Temperature indicating endodontic obturation material

Abstract

A gutta-percha composition for filling a tooth root canal includes a temperature indicating component, such that the user has a visual indication that the material is ready for placement in the prepared canal. The material may include a thermochromatic dye, bismuth oxide or the like, in an otherwise conventional obturation material.

Claims

1. A composition for filling a tooth root canal comprising: a gutta-percha component; a first temperature indicating component; and a second temperature indicating component; wherein said first and said second temperature indicating components provide temperature indication at at least two different temperature ranges from each other; and wherein said first temperature indicating component changes color when it reaches a temperature of from about 40 to about 50 degrees C., and said second temperature indicating component changes color when it reaches a temperature of from about 60 to about 70 degrees C.

2. A composition as in claim 1, wherein said gutta-percha component includes 1,4-polyisoprene.

3. A composition as in claim 1 wherein said thermochromic dye is present in an amount of from about 1 to about 70 percent by weight of said composition.

4. A composition as in claim 1, wherein said second temperature indicating component is bismuth oxide.

5. A composition for filling a tooth root canal comprising: a gutta-percha component, wherein said gutta-percha component includes 1,4-polyisoprene; a thermochromic dye being present in an amount of from about 1 to about 70 percent by weight of said composition; and a radiopacifier; wherein said thermochromic dye changes color when it reaches a temperature of from about 40 to about 50 degrees C. or from about 60 to about 70 degrees C.

6. A composition as in claim 1, further comprising a radiopacifier.

Description

DISCLOSURE OF THE INVENTION

(1) According to the invention, a gutta-percha composition for filling a tooth root canal includes a temperature indicating component. The component can be for example, a Leuco dye. The gutta-percha composition may include a trans 1-4, polyisoprene, wherein the temperature indicating additive is present in an amount of about 1% to about 70% by weight of the gutta-percha composition. The gutta-percha composition may also include a radiopacifier.

(2) In another embodiment of the invention, a composition for filling a tooth root canal includes two different temperature indicating ingredients which indicate different temperature ranges. The two different temperature indicating ingredients may be for example, a Leuco dye and bismuth oxide.

(3) In a further embodiment of the invention, a temperature indicating ingredient may be a wax which blooms to the surface and when warm, producing a glossy surface to the gutta-percha. Such a material may be used with a second temperature indicating ingredient such as a dye or bismuth oxide that indicates a different temperature.

PREFERRED EMBODIMENTS FOR CARRYING OUT THE INVENTION

(4) According to the present invention, an endodontic obturation material is provided that indicates the current temperature of the material by a relative color indication. The Temperature Indicating material of the invention was developed to be used with obturator devices because it was observed that clinicians often touch the gutta-percha with their finger to make sure the gutta-percha was hot and soft. The desire was to provide proof the oven or other conventional heating method or device properly heated the gutta-percha and to avoid any unnecessary contamination by foreign material or bacteria of the gutta-percha prior to inserting it into the prepared root canal.

(5) Temperature indicating gutta-percha is a unique formulation with the same physical and thermal properties of otherwise conventional obturation materials such as Thermafil gutta-percha available from DENTSPLY SIRONA of York, Pa. These gutta-percha materials have good tack and flow once the alpha phase process has been completed. The alpha phase process is a long term (8 to 12 hour) bake at elevated temperature (115 to 160 C.). Many standard gutta-percha formulations separate, even producing a brown oil at these temperatures. The remaining gutta-percha itself becomes brittle.

(6) According to the present invention, gutta-percha survives the alpha phase process without separating or producing the brown oil and the gutta-percha does not become brittle. The thermal properties of the inventive gutta-percha materials after the alpha phase process are changed. The melt flow increases dramatically (5 to >50 g/10 min at 180 C.). The change to the conventional materials includes a certain ratio of processing aids which are shown in the FORMULATION section below.

(7) Another inventive characteristic of the present materials is a temperature indicating property. The following are examples of these gutta-percha formulations.

(8) Example 1replace the majority of the radiopacifier used in a conventional gutta-percha material with bismuth oxide. Standard gutta-percha uses zinc oxide and barium sulfate to generate a radiopacity of 6 mmAl (mm of aluminum). The bismuth oxide is known to be a good radiopacifier however it is also an indicator of temperature. At low temperatures it is a mild yellow color. At elevated temperature it is a bright yellow color.

