JPH0528632B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a hydraulic calcium phosphate cement composition that can be used as a medical cement for filling bone defects and bone cavities and as a dental cement such as a tooth root canal filling material. <Prior Art> Hydraulic calcium phosphate cement compositions are useful as tooth and bone repair materials because they are converted into compounds similar to the main components of teeth and bones in living organisms through setting and hardening, and are also useful as materials for restoring teeth and bones. It is known to be useful as an adsorbent for harmful organic substances or inorganic ions in macromolecules and living organisms. Conventionally, such hydraulic calcium phosphate cement compositions have been prepared by using a combination of salts and dilute acids as a curing liquid (for example, as disclosed in Japanese Patent Application Laid-open No. 59-1989).
88351) and an acidic solution containing an unsaturated carboxylic acid polymer (for example, JP-A-60-253454). However, in such conventional hydraulic calcium phosphate cement compositions, until the hardening of the cement is completed,
The curing liquid was highly acidic and caused considerable irritation to living organisms. Furthermore, even after the cement has hardened, the pH decreases due to the elution of unreacted acids, resulting in the problem of irritation to living organisms. To solve this problem, a hydraulic calcium phosphate cement composition that hardens with water has been developed (Japanese Unexamined Patent Publication No. 37445/1983). This hydraulic calcium phosphate cement composition has an approximately neutral pH and is less irritating to living organisms. However, since the hydraulic calcium phosphate cement composition has a relatively short curing time of 10 to 30 minutes, it has the disadvantage that the curing time is too short when used as a dental root canal filling material, for example. Further, the mixing ratio of α-type tertiary calcium phosphate and dibasic calcium phosphate dihydrate in the hydraulic calcium phosphate cement composition is Ca/P
When the molar ratio is 1.200 to 1.470, and the Ca/P molar ratio is around 1.200 and 1.470, the curing time changes rapidly, so there is a drawback that it is difficult to control the curing time. <Problems to be Solved by the Invention> Therefore, an object of the present invention is to provide a water solution that cures by simply mixing with water and that can sufficiently lengthen the curing time without causing deterioration of physical properties. An object of the present invention is to provide a hard calcium phosphate cement composition. Another object of the present invention is to provide a hydraulic calcium phosphate cement composition whose curing time can be arbitrarily controlled. <Means for Solving the Problems> According to the present invention, in a cement composition containing as a main component a mixed powder of α-type tertiary calcium phosphate and dibasic calcium phosphate, the second
A hydraulic calcium phosphate cement composition is provided, wherein the calcium phosphate contains dibasic calcium phosphate anhydride. The present invention will be explained in more detail below. The cement composition used in the present invention is a composition containing as a main component a mixed powder of α-type tertiary calcium phosphate and dibasic calcium phosphate. The α-type tertiary calcium phosphate is a substance that has the property of changing into apatite and octacalcium phosphate in water and hardening, and the reaction easily proceeds in a weakly acidic range. Since calcium phosphate is a basic substance, some acidic substance may be added. Therefore, in the present invention, in order to lower the increased pH, dibasic calcium phosphate containing at least dibasic calcium phosphate anhydride (hereinafter abbreviated as DCPA) is added to α-type tribasic calcium phosphate. Here, dibasic calcium phosphate 2
Hydrate (hereinafter abbreviated as DCPD) or DCPA and α-type tertiary calcium phosphate react in water as shown in the reaction formula below, for example, to produce octacalcium phosphate and harden. 2Ca ₃ (PD ₄ ) ₂ +2CaHPO ₄・2H ₂ O＋H ₂ O→ Ca ₈ H ₂ (PO ₄ ) ₆・5H ₂ O 2Ca ₃ (PD ₄ ) ₂ +2CaHPO ₄・5H ₂ O→ Ca ₈ H ₂ (PO ₄ ) ₆・5H ₂ O In the present invention, as shown in the reaction formula, DCPA contained as an essential component requires a larger amount of water than DCPD during the hydration reaction.
Exactly the same reaction can be performed using DCPD. Therefore, even when dibasic calcium phosphate and DCPA are used, the curing time is simply extended, but the physical properties of the resulting cured product do not deteriorate. That is, the hydraulic calcium phosphate cement composition of the present invention is effective when used as a dental root canal filling material, etc., which requires a hardening time of 30 minutes or more, and moreover, the hardening time is shorter than that of DCPA. It can be arbitrarily selected depending on the amount used. The DCPA used in the present invention includes, for example, DCPD.
It is preferable to use the anhydride obtained by heating at 100 to 250°C, and it can also be used in combination with DCPD. The amount of DCPA to be used can be selected depending on the curing time, but it is preferably 10 to 100% of the total amount of dibasic calcium phosphate.
It is preferable to use it in a range of % by weight. In the present invention, the mixing ratio of the α-type tertiary calcium phosphate and the dibasic calcium phosphate is as follows:
The Ca/P molar ratio is preferably in the range of 1.20 to 1.498. If the Ca/P molar ratio is outside the above range, the hydration reaction represented by the above reaction formula will not easily occur, the curing power of the cement composition will also decrease, and the curing time will be rapidly extended. is difficult to control, which is undesirable. In the hydraulic calcium phosphate cement composition of the present invention, in addition to the above-mentioned essential components, ceramic powder or the like may be contained, as long as it does not impair biocompatibility, so that the composition has mechanical strength when cured. Furthermore, biocompatibility etc. can also be improved. Examples of the ceramic powder include hydroxyapatite, fluoroapatite, calcium phosphate compounds such as β-type tertiary calcium phosphate, tetracalcium phosphate, and calcium pyrophosphate, alumina, zirconia, silicon nitride, and silicon carbide. In this case, they can be used alone or as a mixture. Furthermore, the hydraulic calcium phosphate cement composition of the present invention may optionally contain an X-ray contrast agent, an antibacterial agent, etc., if necessary. For example, preferred X-ray contrast agents may be selected from the group consisting of barium sulfate, bismuth basic carbonate, iodoform, and mixtures thereof. Preferred antibacterial agents include iodoform and chlorhexidine. The amount of the X-ray contrast agent or antibacterial agent used is not particularly limited;
The amount is preferably 0 to 30 parts by weight per 100 parts by weight. The hydraulic calcium phosphate cement composition of the present invention can be hardened by mixing and kneading with water. Alternatively, a polymeric surfactant can be added to the water. Examples of the polymeric surfactants include synthetic polymers such as polyethylene glycol and polyvinyl alcohol, biopolymers such as methylcellulose, carboxymethylcellulose, and hydroxypropylmethylcellulose, and derivatives of these compounds. Any compound or derivative thereof can be used as long as it is not toxic. <Examples> The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Example 1 α-type tertiary calcium phosphate and dibasic calcium phosphate were used at a Ca/P molar ratio of 1.200, 1.250,
A cement composition was prepared by mixing in a ball mill so that the concentrations were 1.330, 1.450, and 1.470. The dibasic calcium phosphate includes commercially available DCPD and DCPD.
DCPA obtained by heating at 250℃ for 5 hours,
Mixing ratio 90:10, 70:30, 50:50, 30:70, 0:
100 was used for each. Next, 1 part by weight of water was mixed and kneaded with 1.5 parts by weight of the obtained cement composition, and the curing time was measured. The results are shown in Table 1. Comparative Example 1 A cement composition was prepared in the same manner as in Example 1, except that DCPA was not used as the second calcium phosphate, and the curing time was measured. Table 1 shows the results.
Shown below.

