HK1210005B - A dentist tool - Google Patents

Abstract

Method for producing a dentist tool formed by an overlay to be used by a dentist in removing tooth structure, said method comprising the steps of: acquiring three-dimensional data relating to a shape of a tooth and at least a part of a neighbouring tooth; processing said three-dimensional data with a computer so as to determine an overlay fitting said tooth and fitting at least said part of said neighbouring tooth; further processing said three-dimensional data with said computer so as to determine a predetermined part of tooth structure to be removed from said tooth so as to prepare said tooth for further treatment; determining at least two guiding edges of which a first and a second guiding edge are spaced apart from each other by a distance d of at least 0.5 mm, said guiding edges being configured so as to enable said dentist cutting tool to be guided by simultaneously contacting said first and said second guiding edge in such a manner as to enable a guided removal of at least partially said predetermined part of tooth structure; producing said determined overlay having said determined guiding edges.

Description

Dentist tool

The present application is a divisional application of a patent application filed on 2.2.2010 under application number 201080014124.5 entitled "method for manufacturing dental tools".

Technical Field

The invention relates to a method for manufacturing a dentist tool formed by an overlay to be used by a dentist for removing a dental structure from a tooth, the method comprising the steps of:

determining a predetermined portion of the tooth structure to be removed to prepare the tooth for further treatment;

determining a coverage that fits the tooth and that fits at least a portion of an adjacent tooth of the tooth;

simulating a motion to be followed by a dentist cutting tool to remove at least a part of the predetermined portion;

determining a first guiding edge within the cover, the first guiding edge corresponding to the movement such that it is provided to contact the dentist cutting tool following the movement, thereby being provided to guide the dentist cutting tool in a predetermined position, the first guiding edge being part of a guiding tool;

manufacturing the determined overlay with the guiding tool.

The invention further relates to a dentist tool to be used by a dentist for removing a dental structure from a patient's tooth, which tooth is to be prepared for further processing, the dentist tool comprising:

a cover having a shape and size releasably securable to the tooth and connectable to at least a portion of the tooth or an adjacent tooth of the tooth;

a first guiding edge within the cover, the first guiding edge being provided for contacting a dentist cutting tool following a predetermined movement, whereby the first guiding edge is provided to guide the dentist cutting tool in a predetermined position.

Background

When a patient requires a crown, bridge, onlay, inlay, dental cap, or other restorative or other dental prosthetic and/or aesthetic dental treatment, conventionally, upon initial visit to the clinic, the dentist identifies the patient's needs and determines the appropriate treatment. At a subsequent visit, the dentist removes the tooth structure and reconstructs as much of the tooth as possible using conventional techniques, provided that the tooth includes damaged and/or infected tooth structure. Thereafter, the dentist performs a final preparation of the tooth for further processing by removing tooth material, which will be understood as the original tooth structure and the reconstructed tooth structure, with a dentist cutting tool, such as a high speed drill. Visually and empirically, the dentist uses the drill to shape the tooth into a form suitable for further processing, in particular such a form that: a crown, bridge, onlay, inlay, coping or other tooth restoration component may be mounted thereto. The dentist then takes an impression (impression) of the arch in which the prepared tooth is located and sends the impression to a dental laboratory for the dental technician to make the restoration part. Using the prepared impression of the tooth, the dental technician makes a restoration part matching the color, geometry and material specifications and sends it to the dentist. The dentist adjusts the restoration portion as necessary before fitting it into place the last time the patient visits.

Another dentist tool is disclosed in EP 1547544. Such a dentist tool reduces the influence of the experience and knowledge of the dentist on the treatment and is used by the dentist for drilling an artificial root cavity. In EP1547544, a guide tool formed by a cylindrical bore for guiding a drill in a straight manner is provided. In this way, even inexperienced dentists can drill the artificial root cavity with great precision. Furthermore, an appropriate root cavity position may be calculated based on the computer-processed information in order to form a cavity in the jaw bone in an optimal manner.

A disadvantage of the known dentist tools is that the dental tools can only be used by the dentist to drill holes into the jaw bone. Such a dentist tool is not suitable for use by a dentist to prepare the tooth for further treatment.

Another dental tool is disclosed in DE4012327, which is considered as an approximate prior art. Such a dentist tool is formed by a template comprising a guiding edge for guiding the dentist cutting tool along a predetermined movement. The guiding edge is set at a predetermined height so as to guide the depth of the dentist cutting tool in addition to the position of the dentist cutting tool. Furthermore, DE4012327 teaches the dentist how to use the template by: placing the template in a person's mouth, fixing the inclination angle of the dentist cutting tool to a predetermined inclination angle using a movable plate, moving the dentist cutting tool along the guide edge, thereby removing a predetermined tooth structure.

A disadvantage of this known dentist tool is that the inclination angle is fixed at a predetermined inclination angle due to the movable plate. Thus, the dentist's cutting tool cannot be guided in a complex movement where the inclination angle also changes. In particular, such complex motions are preferred when working with complex surfaces such as teeth.

Disclosure of Invention

It is an object of the present invention to provide a method for manufacturing a dentist tool suitable for guiding a dentist cutting tool along a complex movement.

