DENTAL APPARATUS

The present invention relates to a clamp (100) for a tooth. The clamp (100) comprises a body (105) for adjustably supporting a band (110) such that a looped section (115) of the band (110) projects from the clamp (100). The clamp (100) further comprises a removable implement (120) configured to adjust a shape of the looped section (115) of the band (110) once the removable implement (120) has been removed from the clamp (100). The clamp (100) comprising the removable implement (120) may be used by a dentist during restorative procedures, e.g. to fill a tooth cavity.

FIELD

The present invention relates to a dental apparatus for use by a dentist during a restorative procedure such as treatment of a tooth cavity. More particularly, the present invention relates to a clamp for a tooth. The clamp may be of a type generally referred to as a dental matrix clamp.

BACKGROUND

Dentists typically use a dental apparatus, which may be referred to as a dental matrix clamp, when performing restorative procedures such as, for example, filling a tooth cavity. Known clamps comprise a body which is held in the hand by the dentist and a head from which a looped section of a band projects. The band may be referred to as a matrix band. The band typically comprises a strap formed from a thin sheet of metal having a looped section (formed from a central portion of the strap) which projects from the head of the clamp and a flat section (formed from two opposed end portions of the strap) which is held by the body of the clamp. The looped section of the band is placed around a tooth that is to be treated and an actuator, which is typically provided on the body, is used to alter an extent of the looped section of the band and thereby tighten or loosen the looped section of the band around the tooth. A restorative material such as a dental amalgam or composite may then be introduced between the tooth and a portion of the looped section of the band in order to fill the cavity and restore the tooth.

Some known clamps are reusable and are typically made of metal. These known reusable clamps must be cleaned (e.g. autoclaved) between uses to reduce the risk of contamination and infection. However, contamination and infection are still known to occur through, for example, sharps injuries (i.e. penetration of the skin by a medical instrument) which may be suffered by the dentist when replacing the band of the clamp. The looped section of the band of these known reusable clamps projects from the clamp at a fixed angle resulting in an inflexible device and making it difficult for the dentist to position the looped section of the band around some teeth. Other known clamps are disposable and are typically comprise a body formed from plastic and a metal loop. The disposable nature of these known clamps reduces the risk of contamination and infection compared to the known reusable clamps. Some known disposable clamps comprise a rotatable head that can rotate relative to a main portion of the body. Such an arrangement provides some control over an angle at which the looped section of the band projects from the main portion of the body, which may improve the ease with which the dentist can position the looped section of the band around teeth.

Generally, even once the extent of the looped section of the band has been adjusted to tighten the looped section of the band around a tooth, additional finer adjustments to the shape of the looped section of the band may be desirable to improve a fit of the looped section of the band around the tooth. The shapes, sizes, positions and orientations of teeth differ greatly between different patients. It is desirable to provide a clamp for a tooth that obviates or mitigates one or more problems of the prior art whether identified herein or elsewhere.

SUMMARY

According to a first aspect of the invention, there is provided a clamp for a tooth comprising a body for adjustably supporting a band such that a looped section of the band projects from the clamp, and a removable implement configured to adjust a shape of the looped section of the band once the removable implement has been removed from the clamp.

Currently, separate implements, which may be referred to as wedges, are used during many restorative dental procedures to adapt the shape of the looped section of the band to a patient's tooth. The invention of claim1advantageously provides a single product having all implements that may be required by a dentist during such procedures, said implements being quickly and easily accessible. The removable implement may be quickly and easily removed from the clamp and used to improve a fit of the looped section of the band around the tooth, which would not be possible using known clamps.

The clamp may be known in the art as a dental matrix clamp or dental matrix retainer. The band may be known in the art as a dental matrix band. The clamp may be disposable and/or reusable.

The removable implement may taper at one end for insertion of the removable implement between a tooth and the looped section of the band.

The removable implement may be referred to as a wedge. Wedges are the preferred implement used by dentist for procedures involving a dental matrix clamp. The tapered removable implement advantageously assists the dentist with adapting the looped section of the band around the patient's tooth so a desired fit can be achieved.

The removable implement may have a length of between about 1 cm and about 5 cm.

This range of lengths of removable implement advantageously provides the greatest flexibility to the dentist when using the clamp whilst also ensuring that the clamp does not become too large or bulky thereby potentially hindering the actions of the dentist during use. The term “length” may be understood to mean the greatest of the three dimensions of the removable implement.

The clamp may further comprise an actuator configured to alter an extent of the looped section of the band. The removable implement may form part of the actuator.

