Endo 9

Endodontic mishaps or procedural accidents

are those unfortunate occurrences that happen during treatment, some owing toinattention to detail, others totally unpredictable.

If an instrument stops making progress into the root canal (i.e. if one experiences fixed or

loose resistance),

Different Reasons May Include:

• the canal lumen may be truly blocked (e.g. packed with debris or vital pulp tissue);

• flutes on the cutting part of the instrument shaft may be fully loaded;

• friction on the instrument is too high (e.g. dry conditions ,taper lock);

• root canal anatomy (e.g. narrow canals, abrupt curvatures and canals that converge or

diverge);• canal aberrations (e.g. ledges and broken instruments).

Blockage

• Eccentric or excessive root canal preparation willoften result in overpreparation of the inner wall,known as stripping.

• This is a particular problem on the distal surfaceof the coronal part of the mesial roots ofmandibular molars.

To avoid such an occurrence, shaping must be carried out withregard to the anatomy of the tooth and over enlargement must beavoided;

Stripping

A ledge may result from

• the use of excessive apical force,

• repeated insertion of the same file to a fixed level

in the root canal,

• inappropriate file movement (e.g. filing motion

with inflexible files)

• a bad shaping approach

Ledging

Root canal zipping is caused by transportation

(straightening) of the apical one-third towards the outer

aspect of the curve .

Zipping results in the destruction of the apical constriction and the creation of a relatively

large root canal exit with an irregular cross-sectional canal shape that is difficult to clean,

disinfect and obturate.

Zipping

• Perforation may occur at any time

during the shaping of the root canal

system but is more prevalent during

the access preparation and when

undertaking instrumentation in

curved canals.

• Sudden bleeding from the root canal

system is indicative of a perforation.

Perforation

• Instruments may fracture as a result of misuse or overuse.

• Before and during treatment, files should be checked prudently to ensure that the

cutting flutes are not damaged ..

Risk of instrument fracture

The objective is to create a fluid-tight seal along the length

of the root canal system, from the coronal opening to apical

termination (particularly at the apical foramen), to prevent

an ingress of tissue fluid and bacteria & subsequently egress

of irritants.

Objective of obturation (filling the root canal):

Criteria for Filling

1- Prepare the root canal in a manner that

ensures the optimum access to apical area.

2- The tooth must be asymptomatic (no pain

and tendereness).

3- The canal must be dry

4- Negative culture. This is controversial, some

say that they need –ve culture, the other say no

significance from it

Materials used to obturate the root canal

gutta-percha(19-22%),

zinc oxide(59-75%)

variouswaxes,

coloringagents,

antioxidants

metal saltsto provide

radiopacity.

(a) Standardized Cone

It’s either standardized cone or non-standardized cone

b Non-standardized Cone

1) Inert.

2) Dimensionally stable

3) Non-allergenic.

4) Antibacterial.

5) Non-staining to dentin

6) Radiopaque.

7) Compactable.

8) Softened by heat

9) Softened by organic solvents.

10) Removable from the root canal when necessary.

1.Lack rigidity.

2.Do not adhere to dentine.

3.Can be stretched.

Disadvantages:

2) Silver Points

The main disadvantages are that silver cones are round incross section, therefore they can not be used in oval crosssectioned canals,silver cones may produce corrosion products which willbe harmful to the periapical region.

made from silver.

They have the advantage of being rigid;therefore they are used in very narrow andseverely curved canals.

• It is a paste mostly made of radiopaque zinc-oxide

eugenol cement• capable of producing a seal by filling irregularities

between the gutta percha & the dentine walls.

• The sealer acts as lubricant facilitating placement of the

gutta percha cone.

• It is supplied in two pastes or liquid and powder which

are mixed to produce a thick, creamy consistency.

3) Sealer

• Points that are made of absorbent paper which are in the same standardizedsizes as the root canal instruments.

• They are used to dry to the root canal.

4) Absorbent Points