(12) United States Patent (10) Patent No.: US 9,011,147 B2

Transcription

1 US B2 (12) United State Patent () Patent No.: US 9,011,147 B2 Jacquemyn (45) Date of Patent: Apr. 21, 20 (54) DENTIST TOOL 4,144,645 A * 3/1979 Marhall ,223 4, A 3, 1985 Patch (75) Inventor: Evelyne Jacquemyn, 4,778,387 A /1988 Komatu Sint-Marten-Latem (BE) 4.941,826 A * 7/1990 Loran et al /51 (Continued) (73) Aignee: Viax Dental Technologie, LLC, Miami, FL (US) FOREIGN PATENT DOCUMENTS (*) Notice: Subject to any diclaimer, the term of thi S. : A patent i extended or adjuted under 35 U.S.C. 4(b) by 56 day. (Continued) OTHER PUBLICATIONS (21) Appl. No.: 13/524,383 P. Hahn, Fracture trengh of 3-unit inlay bridge after thermo-me (22) Filed: Jun., 2012 chanical fatigue in a chewing imulator, Oct. 25, 2001, 2 page. (65) Prior Publication Data (Continued) US 2012/O27O176A1 Oct. 25, 2012 Primary Examiner Ralph Lewi Related U.S. Application Data (63) Continuation of application No. 12/364,216, filed on Krumholz & Mentlik, LLP Feb. 2, 2009, now abandoned. (57) ABSTRACT (74) Attorney, Agent, or Firm Lerner, David, Littenberg, (51) Int. Cl. A method for p producing 9. a dentit tool for ue in removin 9. A6IC3/02 ( ) tooth tructure i provided. The method include acquiring A6IC I3/00 ( ) three-dimenional data relating to a hape of a tooth and part (52) U.S. Cl. of a neighboring tooth. The method include proceing the CPC... A61C 13/0004 ( ); A61C3/02 data to determine an overlay fitting the tooth and part of the ( ) neighboring tooth. The method further include proceing (58) Field of Claification Search the data to determine the tooth tructure to be removed from CPC... A61C 3702 the tooth to prepare the tooth for further treatment. The USPC /75, 76 method include determining firt and econd guiding edge See application file for complete earch hitory. Such that the two edge are paced apart a ditance of at leat 0.5 mm and configured to enable a dentit cutting tool to be (56) Reference Cited guided by imultaneouly contacting the firt and econd guiding edge to enable a guided removal of at leat partially U.S. PATENT DOCUMENTS the predetermined part of tooth tructure. The method 472,004 A * 3/1892 Sweet et al ,75 include producing the determined overlay having the deter 1407,840 A 2, 1922 Cruttenden mined guiding edge. 3,407,503, 1968 Nealon ,76 3,445,935 A * 5/1969 Marhall /51 26 Claim, 3 Drawing Sheet

2 US 9,011,147 B2 Page 2 (56) 4,997,369 5,118,294 5,224,049 5,257, 184 5,343,391 5, ,472 5,545,039 5,562,448 5,569,578 5,575,656 5,725,376 5,800,168 6,030,211 6,257,892 6, ,786,726 7, ,8,511 7,172,424 7,287,982 7,346,417 7,367,801 7,572,125 7,658,6 7,905,726 8,011, /OO /OO /02826 Reference Cited U.S. PATENT DOCUMENTS 3, , , 1993, , , , , 1996, 1996, , , , , 2000 T/2001 9, , , , , 2007, , /2008 8, , 20 3, , , / , 2005 Shafir Kurer Muhabac Muhabac Muhabac Muhabac Muhabac Muhabac Muhabac Muhabac Hajjar ,219 Poirier ,172 Cacione et al. Sandhau Worthington Worthington Lehmann et al. Tang ,76 Shatkin Wu Riley et al. Luth et al. Saliger Brajnovic Knopp Stumpel Berckman, III et al. Karmaker et al. Wilkinon Suman et al. 2006, O A A1 2009, A1 20/ A A1 20, A1 6/2006 Sogo et al. 12/2008 Metzger et al. 11/2009 Rubbert et al. 7/20 Vogel et al. 8/20 Jacquemyn 8/20 Jacquemyn FOREIGN PATENT DOCUMENTS EP A1 6, 2005 WO WO O2344 WO 2007/4842 A1 * 5, , 2007 OTHER PUBLICATIONS International Search Report and Written Opinion for Application No. PCT/US2012/ dated Sep. 14, Chinee Office Action for Application No dated Sep. 18, Japanee Office Action for Application No dated Dec. 20, Canadian Office Action for Application No. 2,750,698 dated Apr., Autralian Examination Report for Application No dated Jan. 29, Ruian Office Action for Application No dated Feb. 22, Mexican Office Action for Application No. MX/a/2011/ dated Apr. 9, Japanee Office Action for Application No dated Aug. 5, * cited by examiner