To this end, the method for manufacturing a dentist tool according to the present invention is characterized in that it comprises the further steps of:

determining a second guiding edge within the cover, the second guiding edge being spaced apart from the first guiding edge by a distance d of at least 0.5mm, the second guiding edge corresponding to the movement such that the second guiding edge is provided to simultaneously contact the dentist cutting tool following the movement with the first guiding edge, whereby the first and second guiding edges are provided to guide the dentist cutting tool at a predetermined inclination, the second guiding edge being part of the guiding tool.

The presence of the second guiding edge in the cover results in that the movement of the dental cutting tool can be guided along a predetermined surface, whereas in the prior art the movement of the tool can only be guided along a predetermined line. Thereby, guidance of the inclination of the dentist's cutting tool is also obtained, which is not possible in the prior art. The presence of said second guiding edge allows to guide the dentist's cutting tool along a complex movement with a change of position and a change of inclination.

The effect of determining the predetermined portion of the dental structure to be removed is that this is no longer dependent on the skill of the dentist. A guiding edge is determined and manufactured within the cover, said guiding edge being adapted for simultaneous contact with the dentist's cutting tool, allowing the cutting tool to be guided along a well-defined path in an at least partially predetermined manner. The overlay with the leading edge accurately indicates the portion of the tooth that is to be removed from the tooth as determined by a computer. Furthermore, a tool according to the present invention is provided to assist a dentist in removing a dental structure when the tool allows the dentist to remove at least a part of a predetermined portion of the dental structure.

It should be noted that the term fitting should not be understood in the narrow sense that the cover should closely surround the teeth. Furthermore, it should be understood that the cover should surround the tooth for proper contact with the tooth and as such, once applied, it is not released even if some pressure is applied due to normal use of the cover.

Preferably, the method of the present invention further comprises the steps of:

acquiring three-dimensional data relating to at least the shape of the tooth and at least the portion of the adjacent tooth;

processing the three-dimensional data with a computer to determine dimensions and orientations important to the coverage;

processing the three dimensional data to determine the predetermined portion.

Depending on the individual dental condition of the patient, the computer is programmed to determine the best way for shaping the teeth into a shape suitable for further processing.

In a preferred embodiment of the invention, the first and second guiding edges are designed for simultaneously contacting the dentist's cutting tool at contact points longitudinally separated from each other by said distance, whereby the guiding edges define a guiding surface along which the dentist's cutting tool is to be guided.

The cutting tool can be guided at least partially in a predetermined manner by the two guide edges simultaneously contacting the cutting tool at contact points which are longitudinally separated from one another. Preferably, the cutting tool moves along the two guide edges and thereby defines a guide surface. The face comprises said two guiding edges and the cutting tool can be guided along the face. This allows for precise guidance in two dimensions.

Preferably, the guide means comprises a guide slot defining a path extending within the surface of the cover and adapted for guiding the dentist cutting means along said path in a manner enabling guided removal of the predetermined part of at least part of the dental structure.

The two guide edges spaced apart from each other may be arranged one on one side of the path and the other on the other side of the path, thereby defining the path between the two guide edges. For this purpose, the distance between the two guide edges should be substantially equal to the diameter of the cutting tool. Using the dentist cutting tool by simultaneously contacting the two guiding edges and following the path allows guiding the cutting tool in at least two dimensions. Considering a longitudinal cutting tool, the surface defined by the two guiding edges in this configuration will be substantially perpendicular to the direction of the cutting tool in use. In this configuration, the preferred angle of inclination of the cutting tool is perpendicular to the plane formed by the two guide edges.

The two guide edges, which are spaced apart from each other, may also both be located on one side of the path. Then, at least the third guiding edge will define the other side of the path. Considering a longitudinal cutting tool in such a configuration, the surface defined by the two guide edges will be substantially parallel to the direction of the cutting tool in use. The third guide edge in this configuration will provide further guidance to the cutting tool, thereby increasing the accuracy of the process of removing tooth structure. Using the dentist tool by simultaneously contacting the two guiding edges and following the path in this configuration allows to guide the cutting tool in two dimensions and to guide the inclination of the cutting tool.

Preferably, the method comprises the further steps of:

producing a tooth restoration portion having an inner shape determined to fit a predetermined remaining portion of the tooth structure of the tooth and having an outer shape determined to fit the remaining adjacent teeth together.

An advantage of the method according to the invention is that the shape of the remaining part of the tooth structure of the prepared tooth is known in advance as a result of the guided removal of the tooth structure. This improves further processing, such as the preparation of temporary or final inlays, onlays, bridges, crowns or crowns (veneers) in advance based on the three-dimensional data. This results in fewer office visits, as the dentist can prepare the tooth and install the tooth restoration portion onto the prepared tooth in a single visit. This mode of operation not only saves time and thus reduces costs, but also greatly reduces the inconvenience for the patient. Moreover, the possibility of infection of the prepared teeth, and the resulting complications, is minimized.

Preferably, the method comprises the further steps of:

processing the three-dimensional data to simulate a tooth restoration portion having an internal shape determined to fit a predetermined remaining portion of the tooth structure of the tooth and having an external shape determined to fit remaining adjacent teeth together;

manufacturing the tooth restoration part.

