JPH03151313A - Curable calcium phosphate-based dental composition - Google Patents

Abstract

PURPOSE:To provide the subject curable calcium phosphate-based dental composition composed of a powder preparation prepared by blending alpha-tribasic calcium phosphate as the main component with a specified amount of calcium hydroxide, etc., and a liquid preparation mainly composed of a homopolymer of an unsaturated carboxylic acid, etc., and useful as a filling material for root canal. CONSTITUTION:A curing reaction is carried out between a powder preparation prepared by blending a powder composed of alpha-tribasic calcium phosphate as the main component with one or two or more selected from Ca(OH)2, CaO, Mg(OR)2, MgO and water-soluble fluorides in an amount of 1-15wt.% based on the total amount of the powder preparation and a liquid preparation of an aqueous water-soluble organic acid-based material mainly composed of an unsaturated carboxylic acid homopolymer or a copolymer of two or more unsaturated carboxylic acids. In the liquid preparation, the unsaturated carboxylic acid homopolymer or the copolymer of the two or more unsaturated carboxylic acids is dissolved in an amount of 10-30wt.% based on the total amount of the liquid preparation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a hardened calcium phosphate dental composition used as a root canal filling material in the field of clinical dental treatment, particularly in the field of intrafungal therapy.

BACKGROUND OF THE INVENTION Calcium phosphate compositions have excellent biocompatibility, and their use in dental and medical treatment has increased greatly in recent years.

Among these, synthetic hydroxyapatite, α-type tricalcium phosphate, β-type tricalcium phosphate, tetracalcium phosphate, and helicalcium phosphate are extremely similar to biological hard tissues, and contribute highly to biocompatibility. It is known for.

Each of these calcium phosphate compositions has different biological properties, but they are available in simple powder, granule, and
It is used as a sintered body or as a composite crystallized glass body with one or several other inorganic substances for implant-based materials such as bone restorations, cavity restorations, artificial joints, artificial bones, and artificial tooth roots. This is well known and can be said to have entered the practical stage in the oral surgery and periodontal treatment fields.

By the way, these calcium phosphate compositions have the potential to be used as root canal filling materials, lining/covering materials, cement materials, cavity repair materials, etc. in the field of dental preservation, but each field of use is different. In order to achieve the intended purpose, material performance, biological requirements, clinical practicality, etc. must be met.

Problems to be Solved by the Invention Various proposals have been made regarding the application of a calcium phosphate composition by mixing and kneading it with a hardening agent (liquid agent), and although some of them have already begun to be put into practical use, many It is also true that problems remain.

α-type tricalcium phosphate, tetracalcium phosphate, etc. have curing reactivity with polycarboxylic acid-based aqueous solutions and other organic and inorganic acid-based aqueous solutions, so they were quickly noticed and technical applications began. However, all of the following requirements [11 to [4]] have not been completely resolved.

[1] First of all, α-type tricalcium phosphate, tetracalcium phosphate, etc. are inherently bio-absorbable (bio-digr).
xd*ble) material, it often becomes a cored structure even after hardening and gradually disintegrates unless it is completely converted to hydroxyapatite through a hydration reaction or the like.

[2] Second, α-type tricalcium phosphate and tetracalcium phosphate undergo dimensional changes in the negative direction during curing by reaction with an organic acid or after becoming a cured product. In other words, the volume shrinks. This phenomenon creates a gap with living tissue, which is a major factor in causing various adverse effects after treatment.

[3] Thirdly, since the curing liquid is acidic, it goes without saying that the effect of low pH value, that is, acidity, on living tissues cannot be ignored.

[4] Fourthly, from the perspective of clinical practicality, it is difficult to provide good operability because it cannot maintain appropriate fluidity for a certain period of time (preferably 10 minutes or more) and hardens quickly. It is.

OBJECTS OF THE INVENTION The present invention takes all of these four unresolved problems into consideration and aims to provide an excellent hardened calcium phosphate dental composition, particularly for the field of gingival therapy.

Summary of the Invention The gist of the present invention is a hardened calcium phosphate dental composition as set forth in the claims.

Means for Solving the Problems When α-type tricalcium phosphate is used as the main component of a powder, various restrictions are involved in simultaneously satisfying the above-mentioned requirements [1] to [4]. When α-type tricalcium phosphate is used as the main component of a powder, mechanical strength is one of the conditions for use as a root canal filling material, for example.

