JPH0244050A - hydraulic pellets - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Scope of Industrial Application] The present invention relates to a novel curable pellet. Specifically, it is a hydraulic pellet that is easy to handle and can be filled into living organisms reliably and at a high filling rate.

[Conventional technology]

Hardenable materials include bone defect filling materials, bone filling base materials, bone bonding materials, and filling materials for bonding artificial bones and joints for medical use, and luting cement, filling cement, and temporary sealing materials for dental use. There are cement, root canal filling materials, lining materials, etc. These restorative materials are required to have good compatibility with teeth and bones, and to have little harmful effect on living organisms.

Conventionally, compositions that produce hydroxyapatite (HAP), which is the main component of bones and teeth, after hardening have been proposed as such hardenable materials. For example, a mixture containing one or more powders from the group consisting of calcium hydrogen phosphate dihydrate, calcium hydrogen phosphate anhydrate, calcium hemophosphate, and tricalcium phosphate, and tetracalcium phosphate. and water are known.

[Problem that the invention seeks to solve]

However, in order to increase the reactivity of curing, each component of the above composition is pulverized and used, so the bulk density of the composition becomes small, and as a result, it is difficult to increase the filling rate at the filling site. The problem is that it becomes difficult. Also,
Since it is a fine powder, it also has the problem of extremely poor operability during filling.

In order to solve the above problem, it may be possible to knead the curable composition with a kneading liquid such as water and then fill it into the filling area, but depending on the position of the filling area, there may be problems such as dripping after filling. Currently, it is not possible to increase the packing density very much.

[Means for solving problems]

The present inventors have conducted extensive research in order to solve the problems of the above-mentioned composition using tetracalcium phosphate (hereinafter referred to as C4P). As a result, by forming the composition into pellets with a specific compressive strength or less, they are easy to handle and can be easily filled into the filling site, and moreover, they can be easily disintegrated by applying a weak pressing force after filling. It was discovered that the site can be reliably filled with a high filling rate, and the present invention was completed.

In the present invention, tetracalcium phosphate and Ca/P atomic ratio are 1.
Hydraulic pellets are made of a mixture of calcium phosphate with a Ca/P atomic ratio of 3 to 1.8, and have a compressive strength of 20 kg/cal or less.

The C4P powder used in the hydraulic composition of the present invention may be produced by any method.

For example, CaC0:+, Cab, Ca(
OH)z etc., but also P2O3, H3PO4 as P source
, NHatlzPO4, (NHt) JPO4, Ca1lPOt・2HzO, CaH containing both Ca and P
POt, Ca(HzPO4)z, Ca, P, O, etc. are considered, and there are various manufacturing methods depending on the raw materials, but γ-CazP obtained by calcining the known Ca11POs・2H20
A dry manufacturing method in which zOy is mixed and fired with CaC0 is suitable.

This reaction is: 2CaHPO,42HzO→ rCatPzOt + 51120Ca,Pz
Ot + 2CaCO:+ →Ca1P, O, +
It is shown by the reaction formula 2CO□, and if fired at 1200°C or higher and then rapidly cooled outside the furnace, or fired at 1200°C or higher in a nitrogen atmosphere,
Pure C4P without transfer to hydroxyapatite
is obtained.

Further, in the present invention, as the calcium phosphate to be mixed with the above-mentioned C4P, calcium phosphate (hereinafter abbreviated as HPCP) having a Ca/P atomic ratio of less than 1.67 is used in order to efficiently generate hydroxyapatite. As the above I P CP, for example, Ca(HzPO
4) z' 1lzO+ Ca1lPO4H211zO
, CaHPOt.

CaeHz(POt)a・5HzO,Ca*(POa,
) + CazPzOt, etc., among which C
a1PO4' 2HzO and Ca)HPO4 are particularly suitable since they can further improve the mechanical properties of the cured product. For example, as HP CP, CaHPO4・211□0
When using , the reaction formula is expressed as the following formula, and hydroxyapatite is produced.

2 Caa, PzOq + 2 Ca1lPO,, -2
HzO−”Ca+o(POa)b(011)z+2)
1zO In the present invention, the mixing ratio of the mixture of the HPCP powder and C4P dressing powder is such that the Ca/P atomic ratio is 1.3 to 1.8.
It is preferable to adjust the ratio so that hydroxyapatite is efficiently generated and the strength of the resulting cured product is increased.

The particle size of HPCP and C4P is not particularly limited, but in order to accelerate the curing speed and improve the powder-liquid ratio, HPCP has an average particle size of less than 50 μm, preferably 0.1 to 10 μm. C4P powder has an average particle size of 0.1
It is preferable to use particles each having a particle size of 100 μm, preferably 0.5 to 50 μm.

The water-cured pellets of the present invention contain the above-mentioned C4P and HPCP.
Compressive strength of 20 kg/cni or less, preferably 0. It is necessary that the pellet weighs O1 to 10 kg/-. That is, if the compressive strength of the pellet is higher than the above range, the pellet is easy to handle, but
A problem arises in that after the filling site is filled, it becomes difficult to break up the pellets with an amalgam filling device or the like to form a dense filling that adheres closely to the inner wall of the filling site.

In addition, if the above compressive strength is too low, the pellets are likely to break during handling, so 0.01 kg/
It is preferable to have a compressive strength of ca1 or more, preferably 0.05 kg/ca1 or more.

The bulk density of the pellets having the above compressive strength varies somewhat depending on the particle size of the powder constituting the curable composition, the type of HPCP, etc., but is generally 1.5 to 2.5 g/ci. This bulk density is the bulk density of the above powder before molding, which is 0.
．． This is considerably higher than 5 to 1.4 g/cal, and by filling the filling site with it and crushing it, the filling rate can be significantly higher than when filling the powder as it is.

