MILL BLANKS BASED ON A POLYMERIZED, FRACTURE-TOUGH PROSTHESIS MATERIAL

Abstract

The subject matter of the invention is a three-dimensional moulded body, in particular a milling blank, made of a polymerisable prosthetic material, which is suitable for milling machining by means of CNC and/or CAD/CAM, having a fracture toughness of greater than or equal to 1.9 Mpa.Math.m.sup.1/2 and a fracture work of greater than or equal to 900 J/m.sup.2. The milling blank preferably comprises core-shell particles modified by an elastic phase and is optionally based on a content of urethane (meth)acrylate polymerised into the polymer. Moreover, a subject matter of the invention is the use of the milling blanks for the production of at least parts of dental prosthetic parts, such as a prosthesis, artificial teeth, bridges, or of orthodontic appliances and instruments in medical field.

Claims

1. Milling blank made of polymeric prosthetic material wherein the prosthetic material is present in the form of a three-dimensional moulded body, optionally being suitable for ablative machining, suitable as CAD/CAM milling blank, whereby the moulded body has a fracture toughness of 1.9 Mpa.Math.m.sup.1/2 and a total fracture work of 900 J/m.sup.2.

2. Milling blank according to claim 1, which comprises (i) core-shell particles modified by an elastic phase.

3. Milling blank according to claim 1, which comprises (ii) at least one polymer comprising at least one urethane (meth)acrylate polymerised into the polymer.

4. Milling blank according to claim 1, wherein the core-shell particles comprise primary particles, whereby the primary particle size has an average particle size of less than or equal to d.sub.50500 nm to 10 nm.

5. Milling blank according to claim 1, wherein the core-shell particles comprise aggregates of primary particles, whereby the aggregates have an average particle size of less than or equal to (d.sub.50) 400 m (micrometers).

6. Milling blank according to claim 1, comprising (i) 0.001 to 20% by weight of core-shell particles modified by at least one elastic phase, based on the total composition.

7. Milling blank according to claim 1, comprising (ii) 0.001 to 20% by weight of at least one urethane (meth)acrylate polymerised into the polymer, based on the total composition.

8. Milling blank according to claim 1, wherein the distribution of the elastic phase in the modified core-shell particles is selected from possibilities a to d: a) elastic phase as core in solid outer shell (core-shell-particles); b) multiple elastic phases as cores in a solid matrix; c) core-shell particles from a) distributed in solid matrix, and d) solid core with elastic phase as outer shell.

9. Milling blank according to claim 1, wherein the unpigmented prosthetic material has a transparency of greater than or equal to 90% (measured against plates having a height of 3 mm).

10. Milling blank according to claim 1, which additionally comprises one or more substance(s) from the group consisting of fillers, pigments, stabilizers, regulators, antimicrobial additives, UV-absorbing agents, thixotroping agents, catalysts and crosslinkers.

11. Milling blank according to claim 1, which is single-coloured in tooth colours or is colour-adjusted to the gingiva, or the milling blank is designed multi-coloured, wherein defined areas are designed tooth-coloured and/or defined areas are designed colour-adjusted to the gingiva.

12. Milling blank according to claim 1, which comprises greater than or equal to 55% by weight PMMA, based on the total composition.

13. Method for the production of a polymerised prosthetic material in the form of a three-dimensional moulded body, in which a polymerisable prosthetic material comprising components (A) and/or (B) whereby component A) is at least one liquid monomer component, and B) is at least one powdered component, and the polymerisable prosthetic material comprises in component (A) and/or (B) (i) core-shell particles modified by an elastic phase, and (ii) at least one urethane (meth)acrylate, and components (A) and (B) (a) are mixed, (b) are transferred into a three-dimensional mould, (c) and, subsequently, the polymerisable prosthetic material is polymerised.

14. Method according to claim 13, wherein the A) monomer component and the B) powdered component are mixed at a weight ratio of 1:50 to 50:1.

15. Method according to claim 13, wherein A) the liquid monomer component comprises at least one monomer or a mixture of monomers from a) methylmethacrylate, ethylmethacrylate, propylmethacrylate, butylmethacrylate, n-hexylmethacrylate, 2-phenoxyethylmethacrylate, isobornylmethacrylate, isodecylmethacrylate, polypropylene glycol monomethacrylate, tetrahydrofurylmethacrylate, methylacrylate, ethylacrylate, propylacrylate, butylacrylate, n-hexylacrylate, 2-phenoxyethylacrylate, isobornylacrylate, isodecylacrylate, polypropylene glycol monoacrylate, tetrahydrofurylacrylate, hydroxyethylacrylate, hydroxypropylacrylate, hydroxyethylmethacrylate, hydroxypropylmethacrylate, benzyl-, furfuryl- or phenyl(meth)acrylate, a mixture comprising at least one of said (meth)acrylates and/or copolymers comprising one or at least two of the afore-mentioned monomers, and/or b) two- and/or multi-crosslinking agents comprising 1,4-butandiol dimethacrylate (1,4-BDMA) or pentaerythritol tetraacrylate, bis-GMA monomer (bisphenol-A-glycidylmethacrylate, triethylene glycol dimethacrylate (TEGDMA) and diethylene glycol dimethacrylate (DEGMA), tetraethylene glycol di(meth)acrylate, decanediol di(meth)acrylate, dodecandiol di(meth)acrylate, hexyldexandiol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, as well as butanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, ethoxylated/propoxylated bisphenol-A-di(meth)acrylate, a mixture comprising at least one of said (meth)acrylates and/or copolymers comprising one or at least two of the afore-mentioned monomers, and/or B) the powdered component comprises polymeric particles comprising polymers in the form of polymer powder comprising polyalkyl(meth)acrylates, optionally being crosslinked and being present as homopolymer or copolymer, whereby the polymers are based on at least one monomer comprising a (meth)acrylat group, selected from methylmethacrylate, ethylmethacrylate, propylmethacrylate, butylmethacrylate, n-hexylmethacrylate, 2-phenoxyethylmethacrylate, isobornylmethacrylate, isodecylmethacrylate, polypropylene glycol monomethacrylate, tetrahydrofurylmethacrylate, methylacrylate, ethylacrylate, propylacrylate, butylacrylate, n-hexylacrylate, 2-phenoxyethylacrylate, isobornylacrylate, isodecylacrylate, polypropylene glycol monoacrylate, tetrahydrofurylacrylate, hydroxyethylacrylate, hydroxypropylacrylate, hydroxyethylmethacrylate, hydroxypropylmethacrylate, a mixture comprising at least one of said (meth)acrylates and/or copolymers comprising one or at least two of the afore-mentioned monomers, polyamide particles, polyamide fibers, particularly preferred is polymethylmethacrylate (PMMA).