Thereby, a separately designed tooth restoration part can be delivered together with the dentist tool according to the invention. This is possible because the final shape of the prepared tooth is known in advance when the dentist tool is used. The result is that fewer dental visits are required to place the restoration portion.

Preferably, the predetermined portion is determined by:

first determining an outer shape of the restored tooth portion such that the restored tooth portion fits together with the remaining adjacent teeth, and determining an inner shape of the restored tooth portion that is compatible with the outer shape;

secondly determining the shape of the remaining tooth structure such that the restored portion of the tooth having the internal shape matches the shape of the remaining tooth structure;

the predetermined portion is again determined as the portion of the tooth structure to be removed to have the shape of the remaining tooth structure left.

It is advantageous to prepare the teeth starting from the determination of the restored portion of the teeth, rather than by conventional methods. The tooth restoration portion may be determined to have an outer shape to optimally fit with the remaining adjacent teeth. Procedures for determining such external shapes are known to those skilled in the art. An internal shape is then determined, the internal shape being compatible with the external shape. The criteria for compatibility depend on the material to be used and mainly relate to strength parameters, manufacturing parameters and parameters related to the mounting of the restorative portion to the tooth and/or teeth. Preferably, the internal shape is determined in a manner that requires a minimum amount of material to make the tooth restoration portion. This in turn results in the remaining tooth structure that needs to fit to this internal shape being as large as possible, i.e., the more material of the restored tooth is tooth restoration material and the less material of the restored tooth is tooth structure. The predetermined portion may then be determined as the portion of the tooth structure to be removed to have the shape of the remaining tooth structure left. Thus, first determining the tooth restoration portion results in the least tooth structure to be removed from the tooth and the maximum preservation of the original tooth structure. This is an advantage because it is desirable to maintain as much of the original tooth structure as possible.

Providing the determined tooth restoration part having the determined outer and inner shapes together with the dental tool results in less office visits being required as the dentist can prepare the tooth and install the tooth restoration part onto the prepared tooth in a single visit.

Preferably, the dentist tool comprises at least one further cover, the cover and the at least one further cover being determined to guide the dentist tool in a plurality of stages to remove tooth structure, wherein the guiding tool in the cover is provided to guide the cutting tool in one of the plurality of stages and at least one further guiding tool in the at least one further cover is provided to guide the cutting tool in at least one further stage of the plurality of stages, the method further comprising the steps of:

determining at least one additional cover that fits the tooth and that fits at least a portion of the adjacent tooth;

simulating at least one further motion to be followed by the dentist cutting tool to remove at least one further part of the predetermined part;

determining at least one further first guiding edge within the at least one further cover, the at least one further first guiding edge corresponding to the at least one further movement, so that the at least one further first guiding edge is provided to contact the dentist cutting tool following the at least one further movement, thereby being provided to guide the dentist cutting tool in a predetermined position, the at least one further first guiding edge being part of the at least one further guiding tool;

determining at least one further second guiding edge within the at least one further cover, the at least one further second guiding edge being spaced apart from the at least one further first guiding edge by a distance d of at least 0.5mm, the at least one further second guiding edge corresponding to the at least one further movement, such that the at least one further second guiding edge is provided to simultaneously contact the dentist cutting tool following the at least one further movement with the at least one further first guiding edge, whereby the at least one further first and second guiding edges are provided to guide the dentist cutting tool at a predetermined inclination, the at least one further second guiding edge being part of the at least one further guiding tool;

manufacturing the at least one further cover with the at least one further guiding tool.

Manufacturing multiple covers instead of just one provides further flexibility in the method for manufacturing the dental tool. Different covers may be provided for guiding the dentist's cutting tool along different sides of the tooth to be prepared, such that for example a circumferential path may be defined by using a plurality of covers, each cover defining a different segment of said circumferential path. Moreover, multiple covers allow for the use of different dentist cutting tools, which may be necessary in some cases. Different covers may be provided for preparing the tooth in multiple stages, wherein for example a first stage is provided to smooth the upper part of the tooth, a second and third stage is provided to resect longitudinal and lateral sides of the tooth, and a fourth and fifth stage is provided to chamfer the edges between the longitudinal and lateral sides, each at a different side of the tooth. Staging the preparation of the teeth allows each cover to be designed with a guide edge specifically identified for guiding the cutting tool in a particular manner characterized by the particular stage.

Drawings

The invention will now be described in more detail with reference to the accompanying drawings, which illustrate some preferred embodiments of the invention. In the drawings:

figure 1 shows a top view of a cover with a guide slot according to the invention;

FIG. 2 shows a side view of a cover with guide slots placed over a patient's teeth;

FIG. 3 shows a cross-section of a portion of a cover and a cutting tool with a guide tool according to one embodiment of the invention;

FIG. 4 shows a cross-section of a portion of a cover and a cutting tool with a guide tool according to another embodiment of the invention;

FIG. 5 shows a cross-section of a portion of a cover with a guide tool and a cutting tool according to the present invention;

FIG. 6 shows a cross-section of a portion of a cover with a guide tool and a cutting tool according to a further embodiment of the invention;

FIG. 7 illustrates a set of overlays of teeth to be prepared by a dentist for installation of a crown or bridge;

figure 8 shows a cross-section of the cover shown in figure 7 a.

