Micaceous-cordierite-glass ceramic

A stomatological composition for inlays, crowns, structures and bridges, especially of a lateral tooth area, comprising

• a high-strength base body;
• and
• a micaceous-cordierite-glass ceramic at least partially enclosing said high-strength base body, said micaceous-cordierite-glass ceramic having a fracture toughness K.sub.IC of up to 2.0 MPa m.sup.178 , a hardness HV.sub.0.07 of 300-1000, a compressive strength of up to 450 N/mm.sup.2, a linear thermal expansion coefficient of 75-125.times.10.sup.-7 K.sup.1, good chemical stability and excellent machineability as well as high resistance to abrasion and comprising a composition of said micaceous-cordierite-glass ceramic consisting essentially in weight percentages of
• ______________________________________ SiO.sub.2 43-50 Al.sub.2 O.sub.3 26-30 MgO 11-15 R.sub.2 O 7-10.5 F.sup.- 3.3-4.8 Cl.sup.- 0.01-0.6 CaO 0.01-3 P.sub.2 O.sub.5 0.1-5 ______________________________________
• wherein R.sub.2 O is the sum of 3 to 5.5 wt-% Na.sub.2 O and 4 to 6 wt-% K.sub.2 O, a first crystal phase of mica, and a second crystal phase of 5 to 30 volume-% cordierite, wherein relatively large mica crystals of 10 to 200 .mu.m are embedded in the glass ceramic and cordierite crystals of 0.5 to 5 um are arranged in the glass ceramic.

A veneer laminate for the facing of teeth made of synthetic resin, metal frames, or natural teeth, comprising

• a vestibulary layer of a micaceous-cordierite-glass ceramic,
• an oral layer of an organic synthetic material or compound material, and
• an adhesion, facilitator layer interconnecting said vestibulary and oral layers,
• wherein said micaceous-cordierite-glass cereamic has a fracture toughness K.sub.IC of up to 2.0 MPa m.sup.1/2, a hardness HV.sub.0.07 of 300-1000, a compressive strength of up to 450 N/mm.sup.2, a linear thermal expansion coefficient of 75-125.times.10.sup.-7 K.sup.-1, good chemical stability and excellent machineability as well as a high resistance to abrasion and comprises a composition of said micaceous-cordierite-glass ceramic consisting essentially in weight percentages of
• ______________________________________ SiO.sub.2 43-50 Al.sub.2 O.sub.3 26-30 MgO 11-15 R.sub.2 O 7-10.5 F.sup.- 3.3-4.8 Cl.sup.- 0.01-0.6 CaO 0.1-3 P.sub.2 O.sub.5 0.1-5 ______________________________________
• wherein R.sub.2 O is the sum of 3 to 5.5 wt-% Na.sub.2 O and 4 to 6 wt-% K.sub.2 O, a first crystal phase of mica, and a second crystal phase of 5 to 30 volume-% cordierite, wherein relatively large mica crystals of 10 to 200 .mu.m are embedded in the glass ceramic and cordierite crystals of 0.5 to 5 .mu.m are arranged in the glass ceramic.

Micaceous-cordierite-glass ceramic for stomatological purposes having a fracture toughness K.sub.IC of up to 2.0 MPa m.sup.1/2, an adjustable hardness HV.sub.0.07 of 300-800, a compressive strength of up to 450 N/mm.sup.2, an adjustable linear thermal expansion coefficient of 80 to 120.times.10.sup.-7 K.sup.-1, good chemical stability, excellent machineability, a high resistance to abrasion, a bending fracture strength of more than 80 MPa, a hydrolytic stability of class 1 or 2, a roughness depth of 0.15 .mu.m and X-ray opacity, comprising a compositon of said micaceous-cordierite-glass ceramic consisting essentially in weight percentages of

• ______________________________________ SiO.sub.2 43-50 Al.sub.2 O.sub.3 26-30 MgO 11-15 R.sub.2 O 7-10.5 F.sup.- 3.3-4.8 Cl.sup.- 0.01-0.6 CaO 0.1-3 P.sub.2 O.sub.5 0.1-5 ______________________________________
• wherein R.sub.2 O is the sum of 3 to 5.5 wt-% Na.sub.2 O and 4 to 6 wt-% K.sub.2 O, a first crystal phase of mica, and a second crystal phase of 5 to 30 volume-% cordierite, wherein relatively large mica crystals of 10 to 200 .mu.m are embedded in the glass ceramic and cordierite crystals of 0.5 to 5 .mu.m are arranged in the glass ceramic, and wherein properties of the glass ceramic can be adjusted to the properties of natural tooth enamel, to provide a glass ceramic useful for inlays, crowns, structures and bridges, especially of a lateral tooth area.