Depending on the clinical case, the non-curing composition may be applied directly to the voids as shelf material filling. As a general rule, the root canal must be airtightly filled after pulp extraction.
Applications are made in combination with Gatsuta Percha points.

However, there is a possibility of re-treatment, and if it becomes necessary to remove the composition, if the strength is too high, it will have a large effect on living tissue, and the cost cannot be ignored. Therefore, it is clinically sufficient if it has the basics as a curable material. In other words, the composition must harden and not disintegrate after hardening, and physical properties such as compressive strength and hardness do not have to exceed the biostrength in the pulp cavity. .

Some of the four problems [1] to [4] pointed out earlier can generally be solved in proportion to an increase in mechanical strength. There are times when strength is required, but it is not necessary.

[Liquid] In the present invention, the curing liquid composition is a homopolymer of an unsaturated carboxylic acid or a copolymer of two or more unsaturated carboxylic acids, which is a known component widely used as a liquid for various dental cements. An aqueous solution (liquid agent) of a water-soluble organic acid based on 10 to 30% by weight.

Many of the conventionally known technologies do not place importance on the concentration of solids in the liquid, and either the concentration is not set based on clear reasons, or the concentration is set at 30% for the purpose of increasing mechanical strength.
The set value is % by weight or more.

However, at a concentration of 30% by weight or more, the viscosity of the liquid agent generally increases, the consistency (flow value) of the kneaded product decreases, and the reaction time is fast, which is unfavorable in terms of operation.

On the other hand, when the concentration is 30% by weight or less, the viscosity of the liquid agent becomes low, and although the mechanical strength is inferior, the consistency (flow value) of the kneaded product decreases.
This increases the reaction time and increases clinical practicality.

What should be noted here is that for α-type tricalcium phosphate, the reaction time becomes faster when the concentration is below a certain level, and the reaction time becomes faster when the concentration is lower than a certain level. Although it varies depending on the type of acid copolymer and its degree of polymerization, if it is less than 10% by weight, the reaction will surely start at the same time as the powder and liquid are mixed, making it impossible to obtain the operating time.

Therefore, for the purpose of satisfying the requirement to obtain this operation time, the optimum concentration is as low as possible, and moreover, near the limit concentration where no reaction occurs at the same time as mixing. In addition, 0
The reaction mechanism is completely different in the case of a mixture with water or a trace amount of organic acid or inorganic acid-added aqueous solution by weight, so the above phenomenon does not occur.

Therefore, the concentration should be 10 to 30% by weight, preferably 18 to 30% by weight.
27% by weight is suitable.

Examples of homopolymers of unsaturated carboxylic acids include acrylic acid,
Examples include fumaric acid, maleic acid, itaconic acid, etc.
It is desirable to use a copolymer of acrylic acid and one or more other types. The average degree of polymerization is not particularly specified, but it is preferable to have an average molecular weight of 1oooo or more.

Further, small amounts of water-soluble organic acids such as citric acid, malic acid, acetic acid, lactic acid, glycolic acid, tartaric acid, etc. can be added as additives for the purpose of adjusting various physical properties.

By using this liquid agent as a curing liquid, it is possible to partially improve the operation, but if the α-type tricalcium phosphate composition of the known technology is used as a powder agent, the disintegration rate and dimensional change will be lower. However, the pH characteristics are not sufficient, the mechanical strength is sometimes too high, and the requirement for an operation time of 10 minutes or more cannot yet be satisfied.

[Powder] The present invention uses one or two of calcium hydroxide, calcium oxide, magnesium hydroxide, magnesium oxide, and water-soluble fluoride in a calcium phosphate compound powder (powder) containing α-type tricalcium phosphate as a main component. By adding the above total in an amount of 1 to 15% by weight based on the total weight of the powder, a powder that satisfies the above-mentioned requirements is obtained.

In the α-type tricalcium phosphate-polycarboxylic acid composition, the disintegration rate according to the conventional technology is 4% or more, the dimensional change rate is negative, and the initial pH (within 24 hours) is 4.0-4.0%.
It is 6.0.

Since the influence of this low pH value on living tissue cannot be ignored, a method of containing a pH buffer, a basic additive, etc. is generally adopted in order to enable a prompt transition to a neutral region. Calcium compounds such as calcium hydroxide and calcium oxide are sometimes used alone as dental treatment agents, and are also preferable as sources of Ca, with Ca/
P value (Ca/P molar ratio, αTCP=1.5, HA
P=1.67) can be brought closer to the biohardened tissue, so it has high utility value as an additive. When the amount added exceeds about 4.7% by weight based on the total weight of the powder, it becomes a neutral range value.

