DENTAL HANDPIECE

PIECE A MAIN DENTAIRE

English Abstract

A dental handpiece (10) of the type having a body (11), a head (13) and a neck
(12), is improved by having at least one portion of the handpiece (10) formed
by metal injection molding or MIM. The use of MIM allows for improved
fabrication and function. According to one aspect of the invention, the head
(13) and neck (12) of the handpiece (10) are MIM-formed as a single or unitary
piece.

French Abstract

L'invention concerne une pièce à main dentaire (10) du type présentant un corps (11), une tête (13) et un col (12) laquelle est améliorée du fait qu'au moins une partie de la pièce à main (10) est formée par moulage par injection de métal ou MIM. L'utilisation de MIM permet une fabrication et une fonction améliorées. Selon un aspect de l'invention, la tête (13) ainsi que le col (12) de la pièce à main (10) sont formés par moulage MIM d'une seule pièce ou en une pièce unitaire.

Claims

CLAIMS:
1. A dental handpiece fabricated by metal injection molding in a singular
mold as a contiguous piece, the dental handpiece comprising a head portion, a
neck
portion and a body portion, wherein the head portion and the neck portion
combined
have an ergonomic, non-circular shape and the neck portion has a shaped
aperture
for receiving a fiber optic bundle for the transmission of light.
2. The dental handpiece according to claim 1, wherein the dental
handpiece further comprises one or more internal structures.
3. The dental handpiece according to claim 2, wherein the internal
structure is an exhaust port or a fluid passage.
4. The dental handpiece according to any one of claims 1 to 3, further
comprising a body portion.
5. The dental handpiece according to claim 4, wherein the body portion
has a circular shape.
6. The dental handpiece according to any one of claims 1 to 5, which is
fabricated from stainless steel.
7. A method of fabricating a dental handpiece, comprising the step of
metal injection molding in a singular mold as one contiguous piece the
handpiece of
any one of claims 1 to 6.
8. A method of fabricating a dental handpiece having a head portion, a
neck portion and a body portion, comprising the step of metal injection
molding in a
singular mold as one contiguous piece the neck portion, the head portion and
the
body portion of the handpiece, to form a unified head and neck assembly having
an
ergonomic, non-circular cross-section, the neck portion having a shaped
aperture for
receiving a fiber optic bundle for the transmission of light, and internal
structures.
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Description

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DENTAL HANDPIECE
TECHNICAL FIELD
(0002) The present invention is a dental handpiece, or a portion
thereof. More particularly, the invention relates to a dental
handpiece, wherein a portion such as the head, neck or body, is
fabricated from a metal, such as stainless steel_ Specifically, the
invention relates to such a handpiece wherein at least a selected
portion of the handpiece is formed by metal-injection molding_
BACKGROUND OF THE INVENTION
(0003) The present invention is directed generally to improvements
in dental devices and more particularly to novel and improved dental
handpieces. Dental handpieces are known in the art. An exemplary
dental handpiece is shown by way of example, in U.S. Pat. No.
5,716,210, for such disclosure.
. _
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(0004) The present invention provides improvements in the quality
and ease of manufacture of such handpieces. In certain
circtunstances, the present invention may also allow for more
economic fabrication of such handpieces. While the present
invention has application to any and all portions of dental handpieces,
it has particular application to the head and neck portions of
handpieces. It will be understood however, that when the terms
"head and neck" or similar words are used, it is referring to all
portions of the handpiece, including without limitation, all housing
and body portions.
(0005) Present conventional methods of fabricating the head and
neck assembly of dental handpieces include: (1) machining from one
piece of solid metal stock; (2) machining the head and neck
separately, then welding or brazing them together, then machine
finishing (such as is used in the XGT handpiece available from
Dentsply International Inc.); (3) machining the head and neck
separately, then attaching the two with a press-fit, threaded
connection, or adhesive; and, (4) machining from a metal forging or
casting.
(0006) In methods 1 and 3, external shapes are limited to what can be
economically machined, which typically includes circular cross-
sections. Ergonomic, non-
circular, shapes would require
prohibitively expensive contour milling of the head and neck
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assembly. While method 4 does afford some design flexibility, these methods
require
extensive secondary machining to obtain the required precision and surface
finish,
due at least in part to the limited precision of forging and casting methods.
(0007) A need exists therefore, for an economically fabricated dental
handpiece that will allow for non-circular cross sections of the fabricated
product.
BRIEF SUMMARY OF THE INVENTION
(0008) It is therefore, an object of some embodiments of the
invention to
provide a dental handpiece.
(0009) It is an additional object of some embodiments of the
invention to
provide a dental handpiece that has at least some non-circular or "profiled"
cross
sections.
(0010) It is a further object of some embodiments of the invention to
provide
such a handpiece that is efficiently and economically produced.
(0010.1) According to one aspect of the present invention, there is
provided a
dental handpiece fabricated by metal injection molding in a singular mold as a
contiguous piece, the dental handpiece comprising a head portion, a neck
portion
and a body portion, wherein the head portion and the neck portion combined
have an
ergonomic, non-circular shape and the neck portion has a shaped aperture for
receiving a fiber optic bundle for the transmission of light.
(0011) Using metal injection molding (MIM) it is possible to achieve a
unified
head and neck assembly for a dental handpiece, with an ergonomic, non-circular
shape, substantially without any secondary machining of the exterior contours.
Further, MIM produces a "near net shape" part which requires relatively less
machining of internal features such as exhaust ports. Further still, it allows
these
internal
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features to have shapes that would be expensive or even impossible to
achieve with conventional machining.
According to one aspect of the present invention, there is provided a
method of fabricating a dental handpiece having a body portion, a neck
portion, and a head portion, comprising the step of metal injection
molding in a singular mold as one contiguous piece at least the neck and
head portion of the handpiece as a unified head and neck assembly
having non-circular cross-sections and internal structures.
BRIEF DESCRIPTION OF THE DRAWINGS
(0012) Fig. I is a side, perspective view of a handpiece according to some
embodiments of the present invention, the handpiece having body, head and
neck portions.
(0013) Fig. 2 is a perspective view of an alternative embodiment of a
head and neck portion of a dental handpiece.
(0014) Fig. 3 is a side elevational, partially broken away view of a
portion of the head and neck portion shown in Fig. 2.
(0015) Fig. 4 is a cross-sectional, side elevational view of the head
and neck portion of Fig. 2.
(0016) Fig. 5 is a front elevational view of the head and neck portion
of Fig. 2.
PREFERRED EMBODIMENTS FOR CARRYING OUT THE
INVENTION
(0017) An exemplary dental handpiece is generally designated by the
number 10 on the attached drawings. The present invention has
application to the manufacture or fabrication of all or any portion of a
dental handpiece, including for example, the body II, neck 12 or
head 13 thereof. The invention has particular application to the head
=
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13 and neck 12 portions of dental handpieces 10, because these
portions often have cross section with complex profiles, as shown in
Figs 2-5. For example, the neck 12 depicted in the drawings is
provided with a shaped aperture 20, which is useful with a fiber optic
bundle for the transmission of light. As stated above, such contoured
shapes can be machined or otherwise formed in conventional
handpieces, but with an increase in the time and expense involved if
accurate products are to be made.
(0018) As is conventional in the dental handpiece art, handpiece 10
may also be provided with internal structures such as fluid passages,
exhaust ports and the like (not shown). Fig. 4 shows an example of
internal structure, namely internal section 21. Again, such structures
have been fabricated in the past using expensive and difficult
techniques such as machining. The present invention fabricates
products such as those of handpiece 10 using metal injection molding
or MINI techniques. HIM is described in for example, U.S. Pat. Nos.
6,941,354 and 6,274,083. MIM techniques are conventional and need not
be described in detail. Conventionally, the MINI material is a mixture
of metal particles and a non-metallic binder material. One skilled in
the metallurgical arts can specify or select the mixture from a variety
of commercially available formulations to achieve the desired
properties for the resulting portion of the dental handpiece. The