In the drawings, the same reference numerals have been assigned to the same or similar elements.

Detailed Description

The terms "lower", "upper" and the like and derived directional terms such as "horizontal" and "vertical" are based on the normal configuration of covers as shown in the drawings, wherein the covers fit onto the teeth with their roots extending vertically downward. In this context, the term dentist should not be understood restrictively, but may also be understood as a dental technician, a dental assistant physician, a dental assistant, a dental therapist, a dental designer, etc.

The present invention provides a method for manufacturing a dentist tool formed by a cover 1 to be used by a dentist for removing a dental structure. Moreover, the invention provides a cover 1 obtainable by such a method. Fig. 1 and 2 show such a cover 1 arranged onto a patient's tooth 2. Preferably, the present invention provides a method of manufacturing the dentist tool and tooth restoration part in such a way that: the tooth restoration portion will fit the tooth prepared using the dentist's tool.

Preferably, the dentist's tool according to the invention is used by the dentist to prepare the teeth for restoration, e.g. for the placement of inlays and onlays, crowns, bridges, and crown caps. Such restoration requires that the restoration portion be manufactured to fit the tooth after it is prepared. The use of the dentist tool according to the invention results in a predetermination of the shape of the prepared tooth, which is conventionally only known after preparation. Based on this knowledge, the restoration part can be manufactured in advance so that the dentist can obtain this restoration part even before he or she starts to prepare the tooth, and can install it directly after preparing the tooth. This results in less inconvenience to the patient, in particular a reduction in the number of visits to the dentist. Moreover, the possibility of infection of the prepared teeth, and the resulting complications, is minimized.

Preferably, preparing the teeth for further treatment is performed on substantially healthy teeth. When a tooth is damaged or infected, the damaged and/or infected portion of the tooth must first be removed and the tooth must be reconstructed before being prepared for further treatment. This minimizes the likelihood of infection developing under the restored portion of the tooth. This also maximizes the life of the restored portion of the tooth because the base of the restored portion of the tooth, i.e., the tooth, no longer contains the damaged portion.

A cover made for one tooth may be utilized in preparing the teeth of another patient, where the teeth of such other patient are of a very similar size and shape. Thus, covers that have been prepared to be standardized, reused, and/or remanufactured are also within the scope of the invention. Also, the data obtained in the preparation of the previous cover and recovery portions in the design and creation of a new cover having substantially similar size and shape also fall within the scope of the present invention.

Some methods for acquiring three-dimensional data from a patient's dentition are known. Such data may be traced, for example, by processing photographs taken from the patient's dentition. Another approach is to make a physical impression of the dentition and then subsequently scan this impression or reverse cast of the impression. Such scanning may be performed with a CAD/CAM 3D scanning device. An illustrative such device is from SensAble technologies Inc. of Wobbe, MassAlthough such a scanning device may scan a model of the dental arch with a tolerance of about 10 μm, this does not take into account other error factors obtained from making the impression and casting the dental impression. These other error factors or tolerances must be taken into account when making the final restoration part or dental prosthesis.

The CAD program selects a particular configuration of the overlay, sometimes referred to as a reduction tray (reduction tray), and finally the configuration of the prepared tooth by using certain protocols based on prior experience for preparing dental prostheses.

In one embodiment of the invention, the digitized file of the subject tooth may be compared to an existing database for such prosthesis. Such an exemplary database is available from Heraeus Kulzer Tooth Library, Heraeus Kulzer GmbH, Hahate, Germany. This database has also been integrated into the SensAble Digital LabSystem (SDLS). A prosthesis (e.g. crown or onlay) comparable to the prosthesis used for the subject tooth is selected from the Kulzer database. That prosthesis information includes the configuration and dimensions for the prepared teeth that will correspond to the inner surface of the prosthesis. This internal configuration of the crown used for that preparation in the Kulzer database is used to design a cover (reduction tray) for the patient's teeth. In designing the cover, the basic principles and purposes known in the art are utilized, for example, to remove a minimal amount of the original tooth surface.

For example, in a set of lidding or reducing trays, there may be one lidding or tray for reducing the intermediate and distal surfaces (front and rear) and another tray for reducing the keying (top) surface. Also, there may be two finishing trays (finishing tray) that cut the lingual and buccal surfaces of the teeth. In order to prepare for the crown, an additional tray for the gingival margin is required.

Typical uses of the method are described above, but a greater or lesser number of reduction trays or covers may be appropriate to perform preparations for subsequent installation of the dental prosthesis or restoration part. After acquiring the three-dimensional data of the teeth, this data is processed by a computer to determine the coverage 1 of the teeth 2 fitting the patient. To this end, preferably, the inner shape of the cover corresponds to the outer shape of the tooth to be prepared and to the outer shape of at least a part of an adjacent tooth. The covering should fit the teeth in such a way that: once the cover is placed on the tooth, the cover is only removed by applying a sufficiently high force to the cover. During preparation of the tooth, a small force may be applied to the cover, preferably this should not change the position of the cover on the tooth. Preferably, the cover 1 extends over the teeth 2 to also cover the gingiva 3 or a portion of an adjacent tooth for stability and protection purposes. Since the dentist will use the cover 1 for removing tooth material, it is advantageous that the cover is positioned on the tooth in a stable manner. For example, the cover 1, which fits closely to the teeth, two adjacent teeth, and a portion of the gingiva 3, ensures that the dentist can place and hold the cover in a stable position when removing the tooth structure. When the cover 1 covers a part of the gingiva 3, at least this part of the gingiva 3 will be protected during the removal of the tooth structure.

