AESTHETIC DENTAL FILLING MATERIAL HAVING HIGH CURING DEPTH

Abstract

Dental material, which contains at least one radically polymerizable monomer, at least one radiopaque filler, at least one composite filler, at least one inorganic filler and at least one initiator for the radical polymerization. The dental material is particularly suitable as dental filling material.

Claims

1. A dental material, characterized in that it comprises (a) at least one radically polymerizable monomer, (b) at least one radiopaque filler, (c) at least one inorganic filler, (d) at least one composite filler and (e) at least one initiator for the radical polymerization.

2. The dental material according to claim 1, which comprises as component (d) a composite filler with spherical particles.

3. The dental material according to claim 1, which comprises as radically polymerizable monomer (a) 1,6-bis-[2-methacryloyloxyethoxycarbonylamino]-2,2,4-trimethylhexane (RM3), N-(2-methacryloyloxyethyl)carbamic acid-(2-methacryloyloxyethyl)ester (V837), tetramethyl xylylene diurethane dimethacrylate (V380), bisphenol A dimethacrylate, 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropyl)phenyl]propane (bis-GMA), ethoxylated or propoxylated bisphenol A dimethacrylate, bisphenol A dimethacrylate 2-[4-(2-methacryloyloxyethoxyethoxy)phenyl]-2-[4-(2-methacryloyloxyethoxy)phenyl]propane) (SR-348c, 3 ethoxy groups), 2,2-bis[4-(2-methacryloxypropoxy)phenyl]propane, 2-{[(2-(N-methylacrylamido)-ethoxy)-carbonyl]-amino}-ethyl methacrylate (V850), bis-(3-methacryloyloxymethyl)-tricyclo-[5.2.1.0.sup.2,6]decane (TCP), 1,10-decanediol dimethacrylate (D.sub.3MA), 2-([1,1′-biphenyl]-2-oxy)ethyl methacrylate, or a mixture thereof.

4. The dental material according to claim 1, which comprises as radically polymerizable monomer (a) a mixture of (a-1) 20 to 80 wt.-% of at least one urethane dimethacrylate, (a-2) 10 to 40 wt.-% of at least one bisphenol A derivative, (a-3) optionally up to 40 wt.-% of at least one tricyclic dimethacrylate, and (a-4) optionally up to 20 wt.-% other monomers which do not fall into one of the groups (a-1) to (a-3) and (a-5), (a-5) optionally up to 8 wt.-% of at least one chain regulator, in each case based on the total mass of the component (a).

5. The dental material according to claim 4, which comprises at least one difunctional urethane of the general formula 1: ##STR00004## where R.sup.1, R.sup.2=independently of each other in each case H.sub.2C═C(—R.sup.3)—C(═O)—O— or H.sub.2C═C(—R.sup.4)—C(═O)—NR.sup.5—, R.sup.3=H or CH.sub.3; R.sup.4=H or CH.sub.3; R.sup.5=H or CH.sub.3; n, m=independently of each other in each case a whole number from 1 to 4.

6. The dental material according to claim 5, which comprises as component (a-1) a monomer mixture which comprises 5 to 60 wt.-% of at least one urethane dimethacrylate monomer with aromatic groups, from 3 to 30 wt.-% of at least one difunctional urethane of Formula 1, 10 to 70 wt.-%, of at least one further urethane dimethacrylate, in each case based on the total mass of the monomer component (a).

7. The dental material according to claim 1, which comprises as radiopaque filler (b) ytterbium trifluoride with a volume-averaged particle size (D50 value) of ≤25 nm, which is measured as detailed in the description.

8. The dental material according to claim 1, which comprises as inorganic filler (c) glass powder of from 0.1 to 5 μm and/or one or more zirconium silicates of from 2 to 100 nm and/or ZrO.sub.2 particles of from 0.5 to 50 nm, wherein the volume-averaged particle size is each measured as detailed in the description.

9. The dental material according to claim 1, wherein the at least one composite filler (d), comprises ytterbium trifluoride particles with a volume-averaged particle size (D50 value) of ≤25 nm, which is measured as detailed in the description, and/or spherical particles comprising zirconium silicate.

10. The dental material according to claim 1, in which the refractive index of the monomer component (a) corresponds to the refractive index of the filler (c) or is at most 0.03, and/or in which the refractive index of the monomer component (a) corresponds to the refractive index of the filler (d) or is at most 0.025.

11. The dental material according to claim 1, which comprises 5 to 40 wt.-% of at least one radically polymerizable monomer (a), 1 to 30 wt.-% ytterbium trifluoride particles (b), 20 to 90 wt.-% inorganic filler (c), 5 to 60 wt.-% composite filler (d) and 0.005 to 3.0 wt.-% initiator for the radical polymerization (e), in each case based on the mass of the dental material.