Magnesium compounds such as magnesium hydroxide and magnesium oxide are also extremely effective as pH improvers, and their effects are superior to those of calcium hydroxide and calcium oxide. When the amount added exceeds about 3.3% by weight based on the total weight of the powder, it becomes a neutral range value. However, magnesium compounds are known to have a reaction inhibiting effect on α-type tricalcium phosphate, and have not received much attention in the past.

The present invention is characterized in that this is actively utilized to improve physical properties.

In other words, the disintegration rate, which is the other requirement for physical properties, is quite large in the conventional technology, so for example, ISO6876^ [IAS No. 5? It was impossible to satisfy the requirement of 3% or less (24 hour value to 1 week value). However, the disintegration properties of α-type tricalcium phosphate are easily controlled by the environmental pH; the lower the pH, the higher the disintegration rate (solubility). In addition, the hydrolysis reaction is also controlled by the pH range, and at pH<5゜5, Ca)IPO4-2H2
0 (DCPD), 5.5 < pH < 7.5, C
a8H2(PO4) 6”5H20(OCP), pH
>7.5, non-stoichiometric hydroxyapatite (HA P
: 3Cat[+-, (HPO4) Z(PO4)
6, (OH)2-, 2, , O-1
It is presumed that 11"o-2,1)*nHO is produced respectively. From these facts, the low pH value at the initial stage of mixing continues indefinitely. This is undesirable and disadvantageous in terms of irritation, leading to the loss of the characteristics of biocompatible ceramics.

The present invention provides α-type tricalcium phosphate with any one or two of the above magnesium hydroxide or magnesium oxide.
In order to alleviate the reaction inhibition effect caused by this addition and provide practical compressive strength, one or two of calcium hydroxide or calcium oxide is added, and the pH
This solves all of these problems at once by quickly moving the water from a neutral region to a slightly alkaline region.

Various water-soluble sodium salts such as sodium hydrogen phosphate are also effective for adjusting pH, but they do not provide good effects in terms of disintegration. In addition, some conventional technologies use zinc oxide to contribute to improving various physical properties, but in this case, zinc oxide is the main component of the hardening reaction, so calcium phosphate ceramics are simply added to the conventional cement. It becomes a composition. It is not the purpose of the present invention to add zinc oxide and to make it the main body of the curing reaction.

Calcium hydroxide or calcium oxide exhibits unique behavior in reaction with the liquid formulation of the present invention.

When used alone, it coagulates instantly and is impossible to form into a slurry, but when combined with α-type tricalcium phosphate, it is possible to avoid the phenomenon of instant coagulation. At the same time, the dimensional change rate after curing can be 0% or more. This is also a property that is not lost in compositions in which α-tricalcium phosphate is combined as a mixture with magnesium hydroxide or magnesium oxide. Therefore, in the present invention, the shrinkage of the cured product of the α-tricalcium phosphate composition, which originally has poor adhesiveness with tooth structure, which could not be solved with conventional technology, is suppressed, and the adhesive bonding property with living tissue is improved. It became possible to improve defects.

Incidentally, from the viewpoint of operability, it is necessary to maintain appropriate fluidity for more than 10 minutes, but as mentioned above, the reaction with calcium hydroxide or calcium oxide liquid is extremely fast, and it is difficult to use either alone. It condenses instantly and is impossible to use. From this point of view, adding an appropriate amount of magnesium hydroxide or magnesium oxide to α-type tricalcium phosphate as a mixture is a meaningful and effective method, but if it is left as it is, it will not work as described above in the liquid formulation section. No extension of reaction time is obtained. In other words, in the case of a powder that is a composition of a combination of α-type tricalcium phosphate, calcium hydroxide or calcium oxide, and magnesium hydroxide or magnesium oxide, a low-concentration liquid formulation is used alone as α-type tricalcium phosphate. is repeated, the reaction time becomes faster, and the necessary operation time cannot be secured.

Therefore, as a means to solve this requirement while keeping the liquid composition (concentration) unchanged, it is effective to add various fluorides for another purpose, that is, as a reaction rate retarding agent.

Fluoride is used in many dental materials for the purpose of preventing dental caries, including sodium fluoride, tin fluoride, calcium fluoride, strontium fluoride, silver diamine fluoride,
Examples include silver ammonia fluoride.

