Dental composite material with adapted ratio of flexural strength to elastic modulus, and mill blanks made of said composite material

Abstract

A polymerisable dental composite material comprising (i) 60 to 85% by weight of an inorganic filler component comprising at least one tectosilicate and optionally at least one dental glass and/or at least one amorphous metal oxide, (ii) 10 to 40% by weight of a mixture of at least two different urethane(meth)acrylates, (iii) 0.01 to 5% by weight of at least one di-, tri-, tetra- or multi-functional monomer not being a urethane(meth)acrylate, (iv) 0.01 to 10% by weight of at least one initiator, an initiator system and optionally at least one stabiliser and optionally at least one pigment, wherein the total composition of the composite material amounts to 100% by weight, and a polymerised composite material having a flexural strength of greater than or equal to 240 MPa and an elastic modulus of 16 to 20 GPa for the production of indirect dentures.

Claims

1. A polymerisable dental composite material, comprising (i) 60 to 85% by weight of an inorganic filler component comprising at least one tectosilicate comprising 60 to 80% by weight, based on a total weight of the composite material, of at least feldspar or a mixture thereof, (ii) 10 to 40% by weight of a mixture of at least two different urethane (meth)acrylates, (iii) 0.01 to 5% by weight of at least one di-, tri-, tetra- or multi-functional monomer not being a urethane (meth)acrylate, (iv) 0.01 to 10% by weight of at least one initiator, of an initiator system, as well as optionally of at least one stabiliser and optionally of at least one pigment, wherein the total composition of the composite material amounts to 100% by weight.

2. The dental composite material according to claim 1, wherein the tectosilicate has an average particle size d.sub.50 of 0.7 to 3.0 μm.

3. The dental composite material according to claim 1, wherein the inorganic filler component comprises at least one tectosilicate, as well as optionally at least one dental glass and/or at least one amorphous metal oxide.

4. The dental composite material according to claim 1, wherein (ii) comprises a mixture of at least two different urethane (meth)acrylates, wherein the mixture comprises at least one difunctional urethane(meth)acrylate having a bivalent alicyclic group and a difunctional urethane (meth)acrylate having a bivalent alkylene group, and optionally at least one at least tetrafunctional dendritic urethane (meth)acrylate.

5. The dental composite material according to claim 1, wherein (ii) is selected from di-methacrylic esters of polyethers, tri-, tetra- or multi-functional methacrylic esters of polyethers.

6. The dental composite material according to claim 1, wherein the at least one stabiliser comprises water, at least one benzophenone derivative and/or at least one phenol derivative.

7. A polymerised dental composite material obtainable by polymerisation of the composite material according to claim 1.

8. The polymerised dental composite material according to claim 7 having a flexural strength of greater than or equal to 240 MPa to optionally 330 MPa (7 days, 23±2° C., dry storage), and an elastic modulus greater than or equal to 16 to 21 GPa, (7 days, 23±2° C., dry storage) according to EN ISO 6872:2008.

9. The polymerised dental composite material according to claim 7 having a flexural strength of greater than or equal to 260 MPa to 330 MPa (7 days of storage in H.sub.2O deionised at 37° C.), and an elastic modulus greater than or equal to 16 to 22 GPa (7 days of storage in H.sub.2O deionised at 37° C.) according to EN ISO 6872:2008.

10. The polymerised dental composite material according to claim 7 having a flexural strength of greater than or equal to 240 MPa to 300 MPa (7 days of storage in H.sub.2O deionised at 37° C., followed by greater than or equal to 1000 cycles (5° C. to 55° C., retention time greater than or equal to 30 seconds)), and an elastic modulus greater than or equal to 15 to 22 GPa (7 days of storage in H.sub.2O deionised at 37° C., followed by greater than or equal to 1000 cycles (5° C. to 55° C., retention time greater than or equal to 30 seconds)) according to EN ISO 6872:2008.