It is noted that the cover 1 according to the invention can cover a plurality of teeth simultaneously and can be provided to be used by a dentist for preparing a plurality of teeth using one single cover 1. This may be advantageous in preparing the teeth for placement of the crown. As will be further explained, such a cover comprises a guiding means for each tooth that needs to be prepared.

The determined thickness 4 of the cover 1 depends mainly on the strength it needs and therefore also on the material it is made of. The cover 1 according to the invention may have a constant total thickness 4. A substantially constant overall thickness is preferred for the covering of the tooth or teeth that will be used by the dentist to prepare the tooth or teeth for placement of the crown. Preferably, the covering of the teeth to be used by the dentist for preparing the teeth for placing the bridge or crown comprises an upper guide portion 5, and a lower support portion 6. The supporting portion 6 of the cover 1 will ensure that the cover 1 can be arranged in a stable manner onto the tooth 2, while the guiding portion 5 of the cover 1 will guide the dentist cutting tool and preferably will also determine the maximum penetration depth of the cutting tool in the tooth. For this purpose, preferably, the thickness of the guide portion 5 of the cover 1 will be determined case by case together with the determination of the guide groove 7, as will be further explained. The thickness 4 of the supporting portion 6 of the cover 1 can be chosen more freely according to the choice of the dentist and/or the programming of the computer.

After the three-dimensional data is acquired, this data is also processed by a computer to determine a predetermined portion of the tooth structure to be removed from the tooth by the dentist. The predetermined portion will be determined in view of the further processing. If a particular shape of the prepared tooth is desired to allow further treatment, the predetermined portion will be selected so that this particular shape will be maintained after the tooth is prepared.

The determination of the predetermined portion depends on a number of parameters and may vary from case to case. The parameters are the position of the tooth in the patient's mouth, the number and position of the damaged tooth structure, the distance of the tooth to an adjacent tooth, and the like. In a preferred embodiment, the computer will also take into account different parts of the tooth when determining the predetermined part, such as the enamel, dentin, pulp (pulp), cementum, etc. It will also be appreciated within the general aspects of the present invention that the patient's teeth must be created by conventional techniques and materials prior to the actual step of preparing the teeth with the overlay.

According to the invention, the computer is programmed to determine the predetermined portion of the dental structure to be removed without the aid of a dentist other than the input of raw data relating to the tooth. However, also according to the invention, the computer may be programmed to determine the predetermined portion in cooperation with a dentist, wherein, for example, the dentist decides on some parameters. This cooperation can be established by the following steps: visualizing data related to the tooth on a computer display and allowing the dentist to enter at least one parameter related to the preparation of the tooth. Preferably, the preview of the tooth is visualized on the computer display together with a preview of the simulation of the prepared tooth to allow the dentist to see the effect of the selected parameter on the prepared tooth. This latter feature provides the dentist with greater freedom and allows the inexperienced dentist to consult the experienced dentist about the case based on the data in the computer. In this way, the method for manufacturing a dentist tool according to the invention allows an inexperienced dentist to decide on further treatment and prepare a tooth for further treatment in the same quality as if he or she was an experienced dentist.

In another embodiment, the computer is programmed to determine the predetermined portion of the tooth structure to be removed in several stages. At the end of each session, the computer suggests a simulated solution to the dentist and requests approval or correction of the suggested solution.

Preferably, the predetermined portion will be determined in several steps. In a first step, the outer shape of the tooth restoration portion will be determined such that the tooth restoration portion fits with the remaining teeth and into the patient's dental arch. The modification of bite lift (bite lift) or other corrections can be integrated directly into the design of the external shape. Then, based on this determined external shape, an internal shape compatible with the external shape is determined. In this way, a tooth restoration part having an optimal outer shape and an optimal configuration may be determined, in the sense that it is sufficiently strong and requires minimal material. In a subsequent step, the shape of the remaining tooth structure will be determined such that the internal shape of the restored portion of the tooth fits the remaining tooth structure after removal of the tooth structure. In a final step, the predetermined portion of the dental structure is determined as the portion of the dental structure to be removed to have the shape of the remaining dental structure left. This way of working allows to determine the outer shape of the restored portion of the tooth using a best-fit procedure. Conventionally, the dentist does not follow the procedure described above continuously. The dentist will work in other ways as the dentist will need to know the shape of the prepared tooth to determine the inner shape of the restored portion, after which the dentist will determine the appropriate outer shape. According to a preferred embodiment of the present invention, it is first determined that the tooth restoration portion results in a tooth structure that will be minimally removed from the tooth and that a maximum preservation of the original tooth structure can be achieved.