[Table] From the results in Table 1, it was found that the curing time increased as the amount of DCPA added increased, and that the curing time could be appropriately controlled by adjusting the mixing ratio with DCPA. Example 2 In order to improve the X-ray contrast properties of each hydraulic calcium phosphate cement composition prepared in Example 1, barium sulfate, basic bismuth carbonate, and iodoform (Wako Pure Chemical Industries, Ltd.) were further added to the cement composition. , 30 parts per 100 parts by weight of the composition.
Parts by weight were included. The resulting composition was then kneaded with water to form a paste, and the paste was filled into the root canal of a human tooth that had undergone pulp removal treatment. After the paste had hardened, an X-ray was taken, and it was found that
The cement filling area was clearly recognized. When the hydraulic calcium phosphate cement composition prepared in Example 1 was similarly radiographed, it was not possible to identify the location where the cement was filled. Example 3 In order to impart antibacterial properties, each hydraulic calcium phosphate cement composition prepared in Example 1 contained 30 parts by weight of iodoform based on 100 parts by weight of the composition. Next, the obtained composition was kneaded with water and formed into a cylindrical shape with a diameter of 3 mm and a height of 6 mm. Immediately after curing, the cured product after 1 day, 3 days, 7 days, and 30 days was subjected to the following tests. As a result, the cured product containing iodoform showed clear antibacterial properties and significantly inhibited the growth of all bacteria. In addition, the antibacterial activity was strongest immediately after curing and decreased over time. Antibacterial test As test bacteria, Str.faecalis, Str.salivarius,
Five types of bacteria, Staph.epidermidis, B.subtilis, and E.coli, and a mixed culture derived from infected root canals were used. The concentration of bacteria was 1.2× according to the McFarland method.
The concentration was adjusted to 10 ¹² /ml in the medium. Next, 0.1ml of the culture solution from each medium was evenly distributed into tryptone soya agar Petri dishes, dried at room temperature for 30 minutes, and then cultured under aerobic conditions at 37℃ for 48 hours to remove the cement. The bacterial growth inhibition zone to the nearest colony was measured. <Effects of the Invention> The hydraulic calcium phosphate cement composition of the present invention is a cement that hardens simply by mixing with water, and it is possible to sufficiently lengthen the hardening time without causing deterioration of physical properties. Furthermore, since the curing time can be controlled arbitrarily, it is useful as a dental root canal filling material, for example. Also, if desired, in the composition of the present invention,
Furthermore, by containing a compound selected from the group consisting of barium sulfate, basic bismuth carbonate, iodoform, and mixtures thereof, the composition improves X-ray contrast properties when cured and imparts antibacterial properties. You can also do that.

Claims (1)

[Scope of Claims] 1. A cement composition containing as a main component a mixed powder of α-type tertiary calcium phosphate and dibasic calcium phosphate, characterized in that the dibasic calcium phosphate contains dibasic calcium phosphate anhydride. A hydraulic calcium phosphate cement composition. 2. The hydraulic calcium phosphate cement composition according to claim 1, further comprising a compound selected from the group consisting of barium sulfate, basic bismuth carbonate, iodoform, and mixtures thereof.