METHODE POUR FABRIQUER DES DENTS ARTIFICIELLES ET DE PROTHESES DENTAIRES AUXILIAIRES

METHOD FOR PRODUCING TOOTH REPLACEMENTS AND AUXILIARY DENTAL PARTS

Abrégé français

L'application du processus de frittage laser, dans lequel des pièces façonnées faites d'une poudre de frittage sont formées en couches en exposant successivement chaque couche à l'énergie d'un faisceau laser qui conduit à un frittage local, de sorte que le faisceau laser est guidé au-dessus de la couche de poudre respective au moyen d'un système commandé par ordinateur en utilisant des données qui représentent la configuration du corps façonné dans cette couche, pour la production d'éléments de remplacement de dents (couronnes, bridges, incrustations et autres similaires) et/ou de pièces dentaires, de sorte que la poudre comprenne un matériau biocompatible de granulométrie variant entre 0 et 50 Mu m.

Abrégé anglais

Application of the laser sintering process, in which shaped pieces made of a sintering powder are built up in layers by exposing each layer successively to the energy of a laser beam that leads to local sintering, whereby the laser beam is guided over the respective powder layer by means of a computer-controlled system using data that represent the configuration of the shaped body in this layer, for the production of tooth replacement elements (crowns, bridges, inlays and the like) and/or dental parts, whereby the powder comprises a biocompatible material of varying grain size between 0 and 50 µm.

Revendications

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CLAIMS:

1. Method for producing tooth replacement elements or auxiliary dental parts,
wherein the method comprises a laser sintering process, in which shaped bodies
made of a sintering powder are built up in layers by exposing each layer
succes-
sively to the energy of a laser beam that leads to local sintering, whereby
the laser
beam is guided over the respective powder layer by means of a computer-
controlled
system using data that represent the configuration of the shaped piece in this
layer,
whereby the powder comprises a biocompatible material of varying grain sizes
between 0 and 50 µm.

2. Method according to claim 1, characterized by the fact that the powder
comprises an alloy with essentially equal proportions of the alloy components
in
each grain of powder.

3. Shaped body for use as a tooth replacement or as dental auxiliary parts,
wherein the shaped body is built of a powder being laser sintered and
comprising a
biocompatible material of varying grain sizes between 0 and 50 pm and by
applica-
tion of a method according to claim 1 or 2.

Description

CA 02295896 2000-O1-14
SEGO Bremer Goldschlagerei Wilh. Herbst GmbH & Co.,
Wilhelm-Herbst-Strat3e 1, 28359 Bremen, Germany
Method for producing tooth replacements and auxiliary dental parts
Tooth replacements in the form of crowns, bridges, inlays and the like
frequently
comprise complex molded bodies which must usually take account in each
specific case of the spatial configuration of intact tooth parts (tooth
stumps),
entire teeth or parts of the jaw that have been lost, on the one hand, and the
spatial situation in relation to adjacent and/or antagonistic teeth, on the
other
hand. In the prior art, such tooth replacement elements are produced in
complex
processes. The most widespread method is to produce the shaped bodies
required - usually made of precious-metal or base-metal alloys, as well as
pure
metals - in a multi-step impression and casting process. However, computer-
controlled milling of such shaped bodies out of the solid material, which
inevitably leads to considerable waste that has to be reprocessed at great
effort
and expense, has also become known.
The objective of the invention is to provide another, more advantageous way of
producing such shaped bodies (and auxiliary dental parts required in
implantology).


CA 02295896 2000-O1-14
-2-
The invention uses a method that has become known in another field as "rapid
prototyping" for producing complex tools or components. According to said
method, shaped bodies made of a sintering powder are built up in layers by
exposing each layer successively to the energy of a laser beam that leads to
local
sintering, whereby the laser beam is guided over the respective powder layer
by
means of a computer-controlled system using data that represent the
configuration
of the shaped piece in this layer. As a result of supplying such energy, the
powder
elements affected in each case are superficially melted and form a fixed bond
with
each other. Due to the precise focusing of the laser beam, the energy supply
can
be configured exactly - at high density - and controlled in accordance with
the
stored spatial data of the shaped body required.
Furthermore, the invention provides for a powder consisting of a biocompatible
material of varying grain size between 0 and 50 Nm. In contrast to current
application of the laser sintering method for technical purposes, the
invention thus
ensures that the shaped body designed for dental purposes is compatible with
human tissue (see Hoffmann-Axthelm, Lexikon der Zahnmedizin [Encyclopedia of
Dental
Medicine], 6th/1lth edition, p. 97, and Reuling, Biokompatibilitat dentaler
Lec~ieruncten [Biocompatibility of Dental Alloys]). The grain size
distribution ensures
extremely dense sintering with the advantage of a high compressive load
capacity
of the shaped body and minimal creation of cavities, which would be
susceptible
to bacteria cultures forming; in addition, it defines the size and fitting
accuracy of
the restoration.
However, it is also possible to carry out precise local compacting of the
powdery
initial material in another way, whether by supplying energy in a different
manner
or, - in the case of plastics as the initial material - by controlling locally
confined
polymerization. In general, however, optically focusable electromagnetic
radiation
is preferable to other means of energy transfer, such as corpuscular radiation
carried out in a vacuum.
Due to its certain degree of roughness, the sintering surface of the shaped
body
produced in accordance with the invention is particularly well-suited for the
frequently desired veneering process using ceramic or other materials, as is
the
case with crowns or bridges. Furthermore, because it is easy to influence the
file
on which the control process is based, it is possible to make corrections to
the
configuration of the shaped body that may appear desirable (with respect to
the
traced result) for a wide variety of reasons.


CA 02295896 2004-07-21
-3-
The powder preferably comprises an alloy with essentially equal proportions of
the
alloy components in each grain of powder. This provides a major advantage
compared to the conventional production of shaped dental bodies from melted
alloys, because there is no risk of segregation of the alloy components in the
melt
and/or in the shaped body after casting. In addition, the production of semi-
finished
products that are made of certain alloys and are particularly advantageous for
dental
purposes necessitates complicated and costly processes, such as suction
casting
and the like, whereas pulverization of such alloys is significantly less
complex.
However, whereas a melt produced from such a powder (for subsequent production
of shaped cast bodies) is exposed for its part to the risk of segregation and
thus
non-homogeneity, a shaped body that is sintered according to the invention
main-
tains its uniform distribution of alloy components.
A metal powder with the following composition has proved effective for use
with the
method according to the invention, whereby the method is not confined to said
composition:
Ni (Nickel) 61.4


Cr (Chromium) 22.9


Mo (Molybdenum) 8.8


Nb (Niobium) 3.9


Fe (Iron) 2.5


Mn (Manganese) 0.4


Ti (Titanium) 0.1


Total 100