Gutta-Percha and heat
From: marino borrelli
Sent: Wednesday, November 12, 2008 7:18 PM
To: ROOTS
Subject: [roots] gutta-percha and heat
The guttaperca it isn't a adhesive material but it's a optimal filler.
Since Schilder proposed his heating guttaperca's technique, everyone
tried to change it but what they got it's just to make it faster, but
the problems remained the same.
One of the problems is that the guttaperca doesn't heat.
The only way to heats the guttaperca is to increase the shaper
reducing the root dentine, without thinking to the roots anatomy.
The mistake is on the technique of transmission of heat.
The contribution of heat determines the passage of gutta-percha from
the stage to a stable isometric form which is more fluid and
determines an increase in material volume, followed by a contraction
during the cooling. To obtain a valid adaptation of the material to
the canal walls, the cooling of the gutta-percha must be associated
with an efficient compact technique which allows a return to its
original configuration
The heat transfer occurs between 2 bodies at different temperature.
For example, the body A has a temperature of 100° C, the body B has a
temperature 0°C.
When the 2 bodies arriving to touch the body A transfers temperature
,like heat, to body B.
The body B increases the temperature while the body A decreases the
temperature. The transmission of heat continues until the 2 body become
the same temperature. The heat flow determines when it's arrive in heat
balance.
Is the heat transmission happens so sudden and stop sharply, the heat
balance arrive in a few time on 0°C temperature.
All the current techniques provide administration sudden heat and for
this reason that explained before, it not possible to obtain thermal
effects in the material.
Another example is when the body A has a temperature that increases
gradually infact at time 1second is 10 °C, at time 2 seconds is 20°C,
at time 3 seconds is 30°C i.e, when it arrive to touch the body B,
that has a temperature of 0°C, give heat to the body B constantly
because the body A has the greater temperature than the body B.
If the two body have different temperature the transmission of heat is
continually.
A gradual increase in heat allows the gutta-percha to take heat and to
gradually deploy along its mass.
It's better if we decease the time of work and we increase just a
little, the exposition of the material to the gradually increase of
the temperature.
In this way we will have another effect of adaption of the dentine and
the periodontal ligament to heat's increase and the creation of a
environment where all the work to obtainer the change of the material.
Until the transition phase, which accompanies heating, interests the
last apical millimetres, the heat carrier must reach the distance of 4
millimetres from the top of the root. Having placed the cone to 0.5
mm. from the working area, the heating phase of the apical third
covers a mass of gutta-percha of about 3 ½ , which obtains the
transition phase in the last 3 mm, whilst the last ½ mm undergoes
softening and a minimum increase in volume which favours the
compactation phase.
The root canals are not always straight and wide, in fact, often they
are curved and narrow. To reach the apical third, an area where the
endodontic system of the root canals is largely represented,
accessories and side canals, apical delta etc it is necessary to
adopt instruments suitable to the various morphology of the canals on
condition that does not sacrifice a large quantity of dental
substance, altering the original anatomy of the canal and exposing the
tooth element to eventual fracture, stripping, perforation, above all
in the mesial canals of mandibular and jaw molars, in the canals of
the incisors of the jaws, cases in which the quantity of dentin is
less than that present in the other root canals.
It's necessary to have a heat carrier of small dimensions and a
plugger of ductile and flexible material without shape memory which
coincides with the structural anatomy of the canal.
An instrument is in distribution( MaCo International Buccino- Italy )
which pays of heat gradually to a heat carrier of calibre 30 and
conicity 0.4 which heats from grade to grade until it reaches the
temperature required (180/190 C°).
The instrument has a temperature sensor and a setting of seconds for
the temperature required. Resting the end part of the heat carrier on
the thermocouple, we know the operating temperature in record time.
The heat carrier is a hollow metal pointed instrument which carries
inside a metal wire which, being very narrow, does not stand a sudden
change of temperature and burns interrupting the circuit, this does
not happen if the temperature increases gradually.
It can non function as a plugger because the strength of the
compactness, when suddenly bent, provokes a contact between the inside
wall and the wire, interrupting heat conduct .
In the first case it burns, in the second the sudden change of heat
doesn't reach the peak, but it is obtained where contact is made.
For an efficient compactness titanium shutters have been made,
material which is ductile and flexible, but also rigid and resistant.
Titanium shutters have be constructed with different calibre and
conicity to obtain a high level of adaptability to the various canal
anatomies and the different methods of canal preparation . These
inserts for their flexibility can easily follow the complex curves of
the canal system, reaching in any case the depths desired. The
instruments are chosen according to the criteria of dimension, calibre
and conicity dictated by the characteristics of the canal.
The quantity of heat, 180/190 C°, on the end part of the heat carrier
is regulated by the temperature device and by the thermocouple
situated on the instrument. The time to achieve the set temperature is
regulated by the seconds device, 7/8 seconds. Having placed the cone
at a distance of 0,5 mm from the working area, operating the push the
heating starts and with the heat carrier one cuts the excessive part
of the gutta-percha cone at the opening of the canal.
The disactivation of the contact produces a cooling of the tip.
Bringing the tip of the carrier to the cone at the opening of the
canal, activate the contact and start the new heating. The gradual
increase in temperature pushes the heat carrier to 4 mm from the LL
where it is detained until a signal sent off which indicates the
temperature required.
On reaching the signal and with the sound still operating one
retrieves the heat carrier which carries with it the material of the
crown third and medium third. At this point in the apical third of the
canal remains a mass of gutta-percha of 3 ½ mm, which has undergone a
transformation due to the heat carrier. The shutter, chosen previously
according to the type of preparation and the characteristics of the
root canal, is inserted and is pressed up till 2 mm from the working
area, holding it for 20 seconds in expectancy of the cooling of the
material in order to remedy the defects of contraction.
The compactness, the correct measure of the apical diameter, but above
all the plastic consistence of the gutta-percha obtained by heat
allows the injection of the material into the endodontic system of the
apical third and a correct adaptation of the material to the apical
root.
The video is on youtube
http://www.youtube.com/watch?v=8CzWcdZMeeg
MARINO BORRELLI
| 
