DENTAL HYDRAULIC CEMENT COMPRISING ULTRAFINE CALCIUM SILICATE PARTICLES HAVING FAST HARDENING AND SUITABLE MECHANICAL PROPERTIES

Abstract

A dental restoration material made from a dental hydraulic cement that includes ultrafine calcium silicate (UCS) particles, in the presence of a limited amount of water, so that the hydraulic cement fast hardens while providing a material having suitable mechanical properties for dental restoration, and especially a high compressive strength.

Claims

1.-14. (canceled)

15. A kit for producing a dental restoration material, said kit comprising: a first container containing a powder phase comprising: from 15% to 98% in weight of the total weight of the powder phase of ultrafine particles of calcium silicate having a d.sub.10 size ranging from 0.4 μm to 0.8 μm, a d.sub.50 size ranging from 0.7 μm to 2.9 μm and a d.sub.90 size ranging from 1.3 μm to 7 μm, wherein the d.sub.10, d.sub.50 and d.sub.90 sizes are measured by laser diffraction; from 2% to 35% in weight of the total weight of the powder phase of a radiopacifier; and optionally one or more additive selected from setting accelerators, pigments, water reducing agents, texturing agents, pH stabilizing agents, surfactants, and fillers; and a second container containing an aqueous liquid phase; and wherein the weight ratio of the powder phase present in the kit to the liquid phase present in the kit ranges from 2 to 5.

16. The kit according to claim 15, wherein the calcium silicate is selected from tricalcium silicate (C3S), dicalcium silicate (C2S) and any combinations thereof.

17. The kit according to claim 15, wherein the powder phase comprises a Portland cement and/or mineral trioxide aggregates (MTA), as ultrafine calcium silicate particles.

18. The kit according to claim 15, wherein the powder phase further comprises non-ultrafine particles of calcium silicate.

19. The kit according to claim 15, wherein the amount of ultrafine calcium silicate particles ranges from 10% to 100% by weight to the total weight of calcium silicate present in the powder phase.

20. The kit according to claim 15, wherein the radiopacifier is selected from zirconium oxide, bismuth oxide, cerium oxide, barium sulphate, calcium tungstate, titanate dioxide, ytterbium oxide and mixtures thereof.

21. The kit according to claim 15, wherein the powder phase comprises one or more additive, wherein the additive is selected from setting accelerators; and pigments.

22. The kit according to claim 15, wherein the powder phase comprises: from 20% to 60% in weight of the total weight of the powder phase of ultrafine particles of tricalcium silicate having: a specific area, measured by BET technique, ranging from 3 to 11 m.sup.2/g; a d.sub.10 size ranging from 0.4 μm to 0.8 μm; a d.sub.50 size ranging from 0.7 μm to 2.9 μm; and a d.sub.90 size ranging from 1.3 μm to 7 μm; wherein the d.sub.10, d.sub.50 and d.sub.90 sizes are measured by laser diffraction; from 0% to 50% in weight of the total weight of the powder phase of non-ultrafine particles of calcium silicate; from 2% to 35% in weight of the total weight of the powder phase of a radiopacifier; and from 0% to 25% in weight of the total weight of the powder phase of one or more setting accelerator.

23. The kit according to claim 15, wherein the aqueous liquid phase is water.

24. The kit according to claim 23, wherein the aqueous liquid phase further comprises one or more additive, wherein the additive is selected from setting accelerators and water reducing agents.

25. The kit according to claim 24, wherein the aqueous liquid phase comprises: from 60% to 85% in weight of the total weight of the aqueous liquid phase of water; from 5% to 35% in weight of the total weight of the aqueous liquid phase of setting accelerator; and from 0% to 5% in weight of the total weight of the aqueous liquid phase of water reducing agent.

26. A dental composition obtained by mixing the whole content of the first container with the whole content of the second container of the kit according to claim 15.

27. A medical device comprising the kit according to claim 15.

28. The medical device according to claim 27, wherein the medical device is an injection system.

29. The kit according to claim 19, wherein the amount of ultrafine calcium silicate particles ranges from 10% to 70% by weight to the total weight of calcium silicate present in the powder phase.