In the composition of the present invention, sodium fluoride or sodium fluorophosphate is preferable because water-soluble fluoride has a remarkable effect, and one or more of these can be used within a range that does not increase the disintegration property. Add a small amount.

[Additives and auxiliary main ingredients for powders, etc.] Although the present invention requires α-type tricalcium phosphate to be the main curing reaction for the device consisting of a powder and a liquid, other calcium phosphate ceramics, such as tetracalcium phosphate, may also be used. , calcium phosphate, β-type tricalcium phosphate, hydroxyapatite, etc. may be added as additives.

In addition, calcium phosphate ceramics with high reaction activity,
For example, an appropriate amount of tetracalcium phosphate or the like may be used as an auxiliary base ingredient.

The total amount of one or more of calcium hydroxide, calcium oxide, magnesium hydroxide, magnesium oxide, and water-soluble fluoride in these base ingredients is preferably 1 to 15% by weight based on the total weight of the powder. The composition is characterized in that it contains 5 to 10% by weight.

If it is less than 1% by weight, the effects for solving the problems [1] to [4] mentioned above cannot be obtained. If it exceeds 15% by weight, the above-mentioned various effects may be expressed too strongly or, conversely, may have undesirable effects.

Furthermore, various contrast agents such as barium sulfate, bismuth subcarbonate, calcium tungstate, iodoform, etc. may be added to provide X-ray contrast properties, which is a basic requirement for dental treatment agents. It is obvious from the known technology.

[Additives for liquid agent] The liquid agent is an aqueous solution whose main component is a homopolymer of unsaturated carboxylic acid or a copolymer of two or more unsaturated carboxylic acids, and the solid content is 10 to 30% based on the total weight of the liquid agent. % by weight. A small amount of the various water-soluble organic acids described above may be added to this liquid agent for the purpose of adjusting physical properties.

Next, the characteristics of the present invention will be explained using the following experimental examples and examples.

[Experiment example 1] Please refer to Table 1 below.

A powder was prepared by using α-type tricalcium phosphate as the main ingredient and adding one or both of calcium hydroxide and magnesium oxide at the following blending ratios.

Acrylic acid itaconic acid copolymer (average molecular weight: Mw~%
A 25% by weight aqueous solution of 000) was used as a liquid agent.

The powder and liquid were mixed at a powder/liquid ratio of P/L=1.0, and the dimensional change tendency of the cured product was determined as follows. Note that symbols C and M in Table-1.

are those in which calcium hydroxide and magnesium oxide are added alone. The symbols IC2M and 2CIM are
1=2 of calcium hydroxide and magnesium oxide respectively
and a 2:1 mixture. Measurement of dimensional change was performed according to ADAS No. 57.

As is clear from the results, it was found that there is an optimum addition range for the amount to be added in order to obtain a dimensional change of 0% or more. For example, in C of Table 1, the content is 4 to 8% by weight.

[Experiment example 2] Please refer to Table 2 below.

Mixture and hardening of α-type tricalcium phosphate, a powder containing calcium hydroxide or magnesium oxide, and the liquid used in Experimental Example 1 (P/L=1.0)
was immersed in distilled water at 37°C, and the amount of calcium hydroxide or magnesium oxide added to reach the neutral range (pH > 6.5) of the immersion solution after 24 hours was determined, and the results were as shown in Table 2. . Note that the symbol αTCP in Table 2 is a powder containing α-type tricalcium phosphate alone, C is a powder containing calcium hydroxide, and M is a powder containing magnesium oxide.

The sample surface area was 3.77 cm2/20ml HO.

As is clear from the results, it was found that magnesium oxide has an excellent pH increasing effect when added in a small amount, compared to calcium hydroxide.

On the other hand, in the case of α-type tricalcium phosphate alone, the pH is in the neutral range (
pH>6.5) is not reached.

[Experiment example 3] Please refer to Table 3 below.

Mixture and hardening of α-type tricalcium phosphate, a powder containing calcium hydroxide or magnesium oxide, and the liquid used in Experimental Example 1 (P/L=1.0)
Table 3 shows the amount of calcium hydroxide or magnesium oxide added that would cause the disintegration rate to be 3% or less (after 7 days of immersion in distilled water at 37°C).

In Table 3, the symbol αTCP is a powder containing α-type tricalcium phosphate alone, C is a powder containing calcium hydroxide, and M is a powder containing magnesium oxide. Measurement is JIS T 6
It was conducted according to 6G2.

