JPS61218507A - Dental resin composition - Google Patents

Abstract

PURPOSE:A composition, containing specific amounts of a specified thermoplastic resin and inorganic filler material and useful for dental trays or dental base plates with enough operation time without requiring labor in operation nor sticking to fingers and the skin. CONSTITUTION:A dental resin composition obtained by incorporating a thermoplastic resin having 40-100 deg.C, preferably 50-70 deg.C melting point and >=5min half-value period of crystallization in isothermal crystallization at 25 deg.C with an inorganic filler at 10:90-10:2.5 weight ratio. Polyester capable of providing a low melting point and high crystallinity is preferred for the thermoplastic resin, and calcium carbonate, cristobalite, ultrafine particulate silicic acid anhydride, etc., are preferably used as the inorganic filler material from the viewpoint of compatibility with the resin and feeling of the composition. Since the composition is usually premolded into a sheet or horseshoe shape for use, accurate weighing, etc., is not required without sticking to fingers due to the inorganic filler.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to dental resin compositions, particularly dental resin compositions used for making dental personal trays and base plates.

(Prior Art) In dentistry, it is extremely important to take an accurate intraoral impression of a patient when making dentures. To this end, it is common practice to first make a tray that matches the patient's oral cavity, and then use this tray to take an intraoral impression. Also, in the process of actually making dentures,
Before making a complete denture with a resin base material, a wax denture is made in advance and tried on the patient to correct or confirm its suitability. However, since wax dentures are usually made of dental paraffin wax, their strength is insufficient, so a method of reinforcing them with a base plate is adopted. In order to create highly accurate dentures, a base plate that is highly compatible with the oral cavity mold and has little deformation is required. - Commonly used materials suitable for these applications include powdered acrylic resin containing a polymerization catalyst such as benzoyl peroxide, and methyl methacrylate monomer such as N,N'-dimethyl paratoluidine. There is a so-called instant polymerization resin that consists of a liquid component containing an accelerator, and the surgeon mixes the powder and liquid components at a ratio of approximately 2:1 (weight ratio) to make a plastic cake-like material. The material is stretched into a sheet, or directly pressed or rolled onto a pre-formed plaster model, and after a certain period of time, a polymerization reaction is waited for to complete the tray or base plate.

(Problem to be solved by the invention) However, when using such instantly polymerized resins, operations are complicated, as it is necessary to accurately weigh each amount and mix the powder and liquid uniformly. It is. In addition, the mixture may stick to the container or spatula, and the mixture tends to stick to the hands and fingers immediately after mixing, making it impossible for operators such as dentists or dental technicians to start work immediately. Furthermore, it is necessary to spread the mixture into a sheet or directly press or roll it onto a pre-prepared working model, and it requires considerable skill to perform this work uniformly.

It also has drawbacks such as the problem of odor from the acrylic monomer.

In view of the current situation, the present inventors conducted repeated research to obtain a dental resin composition of a type different from the type that polymerizes during work, and as a result, they blended a specific amount of inorganic filler material into a specific thermoplastic resin. It has been found that the composition is extremely suitable as a dental resin composition, particularly as a resin composition for dental trays and base plates.

(Means for solving the problem) That is, the present invention provides (A) a melting point of 40 to 100°C and a temperature of 25°C.
A thermoplastic resin having a half crystallization time of 5 minutes or more in isothermal crystallization and (B) an inorganic filler are blended,
The blending ratio of A):(B) is 10:90 to 10+2.5 (
(weight ratio).

The thermoplastic resin used in the present invention has a melting point of 40 to 10
0°C, preferably 45-80°C, particularly preferably 50-80°C
The temperature is 70°C, and the half crystallization time in isothermal crystallization at 25°C must be within 5 minutes. If the melting point is less than 40° C., the composition will have poor shape retention and may undergo thermal deformation at high temperatures such as in summer, making it unsuitable. Therefore, when used as a tray, accurate intraoral impressions cannot be taken. On the other hand, when used as a base plate, it is also unsuitable because it is deformed by the heat applied when molding dental paraffin wax into a wax denture, or its strength becomes insufficient.