30. The kit according to claim 21, wherein the setting accelerator is selected from calcium carbonate, calcium oxide, calcium phosphate and mixture thereof.

31. The kit according to claim 21, wherein the pigment is an iron oxide.

32. The kit according to claim 25, wherein the setting accelerator is calcium chloride.

33. The kit according to claim 25, wherein the water reducing agent is a modified polycarboxylate.

34. The medical device according to claim 28, wherein the medical device is a syringe.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0398] FIG. 1 is a set of microscopy clichés showing (A) coarsely grinded C3S particles and (B) ultrafine C3S particles.

[0399] FIG. 2 is a set of histograms showing the setting time for each mixture obtained by mixing one of the powder phases comprising ultrafine C3S particles A1, A2, A5, A6, A7 or A10, or a comparative powder phase comprising micronized C3S particles C1-3, C5, C6, C7 or C10, with liquid phase B1 bis.

[0400] FIG. 3 is a set of histograms showing the setting time for each mixture obtained by mixing the powder phase comprising ultrafine C3S particles A5 or the comparative powder phase comprising micronized C3S particles C5, with liquid phases B1 bis, B4 or B4 bis.

[0401] FIG. 4 is a set of histograms showing the compressive strength for each hardened material obtained in example 6.

EXAMPLES

[0402] The present invention is further illustrated by the following examples.

Abbreviations

[0403] C3S: tricalcium silicate;

[0404] CS: calcium silicate;

[0405] g: gram(s);

[0406] MTA: mineral trioxide aggregate;

[0407] m.sup.2/g: square meter per gram;

[0408] min: minute(s);

[0409] mL: milliliter(s);

[0410] mm: millimeter(s);

[0411] μm: micrometer(s);

[0412] ratio p/l: mass ratio of the powder phase on the liquid phase;

[0413] rpm: road per minute;

[0414] UCS: ultrafine calcium silicate

[0415] UTCS: ultrafine tricalcium silicate (tricalcium silicate particles consisting of 100% of ultrafine C3S particles).

[0416] Materials and Methods

[0417] Microscopy

[0418] The morphology of calcium silicate particles such as C3S particles was observed with the Keyence® microscope before and after the grinding process. To avoid agglomerates during the analysis, the sample to be analyzed was placed on a glass slide with a drop of ethanol.

[0419] Size Distribution

[0420] The size distribution the ultrafine calcium silicate particles such as C3S particles, was determined using a Malvern® particle size analyzer based on laser diffraction particle sizing technique. A sample of the powder to be analyzed was dispersed in ethanol and sonicated to separate powder aggregates. A few drops of the suspension are then introduced in the tank of the particle sized analyzer in order to have between 2% and 10% of filling of the measuring cell. The tank is stirred at about 2000 rpm

[0421] Specific Area: BET Technique

[0422] Specific area analyzes were performed by nitrogen adsorption sorptometry with the GEMINI VII Micromeritics® apparatus. The analyzes were done with 1 g of powder. The samples were previously degassed for 3 hours at 250° C. before analysis by nitrogen adsorption.

[0423] Setting Time

[0424] Setting time measurements were performed using a Gillmore apparatus. The material to be tested is placed into molds 10 mm in diameter and 2 mm thick and then placed in a water bath at 37° C. The setting of the material is assessed using a Gillmore needle of 400 g. The material is considered as being set when the needle leaves no trace on the surface of the mold. The setting time corresponds to the period of time between the placement of the molds into the water bath and the observed setting.

[0425] Compressive Strength

[0426] Compressive strength measurements were performed using a compression bench apparatus, from MTS. The cement is slowly introduced into a mold 6 mm high/4 mm in diameter, checking that there are no bubbles. The molds are placed in the water bath at 37° C. for 15 min. The samples are then demolded and placed in a test tube containing purified water and left in the water bath for 24 hours. After 24 h the samples are polished on each side and compressed using a MTS compression bench applying a force of 10 kN.

Part I: Preparation of Ultrafine Tricalcium Silicate Particles

[0427] Particles of C3S having a coarse particle size were grinded in order to obtain ultrafine C3S particles having the following characteristics: [0428] a specific area ranging from 3 to 11 m.sup.2/g; [0429] a d.sub.10 size ranging from 0.4 μm to 0.82 μm, preferably 0.4 μm to 0.8 μm; [0430] a d.sub.50 size ranging from 0.8 μm to 2.1 μm; [0431] a d.sub.90 size ranging from 1.4 μm to 7.0 μm.

