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(12) United States Patent ao) Patent No.: us 6,607,386 Bi
Andersson et al. (45) Date of Patent: Aug. 19,2003
(54) METHOD AND DEVICE FOR, AND USE OF, A DENTAL PRODUCT
(75) Inventors: Matts Andersson, Lerum (SE); Elis Carlstrom, Gothenburg (SE); Mikael Eriksson, Gothenburg (SE)
(73) Assignee: Nobel Biocare AB, Gothenburg (SE)
( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 09/786,918
(22) PCT Filed: Sep. 8, 1999
(86) PCT No.: PCT/SE99/01559
§ 371 (c)(1),
(2), (4) Date: Jul. 5, 2001
(87) PCT Pub. No.: WO00/15137 PCT Pub. Date: Mar. 23, 2000
(30) Foreign Application Priority Data
Sep. 11, 1998 (SE) 9803075
(51) Int. C I. A61C 5/10
(52) U.S. C I 433/201.1
(58) Field of Search 433/201.1, 223,
433/207, 206, 218
(56) References Cited
U.S. PATENT DOCUMENTS
4,661,071 A * 4/1987 Bell et al 433/223
A dental product is produced from material in powder form. In a first manulacturing stage, the product is given a shape which is larger than its final shape, and in lurther manulacturing stages the product is subjected to material shrinkage, sintering and working in order to obtain its final shape. Metal powder is applied to the mold tool, and the mold tool with the applied metal powder is placed in pressuregenerating equipment where the powder applied to the mold tool is subjected to compaction pressure which compacts the powder so that at least 80% basic density is obtained in the material. The compacted material is then machined. After machining, the compacted material is removed from the mold tool. The sintering stage is then carried out so that the final shape is obtained.
30 Claims, 2 Drawing Sheets
METHOD AND DEVICE FOR, AND USE OF, A DENTAL PRODUCT
TECHNICAL FIELD 5
The present invention relates to a method for producing a dental product or other product for the human body using material in powder form. In a first manufacturing stage, with the aid of a mould tool, the product is given a shape which is larger than its final shape, and in further manufacturing stages the product is subjected to working and material shrinkage/sintering to obtain the final shape. The invention also relates to a product intended as a component in a dental application or other application in the human body, where it cooperates with members in the form of implants, attachment parts for implants, bones, for example dentine, tooth remnants, etc. The product is made up from worked and sintered and worked powder material. The invention also relates to a use of the product of the said type. 2Q
It is already known to make products or bodies of the type in question using powder material in the form of ceramic powder. In this context, it is known to use mould tools in 25 which the ceramic powder is applied. The mould tool is given a larger shape or size. The ceramic powder is applied in the mould and is exposed to compression forces, after which the compressed body is worked and shrunk further in a sintering process. 30
Reference may be made in entirely general terms to manufacturing principles which are proposed and used in the Procera technique for manufacturing products of the type in question and where, inter alia, final outer shapes are produced from enlarged outer shapes. 35
Thus, from U.S. Pat. No. 5,192,173 (with the same inventor) it is already known to create a linearly enlarged shape on the tool in question. Reference is also made to European Patent 384,908 Bl same inventor) which shows that a linearly enlarged body can be subjected to a sintering process so as to be given its desired final shape.
It is also known to make products or bodies of the abovementioned type from metal. The outer shape of the product is in this case turned or milled from a blank. An ^ electro-oxidation tool with an outer shape corresponding to the inner shape of the product is made and is used for producing the inner surface of the product by means of electro-oxidation.
DISCLOSURE OF THE INVENTION TECHNICAL PROBLEM
The production of ceramic products and metal products has hitherto had to be carried out using two completely different techniques which have been employed within the 55 technical area of dental technology and technology related to the human body. This has divided resources for manufacturers of these types of products and other products for the human body. There is a requirement for the technical resources to be brought together more effectively and, for go example, for the same types of personnel to be used to produce caps, spacers, bridges, etc. The invention aims to solve this problem among others.
In the sector concerned with the manufacture of products, for example caps, made of metal material, consideration has 65 been given to imitating the principles used for ceramic caps or equivalent. However, there has been strong technical
opposition and considerable bias against its being possible, in serial manufacture of structurally robust caps/products which are to function in a technically severe environment (in the patient's mouth) and therefore must have strict strength requirements and at the same time upholding the precision requirements, to be able to manufacture caps/products in the same way as in ceramic production.
The invention counters this strong technical opposition and bias and takes a completely new approach in order to permit a new type of manufacture of caps/products of the type in question.
There is a need to technically simplify, and to make less expensive, the previous manufacture of caps and other dental products using mechanical working and electrooxidation. The invention solves this problem too and now proposes principles in which previous strength and precision requirements (0.2 fim) can also be maintained.
In connection with the new principles for production of caps/products made of metal, there is a need to be able to vary the strength requirements, precision requirements, manufacturing process, etc. The invention solves this set of problems too and is not confined to individual procedures for achieving the requirements set. The new principles are especially suited to titanium powder which has the best biocompatible character. However, there have been strong doubts as to whether it is in principle possible to make caps and similar products from titanium powder material.
The feature which can principally be regarded as characterizing a method according to the invention is that metal powder is applied to the mould tool, and that the mould tool with the applied metal powder is placed in pressuregenerating equipment where the powder applied to the mould tool is subjected to compaction pressure which compacts the powder so that at least an 80 percent basic density is obtained in the material, and that thereafter the material compacted on the mould is first machined and then removed from the mould tool, after which the said material shrinkage/ sintering stages are carried out so that the final shape is obtained, and at the same time a porosity of at most about 6 percent by volume, preferably at most 2 to 3 percent by volume, is obtained in the sintered product.
In one embodiment, the outer shape of the product is produced or worked (in an enlarged state), after which the product's final shape is obtained in the sintering process. The product is given a distinct or substantial homogeneity with respect to the distribution of the porosity. The material of the product is treated in such a way by the new method that it becomes ductile (substantially ductile) so that there is no tendency to crack or fracture under the effect of force.
In one proposed embodiment, the powder, on application to the mould tool in question, or stamp, is arranged in a powder-receiving unit in which the outer shape of the stamp can be lowered so that the powder surrounds the outer surface of the stamp. The powder can in this case be poured or applied into a tube-like or rubber bladder-like powderreceiving unit with elastic wall, which for example can be a silicone wall, via which the pressure is allowed to act in the pressure-generating equipment. The powder material chosen is preferably titanium powder which can comprise powder of the type TWC-f, whose particles are deformed by the compaction or the action of pressure in the pressuregenerating equipment. The de-moulding of the compacted metal powder from the mould tool or stamp is preferably done in a bath of liquid nitrogen/air, and the stamp and the