Patent Description:
Dental instruments can be used to manipulate various materials which are placed, shaped, and sculpted during procedures. Point flexibility for these instruments is desirable as flexibility aids tremendously in the sculpting and shaping of the material. Commonly, instruments of these types can be manufactured from steel. Given the metallurgic properties of steel, however, manufacturing instruments from steel results in relatively rigid points. Further, if steel points are thinned and used to manipulate materials in the desired manner, the points can break over time, if not immediately, making them potentially unsafe to use.

Prior art is exemplified by <CIT> which discloses a surgical instrument which can acquire an optimal shape during a surgery.

The invention relates to a dental instrument as defined by independent claim <NUM> and to a method of manufacturing a dental instrument as defined by independent claim <NUM>.

The above needs are at least partially met through provision of the embodiments described in the following detailed description, particularly when studied in conjunction with the drawings, wherein:.

For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.

Dental instruments, assemblies, and components for a dental instrument are described herein with a flexible tip end and a stiff shank. A two-material dental instrument component achieves these beneficial results by utilizing the preferred properties of the two materials. In embodiments, the shank can be a stiff material, such as stainless steel, and the tip end can be a NiTi foil, also known as Nitinol foil. Nitinol foil advantageously provides a flexible tip that resiliently bends without breaking.

Example configurations and components for a dental instrument <NUM> are shown in <FIG>. As shown in <FIG>, the dental instrument <NUM> includes a handle portion <NUM> having a shaft configuration for a user to grip and manipulate the dental instrument <NUM>. The handle portion <NUM> has opposite first and second ends <NUM>, <NUM> that can be configured to have a shank <NUM> coupled thereto, if desired. In the illustrated form, the first and second ends <NUM>, <NUM> have a tapered configuration to provide a transition to the relatively smaller diameter of the shank <NUM>.

An example shank <NUM> is shown in <FIG> that includes a coupling end portion <NUM> configured to engage one of the ends <NUM>, <NUM> of the handle <NUM>, a tapering portion <NUM>, first and second bends <NUM>, <NUM>, an intermediate portion <NUM> extending between the first and second bends <NUM>, <NUM>, and a distal portion <NUM> extending from the second bend <NUM> to a distal end <NUM> of the shank <NUM>. The tapering portion <NUM> decreases a diameter of the shank <NUM> from adjacent to the handle <NUM> to the relatively smaller diameter intermediate and distal portions <NUM>, <NUM>, which can have a generally constant diameter.

The first bend <NUM> directs the shank <NUM> along a horizontal plane away from a longitudinal axis L (<FIG>) of the handle <NUM> and the second bend <NUM> directs the shank <NUM> along the horizontal plane back towards the longitudinal axis L of the handle <NUM>. In the illustrated form, the second bend <NUM> is a generally <NUM> degree bend and the intermediate portion <NUM> has a longer longitudinal length than the distal portion <NUM>, such that the distal end <NUM> of the shank <NUM> is spaced from the longitudinal axis L of the handle <NUM> along the horizontal plane. Of course, other bend and length configurations are within the scope of this disclosure.

The distal end <NUM> of the shank <NUM> includes opposing planar sides <NUM> extending inwardly with respect to one another to a rectangular end surface <NUM>. With the distal portion <NUM> being cylindrical, in the illustrated form, the planar sides <NUM> have a parabolic shape. A slot <NUM> with an opening <NUM> disposed along the end surface <NUM> extends within the distal portion <NUM> along a longitudinal axis X (<FIG>) thereof to a desired depth. In the illustrated form, the slot <NUM> extends through the width of the distal end <NUM>. In one example, and as depicted in <FIG>, the slot <NUM> may further include openings <NUM> along an exterior <NUM> of the distal portion <NUM>. The slot <NUM> can be cut into the distal end <NUM> of the shank <NUM> in a hatchet and/or hoe orientation by an electric discharge machining (EDM) wire, micro saw blade, mill, and so forth.

A tip end <NUM> is coupled to the distal end <NUM> of the shank <NUM> to provide desirable characteristics for a particular dental procedure. By one approach, and referring now to <FIG>, the tip end <NUM> is a spatula tip having a thin planar body <NUM> with a curved forward portion <NUM> and a rectangular rear portion <NUM>. As discussed above, the shank <NUM> and tip end <NUM> are different materials and, as such, are secured together with a suitable method, examples of which are described below with reference to <FIG>. The tip end <NUM> also includes an aperture <NUM> extending through the rear portion <NUM> and corresponds to an aperture in the distal end <NUM> of the shank <NUM>, as described more below.