[0432] Depending on the apparatus, distinct processes are carried out that are exemplified, but are not limited, herein below.

Example 1: Process for Manufacturing Ultrafine Tricalcium Silicate (UTCS) Particles by Mechanical Grinding

[0433] The preparation of UTCS particles has been implemented via the general procedure herein below, with the apparatus EMAX® of RETSCH.

[0434] Material

[0435] The crushed C3S particles used in the examples below were obtained by crushing crude C3S with a Retch crusher. The coarsely grinded C3S particles used in the examples below were obtained by further crushing the crushed C3S particles with a grinding roller (Crusher Faure)

[0436] General Procedure

[0437] In a first step, crushed or coarsely grinded C3S particles mixed with isopropanol, are added in the grinding chamber of the apparatus. Then, grinding beads are added to the previous mixture. In the process of the invention, grinding beads may be for example, zirconium oxide beads with a diameter ranging from 0.4 mm to 0.8 mm. Secondly, grinding is carried out for 20 to 30 min. According to the present invention, grinding may be carried out on a longer time period until achieving ultrafine particles having particle sizes as defined above. Finally, the grinded mixture is dried and isopropanol is removed. After being sifted, ultrafine powder of C3S particles is obtained.

[0438] Whatever the apparatus used, the process of the invention requires that grind beads and grinding chamber are not made of stainless steel. Preferably, the process comprises the use of grind beads and grinding chamber made of and/or coated with zirconium oxide, tungsten carbide and/or silicon carbide.

[0439] Example 1a: The general procedure was carried out with 45 g of coarsely grinded C3S particles, 30 mL of isopropanol and 90 g of grinding beads. Grinding with the apparatus EMAX® was carried out with a grinding rate of about 1900 rpm for 20 min. Drying was implemented at about 50° C.

Part II: Characterization of Ultrafine C3S Particles

Example 2: Characterization of Ultrafine C3S (UTCS) Particles Obtained in Example 1a

[0440] Microscopy

[0441] The final powder of C3S particles after being ultra-finely grinded according to the process as described in example 1a, has been compared by optical microscopy with magnificence to initial C3S particles (coarsely grinded C3S).

[0442] FIG. 1 features the significant decreases of particles size for ultrafine C3S particles.

[0443] Particle Size

[0444] The size distribution of C3S particles after being ultra-finely grinded according to the process as described in example 1a, has been compared to those of micronized C3S particles, coarsely grinded C3S particles and crushed C3S particles (Table 1).

TABLE-US-00001 TABLE 1 features the d.sub.10, d.sub.50 and d.sub.90 sizes for each kind of C3S particles: C3S Sample d.sub.10 (μm) d.sub.50 (μm) d.sub.90 (μm) Crushed 2.0 17.0 330 Coarsely grinded 2.1 9.8 28.0 Micronized 0.8 3.4 7.2 Ultrafine batch 1 0.6 1.5-2.1 1.4-6 Ultrafine batch 2 0.534 0.85 1.75 Ultrafine batch 3 0.535 0.853 1.58 Ultrafine batch 4 0.504 0.795 1.50 Ultrafine batch 5 0.534 0.85 1.75 Ultrafine batch 6 0.536 0.858 1.66 Ultrafine batch 7 0.568 0.857 1.51 Ultrafine batch 8 0.626 1.03 2.02 Ultrafine batch 9 0.564 0.893 1.63 Ultrafine batch 10 0.61 0.993 1.95

[0445] The results show that the process of the invention strongly decreases the size distribution of the particles. Especially, ultrafine C3S particles have d.sub.10, d.sub.50 and d.sub.90 sizes over than crushed, coarsely grinded and micronized C3S particles.

[0446] Specific surface S.sub.spé.

[0447] The specific surface of C3S particles after being ultra-finely grinded according to the process as described in example 1a, has been compared to those of micronized C3S particles and coarsely grinded C3S particles (Table 2). The specific surface has been measured by the BET technique as described above.