Once the predetermined portion has been determined, a guidance tool may be determined. The purpose of the guiding tool is to guide a dentist cutting tool, i.e. a drill, along a simulated movement, whereby the cutting tool removes at least a part of the predetermined portion. To this end, it will be appreciated that in some instances, the dimensions of the dentist's cutting tool, such as the length, diameter, cross-sectional form, etc., will be determined for use in moving the cutting tool to remove a particular portion of a tooth structure. It will also be appreciated that in many cases it is not sufficient to perform a single movement for removing all of the predetermined portions. One or more movements for removing the predetermined portion of the dental structure may be simulated by computer calculation and/or simulation. It will be understood that in this context movement is not only related to two-dimensional position, but also to movement of the cutting tool in all aspects, such as horizontal movement, vertical movement and tilting movement.

The guiding means according to the invention comprise at least two guiding edges 11, 12 (fig. 3-6). The two guide edges 11, 12 are spaced apart from each other by a distance d of at least 0.5 mm. The guiding edges 11, 12 are provided to simultaneously contact the cutting tool 10, thereby at least partially guiding the cutting tool 10 into a predetermined movement. It is understood that in this context a surface having a length and a width of at least 0.5mm may be considered as the at least two guiding edges 11, 12. That is, the two outer edges of the surface are provided to simultaneously contact the cutting tool 10 and are spaced apart by a distance d of at least 0.5 mm.

The guiding edges 11, 12 corresponding to the simulated movement of the dentist's cutting tool are determined so that both guiding edges 11, 12 simultaneously contact the cutting tool following the movement. Preferably, the guide edge contacts the cutting tool simultaneously and continuously, preferably throughout the movement. Preferably, the contact between the leading edge and the cutting tool along the movement is a contact point.

Preferably, the two guide edges 11, 12 are spaced apart from each other by a distance d of at least 1mm, more preferably at least 2mm and most preferably at least 3 mm. Increasing the distance d between the two edges 11, 12 increases the guiding quality, since it is easier for the dentist to control the cutting tool 10 over a larger guiding tool.

The guide edges 11, 12 are provided in such a way that they can be contacted simultaneously by the cutting tool at two contact points. As shown in fig. 3, these contact points 11, 12 are preferably longitudinally spaced apart by the distance d, considered on the cutting tool 10. When the cutting tool 10 is arranged substantially perpendicular to the guide edges, the distance between the contact points will be substantially the same as the distance d between the guide edges. Fig. 3 illustrates the cutting tool 10 simultaneously against the two guide edges 11, 12. In this configuration the guide edges 11, 12 define a surface along which the cutting tool 10 can be guided.

However, the leading edges 11, 12 may also contact the cutting tool 10 at two contact points each located on one side of the cutting tool 10, as shown in fig. 4. In this configuration, the guide edges 11, 12 define guide slots in which the cutting tool 10 can be guided. Preferably, said guide groove 7 is defined so as to define a path placed in the upper surface of said cover 1. The slot 7 is provided for guiding a dentist's cutting tool along this path, for which purpose the slot 7 extends through the cover to establish communication between the inside of the cover and the external environment. When more than one path is to be followed for removing the predetermined portion, a plurality of guiding slots 7 will have to be determined.

A combination of these two mentioned configurations is illustrated in fig. 5. In the figure, the first guide edge 11 and the second guide edge 12 can be seen on the left, said first guide edge 11 and second guide edge 12 being said two guide edges separated from each other, said edges defining guide surfaces. A third guide edge 13 can be seen on the right, which edge defines a path together with the first guide edge 11 and the second guide edge 12. This configuration thus allows the cutting tool to be guided both to horizontal movement and to tilt.

As can be seen in fig. 5, the cutting tool 10 preferably includes a collar 14 mounted to the cutting tool 10. Preferably, at least one of the guiding edges 11, 12, 13 is provided to guide a collar 14 of the cutting tool 10, thereby guiding the cutting tool 10 into a predetermined vertical position or height or depth. As can be seen in fig. 5, the guide slot 7 defining the horizontal path further defines a predetermined height 8 for each horizontal position of the cutting tool, to guide the cutting tool 10 along the horizontal path and at a predetermined inclination, and also to guide the cutting tool in a vertical manner.

Fig. 6 illustrates a variant of the embodiment shown in fig. 3, and shows the guide edges 11, 12, the guide edges 11, 12 being provided to contact the cutting tool simultaneously at two contact points longitudinally spaced apart from each other. In this embodiment, the tooth structure located between the two guide edges 11, 12 can be removed. This embodiment will be used, in particular, when preparing teeth for placing a crown of a dental shield.

For mounting a crown or bridge, the tooth will be shaped as a truncated pyramid with rounded edges. To this end, the outer and upper portions of the teeth will be removed. Such removal of the tooth structure may be guided by the dentist tool according to the present invention.

Preferably, the removal of the tooth structure is performed in several stages as shown in fig. 7 for preparing the tooth for mounting the crown or bridge. In a first stage, shown in fig. 7a and 8, the upper part of the teeth is smoothed. This can be done using a cover with guide edges 11, 12 as shown in fig. 6. In practice, however, it is preferred to shape the upper portion into a V-shape. To this end, the upper part is preferably smoothed using two guiding means as shown in fig. 3, which are located on both sides of the tooth in such a way that: the guide means is provided to guide the cutting means to cut the upper portion into a V-shape.