12. The dental material according to claim 11, which comprises 12 to 30 wt.-% radically polymerizable monomer (a), 3 to 10 wt.-% ytterbium trifluoride particles (b) with a volume-averaged particle size (D50 value) of ≤25 nm, which is measured as detailed in the description, 45 to 65 wt.-% inorganic filler (c), 15 to 40 wt.-% composite filler (d) and 0.01 to 0.5 wt.-% initiator for the radical polymerization (e), in each case based on the total mass of the dental material.

13. The dental material according to claim 11, which additionally comprises up to 4 wt.-% additive(s), based on the total mass of the dental material.

14. The dental material according to claim 1, which has a radiopacity of from 140% to 350% Al.

15. The dental material according to claim 1, which has a contrast value (CR value) of from 60 to 75 and a transmittance of from 8 to 25%.

16. A dental material characterized in that it comprises (a) at least one radically polymerizable monomer, (b) ytterbium trifluoride with a volume-averaged particle size (D50 value) of ≤25 nm, measured as detailed in the description, as a radiopaque filler, (c) at least one inorganic filler, (d) at least one composite filler, and (e) at least one initiator for the radical polymerisation comprising a photoinitiator, wherein the dental material contains a radically-polymerizable monomer (a) comprising a mixture of (a-1) 20 to 80 wt. % of at least one urethane dimethacrylate, (a-2) 10 to 40 wt. % of at least one bisphenol A derivative, (a-3) optionally up to 40 wt. % of at least one tricyclic dimethacrylate, (a-4) optionally up to 20 wt. % of other monomers which do not fall into one of the groups (a-1) to (a-3) and (a-5), and (a-5) optionally up to 8 wt. % of at least one chain regulator, in each case based on the total mass of component (a), wherein the refractive index of the monomer component (a) is equal to or at most 0.03 greater than the refractive index of the filler (c), and wherein the refractive index of the monomer component (a) is equal to or at most 0.025 greater than the refractive index of the filler (d).

17. The dental material according to claim 1, for therapeutic application as dental cement, coating, veneering material, filling composite, or bulk-fill composite.

18. A method of using the dental material according to claim 1 for non therapeutic use comprising producing of inlays, onlays, crowns and bridges using the dental material.

19. The dental material according to claim 1, wherein the at least one initiator for the radical polymerization comprises a photoinitiator.

Description

[0162] The invention is explained in more detail below by means of figures and examples:

[0163] FIG. 1 shows a class 2 cavity in a human molar with strongly coloured cavity bottom.

[0164] FIG. 2 shows the human molar from FIG. 1, filled with the dental material according to the invention from Example 6.

[0165] FIG. 3 shows a scanning electron micrograph of the spherical particles from Example 8.

[0166] FIG. 4 shows a bleached human anterior tooth with class 3 mesiobuccal and distobuccal fillings, which were placed using the dental material from Example 10. The fillings blend naturally into the tooth and are practically invisible.

[0167] FIG. 5 shows a human anterior tooth with class 3 mesiobuccal and distobuccal fillings, which were placed using the dental material from Example 14. The fillings blend naturally into the tooth and are practically invisible.

EXAMPLES

[0168] Using the formulations indicated in the following embodiment examples, dental materials were prepared and tested as described. The components were mixed with each other using a magnetic stirrer, a kneader (LPM 0.5 SP machine from Linden) or using a centrifugal mixer (Speedmixer DAC 600.2 from Hauschild).

[0169] To determine the transmittance of the materials, cured round test pieces (diameter: 20 mm, h=1 mm) were produced and measured colorimetrically with the aid of a spectrophotometer (CM-5 spectrophotometer, Minolta). The polymerization was effected with an LED lamp (3 s at 3050 mW/cm.sup.2).

[0170] The measurement of flexural strength and depth of cure was effected in accordance with ISO 4049:2009: Dentistry—Polymer-based restorative materials. Here, the stated value for the depth of cure (DOC) corresponds to half the measured value. From a measured value of DOC/2≥3.5 mm, a material may be referred to as bulk-fillable and a depth of cure of at least 4 mm under dental conditions is deemed to be assured.

[0171] The Vickers hardness was determined using a Vickers hardness tester from Zwick (ZHV 0.2). In addition, the depth of cure [in mm] at which the Vickers hardness of a polymerized test piece, ground down transversely up to the middle, still amounts to 80% of the surface hardness is indicated.

[0172] The radiopacity and the CR value were determined in the manner described in the description.