The removable implement may be an integral part of the actuator. The actuator may comprise a handle connected to a screw. Rotation of the screw in a first rotational direction may increase an extent of the looped section of the band (i.e. increase a perimeter of the looped section of the band), thereby allowing the looped section of the band to fit around larger teeth. Rotation of the screw in an opposite rotational direction may reduce an extent of the looped section of the band (i.e. decrease a perimeter of the looped section of the band), thereby allowing the looped section of the band to fit around smaller teeth. The actuator may house the removable implement within an internal space of the actuator. Available internal space of the body of the clamp may be limited due to the body of the clamp already housing other components, e.g. the band and the screw of the actuator. The actuator may have a larger amount of available internal space to accommodate the removable implement without reducing the structural robustness of the clamp.

The removable implement may be connected to the clamp by a breakable connector.

The breakable connector advantageously provides a simple and quick way of detaching the removable implement from the clamp for use during a dental procedure. The simplicity of the breakable connector advantageously increases an ease with which the clamp may be manufactured.

The clamp may further comprise a head that is rotationally connected to the body by an interference fit, the head comprising a slot through which the looped section of the band projects, wherein the interference fit is arranged to maintain the head at any one of: a centred position in which the looped section of the band projects from the slot in a direction that is substantially parallel to a length of the body; and a plurality of angular positions in which the looped section of the band projects from the slot in a direction that is not substantially parallel to the length of the body, wherein the interference fit is arranged such that the head may be maintained in at least two different angular positions on at least one side of the centred position.

The shape, size, position and orientation of teeth vary greatly between different patients. The interference fit advantageously provides greater flexibility of use of the clamp by offering a greater number of rotational positions of the head. The interference fit increases a dentist's ability to adapt the looped section of the band to different patients' teeth and thereby improves the ease with which the clamp may be used compared to known clamps.

The interference fit may comprise a faceted pin, wherein different facets on the faceted pin correspond to different angular positions of the head.

The faceted pin may be a prism with a cross-section that is a polygon such as a pentagon, a hexagon, a heptagon, an octagon, etc. In general, a greater number of facets on the pin corresponds to a greater number of available angular positions of the head, thereby improving the adaptability and ease of use of the clamp.

The interference fit may comprise a substantially circular pin which allows the head to rotate across and remain at any one of a substantially continuous range of angles between about −90° and about +90° relative to the body.

The circular pin arrangement advantageously provides the greatest degree of adaptability and ease of use of the clamp.

The interference fit may be formed by components that comprise polypropylene.

Polypropylene has been found to be particularly effective in providing a suitable interference fit between the body and the head. That is, polypropylene provides enough friction such that the head will remain in any rotational position it is placed in by a user but not too much friction such that the head may be moved between different angular positions by a user.

According to a second aspect of the invention, there is provided a clamp for a tooth comprising a body for adjustably supporting a band such that a looped section of the band projects from the clamp, and a head that is rotationally connected to the body by an interference fit, the head comprising a slot through which the looped section of the band projects, wherein the interference fit is arranged to maintain the head at any one of: a centred position in which the looped section of the band projects from the slot in a direction that is substantially parallel to a length of the body; and a plurality of angular positions in which the looped section of the band projects from the slot in a direction that is not substantially parallel to the length of the body, wherein the interference fit is arranged such that the head may be maintained in at least two different angular positions on at least one side of the centred position.

Known clamps either comprise a head that is fixed relative to the body or a rotatable head that is only able to move between three discrete locked positions relative to the body: a centred position, a clockwise position and an anti-clockwise position. The rotational freedom of the head of the known disposable clamps may be limited to no rotation or these three discrete locked positions, thereby restricting freedom of use of the clamp by the dentist. The interference fit advantageously provides greater flexibility of use of the clamp by offering a greater number of rotational positions of the head compared to known clamps. The interference fit increases the dentist's ability to align the looped section of the band to different patients' teeth and thereby improves the ease with which the clamp may be used compared to known clamps.

The body may be an elongate body, which may define an axis. The length may be a dimension of the body parallel to the axis.

The interference fit may comprise a substantially circular pin which allows the head to rotate across and remain at any one of a substantially continuous range of angles between about −90° and about +90° relative to the body.

The clamp may further comprise a removable implement configured to adjust a shape of the looped section of the band once the removable implement has been removed from the clamp.

The removable implement may taper at one end for insertion of the removable implement between a tooth and the looped section of the band.

According to a third aspect of the invention, there is provided a kit of parts comprising a clamp according to the first or second aspects of the invention and a band configured to be attached to the clamp.

According to a fourth aspect of the invention, there is provided a method of manufacturing a clamp for a tooth, the clamp comprising a body for adjustably supporting a band such that a looped section of the band projects from the clamp, the method comprising forming a removable implement as part of the clamp, the removable implement being configured to adjust a shape of the looped section of the band once the removable implement has been removed from the clamp.

