropriate rammer is one that is able to penetrate up to 5 mm of the working length.
- Sealing and compaction: the canal is dried and the sealing cement is prepared; the cone is coated with cement and is then slowly inserted to the length to which it was previously adjusted, then it is sectioned at the canal entrance.
- The descent phase: takes place in 3 stages:

The 1st ^step : the temperature is set to 200°C, the rammer is placed in contact with the gutta, then pressure is applied to advance the rammer 4 to 5mm in the apical direction;

The switch is released and the descent is interrupted, but the pressure is maintained cold for five seconds.

The 2nd ^time : The same operation is repeated going down to the middle 1/3;

The 3rd ^step : the same operation is repeated using the same rammer up to 5mm below the apax.