TABLE-US-00002 TABLE 2 features the specific surfaces for each kind of C3S particles: C3S Sample S.sub.sp{acute over (.sub.e)}. (m.sup.2/g) Crushed  0.5 ± 0.01 Coarsely grinded 0.78 ± 0.03 Micronized 1.56 ± 0.03 Ultrafine batch 1 5.17-8.72 ± 0.06     Ultrafine batch 7 10.2 Ultrafine batch 8 7.2 Ultrafine batch 9 9.1 Ultrafine batch 10 6.5

[0448] The results show that the specific surface of ultrafine C3S particles is higher than those of coarsely grinded and micronized C3S particles.

Part III: Compositions of the Invention

Example 3: Preparation of Dental Compositions with Different Calcium Silicate Particles Sizes

[0449] Powder phases A according to the invention and comparative powder phases C (i.e. not comprising ultrafine calcium silicate particles), having the compositions presented in Table 3, were prepared by mixing the powder components.

[0450] Liquid phases B according to the invention having the compositions presented in Table 4, were prepared by mixing the components with water.

[0451] Then, mixed compositions were prepared by mixing a powder phase A with a liquid phase B in a ratio powder phase/liquid phase (w/w) ranging from 1.5 to 6.

TABLE-US-00003 TABLE 3 Powder phases A and comparative powder phases C Amount (% w/w) Category Component C1-3 A1 A2 A3 Calcium Ultrafine C3S 80.7 40.35 24.2 silicate Micronized C3S 80.7 compounds Coarsely grinded C3S 40.35 Crushed C3S 56.5 Total amount of CS mixture 80.7 80.7 80.7 80.7 Setting Calcium carbonate 14 14 14 14 accelerators Calcium oxide 0.25 0.25 0.25 0.25 Calcium phosphate Radiopacifiers Zirconium oxide 5 5 5 5 Bismuth oxide Cerium oxide Pigments Iron oxides 0.05 0.05 0.05 0.05 Amount (% w/w) Category Component C5 C6 A4 A5 A6 Calcium Ultrafine C3S 65 32.5 19.5 silicate Micronized C3S 65 65 compounds Coarsely grinded C3S 32.5 Crushed C3S 45.5 Total amount of CS mixture 65 65 65 65 65 Setting Calcium carbonate 14 14 14 14 14 accelerators Calcium oxide Calcium phosphate Radiopacifiers Zirconium oxide 20 6 16 20 6 Bismuth oxide 6 6 Cerium oxide 6 6 Pigments Iron oxides 1 3 5 1 3 Amount (% w/w) Category Component C7 A7 A7bis A8 A9 Calcium Ultrafine C3S 50 50.67 27.5 17.4 silicate Micronized C3S 50 compounds Coarsely grinded C3S 27.5 Crushed C3S 40.6 Total amount of CS mixture 50 50 50.67 55 58 Setting Calcium carbonate 14 14 14 10 14 accelerators Calcium oxide 3 3 0.25 3 6 Calcium phosphate 3 3 5 Radiopacifiers Zirconium oxide 5 5 35 5 5 Bismuth oxide 10 10 7 Cerium oxide 8 5 Pigments Iron oxides 15 15 0.08 14 5 Amount (% w/w) Category Component C10 A10 A11 A12 Calcium Ultrafine C3S 91 46 27.9 silicate Micronized C3S 91 compounds Coarsely grinded C3S 46 Crushed C3S 65.1 Total amount of CS mixture 91 91 92 93 Setting Calcium carbonate 9 9 8 7 accelerators Calcium oxide Calcium phosphate Radiopacifiers Zirconium oxide Bismuth oxide Cerium oxide Pigments Iron oxides Amount (% w/w) Category Component A13 A14 A15 A16 Calcium Ultrafine C3S 40 32.5 29.5 47.5 silicate Ultrafine C2S 40 32.5 29.5 47.5 compounds Micronized C2S Total amount of CS mixture 80 65 59 95 Setting Calcium carbonate 14 20 14 accelerators Calcium oxide 0.25 2 Calcium phosphate 3 Radiopacifiers Zirconium oxide 5 10 5 Bismuth oxide 3 5 Cerium oxide 9 Pigments Iron oxides 0.75 5 5 Amount (% w/w) Category Component A17 A18 A19 A20 Calcium Ultrafine C3S 40 32.5 29.5 47 silicate Ultrafine C2S compounds Micronized C2S 40 32.5 29.5 47 Total amount of CS mixture 80 65 59 94 Setting Calcium carbonate 14 9 14 6 accelerators Calcium oxide 0.25 5 Calcium phosphate 1 Radiopacifiers Zirconium oxide 5 25 5 Bismuth oxide 8 Cerium oxide 3 Pigments Iron oxides 0.75 1 5 Amount (% w/w) Category Component A21 A22 A21 A24 Calcium Ultrafine C3S 40 32.5 25 47.5 silicate Portland cement 40 32.5 25 47.5 compounds MTA Total amount of CS mixture 80 65 50 95 Setting Calcium carbonate 14 14 14 accelerators Calcium oxide 0.25 3 Calcium phosphate 3 Radiopacifiers Zirconium oxide 5 6 5 Bismuth oxide 6 10 5 Cerium oxide 6 Pigments Iron oxides 0.75 3 15 Amount (% w/w) Category Component A25 A26 A27 A28 Calcium Ultrafine C3S 40 32.5 25 47.5 silicate Portland cement compounds MTA 40 32.5 25 47.5 Total amount of CS mixture 80 65 50 95 Setting Calcium carbonate 14 14 14 accelerators Calcium oxide 0.25 3 Calcium phosphate 3 Radiopacifiers Zirconium oxide 5 16 5 Bismuth oxide 10 5 Cerium oxide Pigments Iron oxides 0.75 5 15