The method may further comprise tapering the removable implement at one end for insertion of the removable implement between a tooth and the looped section of the band.

The method may further comprise injection moulding the clamp and the removable implement.

The method may further comprise forming a breakable connector between the removable implement and the clamp.

The method may further comprise forming a head that is rotationally connected to the body by an interference fit, the head comprising a slot through which the looped section of the band projects, wherein the interference fit is arranged to maintain the head at any one of: a centred position in which the looped section of the band projects from the slot in a direction that is substantially parallel to a length of the body; and a plurality of angular positions in which the looped section of the band projects from the slot in a direction that is not substantially parallel to the length of the body, wherein the interference fit is arranged such that the head may be maintained in at least two different angular positions on at least one side of the centred position.

Using an interference fit may comprise providing a substantially circular pin which allows the head to rotate across and remain at any one of a substantially continuous range of angles between about −90° and about +90° relative to the body.

The method may further comprise using components that comprise polypropylene to form the interference fit.

According to a fifth aspect of the invention, there is provided a method of manufacturing a clamp for a tooth, the clamp comprising a body for adjustably supporting a band such that a looped section of the band projects from the clamp, the method comprising forming a head that is rotationally connected to the body by an interference fit, the head comprising a slot through which the looped section of the band projects, wherein the interference fit is arranged to maintain the head at any one of: a centred position in which the looped section of the band projects from the slot in a direction that is substantially parallel to a length of the body; and a plurality of angular positions in which the looped section of the band projects from the slot in a direction that is not substantially parallel to the length of the body, wherein the interference fit is arranged such that the head may be maintained in at least two different angular positions on at least one side of the centred position.

Using an interference fit may comprise providing a substantially circular pin which allows the head to rotate across and remain at any one of a substantially continuous range of angles between about −90° and about +90° relative to the body.

The method may further comprise using components comprising polypropylene to form the interference fit.

The method may further comprise forming a removable implement as part of the clamp, the removable implement being configured to adjust a shape of the looped section of the band once the removable implement has been removed from the clamp.

DETAILED DESCRIPTION

FIG. 1schematically depicts a perspective view of a clamp100for a tooth according to an embodiment of the invention. The clamp100comprises a body105for adjustably supporting a band110such that a looped section115of the band110projects from the clamp100. In use, a dentist places the looped section115of the band110around a tooth that is to be treated. The body105is elongate and defines an axis145along which the body105generally extends. The body105is generally cylindrical and comprises first and second opposing flat portions125,130which may be gripped by a dentist when the clamp100is being used. The clamp100further comprises a head135that is rotationally connected to the body105about an interference fit140. A portion of the head135forms an interference fit140with a portion of the body105as described below. In the following discussion we will refer to this arrangement as the interference fit140. The interference fit140is shown and discussed in greater detail with respect toFIGS. 7 and 8. The head135comprises a slot265(not visible inFIG. 1, seeFIG. 3A) through which the looped section115of the band110projects. In the example ofFIG. 1, the head135is in a centred position in which the looped section115of the band110projects from the slot265in a direction142that is substantially parallel to the axis145of the body105. The head135may be rotated about the interference fit140into other positions which are herein referred to as angular positions (not shown inFIG. 1). Angular positions are positions in which the looped section115of the band110projects from the slot265in a direction that is not substantially parallel to the axis145of the body105. The interference fit140is configured to allow the head135to be disposed in at least two different discrete angular positions on at least one side of the centred position. Angular positions of the head135with respect to the body105are shown and discussed in greater detail with respect toFIG. 8.

The body105tapers towards the head135and includes third and fourth opposing flat portions150,155. The third and fourth opposing flat portions150,155house a flat section250(not visible inFIG. 1, seeFIG. 3) of the band110. The clamp100further comprises an actuator160. The actuator160may be formed from a plastics material such as, for example, polypropylene. The actuator160is configured to alter an extent of the looped section115of the band110. In the example ofFIG. 1, the actuator160comprises a screw230(not visible inFIG. 1, seeFIG. 2) and a handle165which forms a tail at an end of the body105of the clamp100. The screw230may alternatively be referred to as a screw portion or a threaded portion (which may have an external thread). The handle165of the actuator160may comprise fifth and sixth opposing flat portions180,185which may be gripped by the dentist when rotating the handle165to use the actuator160(relative to the body105). The screw230is held by a screw thread220,225(not visible inFIG. 1, seeFIG. 2) formed within the body105. The screw thread is shown and discussed in greater detail with respect toFIG. 2.