11. A polymerised dental composite material comprising 60 to 85% by weight of at least one inorganic filler compound comprising 60 to 80% by weight of at least one feldspar, as well as optionally at least one dental glass, and/or at least one amorphous silanised metal oxide of a primary particle size of 2 to 45 nm, 10 to 40% by weight of at least one polymer being based on at least one monomer comprising at least one bis-urethane derivative of tetrahydrodicyclopentadiene, at least one di-urethane (meth)acrylate having a bivalent alkylene group, at least one tetra- to decafunctional dendritic urethane methacrylate, and at least one di-, tri-, tetra- or multi-functional methacrylic ester of polyethers, and 0.01 to 10% by weight of at least one pigment, wherein the total composition of the composite material amounts to 100% by weight.

12. The polymerised dental composite material according to claim 7, wherein the polymerized dental composite material is present in the form of a block of material.

13. Method of using a dental composite material according to claim 1 for the production of dental prosthetic restorations in a material-removing process, or for the production of direct adhesive dental restorations.

14. Method according to claim 13 for the production of dental prosthetic restorations comprising crowns, inlay, onlays, superstructures, artificial teeth, dental bridges, dental bars, spacers, abutments or veneers.

15. Dental composite material according to claim 1, wherein in that the tectosilicate has an average particle size i) d.sub.50 of 1.3 to 2.5 μm, optionally d.sub.50 of 2.0 μm with plus/minus 0.25 ii) d.sub.50 of 1.5 μm with plus minus 0.25 μm, and/or iii) d.sub.50 of 0.85 μm with plus/minus 0.15 μm.

16. The polymerized dental composite material according to claim 11, wherein the polymerized dental composite material is present in the form of a block of material.

17. Method of using a dental composite material according to claim 7 for the production of dental prosthetic restorations in a material-removing process, or for the production of direct adhesive dental restorations.

18. Method of using a dental composite material according to claim 11 for the production of dental prosthetic restorations in a material-removing process, or for the production of direct adhesive dental restorations.

Description

EXECUTION EXAMPLES

(1) Three-Point Bending Flexural Test

(2) Flexural properties were determined using a three-point bending flexural test according to ISO 6872:2008 (ISO 6872:2008. Dentistry—Ceramic materials, 3rd ed, International Organization for Standardization, Geneva, 2008). The rod-shaped specimens, 4.0 mm wide, 14.0 mm long and 1.2 mm thick, were produced with a low-speed diamond saw (Isomet, Buehler, Lake Bluff, Ill., USA). All specimens were wet ground and polished with a #600 and #1000 diamond wheel (Maruto, Tokyo, Japan) and #1000 diamond blades (Maruto) mounted on a metallographic lapping machine (Dia-Lap, ML-150P, Maruto) to achieve the required dimensions of 4.0±0.2×14.0±0.2×1.2±0.2 mm. In order to minimize edge breaks in the rod-shaped specimens during the bending test, an edge chamfer, 0.15 mm wide, was incorporated using the lapping machine with a #1000 diamond blade. After polishing, all specimens were stored in a silica gel desiccator for 7 days prior to the bending flexural test. Three groups of ten specimens each were randomly produced from each CAD/CAM block. Specimens of the first group were stored under dry conditions at ambient room temperature (23±2° C.) for 7 days. The second group was stored in 37° C. deionized water for 7 days, while the third group was stored in 37° C. deionized water for 7 days followed by 5000 thermal cycles (thermal cycles=TZ; 5° C. to 55° C., retention time 30 s) using a thermocyclic device (HA-K178, Tokyo Giken Inc., Tokyo, Japan). The width and thickness of each specimen were measured using a digital micrometer (MDC-25M, Mitsutoyo Co., Tokyo, Japan; minimum value: 0.001 mm). A three-point bending flexural test with a support span of 12.0 mm and a traverse speed of 1.0 mm/min was performed at ambient room temperature (23±2° C.) by means of a universal testing machine (AG-X, Shimadzu Corp., Kyoto, Japan). The flexural strength and the flexural modulus were calculated by use of software (TRAPEZIUM X, Shimadzu Corp., Kyoto, Japan). The flexural modulus (E) was calculated according to the following formula:
E=FL.sup.3/4bh.sup.3d
wherein F represents the load at an appropriate point in the linear part of the spring characteristics, L the support span (12.00 mm), b the width of the specimen, h the thickness of the specimen and d the bending at a load F. The flexural strength (a) was calculated with the following formula:
σ=3F.sub.1L/2bh.sup.2
wherein F.sub.1 represents the maximal load during the bending flexural test.