If the temperature exceeds 100°C, a high temperature is required to melt the composition to a state where it can be manipulated by pressing, etc., and it is too hot for the operator to touch it with his/her hands immediately after melting. If the half-crystallization time is less than 5 minutes, even if it is softened, it will quickly become hard, and the time during which operations such as pressure welding can be performed will be too short, making it unsuitable for practical use. On the other hand, if it is too long, it is not preferred from a practical point of view, so it is desirable that the half crystallization time is 20 minutes or less. Here, the semi-crystallization temperature is a value measured using a differential scanning calorimeter (DSC, manufactured by PerkinElmer). That is, the sample in the molten state was cooled to the crystallization temperature of 25°C at a cooling rate of 160°C/min.
After cooling to a constant temperature, measure the heat of crystallization.
It is obtained by measuring the time required to obtain half the value of this heat of crystallization at 5°C.

Examples of such thermoplastic resins include polyurethane, polyester, polyamide, polyesteramide, and ethylene-
Examples include vinyl acetate copolymer, ethylene ethyl acrylate copolymer, etc., but polyesters that have a low melting point and high crystallinity are particularly preferred.

Polyesters are prepared by reaction of dicarboxylic acids and glycols. The dicarboxylic acid component includes aliphatic, alicyclic, and aromatic dicarboxylic acids having 4 to 20 carbon atoms, such as adipic acid, azelaic acid, sebacic acid, dodecandioic acid,
HOOC(C)12) I, C0OH.

Examples include cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, etc., and the glycol component has 2 carbon atoms.
~10 aliphatic or alicyclic glycols or glycols containing ether groups, such as ethylene glycol, propylene glycol, (1).

Examples include 4-butanediol, 1,6-hexanediol, cyclohexanediol, diethylene glycol, triethylene glycol, and the like.

Inorganic fillers used in the present invention include various metal oxides, various carbonates and silicates, various anhydrous silicas, such as alumina, mica, asbestos, calcium carbonate, magnesium oxide and hydroxide, magnesium carbonate, Examples include diatomaceous earth, magnesium silicate, zirconium silicate, ultrafine silicic anhydride, ultrafine anhydrous silica, cristobalite, cellulose, glass fiber, glass powder, carbon black, graphite, kaolin, molybdenum disulfide, and talc. Among these, calcium carbonate, cristobalite, ultrafine silicic anhydride, and the like are preferably used in terms of ease of mixing with the thermoplastic resin and texture of the composition. Also, two or more types of inorganic filler materials may be used in combination.

For example, light calcium carbonate and heavy calcium carbonate,
Favorable properties can be obtained when using a combination of materials with high and low bulk densities, such as in combination with cristobalite or zirconium silicate.

The blending of the thermoplastic resin (A) and the inorganic filler (B) for producing the composition of the present invention includes kneading with a heating kneader,
This may be carried out by kneading using a suitable solvent as a medium, kneading immediately after thermoplastic resin polymerization, or the like. Examples of suitable solvents include methylene chloride, chloroform, chlorinated solvents such as 1,1.14-lichloroethane, tetrahydrofuran,
Examples include dioxane, cyclohexanone, toluene, and methyl ethyl ketone.

The blending ratio of the thermoplastic resin (A) and the inorganic filler (B) (weight ratio XA):(B) needs to be 10:90 to 10:2.5. If the ratio of the inorganic filler exceeds 10:90, uneven mixing will occur, and the tray or base plate will become brittle and prone to cracking and damage. In addition, if the ratio of inorganic filler is less than 10:2.5, heat conduction will be poor, and after the tray or base plate is pressed against the plaster model, differences will occur in the cooling state of each part of the tray or base plate, resulting in crystallization. The curing time will be different, and the edges will be warped, which is undesirable. Additionally, there is a phenomenon in which it adheres to the surgeon's fingers and skin during work. The preferred blending ratio is (A):(B) is 1O; 70-10
:10, more preferably 10:60 to 10:20. With a composition having such a mixing ratio, when the composition is melted and then pressed against a plaster model, it hardens quickly after being pressed, and the edges do not warp, making it possible to form a precision tray or base plate with good compatibility. It is possible to obtain. Furthermore, there is no adhesion to fingers or skin during operation, and edge correction operations using a chisel or the like are easy to perform.