One end of the screw230(in particular an end of the screw distal from the handle165) is attached to the flat section250of the band110within the body105. As described further below with reference toFIG. 3, this attachment of an end of the screw230to the flat section250of the band110is achieved using a fastener245. In use, a dentist may hold the body105in one hand and rotate the handle165of the actuator160(about the axis145relative to the body105) with the other hand. Rotation of the actuator160in a first rotational direction170(e.g. clockwise) about axis145may cause the screw230to move along the inner screw thread220,225and push the band110(along the axis145) further out of the clamp100thereby increasing an extent of the looped section115of the band110that projects from the clamp100. This allows the looped section115of the band110to receive, and fit around, larger teeth. Rotation of the actuator165in an opposite rotational direction175(e.g. anti-clockwise) about axis145may cause the screw230to move along the inner screw thread220,225in the opposite direction (along axis145) and pull the band110into the body105of the clamp100thereby reducing an extent of the looped section115of the band110. This allows the looped section115of the band110to tighten around a tooth received within the looped section115.

Once the looped section115of the band110has been adjusted to a desired extent, the dentist may then position the clamp100such that the looped section115of the band110fits around a tooth that is to be treated. The dentist may then introduce an amalgam between the tooth and a portion of the looped section115of the band110so as to fill a cavity in the tooth. Once the amalgam has set, it may be referred to as a filling. The looped section115of the band110may be held in place by the dentist while the amalgam sets. In the majority of cases, a dentist will also use an implement, which may be referred to as a wedge or an interproximal wedge, to adjust a shape of the looped section115of the band110around the tooth while holding the clamp100in place. Such adjustment of the shape of the looped section115of the band110may improve a shape of the filling formed in the cavity by maintaining pressure at a desired area of the looped section115of the band110and may at least partially account for the finite thickness of the band110when forming the filling. The clamp100ofFIG. 1advantageously comprises a removable implement120configured to adjust a shape of the looped section115of the band110once the removable implement120has been removed from the clamp100. In the example ofFIG. 1, the removable implement120forms part of the handle165of the actuator160. In particular, the removable implement120is provided in an internal space of the handle165of the actuator160. The removable implement120is shown and discussed in greater detail with respect toFIGS. 4-6.

FIG. 2schematically depicts an exploded view of the clamp100shown inFIG. 1. The body105of the clamp100comprises a casing having two halves190,195. The casing may be formed from a plastic such as, for example, polypropylene. At one end of the casing (in particular at an end proximate the head135of the clamp100) the two halves190,195of the casing comprise opposing rings200,205. The head135comprises two pins210,215configured to be inserted into the two rings200,205of the casing. For this reason, the shape of the pins210,215and the shape of the rings200,205are complimentary. The head135may, for example, be formed from a plastic such as polypropylene. Once the pins210,215of the head135have been inserted into the rings200,205of the casing, the body and the head135can be considered to be rotationally connected to each other, in that the pins210,215and rings200,205arrangement allows rotation of the head135with respect to the body105. It will be appreciated that this rotation of the head135with respect to the body105is about an axis that is perpendicular to the axis of the body105. The pins210,215and the rings200,205form an interference fit with one another. The interference fit allows for the head135to be rotated (relative to the body105) between and held stationary in different angular positions with respect to the body105. In the example ofFIG. 2, the pins210,215on the head135are substantially circular pins210,215about which the head135can rotate across and remain at any one of a substantially continuous range of angles between about −90° and about +90° relative to the body105. Multiple forms of interference fit are shown and discussed in greater detail below with reference toFIG. 7.

At the opposite end of the casing (i.e. at an end of the casing proximate the actuator160of the clamp100) the two halves190,195of the casing comprise corresponding halves220,225of an inner screw thread. The inner screw thread is configured to receive at least a portion of the screw230of the actuator165. The two halves220,225of the inner screw thread form an opening235at the end of the casing through which the actuator160projects. A first half190of the casing comprises protrusions240-243along its edge and a second half195of the casing comprises complimentary recesses (not shown) along its edge for receipt of the protrusions240-243of the first half190. The two halves190,195of the casing may fasten together in a snap-fit configuration. Alternatively and/or additionally the two halves190,195of the casing may be welded together using, for example, sonic welding.

FIG. 3, consisting ofFIGS. 3A-3C, schematically depicts perspective views of some of the components of the clamp100at different stages of construction (but with the body105not shown).FIG. 3Aschematically depicts the band110, the head135, a fastener245and the actuator160detached from one another. The band110comprises a thin strip of metal such as, for example, stainless steel. The strip of metal may alternatively be referred to as a strap of metal. The strip may come in a variety of lengths, each of which may be useful for a different range of sizes of a patient's teeth. The strip may have a length of more than about 50 mm. The strip may have a length of less than about 100 mm. The strip may have a length of about 80 mm. The strip may have a thickness of between about 0.01 mm and about 0.1 mm, e.g. about 0.04 mm. The strip is folded in half to form the band110. The band110comprises a flat section250in which two ends of the strip are pressed together and a looped section115in which the two folded halves of the strip separate from one another to form a loop which projects from the head135of the clamp100. During use of the clamp100, the looped section115is to be fitted around a tooth that is to be treated using the clamp100. The strip of metal comprises a plurality of holes260-263at opposing ends of the strip. In the example ofFIG. 3, the strip comprises four holes260-263. The holes260-263are arranged on both ends of the strip such that when the strip is folded in half to form the band110, a first hole260on a first end of the strip aligns with a second hole261on the other end of the strip and a third hole262on the first end of the strip aligns with a fourth hole263on the other end of the strip.