[0173] In the examples, the following materials are used: [0174] accelerator ethyl 4-(dimethylamino)benzoate (CAS No. 10287-53-3) [0175] bis-GMA bisphenol A glycidyl methacrylate (CAS No. 1565-94-2) [0176] BHT butylhydroxytoluene [0177] TCP tricyclodecane dimethanol diacrylate (CAS No. 42594-17-2) [0178] D.sub.3MA 1,10-decanediol dimethacrylate [0179] MA836 2-([1,1′-biphenyl]-2-oxy)ethyl methacrylate [0180] Ge photoinitiator bis(4-methoxybenzoyl)diethylgermanium (CAS No. 1469766-31-1) [0181] phosphine oxide diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (photoinitiator) [0182] glass filler 1 barium-free Sr-, Al- and F-containing dental glass with 6% silanization, average grain size 0.7 μm, refractive index 1.50 (glass G018-163) [0183] glass filler 2 radiopaque dental glass powder with 6% silanisation, refractive index 1.50 (Schott Glass G018-430) [0184] chain regulator 2-(toluene-4-sulfonylmethyl)acrylic acid ethyl ester [0185] RM3 7,7(9)9-trimethyl-4,3-dioxo-3,14-dioxa-5,12-diazohexadecane-1,16-diyldimethacrylate [0186] zirconium silicate spherical zirconium silicate particles, average primary particle size: 20 nm, secondary particle size: 3.44 μm, refractive index 1.50 [0187] SR-348C ethoxylated bisphenol A dimethacrylate (CAS No. 41637-38-1) [0188] V380 urethane dimethacrylate with aromatic groups [0189] V850 methacrylic acid-2-{[2-(N-methylacrylamido)-ethoxycarbonyl]-amino}-ethyl ester [0190] nYbF.sub.3 nanoscale ytterbium trifluoride, average particle size 14 nm [0191] YbF.sub.3 powdered ytterbium trifluoride, average particle size 100 nm [0192] ZrO.sub.2 non-agglomerated ZrO.sub.2 particles with a primary particle size of 8 nm [0193] V837 N-(2-methacryloyloxyethyl)carbamic acid-(2-methacryloyloxy-ethyl)ester (CAS No. 139096-43-8)

Example 1

Preparation of a Composite Filler (Comparison Example)

[0194] A composite material with the composition indicated in Table 1 was prepared in the manner described in Example 1 of EP 1 234 567 A2. The material was thermally cured, subsequently coarsely crushed and then milled using a ball mill to an average grain size of 25 μm. The refractive index of the monomer mixture used was 1.484 before the polymerization and 1.509 after the polymerization. The refractive index of the composite filler was 1.506.

TABLE-US-00001 TABLE 1 Composition of the composite filler Name Proportion [wt.-%] V 380 4.4 RM3 4.6 D.sub.3MA 12.3 Dibenzoyl peroxide 0.69 BHT 0.01 Glass filler 1 78 Total 100

Example 2

Preparation of a Radiopaque Composite Filler

[0195] A composite material with the composition indicated in Table 2 was prepared in the manner described in Example 1 of EP 1 234 567 A2. For this purpose, first of all the monomers were mixed with each other and then the ytterbium trifluoride was incorporated into a portion of the monomer mixture. This was mixed with the remaining monomers and thereafter the glass filler was incorporated homogeneously into the resulting mixture. The material was thermally cured, subsequently coarsely crushed and then milled using a ball mill to an average grain size of 25 μm. The refractive index of the monomer mixture used was 1.482. After the polymerization it was 1.514. The composite filler had a refractive index of 1.506.

TABLE-US-00002 TABLE 2 Composition of the radiopaque composite filler Component Proportion [wt.-%] V380 3.85 RM3 3.85 D.sub.3MA 8.13 nYbF.sub.3 5.5 Dibenzoyl peroxide 0.66 BHT 0.01 Glass filler 1 78 Total 100

Example 3

Dental Material Based on the Composite Filler from Ex. 1 (Comparison Example)

[0196] For the preparation of a dental material with the composition indicated in Table 3, first of all the named monomers were stirred with each other for 12 hours, in order to dissolve all the components. Then, the powdered components were added and homogeneously mixed to form a paste using a mixer (Speedmixer DAC 600.2 VAC-P from Hauschild). The refractive index of the uncured monomer mixture was 1.510.

TABLE-US-00003 TABLE 3 Composition of the composite paste Component Proportion [wt.-%] Bis-GMA 5.45 SR-348C 2.48 V380 3.96 RM3 12.00 TCP 2.64 Camphorquinone 0.05 Accelerator 0.21 Ge photoinitiator 0.05 Additives 0.06 Composite filler from Ex. 1 17.00 Glass filler 1 56.10 Total 100

[0197] Depth of cure (DOC/2), transmittance, flexural strength, elastic modulus and radiopacity were measured as described above. The results are indicated in Table 5.

