Photopolymerizable and dual-curing dental materials based on thiourea derivatives

Abstract

Radically polymerizable dental material which contains as initiator for the radical polymerization a combination of a thiourea derivative and a bisacyldialkylgermanium compound.

Claims

1. A radically polymerizable dental material which comprises an initiator for the radical polymerization, wherein the initiator comprises a combination of a thiourea derivative and a bisacyldialkylgermanium compound, wherein the thiourea derivative is selected from methyl, ethyl, allyl, butyl, hexyl, octyl, benzyl, 1,1,3-trimethyl, 1,1-diallyl, 1,3-diallyl, 1-(2-pyridyl)-2-thiourea, acetyl, propanoyl, butanoyl, pentanoyl, hexanoyl, heptanoyl, octanoyl, nonanoyl, decanoyl, benzoyl thiourea or a mixture thereof; and wherein said radically polymerizable dental material comprises as a polymerizable matrix a mixture of radically polymerizable monomers which comprises at least one highly viscous difunctional methacrylate which is selected from TMX-UDMA (an addition product of HEMA and hydroxypropyl methacrylate (HPMA) with ,,,-tetramethyl-m-xylylene diisocyanate (TMXDI)) and 1,6-bis-[2-methacryloyloxyethoxycarbonylamino]-2,4,4-trimethylhexane (U DMA); at least one low-viscosity difunctional methacrylate which is selected from bismethacryloyloxymethyltricyclo[5.2.1]decane (TCDMA), glycerol dimethacrylate (GDMA) and/or decanediol-1,10-dimethacrylate (D3MA); and p-cumylphenoxyethylene glycol methacrylate (CMP-1E) as a low-volatile monomethacrylate.

2. The dental material according to claim 1, which comprises as the bisacyldialkylgermanium compound, bisbenzoyldiethylgermanium, bisbenzoyldimethylgermanium, bisbenzoyldibutylgermanium, bis(4-methoxybenzoyl)dimethylgermanium, bis(4-methoxybenzoyl)diethylgermanium or a mixture thereof.

3. The dental material according to claim 1, which additionally comprises a hydroperoxide.

4. The dental material according to claim 3, which comprises as the hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, t-butyl hydroperoxide, cumene hydroperoxide, pinane hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, t-amyl hydroperoxide or a mixture thereof.

5. The dental material according to claim 1, which additionally comprises organic or inorganic particulate filler.

6. The dental material according to claim 5, which comprises filler with a maximum particle size of less than 600 nm.

7. The dental material according to claim 1, which comprises (a) 2.0-20 wt.-% of said low-volatile monomethacrylate, (b1) 5.0-25 wt.-% of said highly viscous dimethacrylates, (b2) 5-30 wt.-% of said low-viscosity dimethacrylates, (e) 0.01-4.0 wt.-% of said thiourea derivative, (g) 0.001-1.0 wt.-% of said bisacyldialkylgermanium compound, said composition further comprising (c) 0-15 wt.-% of one or more acid-group-containing adhesive monomers, (d) 20-90 wt.-% filler(s), (f) 0-3.0 wt.-% hydroperoxide(s), (h) 0.1-5.0 wt.-% additive(s).

8. The dental material according to claim 1, which further comprises 10 to 100 ppm of a redox catalyst.

9. The dental material according to claim 1, which is free from TEGDMA and bis-GMA.

10. The dental material according to claim 1, which is free from amines.

11. A method of using of a dental material according to claim 1 as dental cement, filling composite, veneering material, as materials for preparing inlays, onlays, crowns or bridges comprising preparing the ingredients according to claim 7 and applying the ingredients as a dental cement, filling composite, veneering material.

12. The dental material according to claim 1, which comprises (a) 5-15 wt.-% of said low-volatile monomethacrylate, (b1) 5-15 wt.-% of said highly viscous dimethacrylates, (b2) 10-20 wt.-% of said low-viscosity dimethacrylates, (e) 0.1-2.0 wt.-% of said thiourea derivative, (g) 0.005-0.5 wt.-% of said bisacyldialkylgermanium compound, said composition further comprising (c) 0-10 wt.-% of one or more acid-group-containing adhesive monomers, (d) 40-80 wt.-% filler(s), (f) 0.1-2.0 wt.-% hydroperoxide(s), (h) 0.1-2.0 wt.-% additive(s).