(3) The hardness test was carried out using a Zwick universal device: The measured values of the specimens according to the invention are in the range of 800 to 850.

(4) In the following, comparative examples of light-curing products Venus Diamond (VD) and Venus Pearl (VP) have been measured according to ISO 4049 and ISO 6872 (The exposure was carried out point by point according to the method described in EN ISO 4049:2009 7.11 using a Translux 2Wave (1200 mW/cm.sup.2) by means of an exposure time of respectively 20 seconds per exposure point.) and compared with Example 1 according to the invention.

(5) TABLE-US-00002 TABLE 2 Comparison Ex. 1 with Venus products Comparative examples Venus Venus Diamond Pearl Example 1 (VD) (VP) Flexural strength [MPa] 291 MPa 182 MPa 195 MPa according to EN ISO 6872 Elastic modulus [GPa] 19.3 GPa 15.6 GPa 15.8 GPa according to EN ISO 6872 Flexural strength [MPa] 174 MPa 149 MPa according to EN ISO 4049 (24 h/water) Elastic modulus [GPa] 12.0 GPa 11.4 GPa according to EN ISO 4049 (24 h/water)

(6) TABLE-US-00003 TABLE 3 Composition according to the invention Examples 1 to 3: Examole 1 2.0 μm feldspar d.sub.50 % by weight g filler feldspar 69.21% 69.21 metal oxide amorphous SiO.sub.2 5.96% 5.96 urethane(meth)- bis(4′,7′-dioxa-3′,8′-dioxo-2′- 15.68% 15.686 acrylates aza-decyl-9′-en)tetrahydro- dicyclopentadiene urethane methacrylate 0.75% 0.75 dendrimer, hexafunctional 7,7,9-trimethyl-4,13-dioxo- 5.59% 5.59 3,14-dioxa-5,12-diaza- hexadecane-1,16- diylbismethacrylate di- to multi- 1,2-bis(2-(methacryloyloxy)- 1.35% 1.35 funktional ethoxy)ethane monomers initiator system tert.-butylperoxy-2- 0.37% 0.37 ethylhexanoate stabiliser 2,6-bis(1,1-dimethylethyl)-4- 0.04% 0.04 methylphenol 2-hydroxy-4-methoxy- 0.30% 0.3 benzophenone water 0.60% 0.6 pigments and diethyl-2,5-dihydroxy- 0.15% 0.15 others terephthalate, colour pigments

(7) Polymerisation of the dental composites according to the invention was performed for ca. 3 h at 95° C. After polymerisation, the flexural strength amounts to 291 MPa and the elastic modulus to 19.33 MPa.

(8) TABLE-US-00004 TABLE 4 Flexural strengths (according to EN ISO 6872) after 7 days (RT) 24 h/ after thermal dry water 7 day/water cycles*/water Example 1 290 MPa 284 MPa 251 MPa *5000 7 days 37° C. H.sub.2O 5000 thermal cycles

(9) TABLE-US-00005 TABLE 5 E-modulus (elastic modulus) after 7 days (RT) 24 h/ after thermal dry water 7 days/water cycles*/water Example 1 19.5 GPa 20.1 GPa 17.3 GPa *5000 7 days 37° C. H.sub.2O 5000 thermal cycles