In the second and third stages, shown in fig. 7b and 7c, the longitudinal and transverse sides of the tooth are cut to obtain a truncated pyramid shape. The cutting of these sides may be guided by a cover with guiding means as shown in fig. 3, 4 or preferably fig. 5. Preferably, one cover comprises two such guiding means, each defining a path extending in a surface of the cover, the paths extending parallel to each other, each path being on one side of the tooth.

In the fourth and fifth stages, shown in fig. 7d and 7e, the edges of the pyramid are chamfered. The chamfering of these edges may be guided by a cover as shown in fig. 1 and 2. Such a cover includes a path extending in a surface of the cover and defining a portion of a circle. Each side of the path is defined by a guide surface having at least two guide edges, as shown in fig. 3. The height of the guiding portion 5 of the cover 1 is defined to guide the guiding means 10 in a predetermined vertical position.

In this successive phase, the first phase may be implemented as the last phase rather than as the first phase. However, tests have proven advantageous in preparing the teeth starting from smoothing the upper part of the teeth.

Once the cover 1 and the guiding means are determined, a determined cover 1 with the determined guiding means can be manufactured. This can be done by any known method such as CAD/CAM systems, rapid prototyping or 3D printing. When a plurality of guiding means has been determined, a plurality of covers 1 can be manufactured, each cover 1 comprising one or several guiding means. Preferably, the rapid prototyping apparatus produces a coverage with a tolerance of about 30 μm.

As already mentioned above, the cover 1 has a lower bearing portion 6 and an upper guide portion 5. As can be seen in the figures, the guide portion 5 has a specific thickness 8, the specific thickness 8 defining the height 8 of the path and being able to guide the cutting tool in the perpendicular manner. Preferably, the support part 6 and/or the guide part 5 comprise a vertical opening 9 from the side to the guide slot 7, the vertical opening 9 being provided for access into the guide slot 7 for the dentist's cutting tool. This opening is advantageous especially when the cutting tool has a tip portion with a diameter larger than the diameter of the main portion of the cutting tool, such as a high speed drill with a tip in the shape of a sphere. Entering such a cutting tool into the guide slot 7 through the upper part of the cover will at least partly widen the guide slot 7, thereby at least partly taking away the possibility of guiding the cutting tool stably along the predetermined path. Furthermore, a side access 9 is preferred over an access through the upper part, since it will be easier to get the cutting tool into the guide groove 7 in a controlled manner.

When the guiding groove 7 is determined to form a circular path in said horizontal plane, it is preferable to split this path into several segments, and to manufacture a plurality of covers 1, each cover 1 having a guiding groove 7 corresponding to one segment of this path. This results in a set of covers 1 which can be used one after the other by the dentist to remove tooth structure following this circular path. Each cover 1 of the set of covers 1 will guide the cutting tool along a specific side of the tooth.

In embodiments where the predetermined portion is determined not based on the shape of the restored portion of the tooth, the latter may be determined based on data in the computer. The outer shape of the restored portion of the tooth can be determined in several ways, all of which are known to those skilled in the art. Modifications of bite lift (bite lift) or other corrections may be incorporated directly into the design of the outer shape. A first possibility is to shape the restored portion of the tooth so that it resembles the outer shape of the original tooth. A second possibility is to shape the tooth restoration portion so that it fits the adjacent tooth. A third possibility is a combination of the first and second possibilities and altering the shape of the original tooth to better fit the adjacent tooth. The internal shape of the restored portion of the tooth will be determined based on a simulation of the preparation of the tooth. Since the tooth is to be prepared in a guided manner, it is known in advance what shape the prepared tooth will have. The internal shape of the tooth restoration portion will be selected so that it matches the shape of the prepared tooth.

Preferably, the method according to the present invention further comprises the step of manufacturing the tooth restoration part.

Similar to the determination of the predetermined portion, the tooth restoration portion may be determined by a computer without any cooperation of dentists. Preferably, however, the computer cooperates with a dentist to determine the tooth restoration part, for example in the manner described above. In this process of determining the tooth restoration portion, the computer may perform a predetermined clinical examination and alert the dentist if the tooth restoration portion does not meet the standard specification. This will enable the dentist to design the tooth restoration part in a quick and reliable way.

The manufacture of the tooth restoration part can be performed by any means known to the person skilled in the art, such as a CAD/CAM system.

Claims (20)

1. A cover for guiding a dentist cutting tool in removing a predetermined tooth structure from a tooth to be treated, the cover comprising:

an inner surface having a shape and size corresponding to an outer surface of the tooth to be treated such that the inner surface is releasably secured to the tooth to be treated, or an adjacent tooth of the tooth to be treated, or the tooth to be treated and the adjacent tooth of the tooth to be treated;

a first guide edge extending through the thickness of the covering, including through the inner surface, the first guide edge having a profile corresponding to at least one of horizontal, vertical, and oblique movements followed by a dental cutting tool; and

a second guide edge extending through the thickness of the covering, including through the inner surface, and spaced from the first guide edge, the second guide edge having a profile corresponding to at least one of horizontal, vertical, and oblique movements followed by a dental cutting tool.

