3. Endodontic mishaps or procedural accidents
are those unfortunate occurrences that happen during treatment, some owing to
inattention to detail, others totally unpredictable.

4. 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

5. • Eccentric or excessive root canal preparation will
often result in overpreparation of the inner wall,
known as stripping.
• This is a particular problem on the distal surface
of the coronal part of the mesial roots of
mandibular molars.
To avoid such an occurrence, shaping must be carried out with
regard to the anatomy of the tooth and over enlargement must be
avoided;
Stripping

6. 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

7. 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

8. • 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

9. • 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

11. 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):

12. 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

13. Materials used to obturate the root canal
gutta-percha
(19-22%),
zinc oxide
(59-75%)
various
waxes,
coloring
agents,
antioxidants
metal salts
to provide
radiopacity.

14. (a) Standardized Cone
It’s either standardized cone or non-standardized cone
b Non-standardized Cone

15. 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.

16. 1.Lack rigidity.
2.Do not adhere to dentine.
3.Can be stretched.
Disadvantages:

17. 2) Silver Points
The main disadvantages are that silver cones are round in
cross section, therefore they can not be used in oval cross
sectioned canals,
silver cones may produce corrosion products which will
be harmful to the periapical region.
made from silver.
They have the advantage of being rigid;
therefore they are used in very narrow and
severely curved canals.

19. • 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

20. • Points that are made of absorbent paper which are in the same standardized
sizes as the root canal instruments.
• They are used to dry to the root canal.
4) Absorbent Points