In each securing example, the tip end <NUM> is inserted into the slot <NUM> to mount to the distal end <NUM> of the shank <NUM>. The orientation of the planar sides <NUM> with respect to the horizontal plane can provide a hoe orientation for the tip end <NUM> or a hatchet orientation for the tip end <NUM>, as desired. In addition, in each example, the shank <NUM> may comprise a stiff material, such as stainless steel, and the tip end <NUM> may comprise a NiTi foil, also known as Nitinol foil.

In one form, the dental instrument <NUM> includes shanks <NUM> on both sides <NUM>, <NUM> of the handle <NUM> with one shank <NUM> having distal end <NUM> with a hoe orientation where the tip end <NUM> is generally orthogonal to the horizontal plane and the other shank <NUM> having a distal end <NUM> with a hatchet orientation where the tip end <NUM> is generally parallel with the horizontal plane to provide a user with both functionalities. Further, if desired, the tip end <NUM> and slot <NUM> can be configured so that forward portion <NUM> of the tip end <NUM> extends to intersect the longitudinal axis L of the handle <NUM> so that a user has precise manipulation of the tip end <NUM>.

In a first embodiment, shown in <FIG>, the tip end <NUM> is secured to the distal end <NUM> of the shank <NUM> with a pin <NUM>. More specifically, the distal end <NUM> of the shank <NUM> has an aperture <NUM> extending radially through a portion thereof including the slot <NUM> in a direction generally orthogonal to the longitudinal axis X of the distal portion <NUM>. The aperture <NUM> of the tip end <NUM> corresponds to the aperture <NUM> of the distal end <NUM> of the shank <NUM>. So configured, with the rear portion <NUM> inserted into the slot <NUM>, the pin <NUM> can be inserted through both the aperture <NUM> and the aperture <NUM> to secure the tip end <NUM> to the shank <NUM>. By one approach, the pin <NUM> can have a cross-section dimension greater than one or both of the apertures <NUM>, <NUM> so that the insertion of the pin <NUM> therethrough creates an interference fit. Further, the pin <NUM> can be permanently joined to the shank <NUM> by swaging and grinding an outer surface <NUM> of the pin <NUM> so that the outer surface <NUM> is smooth and aligned with adjacent portions of the shank <NUM>. In the illustrated form, the pin <NUM> and apertures <NUM>, <NUM> are cylindrical. Of course, other shapes and configurations can alternatively be used. For example, the pin <NUM> and apertures <NUM>, <NUM> can have a cross-section shape to aid in resisting rotation of the tip end <NUM>, such as a triangle, square, star, ovular, and so forth.

In a second embodiment, shown in <FIG>, the shank <NUM> has a configuration similar to the above embodiment and, as such, only the differences will be described. In this form, the tip end <NUM> is secured to the distal end <NUM> of the shank <NUM> with a second pin <NUM> in addition to the first pin <NUM>. As such, the distal end <NUM> of the shank <NUM> has a second aperture <NUM> that extends radially through a portion thereof including the slot <NUM> in a direction generally orthogonal to the longitudinal axis X of the distal portion <NUM>. The second aperture <NUM> is spaced from the first aperture <NUM> along a length of the distal portion <NUM>. The tip end <NUM> includes a corresponding second aperture <NUM> that extends through the rear portion <NUM> thereof, as depicted in <FIG>. So configured, with the rear portion <NUM> inserted into the slot <NUM>, the second pin <NUM> can be inserted through the aligned second apertures <NUM>, <NUM> to further secure the tip end <NUM> to the shank <NUM>. Using a plurality of pins <NUM>, <NUM> accommodates a larger tolerance stack when installing the tip end <NUM> to the shank <NUM>, which advantageously results in more efficiencies during manufacturing. For example, the length of the tip rear portion <NUM> is on the shorter end of the tolerance and the depth of the shank slot <NUM> is on the larger end of the tolerance, a gap would exist that would allow for rotation of the tip end <NUM>. Using two or more points to secure the tip end <NUM> to the shank <NUM> prevents tip rotation in such a tolerance scenario.