3 U.S. Patent Apr. 21, 20 Sheet 1 of 3 US 9,011,147 B2 A fg. 2

4 U.S. Patent Apr. 21, 20 Sheet 2 of 3 US 9,011,147 B2 w r w w w

5 U.S. Patent Apr. 21, 20 Sheet 3 of 3 US 9,011,147 B2 A fg. 7c. A fg. 7d. A fg. 7e

6 1. DENTIST TOOL CROSS-REFERENCE TO RELATED APPLICATIONS The preent application i a continuation of U.S. patent application Ser. No. 12/364,216, filed Feb. 2, 2009, the di cloure of which i incorporated herein by reference. SUMMARY OF THE INVENTION The preent invention concern a method for producing a dentit tool formed by an overlay to be ued by a dentit in removing tooth tructure, aid method compriing the tep of: acquiring three-dimenional data relating to a hape of at leat one predetermined tooth and at leat a part of a neigh bouring tooth of aid predetermined tooth; proceing aid three-dimenional data with a computer o a to determine an overlay fitting aid tooth and fitting at leat aid part of aid neighbouring tooth; determining guiding mean within aid overlay, Suitable for guiding a dentit cutting tool; producing aid determined overlay having aid determined guiding mean. The preent invention further concern a dentit tool obtained by the application of the decribed method. When a patient need a crown, bridge, onlay, inlay, Veneer, or other retoring and/or aethetic tooth treatment, conven tionally, during an initial office viit, the dentit identifie the need of the patient and determine an appropriate treatment. During Subequent viit, in cae the tooth comprie dam aged and/or infected tooth tructure, the dentit remove thi tooth tructure and recontruct the tooth a much a poible uing conventional technique. Thereafter, the dentit per form the final preparation of the tooth for further treatment by removing tooth material, which i to be interpreted a original tooth tructure and recontructed tooth tructure, with a dental cutting tool Such a a high-peed drill. Relying upon eyeight and expertie, the dentit ue the drill to hape the tooth in a form that i uitable for further treatment, in particular a form onto which a crown, bridge, onlay, inlay, Veneer or other tooth retoring part can be mounted. Then, the dentit take an impreion of the dental arch in which the prepared tooth i located, and end the impreion to the dental laboratory to have the dental technician make the re toration part. Uing the impreion of the prepared tooth, the dental technician produce a retoration part that matche the colour, geometrical and material pecification, and end it to the dentit. At the patient final viit, the dentit adjut the retoration part a neceary before fitting it in place. Such a dentit tool i dicloed in EP The known dentit tool decreae the impact of the experience and exper tie of the dentit onto the treatment, and it i ued by a dentit in boring an artificial tooth root cavity. In EP47544, guid ing mean, formed by a cylindrical hole, for guiding a drill in a traight-forward way, i provided. In uch a manner an artificial tooth root cavity can be bored with greater preciion even by a le experienced dentit. Moreover a uitable root cavity poition can be calculated baed on the information proceed by the computer, o a to form in the mot optimal way a cavity in the jaw bone. A drawback of the known dentit tool i that it can only be ued by a dentit in boring hole into the jaw bone. Thi dentit tool i not uitable to be ued by a dentit in preparing a tooth for further treatment It i an object of the preent invention to provide method for producing a dentit tool that i Suitable for being ued by a dentit in preparing a tooth for further treatment. To thi end, a dentit tool according to the preent invention i characterized in that aid method comprie the further tep of: before determining aid guiding mean, determining a pre determined part of tooth tructure to be removed from aid tooth o a to prepare aid tooth for further