Example 4

Dental Material Based on the Composite Filler from Example 2

[0198] For the preparation of a dental material with the composition indicated in Table 4, first of all the named monomers were homogeneously mixed with stirring and then the YbF.sub.3 was incorporated into a portion of the mixture, with the result that a transparent liquid was obtained. Thereafter, the remaining monomers and then the powdered components were added and homogeneously mixed to form a paste. The filler enriched with YbF.sub.3 from Example 2 was used as composite filler. The refractive index of the uncured monomer mixture was 1.508.

TABLE-US-00004 TABLE 4 Composition of the radiopaque composite paste Component Proportion [wt.-%] Bis-GMA 2.98 SR-348C 1.45 V380 4.36 RM3 9.95 TCP 2.91 Camphorquinone 0.05 Accelerator 0.21 Ge photoinitiator 0.05 Composite filler from Ex. 2 17.00 Additives 0.06 Glass filler 1 53.74 nYbF.sub.3 7.30 Total 100.06

[0199] The material was analyzed in the manner described above. The results are indicated in Table 5.

TABLE-US-00005 TABLE 5 Properties of the cured dental materials Measurement parameter Ex. 3*.sup.) Ex. 4 DOC/2 4.1 4.5 Transmittance (%) 15.14 18.19 Flexural strength (MPa) 111 114.7 Depth of cure at 80% hardness [mm] 6.5 6.8 Radiopacity (% Al) 90 190 *.sup.)Comparison example

[0200] Table 5 shows that the addition of nanoparticulate YbF.sub.3 does not have a negative effect on the properties of the paste. The paste according to the invention has a high depth of cure and transmittance in spite of significantly higher radiopacity.

Example 5

Dental Material Based on the Composite Filler from Example 2

[0201] For the preparation of a dental material with the composition indicated in Table 6, first of all the monomers bis-GMA, RM3 and Sr-348C were homogeneously mixed with stirring and then the YbF.sub.3 was incorporated into the mixture, with the result that a transparent liquid was obtained. The refractive index of this mixture was 1.509 before and 1.533 after the polymerization. The difference between these values is 0.024. Thereafter, the remaining monomers and then the powdered components were added and homogeneously mixed to form a paste.

[0202] The material was analyzed in the manner described above. The results are indicated in Table 7. All the values exceed the requirement of the dental standard EN-ISO 4049.

TABLE-US-00006 TABLE 6 Composition of the radiopaque composite paste Component Proportion [wt.-%] Bis-GMA 2.9 SR-348 1.4 RM3 9.7 TCP 2.8 V380 2.8 V850 1.4 Additives 0.1 Accelerator 0.2 Ge photoinitiator 0.1 Camphorquinone 0.1 Composite filler from Ex. 2 20.0 Glass filler 1 51.3 nYbF.sub.3 7.2 Total 100

TABLE-US-00007 TABLE 7 Properties of the cured dental material Measurement parameter Material DOC/2 (mm) 4.3 Transmittance (%) 17.5 Flexural strength (MPa) 105 Depth of cure at 80% hardness [mm] 6.6 Radiopacity (% Al) 160 CR value 60.8

Example 6

Colouring the Dental Material from Example 5

[0203] The composite paste from Example 5 was set to the following L, a, b, CR values by the stepwise addition of the pigment Sicotrans Red and intensive mixing. Then the paste was deaerated in a centrifugal mixer (SpeedMixer, Hauschild & Co. KG, Germany) for 5 min at 23,500 revolutions/min and 100 mbar.

TABLE-US-00008 L* a* b* CR 81 6.63 26.28 63.35 L*: Lightness, a*: Red value, b*: Yellow value, CR: Contrast ratio

[0204] The colours were determined according to the L*a*b* colour model corresponding to DIN EN ISO 11664-4. The colour measurement was carried out with a commercially available measuring instrument (Minolta CM-3700d spectrophotometer). The depth of cure (DOC/2) was 3.7 mm.

[0205] To check the covering behaviour, an extracted human side tooth corresponding to the Vita shade A3.5 was drilled out and the cavity bottom was coloured greyish-black using two flowable effect materials (Empress Direct Color Grey and Empress Direct Color Brown; from Ivoclar Vivadent AG). FIG. 1 shows the coloured cavity bottom, FIG. 2 shows the same tooth filled with the above dental material. The discoloration hardly shows through; the tooth looks very natural. As a result of the good depth of cure, the material can be cured in one layer in the 4-mm-deep cavity.