Micaceous-cordierite-glass ceramic having a fracture toughness K.sub.IC of up to 2.0 Mpa m.sup.1/2, a hardness HV.sub.0.07 of 300-1000, a compressive strength of up to 450 N/mm.sup.2, a linear thermal expansion coefficient of 75-125.times.10.sup.-7 K.sup.-1, good chemical stability and excellent machineability as well as a high resistance to abrasion, comprising a composition of said micaceous-cordierite-glass ceramic consisting essentially in weight percentages of

• ______________________________________ SiO.sub.2 43-50 Al.sub.2 O.sub.3 26-30 MgO 11-15 R.sub.2 O 7-10.5 F.sup.- 3.3-4.8 Cl.sup.- 0.01-0.6 CaO 0.1-3 P.sub.2 O.sub.5 0.1-5 ______________________________________
• wherein R.sub.2 O is the sum of 3 to 5.5 wt-% Na.sub.2 O and 4 to 6 wt-% K.sub.2 O, a first crystal phase of mica, and a second crystal phase of 5 to 30 volume-% cordierite, wherein relatively large mica crystals of 10 to 200 .mu.m are embedded in the glass ceramic and cordierite crystals of 0.5 to 5 .mu.m are arranged in the glass ceramic, wherein said micaceous-cordierite-glass ceramic is formed in the shape of an adhesive bracket for application in dental orthopedics and orthodontics, said bracket comprising a wall thickness of at least 1 mm, a maximum height of 3 mm, a bottom portion having a length of 2.5 to 6 mm and a top wing portion, said bottom portion having a roughness of more than 5 .mu.m, said bracket being provided with a slit having a width of 0.45 to 0.55 mm and a depth of 0.63 to 0.71 mm and extending in the direction of the length of said bottom portion, said glass ceramic adhesive bracket being machineable during clinical utilization so as to be fitted to the anatomy of a tooth.

Micaceous-cordierite-glass ceramic having a fracture toughness K.sub.IC of up to 2.0 MPa m.sup.1/2, a hardness HV.sub.0.07 of 300-1000, a compressive strength of up to 450 N/mm.sup.2, a linear thermal expansion coefficient of 75-125.times.10.sup.-7 K.sup.-1, good chemical stability and excellent machineability as well as a high resistance to abrasion, comprising a composition of said micaceous-cordierite-glass ceramic consisting essentially in weight percentages of

• ______________________________________ SiO.sub.2 43-50 Al.sub.2 O.sub.3 26-30 MgO 11-15 R.sub.2 O 7-10.5 F.sup.- 3.3-4.8 Cl.sup.- 0.01-0.6 CaO 0.1-3 P.sub.2 O.sub.5 0.1-5 ______________________________________
• wherein R.sub.2 O is the sum of 3 to 5.5 wt-% Na.sub.2 O and 4 to 6 wt-% K.sub.2 O, a first crystal phase of mica, and a second crystal phase of 5 to 30 volume-% cordierite, wherein relatively large mica crystals of 10 to 200 .mu.m are embedded in the glass ceramic and cordierite crystals of 0.5 to 5 .mu.m are arranged in the glass ceramic, and wherein said micaceous-cordierite-glass ceramic is formed in the shape of an adhesive button for application in dental orthopedics and orthodontics, said button comprising a wall thickness of at least 1 mm, a maximum height of 3 mm and a base portion having base edges each measuring 2.5 to 3 mm, said base portion having a roughness of more than 5 .mu.m, and said ceramic adhesive button being workable during clinical utilization so as to be fitted to the anatomy of a tooth.