13. The dental material according to claim 1, which further comprises 20 to 80 ppm of a redox catalyst.

14. The dental material according to claim 1, which comprises 30 to 80 ppm of a redox catalyst.

15. The dental material according to claim 1, which comprises TMX-UDMA.

16. The dental material according to claim 1, which comprises CMP-1E.

17. The dental material according to claim 1, which comprises TMX-UDMA and CMP-1E.

Description

EXAMPLES

Examples 1-8

(1) Light-Curing Composites Based on an Initiator Composition According to the Invention

(2) Corresponding to Table 1 set out below, composites were prepared (all values given in mass-%) based on 44.5% of a silanized SiO.sub.2 mixed oxide with a content of 30% ZrO.sub.2), 20% ytterbium fluoride and 35.5% of a methacrylate mixture (20% CMP-1E, 20% GDMA, 20% TMX-UDMA, 25% UDMA and 14.5% D.sub.3MA as well as 0.5% BHT as stabilizer). The components detailed in Table 1 were contained as initiator system. The composites were prepared using a kneader (Linden). To measure the Vickers hardness, metal moulds (h=2 mm, =10 mm) were filled with composite and covered with a PET film. The polymerization was carried out by irradiation from above with a polymerization lamp (LED Bluephase; Ivoclar Vivadent AG; 10 s at 650 mW/cm.sup.2).

(3) After preparation, the test pieces were stored in a drying oven at 37 C. for 24 h and then the illuminated upper side of the test pieces was ground flat first with a 2500, then with a 4000 abrasive paper and finally polished with polishing paste. The Vickers hardness was measured on the polymerized upper side with a universal hardness tester (model ZHU0.2; Zwick/Rll). 3 individual measurements were carried out on each test piece. The resulting average values are given in Table 1.

(4) The results demonstrate that composites which contain a thiourea derivative in addition to a Ge photoinitiator (Ivocerin) have a significantly increased Vickers hardness compared with composites which contain amine accelerator (EMBO or DABA). This means high abrasion stability and makes it possible to prepare dental restorations with high surface smoothness, high gloss and improved stability in the mouth.

(5) TABLE-US-00001 TABLE 1 Initiator content in the monomer of the composites and Vickers hardness Ivocerin.sup.1) ATU.sup.2)/Cu.sup.3) Amine Vickers hardness Ex. [wt.-%] [wt.-%] [wt.-%] (MPa) 1*.sup.) 0.035 0 0 92.64 4.3 2 0.035 1.50/65 0 129.1 7.7 3*.sup.) 0.050 0 0 206.2 9.7 4 0.050 1.50/65 0 242.8 10.1 4a*.sup.) 0 1.50/65 0 does not polymerize 4b*.sup.) 0 1.50/0 0 does not polymerize 5*.sup.) 0.035 0 0.5/EMBO.sup.4) 94.0 2.1 5a*.sup.) 0.035 0 1.5/EMBO.sup.4) 98 11.5 6*.sup.) 0.035 0 0.5/DABA.sup.5) 100.0 5.8 6a*.sup.) 0.035 0 1.5/DABA.sup.5) 95 0.5 7*.sup.) 0.050 0 0.5/EMBO.sup.4) 210.3 15.5 8*.sup.) 0.050 0 0.5/DABA.sup.5) 196.4 8.4 *.sup.)Comparison example .sup.1)Bis-(4-methoxybenzoyl)diethylgermanium (Ivoclar Vivadent AG) .sup.2)1-Acetylthiourea .sup.3)Cu-acetylacetonate (Cu content in ppm) .sup.4)(4-Dimethylamino)benzoic acid ethyl ester .sup.5)N,N-diethyl-3,5-di-tert-butylaniline