16. Polymerised prosthetic material obtainable by a method according to claim 13, wherein the prosthetic material is present in the form of a three-dimensional moulded body.

17. Polymerised prosthetic material according to claim 16, which has a fracture toughness of 1.9 MPa.Math.m.sup.1/2 and a total fracture work of 900 J/m.sup.2.

18. Method of using core-shell particles modified by at least one elastic phase for the production of milling blanks.

19. Method of using a milling blank according to claim 1, for the production of dental or orthopedic components, prosthesis base plates, occlusal splints, crowns, bridges, artificial teeth, veneers, inlays, onlays, orthodontic appliances, active or passive orthodontic appliances, Crozat-appliances, modified activators, implants, superstructures, dental bars, abutments, dental fastening means, dental screws, surgical guides for implantology, telescopic prostheses and telescopic crowns, mouthguards, artificial articular protheses, braces, brackets, multibracket appliances, orthodontic instruments and/or multiband appliances or of at least parts of the afore-mentioned components, in the veterinary field, for hoof repair components.

Description

EXEMPLARY EMBODIMENT

[0105] Producing the Powder Mixture (B) According to the Invention:

[0106] A mixture is produced from PMMA beads of different grain sizes (bead 1 homopolymer (d.sub.5040-50 m) 60-70%, bead 2 (d.sub.5055-70 m) 15%, bead 3 copolymer (d5040-50 m) 15%) with the addition of barbituric acid and colour pigments.

[0107] Producing the Liquid/Monomer Mixture (A) According to the Invention:

[0108] A mixture is produced from methylmethacrylate, and another methacrylate-based multi-crosslinker with the addition of stabilizers and initiators (barbituric acid/copper-system). In addition, the urethane dimethacrylate according to the invention, as well as the core-shell particles according to the invention are being added.

[0109] Example according to the invention powder mixture and liquid mixture:

TABLE-US-00001 Liquid Example 1 methylmethacrylate 93.3 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-((hexyl)oxy)- 0.3 phenol N-methyl-N,N-dioctyloctane-1-ammoniumchloride 0.2 solution of copper(II) chloride 0.1 N,N-Bis(2-hydroxyethyl)-p-toluidine 0.1 total 94.00 di-functional aliphatic urethane acrylate oligomer 3.00 tris(2-hydroxyethyl)-isocyanurate triacrylate 1.00 core-shell particles 2.00 total 100.00

TABLE-US-00002 Powder PMMA/PMA d.sub.50~40-45 m 67.5 PMMA d.sub.50~40-55 m 15.000 cross-linked PMMA d.sub.50~55-70 m 15.000 phenylbenzylbarbituric acid 2.5 total 100.000

TABLE-US-00003 TABLE 1 Comparison of the example according to the invention and the comparative examples Physical properties (Norm ISO 20795-1) Example 1 PMMA flexural strength [MPa] >60 71.1 85.9 E-modulus [MPa] >1500 2389 2518 fracture toughness [MPa m1/2] >1.9 2.36 1.42 total fracture work [J/m.sup.2] >900 1030.85 197.64 transparency [delta %] (after 6 3.16 d/37 C. of storage in Ringer's solution)

[0110] Production of Test Bodies, Determination of Colour Values, Determination of Mechanical Properties:

[0111] Colour Test Bodies:

[0112] The following powder mixtures and monomer mixtures at a ratio of 10 g powder to:7 ml liquid are being vigorously mixed and test bodies with dimensions of 30303 mm are being poured after the swelling phase (approximately 5 min at 23 C.) and being polymerised in Palamat elite for 30 min at 55 C. and 2 bar pressure.

[0113] Test Bodies for Mechanical Strength:

[0114] The following powder mixtures and monomer mixtures at a ratio of 150 g powder:105 ml liquid are being vigorously mixed for about 30 seconds and test bodies are being poured into a metal mould after the swelling phase (approximately 3 min at 23 C.). The metal mould brass tube closed at one side having an inner diameter of 102 mm and a height of 50 mm. The polymerisation proceeds in a pressure pot Palamat elite for 30 min at 55 C. and 3.8 bar pressure.

[0115] The test bodies are being milled out of the received milling blank by means of CAD/CAM according to the requirements of ISO 20795-1 and tested.

[0116] Test bodies for colorimetric tests are produced in duplicating gels.

[0117] To determine the transparency, the test bodies are stored for 5 days in Ringer's solution at 37 C., and the colour values and transparency are determined both before and after storage using 3 mm-plates. The measurements of table 1 are made according to DIN EN ISO 20795-1.

[0118] The monomer mixture according to the invention shows significantly improved fracture toughness over all comparative examples, increased transparency, as well as the least loss of transparency after storage in Ringer's solution (reduced tendency to whitening).