Cleaning and

Shaping

CLEANING

Debridement

Debridement is the removal of existing or

potential irritants from the root canal system

The goal is elimination; in actual practice, there is usually only a significant reduction.

These irritants consist of the following, either

singly or in combination:

Bacteria, bacterial byproducts, necrotic tissue, organic debris, vital tissue, salivary byproducts,

hemorrhage, and other contaminants.

TechniqueIdeally, instruments contact and plane all walls to loosen debris.

The chemical action of irrigants

Further dissolves organic remnants and destroys microorganisms.

Irrigants then flush the loosened and suspended debris from the canal space. Despite a practitioner's best efforts, remnants usually persist after the most careful chemomechanical preparation of the canal .

The use of irrigating solutions is an important part of effective chemomechanical preparation.

Antibacterial agent.

Tissue solvent.

Flush debris.

Lubricant.

Eliminate the smear layer.

Irrigation

So, realistically, the objectives are :

(1)to reduce these irritants to a subsignificant level

(2)to obturate so that the remnants are sequestered within the canal.

CLEANING

LimitationsThe root canal system is a very difficult

environment in which to operate. To reemphasize an important concept, files must

contact and plane the walls to debride effectively Such contact is often impossible owing to the design and

physical properties of instruments and the irregularities of the pulp system.

SHAPING

Schilder' outlined the principles of shaping as follows:

•To develop a continuously shaped conical form from apical to coronal.

•The apical preparation should be as small as is practical and in its original position spatially.

•In addition, removal of a uniform layer of dentin in all dimensions and all regions of the canal is also

desirable.

Enlargement

The canal should be enlarged enough to permit adequate debridement as well as manipulation and control of obturating

materials and instruments, but not so much that the chances of making procedural

errors and needlessly weakening the root are increased.

Taper

Generally, taper should be sufficient to permit deep penetration of spreaders or

pluggers when obturating with gutta-percha. Excessive taper may result in

unnecessary removal of dentin and weakening of the root.

Adequate shaping basically reflects adequacy of preparation for obturation.

That is, whether the technique is lateral or vertical condensation, the canal must be

flared and enlarged to permit control and to achieve adequate depth for spreader or

plugger insertion during obturation."

To test adequacy, selected obturating instruments are "tried-in" during canal shaping.

When taper is sufficient to permit spreader penetration deep into the canal (0 to 1 mm from the apical stop) with

some space adjacent for gutta-percha, the flare is adequate With lateral condensation, the deeper the spreader penetrates during its initial insertion alongside the

guttapercha, the better the apical seal." With vertical condensation, sufficient flare is required to allow placement of pluggers within 3 to 5 mm of working

length.

Cleaning and

Shaping

Pretreatment – ensure restorability

Access for Success – remove the pulpal roof entirely,

obtain straight line access, visualize all orifices without

moving the mouth mirror, achieve axial walls with adequate

taper and access the canals.

MASTER APICAL FILE

DETERMINATION

The master apical file (MAF) is by definition the largest file that binds slightly at the

corrected working length. The MAF is determined by passively placing

successively larger files at the correct working length until a size is reached that slightly binds at the tip. This determination is made after straight-

line access .