Gutta-percha

المشرف العام تاريخ التسجيل : 05/09/2009

Gutta-percha.

Gutta-percha is a polymer,
mainly polyisoprene, which is extracted from a
tropical tree in Malaysia.

At room temperature it is 60 % crystalline, while the rest of the mass has an amorphous structure.

As is normal for polymers, the material is viscoelastic, which means that it has a certain elasticity, but at the same time it has the characteristics of a viscous fluid. When heated, gutta-percha is softened and deformed and it becomes liquid when the temperature
exceeds 65 °C. The material can also be
dissolved in organic solvents such as chloroform, xylene, and eucalyptol. If gutta-percha is exposed for some time to light and air, it oxidizes and becomes hard and brittle. It can be reconditioned by means of
warm water (40 °C).

Already at the beginning of the 19th century,
attempts were made to use gutta-percha in dentistry, but without success. Not until it was
learned how to alter its physical characteristics
by adding zinc oxide and other substances did
it receive real attention.
It has been in continuous use as a root canal filling material since the 1860s and is still by far the most widely used material for obturation of the root canal space.
Today, gutta-percha is available in two types of
points, standardized points and accessory points
The composition of the points may
vary from one manufacturer to the other, but
generally they contain 60–70 % zinc oxide, up to
17 % heavy metal salts, and 1–4 % waxes, resins, antioxidizing agents, etc. The actual amount of gutta-percha in the points, therefore, is only about 20 % of the total content.
The standardized gutta-percha points are
manufactured to correspond in size and shape
to the standardized root canal instruments
However, due to the nature of the material,
the manufacturing process of standardized
sizes is difficult, and diameter tolerances of
± 0.05 mm have to be accepted at the present
time. This is unfortunate, as two points of allegedly
the same size may vary in diameter as much
as 0.10 mm, which in points smaller than no. 60
may represent 3 instrument sizes. Still, even
with its present weaknesses, the standardization
of the gutta-percha points is extremely
helpful when selecting a master point to fit as
well as possible in the apical part of the root canal.
In addition to the standardized master
points with taper 0.02 mm, standardized points
with tapers 0.04 mm and 0.06 mm are also
available.

The accessory gutta-percha points
have a pointed shape
They are available in assorted sizes and are used to supplement the standardized master point to fill the coronal flared part of the root canal.
Gutta-percha points fulfill most of the requirements of a root canal filling material. An
important characteristic of the material is its favorable biological properties in that it is virtually nonirritating to contacting connective tissue. Moreover, with a sensible technique, it is
relatively easily inserted into the root canal. It
does not discolor the tooth, it provides good radiographic contrast, and it is readily removed
from the canal.

However, gutta-percha does not provide a bacteria-tight seal of the root canal Attempts
have been made to overcome this weakness
by softening the points in an organic solvent,
usually chloroform. In this manner, the
material can be molded according to the shape
of the canal to fill it completely in three dimensions.
However, the material loses its dimensional
stability when exposed to a solvent, and
when the solvent has evaporated, shrinkage will
occur. Gutta-percha will shrink if softened by
heat as well and regardless of method, the more
it is softened, the larger is its shrinking potential.

Thus, gutta-percha points should preferably not
be softened at all, but even if they are, they should always be used in combination with a second material, a root canal sealer, to obtain the necessary bacteria-tight seal of the root canal

لاتنسونا من صالح الدعاء Gutta-percha 373726