The head135of the clamp100comprises a slot265through which the looped section115of the band110projects. The head135has a generally hemicylindrical shape which may help allow the head135to rotate about the body of the clamp100. The slot165is formed in a curved section of the hemicylindrical head135. The two pins210,215of the head135are formed on different opposed flat sections of the hemicylinder.

The fastener245is configured to fasten the band110at a first end whilst connecting to the actuator160at the opposing end. The fastener245may be formed from a plastic such as, for example, polypropylene. The fastener245comprises first and second plates270,275which are connected together by a hinge280. The plates270,275may be formed from the same material and the hinge280may be a living hinge formed from a portion of the same material that connects the plates270,275together. The first plate270includes a plurality of protrusions282,284(visible inFIG. 3C). The second plate275includes an equal number of apertures286,288. In the example ofFIG. 3, the first plate270includes two protrusions282,284and the second plate275includes two apertures286,288for receipt of the protrusions282,284. The protrusions282,284of the first plate270are aligned with the apertures286,288of the second plate275such that, when the second plate275is folded over the hinge280towards the first plate270, the protrusions282,284of the first plate270pass through the apertures286,288of the second plate275. The protrusions282,284of the first plate270and the apertures286,288of the second plate275may be sized and shaped so as to act as a snap-fit when they are brought together in order to fasten the first and second plates270,275together. In this regard, the protrusions282,284of the first plate270and the apertures286,288of the second plate275may be thought of, and referred to, as snap-fit buttons.

During assembly, the flat section250of the band110may be passed through the slot265in the head235and the apertures260-263at both ends of the strip may be aligned with one another and the protrusions282,284of the first plate270(this arrangement is shown inFIG. 3B). The protrusions282,284of the first plate270may be passed through the apertures260-263of the flat section250of the band110. In particular, the first hole260and the second hole261are aligned with and receive one protrusion282and the third hole262and the fourth hole263are aligned with and receive the other protrusion280. The second plate275may then be folded over the hinge280towards the first plate270and the protrusions282,284of the first plate270may pass through the apertures286,288of the second plate275so as to clamp the band110in place between the first and second plates270,275of the fastener245.

The second end of the fastener245comprises a socket290. The actuator160comprises a generally cylindrical plug295. The socket290of the fastener245is configured to receive and hold the plug295of the actuator160so as to connect the actuator160to the fastener245(as is shown inFIGS. 3B and 3C). Inner dimensions of the socket290are such that the plug295can, in use, rotate about axis145within the socket290and such that the plug295cannot move significantly relative to the socket along the axis145. The two halves of the casing (not shown inFIG. 3) may be brought together to enclose the flat section250of the band110, the fastener245and at least a portion of the screw230of the actuator160(as shown inFIG. 1).

FIG. 4, consisting ofFIGS. 4A and 4B, schematically depicts different views of the actuator160comprising the removable implement120according to an embodiment of the invention.FIG. 4Aschematically depicts a view from the side of the actuator160.FIG. 4Bschematically depicts a cross-sectional view of the actuator160through the line X-X shown inFIG. 4A. The removable implement120forms part of the handle165of the actuator160. The removable implement120is provided in an internal space320of the handle165of the actuator160. The removable implement120tapers to a point at one end300for insertion of the removable implement120between a tooth and a portion of the looped section115of the band110when the clamp100is being used. The removable implement120includes a base portion305at an opposite end of to the end300at which the removable implement120tapers to a point. The base portion305may be referred to as a stud305. The base portion305projects out of internal space320of the handle165of the actuator160.

FIG. 5schematically depicts a magnified view of an end portion of the handle165of the actuator160shown inFIG. 4Abut in a plane that is orthogonal to the plane ofFIG. 4A(such that the internal space320of the handle165is not visible inFIG. 5). The removable implement120is connected to the handle165of the actuator160by a breakable connector310. The breakable connector310may be formed from a plastic such as, for example, polypropylene. In the example ofFIG. 5, the stud305of the removable implement120is connected to the handle165of the actuator by the breakable connector310. It will be appreciated that the removable implement120and the handle165of the actuator160may be integrally formed as a single member from the same material (the breakable connector310comprising a relatively thin portion of said single member). The breakable connector310comprises material that becomes thinner at a breaking location315thereby forming a structural weakness at the breaking location315. A user may remove the removable implement120from the handle165of the actuator160by applying force to the stud315of the removable implement120such that the breakable connector310breaks at the breaking location315thereby separating the removable implement120from the clamp100.