Example 7

Comparison of Dental Materials with Nanoscale and Conventional YbF.SUB.3

[0206] Materials with the composition indicated in Table 8 (materials A and C) were prepared in the manner described in Example 3. In parallel to this, a radiopaque dental material with the composition also indicated in Table 8 (material B) was prepared in the manner described in Example 5. The materials were analyzed in the manner described above. The results are indicated in Table 9.

TABLE-US-00009 TABLE 8 Composition of materials A, B and C Material A*.sup.) Material B Material C Component [wt.-%] [wt.-%] [wt.-%] Bis-GMA 3.88 2.90 3.88 SR-348C 1.89 1.40 1.89 V380 3.60 2.70 3.60 V850 1.86 1.39 1.86 RM3 12.61 9.45 12.61 TCP 3.66 2.74 3.66 Additives 0.08 0.08 0.08 Camphorquinone 0.05 0.05 0.05 Accelerator 0.21 0.21 0.21 Ge photoinitiator 0.05 0.05 0.05 Composite filler from Ex. 1 20 0 20 Composite filler from Ex. 2 0 20 0 Glass filler 1 52.11 51.81 47.11 YbF.sub.3(100 nm) 0 0 5 nYbF.sub.3 (14 nm) 0 7.22 0 Total 100 100 100 *.sup.)Comparison example

[0207] The materials have a similar composition, with the difference that material A contains no YbF.sub.3, material B contains nanoscale YbF.sub.3 (nYbF.sub.3) and material C contains YbF.sub.3 powder with an average particle size of 100 nm. Materials A and B have a comparable depth of cure DOC/2 of 4.3 mm and 4.2 mm, respectively. This shows that the addition of the nanoscale YbF.sub.3 does not significantly impair the depth of cure. A sufficiently large scope thus remains for coloration of the materials. Pigments and other dyes can be added up to the threshold value for bulk-fill materials of 3.5 mm. In contrast, material C only has a DOC/2 of 3.8 mm. Here, only a little scope is available for coloration. The clouding effect of larger YbF.sub.3 particles becomes clear here. Moreover, the difference between the transmittance before and after the curing is significantly lower in the case of material C than in the case of material B, which is preferred according to the invention. Material C is thus less well-suited as bulk-fill material. In contrast, the comparison of materials A and B shows that the addition of nanoscale YbF.sub.3 only has a small influence on the difference between the transparency before and after the curing. This shows that nanoscale ytterbium fluoride is best suited to increasing the radiopacity without impairing the optical properties of the material to a significant degree.

TABLE-US-00010 TABLE 9 Properties of the cured dental materials Measurement parameter Material A*.sup.) Material B Material C DOC/2 (mm) 4.3 4.2 3.8 Transmittance (%) 40.3 36.8 29.4 before the curing Transmittance (%) 19.3 17.8 16.4 after the curing Difference −21 −19 −13 Flexural strength (MPa) 106 106 113 Radiopacity (% Al) 90 190 180

Example 8

Preparation of Composite Filler with Spherical Particles

[0208] For the preparation of a composite filler with the composition indicated in Table 10, first of all the monomers named in the table were mixed with each other and then the zirconium silicate was incorporated into the monomer mixture. The dispersion was effected in a glass cylinder by moderate stirring for 6 to 24 hours. Then, 0.3 wt.-% camphorquinone and 0.6 wt.-% ethyl 4-(dimethylamino)benzoate were added and further stirred until the initiator components had dissolved. The mixture was then pumped, at 20 ml/min, into an atomizing nozzle, which was operated at a pressure of 2.1 bar under nitrogen. The finely atomized droplets were polymerized using six 100-Watt LED lamps of the wavelength 470 nm. The size of the cured particles was determined by means of laser diffraction (Microtrac X100 particle size analyzer). The particles had a spherical structure and an average particle size of 20 μm. The particle size can be controlled by the addition of acetone to the monomer mixture before the atomizing (0 to 25%). FIG. 4 shows a scanning electron micrograph of the spherical particles. The composite filler had a refractive index of 1.506.

TABLE-US-00011 TABLE 10 Composition of the spherical composite filler Component Proportion [wt.-%] V380 7.40 RM3 8.18 D.sub.3MA 14.12 Camphorquinone 0.3 Accelerator 0.6 Zirconium silicate 69.4 Total 100

Example 9

Preparation of a Radiopaque Composite Filler with Spherical Particles

[0209] Analogously to the manner described in Example 8, a spherical composite filler with the composition described in Table 11 was prepared. The filler additionally contains nanoscale YbF.sub.3 particles. For the preparation of the composite filler, the monomers named in the table were mixed with each other and then the ytterbium trifluoride and subsequently the further fillers were incorporated into the monomer mixture. The monomer mixture had a refractive index of 1.478, the refractive index of a mixture made of 50% monomer mixture and 50% YbF.sub.3 had a refractive index of 1.481. The refractive index of the YbF.sub.3 was 1.54.

