Gutta percha

The word “gutta-percha” comes from a Malay plant name “getah perca,” which means “percha sap.” In its pure molecular structure, guttapercha is the trans isomer of polyisoprene and has approximately 60% crystalline form. Guttapercha is the predominant material used to obturate or fill the root canal space. Its physical and chemical properties such as its inertness, biocompatibility, plasticity, and easy removal (re-treatment) are responsible for its use in endodontics. Though gutta-percha has many good qualities, it exhibits a degree of tissue irritation probably related to the high content of zinc oxide.

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History

• John Tradescant (1656): Introduced gutta-percha to Europe
• Dr. William Montgomery: Surgical instruments as a substitute for rubber
• Alexander, Cabriot, and Duclos (1846): First patent for gutta-percha
• Edwin Truma (1847): Temporary filling material
• Bowman (1867): Introduced gutta-percha for obturation of root canals
• S.S. White Company (1887): First commercial manufacturer of gutta-percha points
• Callahan (1914): Chemically softened gutta-percha
• Ingle and Levine (1959): Introduction of standardized gutta-percha cones in endodontics

Application

• Obturating material
• Tracing a sinus tract
• Thermal pulp testing
• Temporary stopping in inlay cavity

Composition of Gutta-Percha points

• 18%–22% gutta-percha: Matrix
• 59%–75% zinc oxide: Filler
• 1%–4% waxes, rosins: Plasticizers
• 1%–18% metal salts: Radiopacifier

The composition of gutta-percha sticks used for thermal testing and as a temporary stopping contains bleached gutta-percha, carbonate of lime, and quartz.

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Guttapercha

Classification of Gutta percha

Depending on the phases

Gutta-percha is present in its beta phase (crystalline form) at normal room temperature. It transforms to another crystalline form alpha phase when it is heated to 42°C–44°C. When the temperature is further increased to 56°C–64°C, gamma phase (amorphous form) is formed. These forms are interchangeable, depending on the temperature of the material.

When gutta-percha is heated, it exhibits the property of plasticity or flow. The plasticity of gutta-percha is advantageous in filling canal irregularities. However, it has a drawback—the more the gutta-percha is plasticized, the greater will be the shrinkage of the filling material as it cools or returns to a solid-core state.

Depending on the mode of use

Cold gutta-percha points

These are guttapercha points in beta-phase used in lateral compaction technique. They are color coded (15—white, 20—yellow, 25—red, 30—blue, 35—green, 40—black, 45—white, 50—yellow, 55—red, 60—blue, 70—green, 80—black) and are available in different tapers (0.02%, 0.04%, 0.06%, etc.) and sizes that correspond to the specifications of particular-sized endodontic instruments.

• Chemically plasticized cold guttapercha: Gutta-percha can be chemically softened with chloroform and eucalyptol to form chloropercha and eucapercha,

respectively. Chemically softened guttapercha is no longer recommended because of its shrinkage on setting, inadequate seal, lack of control, and periapical irritation.

Thermally softened gutta-percha

• Thermoplasticized injectable guttapercha: This type of gutta-percha is supplied as pellets or cartridges, e.g., Obtura III and Elements obturating system extruder. The pellets or cartridges can be loaded in a heating gun; the extruder is positioned 3–5 mm short of the apex; the gutta-percha is squeezed gradually while withdrawing the extruder and compacted in the root canal. This type of guttapercha can flow into the lateral and accessory canals. The disadvantages are lack of control (hence not suitable for apical one-third fi lling) and shrinkage on setting.
• Thermocondensation gutta-percha: This technique involves the compaction of gutta-percha using a device with a heated plugger (System B).
• Carrier-based thermoplasticized guttapercha:

This type of gutta-percha is available in different ISO sizes and tapers, which has a central plastic carrier coated with a phase gutta-percha. These special obturating points have to be heated in a heating device before use (ThermaPrep Plus).

Depending on size

Gutta-percha is manufactured in the form of cones in both standardized and nonstandardized sizes. Gutta-percha can be custom made also.

Standardized sizes

Standardized sizes correspond with the ISO sizes 15–140 (color coded to the corresponding file size). These points are indicated in the lateral condensation technique, in which the master cone chosen corresponds to the size of the last instrument.

Nonstandardized sizes

Nonstandardized sizes are designated as extra-fine, fine, medium-fine, medium, medium-large, large, and extra-large. The sizes most commonly used are “fine,” “mediumfine,” “medium,” and “medium large.” The nonstandardized cones are much more conical and pointed. It is indicated in the warm vertical compaction technique, since their greater conicity allows better adaptation to the tapered preparation form of this technique.

Custom-made gutta-percha

Two or more gutta-percha can be heated or soaked in solvents and rolled together between two glass slabs and then inserted into the root canal to take the impression of the canal.

Modifications

Medicated gutta-percha

Gutta-percha cones containing an iodoform component called medicated gutta-percha (MGP) that helps in enhancing their antimicrobial properties have become available.

Calcium hydroxide gutta-percha points

Gutta-percha cones containing calcium hydroxide (40%–60%) were introduced to permit simple placement of the medicament in the root canal between appointments.

Calibrated gutta-percha points

These gutta-percha points have markings, which indicate the length of the gutta-percha.

Sterilization of Gutta percha

The most practical method is to disinfect the gutta-percha by immersing in a 5.25% solution of sodium hypochlorite for 1 minute; before obturation, they must be immersed in 60% ethyl alcohol to remove crystallized sodium hypochlorite.

Aging and Rejuvenation of Gutta percha

Aging results in oxidation, which transforms gutta-percha to a more crystalline form leading to its brittleness. Aged brittle cones can be made reusable by a rejuvenation treatment. The cones are immersed in hot water at 55°C for approximately 1 or 2 seconds and then immediately immersed in cold water.

Limitations

Gutta-percha is neither molecularly condensable nor compressible, but once it is softened by heat, it can be compacted against the canal walls in such a way as to eliminate and collapse any voids present in commercial gutta-percha. Guttapercha adheres to the dentinal walls to which it fits without establishing any bonds. A sealer has to be used to seal the gap between gutta-percha and the canal walls.

Advantages

1. If heated and compacted with appropriate instruments, it may assume any shape.
2. It is also readily sterilizable.
3. It is inert and has good tissue tolerance.
4. If necessary, gutta-percha can be removed easily with the help of solvents when compared to other materials such as silver cones or glass ionomer cement.

Disadvantages

1. It cannot be pushed to overcome any errors in canal preparation such as a ledge since it lacks rigidity.
2. Thermoplastic or chemically softened guttapercha shrinks on setting which can lead to microleakage.
3. It lacks adhesive qualities.

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