FIG. 6, consisting ofFIGS. 6A and 6B, schematically depicts different views of the actuator160ofFIG. 4after the removable implement120has been removed from the handle165of the actuator160. The removable implement120may have a length325of about 1 cm or more. The removable implement120may have a length325of about 5 cm or less. The removable implement120may have a length325of about 1.5 cm, or 2.0 cm, or 2.5 cm, or 3 cm, or 3.5 cm, or 4 cm, or 4.5 cm. A body of the removable implement may have a greatest width330of more than about 1 mm. The body of the removable implement may have a greatest width330of less than about 5 mm. The width of the body of the removable implement may reduce in size (i.e. taper) from the greatest width330to an end point300of the removable implement120at which the width of the removable implement120is substantially zero (e.g. about 0.1 mm). The body of the removable implement120may have a greatest height335of more than about 2 mm. The body of the removable implement120may have a greatest height335of less than about 5 mm. The body of the removable implement120may have a greatest height335of about 2.5 mm, or about 3 mm, or about 3.5 mm, or about 4 mm, or about 4.5 mm. The height of the body of the removable implement120may reduce in size (i.e. taper) from the greatest height335to an end point300of the removable implement120at which the height of the removable implement120is substantially zero (e.g. about 0.1 mm).

A base340of the removable implement120may curve towards the end point300of the removable implement120. The removable implement120may be described as having a shape similar to that of a straightened claw. The removable implement120may be referred to as a dental wedge, an anatomical wedge or an interproximal wedge. Such wedges are used by dentists during many restorative dental procedures such as, for example, plastic restorations. For example, the wedge may be used to adapt the shape of the looped section of the band to a proximal part of a tooth cavity such that, once the cavity is filled with amalgam, the solidified amalgam has a desired shape with respect to the rest of the tooth and the surrounding teeth and gums. This may be achieved by inserting the end300of the removable implement120between the looped section115of the band110and an adjacent tooth.

The clamp100advantageously provides a single product having all implements that may be required by a dentist during such procedures, said implements being quickly and easily accessible. The removable implement120may be quickly and easily removed from the clamp100and used to improve a fit of the looped section115of the band110around the tooth, which would not be possible using known clamps.

FIG. 7, consisting ofFIGS. 7A-F, schematically depicts magnified views from the side of different forms of interference fit140between the head135and the body105of the clamp100according to embodiments of the invention. As previously discussed, a portion of the head135forms an interference fit140with a portion of the body105. The arrangement of the portion of the head135(i.e. the pin215) and the portion of the body105(i.e. the ring205) is herein referred to as the interference fit140. The interference fit140comprises flexible and resilient material such that the head135can rotate relative to the body105about the interference fit140. The interference fit140may be formed by components (e.g. the pins210,215and the rings200,205) that comprise polypropylene which has been found to have a good degree of flexibility and resilience for providing the interference fit140.

In the example ofFIG. 7A, the interference fit140is formed between a substantially circular pin215about which the head135can rotate across and remain at any one of a substantially continuous range of angles between about −90° and about +90° relative to the body105of the clamp. That is, the interference fit140provides a suitable amount of friction between the pin215of the head235and the rings205of the body105such that a user may rotate the head135and thereby position the head135at any desired angular position relative to the body105within a semicircle of travel and, when the user releases the head135, the interference fit140ensures that the head135remains at the desired angular position. In practice, the range of travel of the head135may be slightly less than a semicircle due to the presence of the band110. For example, the range of travel of the head135relative to the body105may be about ±85°, ±75°, ±70°, etc. The range of movement of the head135relative to the body105is shown inFIG. 8.

In the examples ofFIGS. 7B-7F, the interference fit140is formed between a faceted pin350on the head135of the clamp and complimentarily faceted rings360on the body105of the clamp. The gap between the pin350of the head135and the ring360of the body105has been exaggerated inFIGS. 7B-Efor clarity and ease of understanding. The faceted arrangement shown inFIG. 7Fmay also be referred to as a ribbed pin350and ribbed rings360. The faceted pin350may be rotated relative to the faceted ring360. Different facets (i.e. faces or sides) on the pin350correspond to different angular positions of the head135. That is, each time the pin350is rotated such that the facets of the pin350align with the facets of the ring360, the head135may remain in that angular position until the head135is rotated again by a user. In general, the greater the number of facets or ribs there are on the pin350and rings360, the greater the number of available angular positions of the head135there are relative to the body105. In general, the smaller the distance between neighbouring facets or ribs on the pin350and rings360, the greater the precision with which the angular position of the head135may be changed. The faceted structure of the pin350and ring360arrangement may take a variety of forms. In cross section, the pin350and ring360have shapes that may generally be referred to as polygons having a desired number and/or size of facets or ribs to achieve a desired number of angular positions and angular positioning precision of the head135relative to the body105. For example, the pin350and the rings360may be faceted such that, in cross section, they are generally pentagonal (as shown inFIG. 7B), generally hexagonal (as shown inFIG. 7C), generally heptagonal (as shown inFIG. 7D), generally octagonal (as shown inFIG. 7E), etc.