TABLE-US-00004 TABLE 4 Liquid phases B Amount (% w/w) Category Component B1 B1bis B2 B3 B4 B4bis B5 Aqueous Water 85 69 42.5 37.5 60 60 45.5 liquid Non- Ethylene glycol 42.5 19.5 aqueous Polyethylene glycol 37.5 15 liquids (M = 4000 g/mol) Polyethylene glycol 15 (M = 300 g/mol) Total aqueous + non-aqueous liquid 85 69 85 75 75 75 65 Setting Calcium chloride 15 29 10 8 20 20 accelerator Water Glenium 5 reducing Polynaphtalenesulfonate 5 agents Modified 2 12 5 5 35 polycarboxylate

Part IV: Properties of the Compositions of the Invention

Example 4: Comparison of the Setting Time of Dental Compositions Comprising Ultrafine C3S Particles with Composition Comprising Non-Ultrafine C3S Particles

[0452] This experiment aims to evaluate the improvement in terms of setting time of self-hardening dental compositions comprising ultrafine C3S particles, while keeping good handling properties such as appearance and working time, compared to compositions devoid of ultrafine C3S particles but comprising instead micronized C3S particles.

[0453] Several compositions according to the invention have been prepared by mixing one of the powder phase A1, A2, A5, A6, A7 or A10 as described in Table 3, with one of the liquid phase B1 bis, B4 or B4 bis as described in Table 4.

[0454] For comparison, compositions equivalent to above composition but comprising only micronized C3S particles were prepared by mixing one of the powder phases C1-3, C5, C6, C7 or C10 as described in Table 3, with one of the liquid phase B1 bis, B4 or B4 bis as described in Table 4.

[0455] Ratio p/l

[0456] First, experiments have been carried out for determining suitable mass ratios of the powder phase to the liquid phase (ratio p/l) for each of the compositions, in order to provide a homogenous creamy appearance when mixing the powder phase with the liquid phase. Especially, various proportions of powder phase and liquid phase were tested until the expected creamy appearance is obtained.

[0457] The ratio reported in Table 5 were determined as being suitable to provide expected appearance and workability to the composition.

TABLE-US-00005 TABLE 5 Mass ratios (powder phase/liquid phase) B1 bis B4 B4 bis C1-3 3.4 ND ND A1 2.7 ND ND A2 3.9 ND ND C5 3.4 4.6 5.1 A5 3.3 3.7 4.1 C6 3.4 4.6 5.3 A6 3.3 ND ND C7 2.8 4.2 5.1 A7 1.9 ND ND C10 3.2 4.1 ND A10 2.3 ND ND ND: not determined

[0458] Therefore, the adaptation of the ratio p/l enables to provide a suitable texture, and depends on the compositions of the powder and liquid phases used for the mixture.