TABLE-US-00012 TABLE 11 Composition of the spherical composite filler Component Proportion [wt.-%] V380 3.75 RM3 4.10 D.sub.3MA 7.05 nYbF.sub.3 15.00 Camphorquinone and accelerator 0.90 Zirconium silicate 34.60 Glass filler 1 34.60 Total 100

Example 10

Dental Material Based on the Composite Filler from Ex. 8

[0210] For the preparation of a dental material with the composition indicated in Table 12, first of all the named monomers were homogeneously mixed with stirring and then the YbF.sub.3 was incorporated into a portion of the mixture, with the result that a largely transparent liquid was obtained. Then, the remaining monomers and thereafter the powdered components were added and homogeneously mixed to form a paste. The material was analyzed in the manner described above. The results are indicated in Table 13.

[0211] The paste has a very good depth of cure. This is also reflected in the good value of approx. 7 mm for the depth of cure at 80% of the Vickers hardness. Pastes of this type can be pigmented without problems, without losing their bulk-fill properties. In comparison with Example 5, a significant improvement in the flexural strength could be achieved by using the spherical composite filler from Example 8 in place of the milled composite filler from Example 2.

TABLE-US-00013 TABLE 12 Composition of the radiopaque composite paste Component Proportion [wt.-%] Bis-GMA 2.78 SR-348C 1.35 RM3 9.25 V380 2.68 V850 4.12 Additives 0.09 Chain regulator 1.16 Accelerator 0.21 Ge photoinitiator 0.05 Camphorquinone 0.05 Composite filler from Ex. 8 27.25 Glass filler 1 44.21 nYbF.sub.3 6.8 Total 100

TABLE-US-00014 TABLE 13 Properties of the cured dental material Measurement parameter Material DOC/2 (mm) 4.2 Transmittance (%) 17.0 Flexural strength (MPa) 136 Depth of cure at 80% Vickers hardness [mm] 6.9

Example 11

Bis-GMA-Free Dental Material Based on the Composite Filler from Example 9

[0212] For the preparation of a bis-GMA-free dental material with the composition indicated in Table 14, first of all the monomers named in the table were mixed with each other and then the ytterbium trifluoride was incorporated into the monomer mixture. Thereafter, the powdered components were added and homogeneously mixed to form a paste. The material was analyzed in the manner described above. The results are indicated in Table 15.

TABLE-US-00015 TABLE 14 Composition of the radiopaque composite paste Component Proportion [wt.-%] V380 4.67 RM3 4.87 SR-348C 3.5 TCP 4.77 V850 1.49 Additives 2.8 nYbF.sub.3 6.6 Accelerator 0.2 Ge photoinitiator 0.05 Camphorquinone 0.05 Composite filler from Ex. 9 20 Glass filler 1 51 Total 100

TABLE-US-00016 TABLE 15 Properties of the cured dental material Measurement parameter Material DOC/2 (mm) 4.8 Transmittance (%) 45.1 before the curing Transmittance (%) 18.9 after the curing Difference 26.2 Flexural strength (MPa) 133 Elastic modulus (MPa) 1100 Depth of cure at 80% Vickers hardness [mm] 6.5 Radiopacity (% Al) 182 CR value 60.17

[0213] The paste has a very good flexural strength and an excellent depth of cure. The large difference between the transmittance before and after the curing enabled the light to penetrate deep into the initially very transparent paste and to cure the test piece even at depth. After the curing, the material had a lower transmittance, which is thus advantageous for aesthetic reasons.

Example 12

Coloration of the Paste from Example 11 in the Shade Bleach

[0214] The composite paste from Example 11 was set to the following L, a, b, CR values by the stepwise addition of white pigment. Then, the transmittance, depth of cure and the Vickers hardness were measured.

TABLE-US-00017 L* a* b* CR Transmittance DOC/2 Vickers hardness 86.84 0.59 14.65 65.52 13.08 3.5 5.5

[0215] The DOC/2 achieved conforms to standards and, at a depth of 5.5 mm, the material still has 80% of the surface hardness.

[0216] FIG. 4 shows a bleached human anterior tooth with class 3 mesiobuccal and distobuccal fillings, which were placed using the coloured composite paste. The fillings blend naturally into the tooth. They can only be seen at all because of the magnified representation. At speaking distance, the fillings are invisible.