FIG. 7Fdepicts a pin350comprising a plurality of ribs385forming an interference fit140with a ring360comprising a plurality of ribs380. The ribs385of the pin350and the ribs380of the ring360interdigitate with one another in each angular position of the head135. The pin350may be rotated within the ring360such that the ribs385of the pin350and the ribs380of the ring360deform as they move past one another until the ribs380,385interdigitate with one another again such that the head135is in a different angular position.

FIG. 8, consisting ofFIGS. 8A-E, schematically depicts views from the side of a clamp100according to an embodiment of the invention with the head135located in different rotational positions relative to the body105. As previously discussed, the head135is rotationally connected to the body105by an interference fit140, and the head135comprises a slot through which a looped section115of the band110projects from the clamp100for fitting around a tooth.FIG. 8Aschematically depicts the head135in a centred position relative to the body105in which the looped section115of the band110projects from the clamp100in a direction370that is substantially parallel to the axis145of the body105. When we discuss a direction in which the looped section115of the band110projects from the clamp100, we are referring to the direction in which the slot265of the head135is facing. A length147of the body105may be considered to be the greatest of the three dimensions of the body105, and generally defines the axis145along the body105.

FIGS. 8B-Eshow the head135in different angular positions in which the looped section115of the band110projects from the clamp100in directions371-374that are not substantially parallel to the axis145of the body105. In the example ofFIG. 8B, the head135has been rotated to a first angular position in which the looped section115of the band110projects from the clamp100in a direction371that is about 45° anti-clockwise from the centred position shown inFIG. 8A. The interference fit140between the head135and the body105ensures that the head135stays in the first angular position once the user has stopped applying a rotational force to the head135. In the example ofFIG. 8C, the head135has been further rotated to a second angular position in which the looped section115of the band110projects from the clamp100in a direction372that is about 90° anti-clockwise from the centred position shown inFIG. 8A. The interference fit140between the head135and the body105ensures that the head135stays in the second angular position once the user has stopped applying a rotational force to the head135. In the example ofFIG. 8D, the head135has been rotated in the opposite rotational direction to a third angular position in which the looped section115of the band110projects from the clamp100in a direction373that is about 45° clockwise from the centred position shown inFIG. 8A. The interference fit140between the head135and the body105ensures that the head135stays in the third angular position once the user has stopped applying a rotational force to the head135. In the example ofFIG. 8E, the head135has been further rotated to a fourth angular position in which the looped section115of the band110projects from the clamp100in a direction374that is about 90° clockwise from the centred position shown inFIG. 8A. The interference fit140between the head135and the body105ensures that the head135stays in the fourth angular position once the user has stopped applying a rotational force to the head135.

AlthoughFIG. 8only shows five examples of different rotational positons of the head135relative to the body105of the clamp100, it will be understood that the head135of the clamp100ofFIG. 8may be positioned at any one of a substantially continuous range of angles between about −90° and about +90° relative to the body105of the clamp100.

The interference fit140between the head135and the body105of the clamp100provides for at least two different angular positions of the head135on at least one side of the centred position shown inFIG. 8A. For example,FIGS. 8B and 8Cshow the head135at two different angular positions on the left-hand side (i.e. in an anti-clockwise rotational direction) of the centred position shown inFIG. 8A. As a further example,FIGS. 8D and 8Eshow the head135at two different angular positions on the right-hand side (i.e. in a clockwise rotational direction) of the centred position shown inFIG. 8A.

Known clamps comprising a rotatable head may only be able to move between three discrete locked positions relative to the body: a centred position, a clockwise position and an anti-clockwise position. The rotational freedom of the head of the known disposable clamps may be to these three discrete locked positions, thereby restricting freedom of use of the clamp by the dentist. The interference fit140advantageously provides greater flexibility of use of the clamp100by offering a greater number of rotational positions of the head135compared to known clamps. The interference fit140increases the dentist's ability to adapt the looped section115of the band110to different patients' teeth and thereby improves the ease with which the clamp100may be used compared to known clamps.

