Dental composition comprising a dental filler containing a structural filler and silanated glass flakes

Abstract

The present invention relates to a dental composition comprising a dental filler containing a structural filler and silanated glass flakes. Furthermore, the present invention relates to the use of silanated glass flakes for preparing a dental composition.

Claims

1. A dental composition comprising: (i) a dental filler containing (A) a structural filler having an average particle size of from 0.1 to 3 m; and (B) silanated glass flakes, (a) wherein the silanated glass flakes have an average thickness between 50 nm and 1000 nm; and (b) wherein the silanated glass flakes have an average aspect ratio (long diameter/thickness) in the range of from 2:1 to 50:1; (ii) one or more polymerizable compounds; and (iii) an initiator system.

2. The dental composition according to claim 1, wherein the glass of the silanated glass flakes (B) comprises the following components as oxides in percent by weight: SiO.sub.2=64-70 B.sub.2O.sub.3=2-5 ZnO=1-5 Na.sub.2O=8-13 MgO=1-4 CaO=3-7 Al.sub.2O.sub.3=3-6 and up to 3 percent of K.sub.2O and TiO.sub.2, and/or wherein the structural filler (A) is a dental glass selected from the group consisting of inert glasses, reactive glasses and fluoride releasing glasses.

3. The dental composition according to claim 1, wherein the silanated glass flakes (B) include silanated glass flakes having a thickness of 30 nm to 1500 nm in an amount of at least 90% by weight.

4. The dental composition according to claim 1, wherein the silanated glass flakes (B) are obtained by milling glass flakes having an aspect ratio of at least 20:1, and subsequently silanating the milled glass flakes.

5. The dental composition according to claim 4, wherein the silanating of the milled glass flakes is carried out with a silane having one or more polymerizable groups reactive with the polymerizable compounds (ii).

6. The dental composition according to claim 1, wherein the ratio of the average particle size of the structural filler (A) and the average thickness of the silanated glass flakes (B) is in the range of 10:1 to 1:1.

7. The dental composition according to claim 1, wherein the dental composition contains 1 to 85 percent by weight of the dental filler (i) based on the total weight of the composition.

8. The dental composition according claim 1, wherein the dental composition contains the silanated glass flakes (B) in an amount of from 0.5 to 40 percent by weight based on the total weight of the composition.

9. The dental composition according to claim 1, wherein the ratio of the weight of structural filler (A) and the weight of the silanated glass flakes (B) in the dental composition is in a range of from 80:1 to 0.5:1.

10. The dental composition according to claim 1, wherein the silanated glass flakes (B) have a refractive index in a range of 1.46 to 1.60.

11. The dental composition according to claim 1, wherein the structural filler (A) has a sphericity of at least 0.5.

12. The dental composition according to claim 1, wherein the silanated glass flakes (B) have a particle size distribution determined by light scattering, wherein at least 70 percent of the particles have a particle size of less than 50 m.

13. The dental composition according to claim 1, wherein: the dental composition further comprises a further filler (C) being at least one selected from the group consisting of granulated prepolymerized fillers, ground prepolymerized fillers and filler aggregates; and/or the dental composition is a dental composite or a dental cement.

14. A method for preparing a dental composition comprising combining: (a) silanated glass flakes having an average thickness between 50 nm and 1000 nm and an average aspect ratio in the range of from 2:1 to 50:1; (b) a structural filler having an average particle size of from 0.1 to 3 m; (c) one or more polymerizable compounds; and (d) an initiator system.

Description

(1) FIG. 1 to FIG. 4 show the flakes listed in Table 2 after silanization according to example 2. Specifically, FIG. 1 shows ECR Glassflakes GF350 nmM after grinding for 0.5 h and silanization. FIG. 2 shows ECR Glassflakes GF350 nmM after grinding for 1 h and silanization. FIG. 3 shows ECR Glassflakes GF350 nmM after grinding for 2 h and silanization. FIG. 4 shows ECR Glassflakes GF350 nmM after grinding for 4 h and silanization.

(2) FIG. 5 and FIG. 6 show ECR glass flakes with a nominal thicknesses of 350 nm and 5 m, respectively.

(3) FIG. 7 and FIG. 8 show ECR glass flakes with a nominal thickness of respectively. FIG. 9 shows a composite containing glass flakes.

COMPARATIVE EXAMPLE 1

US 20060241205 Filler Materials For Dental Composites

(4) In example E and G to I of US 20060241205, pastes are disclosed containing a polymerizable resin mixture and silane-treated glass flakes in combination with a further filler. The silane-treated glass flakes have a thickness of 5 m and either an average glass flake dimension of about 15 microns or of about 160 microns. In case of examples E and H the ratio of flakes to silane-treated glass filler is 40 to 60.

(5) Following those examples, pastes containing silanized flakes of 350 nm and 5 m, respectively, and 0.6 m Ba glass were prepared. The total filler content of 74.0% and a flake to 0.6 m Ba glass ratio of 40 to 60 was used. The flakes used for paste preparation are listed in the following table 4:

(6) TABLE-US-00004 TABLE 4 experimental pastes containing flakes of various nominal thickness Untreated Glass Flakes Median Paste Nominal Grinding flake size FIG. No. Name Thickness.sup.1) time d.sub.3,50 no..sup.3) 1 ECR GF350 ca. 350 nm 1 h 17.1 m FIG. 2 nmM 2 ECR GF350 ca. 350 nm 2 h 11.4 m FIG. 3 nmM 3 ECR GF007 4-6 m no grinding 30.8 m FIG. 7 4 ECR GF007 4-6 m 2 12.0 m FIG. 8 passages.sup.2) .sup.1)Nominal flake thickness acc. to manufactures technical data sheet .sup.2)Instead of circulating the suspension via the pearl mill, the flake suspension was pumped once via the pearl mill and collected at the mill outlet in a separated bucket (=1 passage). When necessary this procedure was repeated. .sup.3)SEM pictures were taken after silanization according to example 2

(7) After grinding the flakes were silanized according to Example 2 and the pastes prepared according to example 3. The results of the flexural strength and E-modulus determinations of the four pastes are summarized in Table 5:

(8) TABLE-US-00005 TABLE 5 experimental pastes containing flakes of various nominal thickness Flexural strength.sup.1) E-modulus Paste No. MPa GPa 1 161 12.1 2 163 11.7 3 144 10.2 4 141 9.3 .sup.1)determined according to ISO 4049: 2009

(9) From Table 5 it can be seen that for an identical formulation the flexural strength and E-modulus is favorably higher in case of the thinner flakes (nominal thickness of 350 nm, paste no. 1 and 2) compared to the thicker flakes (nominal thickness of 5 m, paste no. 3 and 4).