By one approach, the second pin <NUM> can have a cross-section dimension greater than one or both of the second apertures <NUM>, <NUM> so that the insertion of the second pin <NUM> therethrough creates an interference fit. Further, the second pin <NUM> can be permanently joined to the shank <NUM> by swaging and grinding an outer surface <NUM> of the second pin <NUM> so that the outer surface <NUM> is smooth and aligned with adjacent portions of the shank <NUM>. In the illustrated form, the second pin <NUM> and apertures <NUM>, <NUM> are cylindrical. Of course, other shapes and configurations can alternatively be used. For example, the pins <NUM>, <NUM>, and apertures <NUM>, <NUM>, <NUM>, <NUM> can have a cross-section shape to aid in resisting rotation of the tip end <NUM>, such as a triangle, square, star, ovular, and so forth. Further, although only two pins are shown, it will be understood that additional pins can be utilized and configured in a similar manner.

In a third embodiment, the slot <NUM> can have a wider configuration relative to the thickness of the tip end <NUM> as compared to the above embodiments. This allows the tip end <NUM> to be inserted into the slot <NUM> with little to no resistance. After the tip end <NUM> has been inserted into the slot <NUM> to a desired depth, a user can then pinch the planar sides <NUM> of or otherwise physically deform the distal end <NUM> of the shank <NUM> to clamp down on the tip rear portion <NUM> to secure the tip end <NUM> to the shank <NUM>. This clamping action can be achieved by the use of any suitable tools.

In other embodiments, shown in <FIG>, the tip rear portion <NUM> can be inserted into the slot <NUM> and secured therein using a third material <NUM>. In a first example, the third material <NUM> is an adhesive disposed within the slot <NUM> or applied to the tip rear portion <NUM>. In a second example, the third material <NUM> is a filler metal flowed into the joint between the tip end <NUM> and shank <NUM> in a brazing process. Utilizing an adhesive or a brazing process secures the tip end <NUM> to the shank <NUM> without the added steps and components of the above embodiments including forming the apertures <NUM>, <NUM>, <NUM>, <NUM> and inserting the pins <NUM>, <NUM>. Of course, an adhesive or brazing process can alternatively be used in combination with the pin embodiments discussed above to ensure that the tip end <NUM> is securely coupled to the shank <NUM>.

A stainless steel shank provides several advantages, including: a stiffness that provides maximum control and manipulation of the tip end for a user, good material formability enabling a two-bend shank configuration that allows a user access and visibility inside a patient's mouth, no reduction in appearance or strength of the shank after being sterilized multiple times, patient bio-compatibility, and a relatively low cost manufacturing to obtain a desired shank geometry.

A Nitinol foil tip end provides several advantages, including: superelastic flexibility at room temperature, about <NUM>-<NUM> times ordinary metal, for spreading and controlling composite onto a tooth, implant surface, or other application location, very good strain recovery allowing for excellent kink resistance even at very aggressive bend angles, an advantageous shape memory effect allowing the foil to recover an original shape upon heating above a transformation temperature after being deformed at a lower temperature, the Nitinol foil tip can be cut into a variety of tip end shapes allowing for a range of surface access and orientations, ability to sterilize the instrument multiple times with no reduction in appearance, flexibility, or strength, and patient bio-compatibility.

Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the scope of the invention as defined by the appended claims.

Claim 1:
A dental instrument comprising:
a handle (<NUM>);
a two-piece tip attached to the handle (<NUM>), the two-piece tip including:
a steel shank (<NUM>) including a distal portion (<NUM>) with an end surface (<NUM>), the distal portion (<NUM>) extending along a longitudinal axis, characterised in that the shank (<NUM>) has a bent configuration, comprising first and second bends (<NUM>, <NUM>) within a horizontal plane, wherein the end surface (<NUM>) includes a slot (<NUM>);
a Nickel Titanium foil tip end (<NUM>) being a spatula tip having a thin planar body with a rear portion (<NUM>) inserted within the slot (<NUM>) to couple the Nickel Titanium foil tip end (<NUM>) to the distal portion (<NUM>) of the shank (<NUM>); and
a material (<NUM>) disposed within the slot (<NUM>) between the rear portion (<NUM>) and the distal portion (<NUM>) to secure the Nickel Titanium foil tip end (<NUM>) to the steel shank (<NUM>).