[0459] Setting Time

[0460] The setting time of the compositions obtained by mixing powder phases A and liquid phases B in above determined ratios was measured. Results are provided in Table 6 and also represented in FIGS. 2 and 3.

TABLE-US-00006 TABLE 6 Setting times (min) B1 bis B4 B4 bis C1-3 12.0 ND ND A1 5.1 ND ND A2 4.4 ND ND C5 16.5 14.7 16.7 A5 5.8 7.1 6.9 C6 16.9 16.3 19.0 A6 9.4 ND ND C7 20.6 14.5 11.5 A7 10.6 ND ND C10 16.7 17.2 ND A10 7.3 ND ND ND: not determined

[0461] As evidence with above results and as clearly represented in FIGS. 2 and 3, the use of the ultrafine calcium silicate particles of the invention enable to significantly reduce the setting time of the compositions, compared to the use of micronized calcium silicate particles only.

[0462] Especially, it is shown in FIG. 2 that the use of the liquid phase B1 bis with the various powder phases of the invention (A1, A2, A5, A6, A7 and A10) compared with their equivalent phases comprising only micronized calcium silicate particles (C1-3, C5, C6, C7, and C10) enables to reduce the setting time by at least 44% (A6 vs C6) up to 65% (A5 vs C5), with a mean of about 56% for these compositions.

[0463] In FIG. 3, it is evidenced that whatever the liquid phase that is used (B1 bis, B4 or B4bis), the reduction of the setting time can be obtained by using a powder phase of the invention (A5) compared with the equivalent phase comprising only micronized calcium silicate particles (C5).

Compressive Strength

Example 5: Comparison of the Compressive Strength of Dental Compositions Comprising Ultrafine C3S Particles with Composition Comprising Non-Ultrafine C3S Particles

[0464] This experiment aims to evaluate the retention of compressive of self-hardening dental compositions comprising ultrafine C3S particles, compared to compositions devoid of ultrafine C3S particles but comprising instead micronized C3S particles.

[0465] Several compositions were prepared by mixing powder phase A2 or A7bis as described in Table 3, with liquid phase B1 bis as described in Table 4. Powder phase C1-3 comprising micronized C3S particles instead of ultrafine C3S particles was used for comparison.

[0466] Different batches of C3S particles were used for the ultrafine C3S particles. The size distributions of the C3S particles used in the compositions of this example are detailed in Table 7.

TABLE-US-00007 TABLE 7 d.sub.10, d.sub.50 and d.sub.90 sizes for the batches of C3S particles used in this example: C3S Sample d.sub.10 (μm) d.sub.50 (μm) d.sub.90 (μm) Coarsely grinded 2.4 9.3 25 Micronized 0.8 3.4 7.2 Ultrafine U1 0.5 1.04 2.05 Ultrafine U2 0.72 1.29 2.47 Ultrafine U3 0.76 1.50 3.12 Ultrafine U4 0.82 1.93 4.55

[0467] The compressive strength of the hardened material was measured and results are reported in Table 8 and also represented in FIG. 4.

TABLE-US-00008 TABLE 8 Compositions, weight ratio powder/liquid and compressive strength: Assay number Control 1 2 3 4 5 6 Powder phase A C1-3 A2 A2 A2 A2 A7bis A7bis Liquid phase B B1Bis B1Bis B1Bis B1Bis B1Bis B1Bis B1Bis Ratio   3.04   3.33   3.79   4.19   4.19   3.56   3.91 powder/liquid Ultrafine C3S \ U1 U2 U3 U4 U3 U4 batch Compressive 181.1 173.9 194.3 250.2 243.2 160.9 174.5 strength (Mpa)

[0468] As evidence with above results and as clearly represented in FIG. 4, the use of the ultrafine calcium silicate particles of the invention enable to maintain or even increase the compressive strength of the hardened restorative material, compared to the materials obtained using micronized calcium silicate particles.