FIG. 9, consisting ofFIGS. 9A and 9B, schematically depicts the pins210,215of the head135of the clamp100and a ring205of the body105of the clamp100according to an embodiment of the invention.FIG. 9Aschematically depicts a view from the side of the head135of the clamp100.FIG. 9Bschematically depicts a cross-sectional view from the side of a portion of one half195of the casing of the body105of the clamp100. One of the pins215shown inFIG. 9Ais configured to be received in the ring205shown inFIG. 9Bto thereby form the interference fit between the head135and the body105of the clamp100. The pins210,215of the head135taper along their axes such that the diameter of the pins210,215increases when travelling towards a central portion of the head135. The taper may assist in assembly of the clamp100. That is, the taper of the pins210,215may make it easier to insert the pins210,215in the rings200,205when forming the interference fit between the head135and the body105.

The head135, along with other components of the clamp100such as the casing190,195, the actuator160comprising the removable implement120and the fastener245, may be formed by injection moulding plastics material, such as polypropylene, into a mould made of, for example, metal. The mould may be an inverse or negative image of the component (e.g. the head135) such that when the mould is filled with the plastics material and the plastics material is allowed to set, the component (e.g. the head135) is formed within the mould. When the mould is first formed, the portion of the mould that corresponds to the pins210,215may be substantially the same size as the portion of the mould that corresponds to the rings200,205. The portion of the mould that corresponds to the pins210,215may be further machined to remove some material and thereby slightly increase a size of the pins210,215and/or to create the taper of the pins210,215that result from the injection moulding process. This in turn may assist in forming a suitable interference fit between the pins210,215and the rings200,205. This technique of removing some of the mould material may be referred to as a tool-safe mould change.

The pins210,215may, for example, have a smallest diameter400of about 1 mm or more. The pins210,215may, for example, have a smallest diameter400of about 3 mm or less. The pins210,215may, for example, have a smallest diameter400of about 2.5 mm. The pins210,215may, for example, have a greatest diameter405of about 2 mm or more. The pins210,215may, for example, have a greatest diameter405of about 4 mm or less. The pins210,215may, for example, have a greatest diameter405of about 2.7 mm.

The rings200,205of the head135taper along their axes such that the diameter of the rings200,205increases when travelling towards a region which receives the head135. The taper may assist in assembly of the clamp100. That is, the taper of the rings200,205may make it easier to insert the pins210,215in the rings200,205when forming the interference fit between the head135and the body105.

The rings200,205may, for example, have a smallest diameter410of about 1 mm or more. The rings200,205may, for example, have a smallest diameter410of about 3 mm or less. The rings200,205may, for example, have a smallest diameter410of about 2.9 mm. The rings200,205may, for example, have a greatest diameter415of about 2 mm or more. The rings200,205may, for example, have a greatest diameter415of about 4 mm or less. The rings200,205may, for example, have a greatest diameter415of about 3.0 mm.

The tapered diameters of the pins210,215may be slightly smaller than the tapered diameters of the rings200,205whilst still providing an interference fit. For example, the tapered diameters of the pins210,215may be up to about 0.3 mm less than the tapered diameters of the rings200,205. Alternatively, the tapered diameters of the pins210,215and the tapered diameters of the rings200,205may be substantially the same. Alternatively, the tapered diameters of the pins210,215may be slightly greater than the tapered diameters of the rings200,205. For example, the tapered diameters of the pins210,215may be up to about 0.3 mm greater than the tapered diameters of the rings200,205. In any case, the tapered diameters of the pins210,215and the tapered diameters of the rings200,205are similar enough such that, when they are assembled, an interference fit forms between the pins210,215and the rings200,205which allows a user to rotate the head135about the body105and allows the head135to remain at a desired angular position relative to the body105once the user has released the head135.

A method of manufacturing the clamp100discussed and depicted herein may comprise forming the removable implement as part of the clamp100. For example, part of the clamp100(for example the actuator160) and the removable implement120may be formed by injection moulding. For example, when the removable implement120forms part of the handle165of the actuator160, the actuator160, the removable implement120and the breakable connector310in-between may all be formed by injection moulding using a single cast. The method of manufacture may further comprise tapering the removable implement120at one end for insertion of the removable implement120between a tooth and the looped section115of the band110.

The method of manufacture of the clamp100may additionally or alternatively comprise forming a head135comprising a slot265through which a looped section115of the band110projects and rotationally connecting the head135to the body105using an interference fit140which provides for at least two different angular positions on at least one side of a centred position of the head135. Using an interference fit140may comprise providing a substantially circular pin215about which the head135can rotate across and remain at any one of a substantially continuous range of angles between about −90° and about +90° relative to the body105. The components used to form the interference fit140may comprise polypropylene.