[0217] Filling materials with the Bleach shade are suitable for very bright teeth, such as for example milk teeth or for bleached teeth. Since the coloration to the Bleach shade requires a great deal of white pigment in order to create the bright impression, it leads to a greater loss in depth of cure than other shades which require fewer pigments. For this reason, materials with this coloration usually only have a low depth of cure. The above results show that, even with this shade, the material according to the invention has a relatively high depth of cure, which is sufficient for the use as bulk-fill material. It is thus possible to also produce other shades with a sufficient depth of cure.

Example 13

Dental Material Based on the Composite Filler from Example 9 and ZrO.SUB.2

[0218] The preparation of the dental material with the composition indicated in Table 16 was effected analogously to the examples described previously. In addition, the monomer mixture contained the monomer D.sub.3MA. The ZrO.sub.2 was suspended in the D.sub.3MA and this suspension was then mixed with the other constituents. The paste was polymerized for 3 s at 3050 mW/cm.sup.2 and then analyzed in the manner described in Example 3. The results are indicated in Table 17.

[0219] The composite paste has a good depth of cure. The transmittance is lower in comparison with Example 8. In addition, the CR value could be increased through the increased content of YbF.sub.3 and the addition of ZrO.sub.2.

TABLE-US-00018 TABLE 16 Composition of the dental material Component Proportion [wt.-%] V380 3.66 RM3 4.16 SR-348C 2.85 TCP 3.45 V850 3.59 D.sub.3MA 0.87 ZrO.sub.2 0.58 Additives 0.08 nYbF.sub.3 9.39 Accelerator 0.16 Ge photoinitiator 0.04 Camphorquinone 0.04 Composite filler from Ex. 9 30 Glass filler 1 41.13 Total 100

TABLE-US-00019 TABLE 17 Properties of the cured dental material Measurement parameter Material DOC/2 (mm) 4.1 Transmittance (%) 38.7 before the curing Transmittance (%) 15.9 after the curing Difference 22.8 Flexural strength (MPa) 136 Depth of cure at 80% hardness 6.5 Radiopacity (% Al) 183 CR value (24 h after polymerization) 62.4

Example 14

Coloration of the Paste from Example 13 in a Shade Suitable for Dark Teeth

[0220] The composite paste from Example 13 was set to the following L, a, b, CR values by the stepwise addition of the pigments Sicotrans Red and Xerogel yellow. Then, the transmittance, depth of cure and the Vickers hardness were measured.

TABLE-US-00020 L* a* b* CR Transmittance DOC/2 Vickers hardness 78.71 9.33 31.0 65.0 13.08 3.5 5.2

[0221] The DOC/2 achieved conforms to standards, and at a depth of 5.5 mm, the material still has 80% of the surface hardness.

[0222] FIG. 5 shows a human anterior tooth, which would usually be restored with a filling with the shade A3.5 (Vita shade system), with class 3 mesiobuccal and distobuccal fillings which were placed using the coloured composite paste. The fillings blend naturally into the tooth. They can only be seen at all because of the magnified representation. At speaking distance, the fillings are invisible.

[0223] Dental materials for dark teeth require a relatively large amount of pigments for setting the shade. For this reason, such materials usually only have a low depth of cure. The above results show that the material according to the invention has a relatively high depth of cure, which is sufficient for the use as bulk-fill material. It is thus possible to also produce other shades with a sufficient depth of cure.

Example 15

Dental Material Based on the Composite Filler from Example 9 and Zirconium Silicate

[0224] Analogously to Example 13, a dental material was prepared which additionally contained zirconium silicate as filler and a higher proportion of ZrO.sub.2. The composition is indicated in Table 18. The paste was polymerized for 3 s at 3050 mW/cm.sup.2 and then analyzed in the manner described in Example 3. The results are indicated in Table 19. The measurement results identify the composite as a bulkable paste with good radiopacity.

TABLE-US-00021 TABLE 18 Composition of the dental material Component Proportion [wt.-%] V-380 3.71 RM3 4.05 SR 348C 2.50 TCP 3.2 V850 3.12 D.sub.3MA 1.44 ZrO.sub.2 0.96 Additives 0.08 nYbF.sub.3 7.2 Accelerator 0.16 Ge photoinitiator 0.04 Camphorquinone 0.04 Composite filler from Ex. 9 30.00 Glass filler 1 33.50 Zirconium silicate 10.00 Total 100

TABLE-US-00022 TABLE 19 Properties of the cured dental material Measurement parameter Material DOC/2 (mm) 4.5 Transmittance (%) 37.2 Transmittance (%) 15.2 after the curing Difference 22 Flexural strength (MPa) 120 Depth of cure at 80% hardness 6.8 Radiopacity (% Al) 200 CR value (24 h after polymerization) 62

Example 16

Materials with YbF.SUB.3 .with Different Particle Sizes

[0225] Three pastes with the composition indicated in Example 15 were prepared. Here, the YbF.sub.3 used in Example 15 was replaced in each case by YbF.sub.3 with a different particle size: Paste A: 20 nm, Paste B: 40 nm and Paste C: 60 nm. A depth of cure DOC/2 of 4.4 mm could be achieved with paste A. The coarser particles yielded a depth of cure of only 3.8 mm.