The shape and size of the pellets of the present invention can be used without any particular limitations. In general, shapes such as spherical, cylindrical, prismatic, semi-cylindrical, etc. can be suitably used. Although the size varies depending on the area to which it is applied, a size of 1/13 to 2,000 m3, more preferably 10/3 to 1,000 m3 is suitable.

The pellets of the present invention may be manufactured by any method. For example, press molding with a metal mold, rubber press molding, molding with a tablet machine, granulator, etc. can be used.

In the above molding, since the mixture consisting of C4P and HPCP has moldability, no molding aids are particularly required.1 However, depending on the purpose, known molding aids that do not have a significant adverse effect on curing may be used. Good too. Examples of such molding aids include carboxymethyl cellulose, polyethylene glycol, glycerin, and the like.

If necessary, other components may be added to the hydraulic pellets of the present invention within a range that does not significantly adversely affect the curability. For example, in order to provide XvA contrast properties, it is preferable to add 10 to 50 parts by weight of barium sulfate, barium glass, strontium glass, zirconia, iodoform, etc. to 100 parts by weight of the hydraulic composition. Furthermore, in order to adjust the curing time and strength, hydroxyapatite, silica, calcium fluoride, titanium dioxide, calcium hydroxide, alumina, sodium phosphate, ammonium phosphate, etc. can be added.

〔effect〕

Since the hydraulic pellets of the present invention are shaped into pellets, they are easy to handle and can be easily filled into filling sites such as bone defects without being mixed with a kneading solution. Further, after filling, the pellets are easily disintegrated by simply being pressed, so that filling at a high filling rate in close contact with the filling site can be performed reliably and easily. After such filling, a high-strength hardened hydroxyapatite body is generated by reacting with moisture in body fluids. Therefore, the hydraulic Pelle-nod of the present invention can be applied to periodontal pockets and tooth extraction sockets in dental areas, where it has been difficult to achieve high filling with powders made of C4P and HP CP.
It is extremely useful as a filling material for dental root cysts, alveolar ridge elevation, etc., and as a repair material for filling sites such as bone defects in orthopedic surgery.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Ca11PO,'211zO was calcined at 500°C for 2 hours to obtain T-Ca, P2O. This powder and CaC0 powder were mixed at l:2 (molar ratio), and
After firing for a period of time, the product was allowed to cool outside the furnace to obtain C4P. This C4
P and Ca11PO4 were mixed and pulverized so that the Ca/P atomic ratio was 1.67, and then passed through a 200 mesh sieve to obtain a calcium phosphate mixed powder. Put this powder into a mold,
A cylindrical pellet of 3 msφ×4 cranes was produced by pressing at a pressure of 4 kg/cal.

The compressive strength of the above pellet was measured and was 0.8 kg/
It was cJA. Also, the bulk density of the mixed powder before molding is 0.
．． The bulk density of the pellets was 2.0 g/mm'', whereas it was 1 g/m3.

Next, this pellet was placed in a mold with a cylindrical hole with an inner diameter of 4 mm and a depth of 2 mm, and when it was pressed with an amalgam filling machine with 1 kg, it collapsed easily and the pellets stuck to the wall of the cylindrical hole. Good adhesion was achieved. The mold filled with the above pellets was left in an atmosphere of 37°C maintained at 100% humidity by a humidifier for two weeks to harden the filling, and then the cured product was removed from the mold, As a result of measuring the compressive strength, it was 310 kg/cd.

Example 2, Comparative Example 1.2 Pellets were produced in the same manner as in Example 1, except that the molding pressure of the press was changed. The physical properties of the obtained pellets were measured in the same manner as in Example 1. The results are shown in Table 1.

Example 3 Various HPCs were used instead of CaHPO4 in Example 1.
Pellets were produced in the same manner except that P was used. The physical properties of the obtained pellet 7) were measured in the same manner as in Example 1. The results are shown in Table 2.

Example 4 0.07 g of the mixed powder obtained in Example 1 was placed in a glass tube with an inner diameter of 4 mm and a length of 8 values, one end of which was placed against a metal plate, and a glass rod of the same diameter (shaped like a syringe) was used. Pressure (1kg/c
IJ) L, pellets were made. When this pellet was taken out of the glass tube and its compressive strength was measured, it was 0.12 kg.
/cJ, and the bulk density was 1.6 g/aj. Further, the physical properties of this pellet were measured in the same manner as in Example 1.

As a result, the collapse adhesion was extremely good, and the degree of pressure reinforcement after curing was 273 kg/cd.

Example 5 An adult mongrel was given general anesthesia, and a semicircular bone defect with a diameter of 4 fins and a maximum depth of 2 fins was artificially created in the femur. The bone defect was filled with the pellets of Example 4 by extrusion from a glass tube, and then crushed with an amalgam filling device and filled into the bone defect. After the surgery, X-ray observation confirmed that the bone defect was filled with sufficient adhesion. Furthermore, 1 to 3 months after the surgery, X-ray contrast increased and new bone formation was observed.

Claims (1)

[Claims] Tetracalcium phosphate and calcium phosphate having a Ca/P atomic ratio of less than 1.67 are mixed into a calcium phosphate having a Ca/P atomic ratio of 1.3 to 1.
It is made of a mixture mixed in a ratio of 8, and has a compressive strength of 2.
Hydraulic pellets with a weight of 0 kg/cm^2 or less.