(9) Example 2replace the conventional colorant with thermochromic dyes. A red colorant is often used in standard gutta-percha to give it a standard and well-known pink color. Thermochromic dyes used in the present invention are designed to change from a color to clear at a specified temperature. They preferably fall into two temperature ranges; 40 to 50 C. and 60 to 70 C. These temperature ranges are ideal for gutta-percha obturation materials. Gutta-percha begins to melt at about 42 C. The 40 to 50 C. dye indicates the gutta-percha has melted and the 60 to 70 C. dye indicates the gutta-percha is much hotter than needed to melt.

(10) Color:

EXAMPLE 1

Bismuth Oxide

(11) TABLE-US-00001 Ingredients Weight % Trans-1,4-polyisoprene 25 Zinc Oxide 28.5 Bismuth Oxide 36 Antioxidant 1 Antiozidant 2.5 Processing Aid 1.5 White Colorant 5 Red Colorant 0.5 Total 100

EXAMPLE 2

Thermochromic Dye

(12) TABLE-US-00002 Ingredients Weight % Trans-1,4-polyisoprene 25 Zinc Oxide 51 Barium Sulfate 10 Antioxidant 1 Antiozidant 2.5 Processing Aid 1.5 White Colorant 5 TP060B Blue 2 TP047R Red 2 Total 100
Another exemplary formulation is shown below in Table 1.

(13) TABLE-US-00003 TABLE 1 Example Formulation Ingredient Weight % Trans-1,4-polyisoprene 24.2 Zinc Oxide 70.7 QCR TP047K (47C Black 4.9 Thermo) Total 100

(14) The trans-14-polyisoprene is first baked in a 130 C. oven for 7.5 hours. The baked polyisoprene was then allowed to cool for at least 24 hours. The polyisoprene was placed into a 71 C. oven for a half-hour, and then the polyisoprene was formed into a ball and placed back into the oven. After a half-hour, the polyisoprene was removed from the oven and placed onto a heated two-roll mill that was set to 60 C. The Zinc Oxide was then added to the polyisoprene on the mill a little at a time. Once all of the Zinc Oxide was incorporated, the material was cross-cut at least 5 times. The QCR TP047K (47C Black Thermo) was then added in the same way as the Zinc Oxide. Once all of it was added, the formulation was again cross-cut at least 5 times in order to fully mix in the colorant. The formulation was then pigged at least 3 times, and then removed from the mill, laid down on a flat surface covered with release liner, and allowed to cool for at least 24 hours.

(15) The material produced in Table 1 was then converted into pellets with a nominal diameter of 1 mm and 14 mm length. The pellets were then applied to carriers. This process can be used to produce finished obturators.

(16) The pellets produced in the above example can also be loaded into cartridges and used in obturation devices such as the Calamus brand obturation devices available from DENTSPLY International of York, Pa.

(17) Table 1 presents an example of the present invention. Table 2 presents several examples with a similar functionality.

(18) TABLE-US-00004 TABLE 2 Several Example Formulations Ingredient Example 1 Example 2 Example 3 Example 4 Trans-1,4- 25% 25% 25% 25% polyisoprene Zinc Oxide 70% 65% 65% Leuco Dye 47 C. 5% 5% Leuco Dye 69 C. 5% Bismuth Oxide 75% Wax 10% Total 100% 100% 100% 100%

(19) Example 1 has already been explained. Example 2 has the unique property to identify when the material is not only warm so that it is soft but also when it is too hot and may be too runny. The material is a bas color about 60 C. Between 47 and 69 C. it is the color of the Leuco Dye 69 C. And the gutta-percha is the optimum temperature with the optimum properties. As the material cools to below 47 C. the color changes to a blend of Leuco Dye 47 C. and Leuco Dye 69 C. (red and blue=purple).

(20) Example 3 has been explained that bismuth oxide will also indicate a temperature change and doubles as a radiopacifier.

(21) Example 4 indicates the gutta-percha is heated by the blooming wax melting. This would provide a glassy look to the surface.

(22) It is therefore evident that an endodontic obturation material having desirable and inventive characteristics has been provided by the present invention. The invention has been characterized herein by way of examples and discussion for exemplary purposes only.