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material selected to fabricate the product should be one
conventionally employed with dental devices, such as a stainless steel
or the like.
(0019) While any conventional MIM technique is within the scope of
the invention, one such technique includes a metal/binder mixture
that is preferably heated in a suitable injection-molding machine and
introduced under pressure into a mold, of which the contour
corresponds to those of the desired portion of the handpiece, such as
head 13 and neck 12.
(0020) There are other metal fabrication techniques that may be
employed to make a dental handpiece, such as die casting, rubber-
plaster casting, investment casting and the like, but it is believed that
none currently achieve the combination of metal density, ability to
mold stainless steel, reasonable finished cost, and high accuracy
afforded by MIM.
(0021) Metal injection molding (MIM) makes it possible to achieve a
unified head 13 and neck 12 assembly with an ergonomic, non-
circular shape, as is shown in the drawings. Employing NOM
according to the invention produces a "near net shape" part that
requires relatively less machining of internal features such as exhaust
ports. MIM allows these internal features to have shapes that would
be expensive or even impossible to achieve with conventional
machining.
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(0022) Of course, the use of MEV! to fabricate handpiece 10 can be
used to prepare any part thereof, including for example, portions
having a circular cross section such as in body 11. Similarly, while
the invention has application to contoured surfaces or those having a
"complex profile" it also has application to any other shape, such as
smooth or circular.
(0023) According to one embodiment of the invention, the head 13
and neck 12 are of unitary construction. That is, they are fabricated
in a singular mold as one contiguous piece. Of course, various parts
such as the body 11, neck 12 and head 13 may be formed as
individual components that are then joined, and still fall within the
scope of the invention. However, it has been found that the unitary
head 13 and neck 12 construction has particular and unexpected
advantages. The unified head and neck produced by MIM eliminates
a joint, which may reduce noise created by relative vibration between
the two parts. The unified construction eliminates the potential
safety/reliability problem caused by failure of the brazed joint in
conventional two-part construction, and it eliminates need for
separate fiber-optic ring part.
(0024) While particular embodiments of the invention have been
shown and described in detail, it will be obvious to those skilled in
the art that changes and modifications of the present invention, in its
various aspects, may be made without departing from the invention in
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its broader aspects, some of which changes and modifications being
matters of routine engineering or design, and others being apparent
only after study. As such, the scope of the invention should not be
limited by the particular embodiment and specific construction
described herein but should be defined by the appended claims and
equivalents thereof. Accordingly, the aim in the appended claims is
to cover all such changes and modifications as fall within the true
spirit and scope of the invention.
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Representative Drawing