Other additives may be added to the composition of the present invention as required. Examples of additives that may be included include polyhydric alcohols, vegetable oils, mineral oils, and the like. The composition may also be colored by adding pigments or dyes, such as titanium white, red red, ultramarine blue, toluidine red, and benzimine yellow. It is also possible to blend a thermoplastic substance that changes color at a temperature near the melting point of the thermoplastic resin, so that the softening and hardening states of the composition can be determined by the change in color.

The composition of the present invention is supplied in a sheet having a suitable size, with a thickness of 0.5 to 5.0 y,z, preferably 1.5 to 3.0 y,z.

(Example) The present invention will be explained in more detail with reference to Examples.

In the examples, parts and percentages are by weight unless otherwise indicated.

Examples 1 to 4 and Comparative Examples 1 to 2 73 parts of adipic acid, 47 parts of ethylene glycol, and 0.06 parts of antimony trioxide were placed in a 3-ton flask, and esterified by heating at 245°C for 1 hour in a nitrogen stream. rear,
Polycondensation was carried out at 245°C for 4 hours under reduced pressure to 0.1 mmHg, and the intrinsic viscosity [measured at 20°C in a mixed solvent of phenol:tetrachloroethane=I:l (weight ratio)] was 0.
．． 55 thermoplastic polyester resins were obtained. DSC
(manufactured by PerkinElmer) The melting point was 53°C, and the half crystallization time at 25°C was 10 minutes. The obtained thermoplastic polyester resin and calcium carbonate as an inorganic filler were blended at various blending ratios (weight ratios) shown in Table 1j, and kneaded for 1 hour at 30°C using a twin-screw kneader. , a composition for a tray or base plate was obtained.

Table-I These compositions were melt extruded at a temperature of 150°C, and 3ypt
A sheet of tt thickness was molded. Each of these sheets is 5
When immersed in warm water at 5°C, melting of the crystalline part of the resin was observed in about 1 minute, and the entire body became soft.

The performance of these sheets as trays and base plates was evaluated and the results are shown in Table 2.

The softening time is 55% for a 20x20x3xg sample square plate.
After immersing in a constant temperature water bath at ℃, immediately place a picker needle (mass: 4509, needle diameter: 1.25 m) on the square plate, and measure the time from this point until the needle tip begins to embed in the square plate. shows.

The curing time is determined by immersing the square plate in a constant temperature water bath at 55°C for 30 seconds, then taking it out and placing the picker needle on the square plate.
It shows the time until the needle tip no longer embeds in the square plate.

Free machinability is a measure of how easy it is to carve with a carving blade.

Bending strength: 2 inches wide, 2 inches long, 1/4 thick
It was measured using a 3-point bending test method according to ASTM D-790 using an inch test piece.

Stiffness was evaluated by taking an impression using a tray and by its reproducibility.

Compatibility was evaluated by the adhesion of the edges of the tray or base plate to the plaster cast.

The softening time was 50 seconds in all six cases, which is appropriate for waiting time before starting the pressure welding operation, but the curing time was 18 minutes in Comparative Example 1, which was too long, resulting in a long waiting time before starting the next operation. Too much. For Examples 1 to 4, the time is 5 minutes to 9 minutes, which is appropriate because it closely matches the actual pressure welding operation time of about 3 minutes to 7 minutes. Others■
The overall judgment was as above, taking into consideration the qualitative tests of ~■.