2. The cover of claim 1, wherein said inner surface has a shape and size such that said inner surface is releasably secured to an adjacent tooth of a plurality of said teeth to be treated, said inner surface, when secured to said adjacent tooth, being in sufficient contact with said adjacent tooth such that said cover does not release or move due to the application of pressure during normal use of said cover to guide said cutting tool.

3. The cover of claim 1, wherein the first and second guide edges are spaced apart by at least 0.5 mm.

4. The cover of claim 1, wherein the first and second guide edges are spaced apart by a fixed distance between corresponding contact points along the respective lengths of the first and second guide edges.

5. The cover of claim 1, wherein the first and second guide edges are spaced apart a fixed distance for contacting the dental cutting tool at their corresponding contact points.

6. The cover of claim 1, wherein the cover is a unitary indivisible structure.

7. The cover of claim 1, wherein the first and second guide edges define a first guide slot, the cover comprising:

a second guide slot defined by another set of the first and second guide edges spaced apart from each other, the second guide slot being separate from the first guide slot.

8. A dentist's cutting tool comprising a structure having the ability to engage at least one guide edge of the cover of claim 1.

9. A system for use by a dentist in removing a predetermined tooth structure from a tooth to be treated, the system comprising:

a dentist cutting tool; and

the cover of claim 1.

10. The system of claim 9, wherein a portion of the dental cutting tool has a thickness such that the dental cutting tool simultaneously contacts the first and second guide edges of the covering as the dental cutting tool moves along the path defined by the first and second guide edges.

11. The system of claim 9, wherein the dental cutting tool includes a cutting portion and a collar, at least one of the first and second leading edges of the cover for contacting the collar to ensure that the cutting tool guided by the cover has a predetermined depth.

12. A set of covers for guiding at least one dentist cutting tool in removing a predetermined tooth structure from a tooth to be treated, the set of covers comprising two or more of the following covers:

a first cover having a shape and dimensions for guiding at least one dentist cutting tool to resect at least a portion of an upper portion of a tooth after the upper portion of the tooth is removed based on a desired height of a remaining tooth structure;

a second cover having a shape and dimensions for guiding at least one dentist cutting tool to resect at least a portion of a longitudinal side of the tooth;

a third cover having a shape and dimensions for guiding at least one dentist cutting tool to resect at least a portion of a lateral side of the tooth;

a fourth cover having a shape and dimensions for guiding at least one dentist cutting tool to chamfer an edge between the longitudinal and lateral sides of a tooth on one side of the tooth;

a fifth cover having a shape and dimensions for guiding at least one dentist cutting tool to chamfer an edge between the longitudinal and lateral sides of a tooth on another side opposite the one side of the tooth.

13. A set of covers as claimed in claim 12, wherein at least one of said set of covers has an inner surface having a shape and size such that said inner surface is releasably secured to: the tooth to be treated, or an adjacent tooth of the tooth to be treated, or the tooth to be treated and the adjacent tooth of the tooth to be treated.

14. A set of covers as claimed in claim 13, wherein at least one of said set of covers comprises:

a first guide edge extending through a thickness of the at least one cover, the first guide edge having a profile corresponding to at least one of horizontal, vertical, and oblique motions followed by a dental cutting tool; and

a second guide edge extending through a thickness of the cover and spaced apart from the first guide edge, the second guide edge having a profile corresponding to at least one of horizontal, vertical, and oblique movements followed by a dental cutting tool.

15. The set of covers of claim 14, wherein the first and second guide edges define a first guide slot, the cover comprising:

a second guide slot defined by another set of the first and second guide edges spaced apart from each other, the second guide slot being separate from the first guide slot.

16. The set of covers of claim 12, wherein at least one of the set of covers has an inner surface having a shape and size such that the inner surface is releasably secured to an adjacent tooth of the plurality of teeth to be treated, the inner surface being in sufficient contact with the adjacent tooth when secured thereto such that the at least one cover does not release or move due to the application of pressure in normal use of the at least one cover to guide the cutting tool.

17. A dentist's cutting tool comprising a structure having the ability to engage with one or more guide edges of at least one cover of the set of covers of claim 12.

18. A system for use by a dentist in removing a predetermined tooth structure from a tooth to be treated, the system comprising:

a dentist cutting tool; and

a set of covers according to claim 12.

19. The system of claim 18, wherein at least one of the set of overlays comprises:

an inner surface having a shape and size corresponding to an outer surface of the tooth to be treated such that the inner surface is releasably secured to: the tooth to be treated, or an adjacent tooth of the tooth to be treated, or the tooth to be treated and the adjacent tooth of the tooth to be treated;

a first guide edge extending through the thickness of the covering, including through the inner surface, the first guide edge having a profile corresponding to at least one of horizontal, vertical, and oblique movements followed by a dental cutting tool; and

a second guide edge extending through the thickness of the covering, including through the inner surface, and spaced from the first guide edge, the second guide edge having a profile corresponding to at least one of horizontal, vertical, and oblique movements followed by a dental cutting tool.

20. The system of claim 19, wherein a portion of the dental cutting tool has a thickness such that the dental cutting tool simultaneously contacts the first and second guide edges of the covering as the dental cutting tool moves along the path defined by the first and second guide edges.