As is clear from the results, these additives were found to be extremely effective in improving the disintegration rate.

Next, various characteristics of specific examples according to the present invention are shown in Tables 4 to 8 for Examples 1 to 5.

All liquids are acrylic acid itaconic acid copolymer (Mw 4% 0
00), and the measurement was conducted according to JIS T 6.
602. ADAS No. 57. This was done by applying ISO6876. In addition, ■ in various properties is the powder/liquid ratio P/L value (g/g).

■ is the operation margin time (room temperature, m1n).

■ is the dimensional change rate (after immersion in distilled water at 37°C for 30 days).

+: 0.1% or more, -knee 9.1% or less.

±knee 0.1% to 0.1%).

■ indicates the disintegration rate (wt% after 7 days of immersion in distilled water at 37°C).

(2) shows the results of the pH value (after immersion in distilled water at 37°C for 24 hours; sample surface area = 3.77 cm2/20m1H20).

In Examples 1 to 5 shown in Tables 4 to 8, the mixed kneaded products of powder and liquid had fluidity for 10 minutes or more after the start of kneading, and the dimensional change rate after curing was 0% or more. The disintegration rate is 3% or less, and the pH becomes neutral within 24 hours (pH=
6.5-7.5) to slightly alkaline (pH = 7.5-9
．． The reason why the fluidity transitioning to 0) is determined for 10 minutes or more is to obtain sufficient operational margin time. The reason why the dimensional change rate after curing is set to 0% or more is to prevent the cured product from shrinking and creating gaps in the filled portion. The purpose of setting the collapse rate to 3% or less is to prevent the filled cured material from collapsing and disappearing, thereby preventing loss of airtightness. The pH changes from acidic to neutral within 24 hours.
: 6.5-7.5) to slightly alkaline (pH 7.5-9.
0) to avoid the effects of low pH values on living tissues.

Effects of the Invention According to the invention of claim 1, the composition has an effect on ecology;
Alternatively, various problems in clinical application of conventional techniques can be solved. That is, the pH can be improved from an acidic range to a neutral to slightly alkaline range, and does not affect living tissues. The disintegration of the cured product of the α-type tricalcium phosphate composition can be suppressed to a slight degree, the dimensional change after curing can be made 0% or more, and the reaction rate can be delayed to obtain good operability.

According to the invention of claim 2, since the viscosity of the liquid agent is reduced,
The consistency (flow value) of the kneaded product mixed with the powder agent increases, the kneaded product becomes soft and has an appropriate consistency, and clinical practicality can be improved.

According to claim 3, the α-type tricalcium phosphate-polycarboxylic acid composition satisfies various regulations as an in-house therapy treatment material stipulated in various dental material standards, which could not be achieved using conventional techniques. becomes possible.

As is clear from the above, the present invention has achieved a truly applicable hardened calcium phosphate that simultaneously satisfies all the various requirements required as a root canal filling material in the field of dental clinical treatment and endotherapy. The company provides dental compositions based on dental materials.

Table-1 +: Dimensional change rate 0.1% that's all -0.1% below ±　d -〇、1% 0.1% Table-2 Table-4 Table-5 Table-6 Table-7 Table-8

Claims (1)

[Claims] 1. One or two of calcium hydroxide, calcium oxide, magnesium hydroxide, magnesium oxide, and water-soluble fluoride are added to the powder containing α-type tricalcium phosphate as the main component.
A powder containing a total of 1 to 15% by weight based on the total weight of the powder, and a homopolymer of an unsaturated carboxylic acid or a copolymer of two or more unsaturated carboxylic acids as the main components. It consists of a liquid agent which is an aqueous solution of a water-soluble organic acid, and is formed by a curing reaction between the powder agent and the liquid agent.
Hardened calcium phosphate dental composition. 2. The liquid agent is a homopolymer of unsaturated carboxylic acid or
The dental composition according to claim 1, which is an aqueous solution in which the copolymer of one or more unsaturated carboxylic acids is dissolved in an amount of 10 to 30% by weight based on the total weight of the solution. 3. The mixed kneaded product of powder and liquid has fluidity for 10 minutes or more after the start of kneading, has a dimensional change rate of 0% or more after hardening, has a disintegration rate of 3% or less, and has a pH of 24 from neutral (pH=6.5-7.5) to slightly alkaline (pH=
7.5 to 9.0).