Example 5 94 parts of azelaic acid, 47 parts of ethylene glycol, and 0.06 part of antimony trioxide were placed in a 3-ton flask and heated at 260°C for 1 hour in a nitrogen stream to esterify.
．． Polycondensation was carried out for 4 hours while reducing the pressure to 1xxHy to obtain a thermoplastic polyester resin with an intrinsic viscosity of 0.84. D
The melting point measured by SC (manufactured by PerkinElmer) at a heating rate of 20°C/min was 46°C, and the half crystallization time at 25°C was 12 minutes.

For 10 parts of this polyester resin, 5 parts of calcium carbonate
0 parts and 10 parts of zirconium silicate,
A composition was obtained by kneading at 120° C. for 1 hour using a shaft kneader. Using this material, the performance was evaluated in test items (1) to (4) in the same manner as in Examples 1 to 4, and it was determined that the product had good performance in all items.

Example 6 19 parts of dimethyl terephthalate, 81 parts of sebacic acid, 47 parts of ethylene glycol, and 0.06 parts of antimony trioxide were placed in a 3-tube flask and heated to 260°C for 1 hour in a nitrogen stream to esterify the mixture. Polycondensation was carried out at 280° C. for 2 hours while reducing the pressure to IyuH9 to obtain a thermoplastic polyester resin with an intrinsic viscosity of 0.63. DSC(
The melting point measured at a heating rate of 20°C/min using a PerkinElmer Co., Ltd. was 62°C, and the half-crystallization time at 25°C was 9.
It was a minute. The composition obtained by blending 10 parts of the obtained resin with 40 parts of cristobalite as a filler exhibited good performance equivalent to that obtained in Example 5.

Example 7 73 parts of adipic acid, 89 parts of 1.6-hexanediol, and 0.06 sites of antimony dioxide were polymerized in the same manner as in Example 1 to obtain a thermoplastic polyester resin having an intrinsic viscosity of 0.58.

The melting point of the obtained resin was 56°C, and the half crystallization time at 25°C was 13 minutes. A composition obtained by blending 10 parts of the obtained resin with 45 parts of zirconium silicate exhibited good performance equivalent to that obtained in Example 5.

Example 8 73 parts of adipic acid, 68 parts of 1,4-butanediol and 0.06 part of antimony trioxide were polymerized in the same manner as in Example i to obtain a thermoplastic polyester resin having an intrinsic viscosity of 0.65. The melting point of the obtained resin was 58°C.

The half-crystallization time at 25°C was 11 minutes.

10 parts of this resin, 45 parts of calcium carbonate as a filler,
The composition obtained by blending 2 parts of ultrafine silicic anhydride exhibited good performance equivalent to that obtained in Example 5.

(Effects of the Invention) The composition of the present invention is usually preformed into a sheet shape or a horseshoe shape before use, and allows the operator to accurately weigh and mix it like a conventional powder-liquid type composition or to form a mochi-shaped composition. There is no need to make something or roll it out into a sheet, which saves the user's time.

40-100°C when using the composition of the present invention
Pressure welding onto a working model can be performed simply by immersing it in hot water at a temperature of 100 mL to melt the thermoplastic resin. Furthermore, since it takes a long time to recrystallize after melting, there is plenty of time for operation, and since it contains an inorganic filler, it does not adhere to the operator's fingers or skin during operation. Therefore, the operation is extremely easy and the drawbacks of the powder-liquid type are eliminated.

Claims (1)

[Claims] 1. (A) a thermoplastic resin having a melting point of 40 to 100°C and a half crystallization time of 5 minutes or more in isothermal crystallization at 25°C and (B) an inorganic filler are blended. (A):(B
) in a ratio of 10:90 to 10:2.5 (weight ratio). 2. The dental resin composition according to claim 1, wherein the dental resin composition is a resin composition for dental trays. 3. The dental resin composition according to claim 1, wherein the dental resin composition is a resin composition for a dental base plate.