Example 17

Bis-GMA-Free Dental Material Based on the Composite Filler from Example 9 and ZrO.SUB.2

[0226] For the preparation of a bis-GMA-free dental material with the composition indicated in Table 20, first of all the monomers named in the table were mixed with each other and then the ytterbium trifluoride was incorporated into the monomer mixture. Thereafter, the powdered components were added and homogeneously mixed to form a paste. The material was analyzed in the manner described above. The results are indicated in Table 21.

[0227] The paste shows a very good reduction in transmittance during the polymerization and a high value for the depth of cure at 80% of the hardness. It is therefore excellently suitable as bulk-fill material.

TABLE-US-00023 TABLE 20 Composition of the dental material Component Proportion [wt.-%] V-380 3.5 RM3 4.2 SR 348C 4.1 TCP 3.27 V837 1.8 D.sub.3MA 1.5 ZrO.sub.2 1 Additives 0.07 nYbF.sub.3 7.5 Accelerator 0.04 Ge photoinitiator 0.01 Camphorquinone 0.01 Composite filler from Ex. 9 25 Glass filler 1 48 Total 100

TABLE-US-00024 TABLE 21 Properties of the cured dental material Measurement parameter Material DOC/2 (mm) 4.3 Transmittance (%) 37.7 before the curing Transmittance (%) 14.7 after the curing Difference 23 Flexural strength (MPa) 122 Depth of cure at 80% hardness 8.0 Radiopacity (% Al) 200 CR value (24 h after polymerization) 61

Example 18

Dental Material Based on an Alternative Monomer Mixture

[0228] For the production of the dental material with the composition given in Table 22, first the monomers mentioned in the table were mixed together and then the ytterbium trifluoride was incorporated into the monomer mixture. Then, the powdered components were added and mixed homogeneously to form a paste. The material was analysed in the manner described above. The results are given in Table 23. The refractive index of the uncured monomer mixture was 1.508. The refractive index of the fillers was 1.50.

[0229] The paste showed a good decrease in transmission on polymerization and a very high value for depth of cure at 80% of hardness.

TABLE-US-00025 TABLE 22 Composition of the dental material Component Proportion [wt.-%] bisGMA 6.42 RM3 3.98 D.sub.3MA 5.33 SR 348C 1.97 Chain regulator 0.96 Additives 0.08 nYbF.sub.3 7.53 Accelerator 0.14 Ge photoinitiator 0.02 Camphorquinone 0.04 Phosphine oxide 0.03 Composite filler from Ex. 9 27.50 Glas filler 2 36.00 Zirconium silicate 10.00 Total 100

TABLE-US-00026 TABLE 23 Properties of the hardened dental material Measurement parameter Material DHT/2 (mm) 5 Transmission (%) 33.4 before hardening Transmission (%) 15.19 after hardening Difference 18.21 Flexural strength (MPa) 104

Example 19

Dental Material with the Monomer MA 836

[0230] For the production of the dental material with the composition given in Table 24, first the monomers mentioned in the table were mixed together and then the ytterbium trifluoride was incorporated into the monomer mixture. Then the powdered components were added and mixed homogeneously to form a paste. The material was analysed in the manner described above. The results are given in Table 25. The refractive index of the uncured monomer mixture was 1.511. The refractive index of the fillers was 1.50.

[0231] The paste shows a very high decrease in transmission on polymerization combined with a very high value for depth of cure at 80% of hardness.

TABLE-US-00027 TABLE 24 Composition of the dental material Component Proportion [wt.-%] TCP 4.13 bisGMA 4.01 MA836 0.72 RM3 4.01 D.sub.3MA 2.89 SR 348C 1.95 Chain regulator 0.96 Additives 0.05 nYbF.sub.3 7.54 Accelerator 0.14 Ge photoinitiator 0.02 Camphorquinone 0.04 Phosphine oxide 0.03 Composite filler from Ex. 9 27.50 Glas filler 2 36.00 Zirconium silicate 10.00 Total 99.99

TABLE-US-00028 TABLE 25 Properties of the hardened dental material Measurement parameter Material DHT/2 (mm) 5 Transmission (%) 46.5 before hardening Transmission (%) 14.21 after hardening Difference 32.29 Flexural strength (MPa) 104