treatment; determining at leat two guiding edge of which a firt and a econd guiding edge are paced apart from each other by a ditance of at leat 0.5 mm, aid guiding edge being part of aid guiding mean (7), aid guiding edge being configured So a to enable aid dentit cutting tool to be guided by imultaneouly contacting aid firt and aid econd guiding edge in Such a manner a to enable a guided removal of at leat partially aid predetermined part of tooth tructure. The determination of a predetermined part of tooth truc ture to be removed reult in that thi doe not any more depend on the kill of the dentit. Depending on the indi vidual dental ituation of a patient, the computer i pro grammed to determine an optimal way for haping the tooth into a hape that i uitable for further treatment. Determining and producing guiding edge into an overlay, which guiding edge are Suitable for imultaneouly contacting the dentit cutting tool, allow the cutting tool to be guided along a well determined path in an at leat partially predetermined way. The overlay, having the guiding edge, accurately indicate onto the tooth the part to be removed from the tooth a determined by the computer. Moreover the tool according to the invention i provided to ait the dentit in removing tooth tructure a the tool allow a dentit to remove at leat part of a predetermined part of tooth tructure. It i to be noted that the term fitting i not to be interpreted in the narrow ene that the overlay hould cloely urround the teeth. It moreover hould be interpreted a that an overlay hould Surround the teeth So a to be adequately in contact with the teeth and o that, once applied, it will not be releaed even if certain preure, due to a normal ue of the overlay, i applied. In a preferred embodiment of the invention, aid firt and aid econd guiding edge are deigned for imultaneouly contacting aid dentit cutting tool at contacting point being longitudinally ditanced from each other by aid ditance, aid guiding edge thereby defining a guiding Surface along which aid dentit cutting tool i to be guided. By imultaneouly contacting two guiding edge with a cutting tool at contacting point being longitudinally di tanced from each other, the cutting tool can be guided at leat partially in a predetermined way. Preferably the cutting tool move along the two guiding edge and thereby define a guiding Surface. Thi urface comprie the two guiding edge, and a cutting tool can be guided along thi urface. Thi allow an accurate guiding in two dimenion. Preferably, in determining aid guiding mean, a guiding groove i determined, which define a path extending in a Surface of aid overlay and Suitable for guiding aid dentit cutting tool along aid path in Such a manner a to enable a guided removal of at leat partially aid predetermined part of tooth tructure. The two guiding edge, being ditanced from each other, can be located one on the one ide and the other on the other ide of the path thereby defining the path between the two guiding edge. To thi purpoe, the ditance between the two guiding edge hould be ubtantially equal to a diameter of the cutting tool. Uing the dentit cutting tool by imulta neouly contacting the two guiding edge and following the

7 3 path allow a guidance of the cutting tool at leat in two dimenion. Conidering a longitudinal cutting tool, the Sur face defined by the two guiding edge in thi configuration will be ubtantially perpendicular to the direction of the cutting tool in ue. The two guiding edge, being ditanced from each other, can alo be both located on one ide of the path. At leat a third guiding edge will then define the other ide of the path. Conidering a longitudinal cutting tool in thi configuration, the urface defined by the two guiding edge will be ubtan tially parallel to the direction of the cutting tool in ue. The third guiding edge in thi configuration will provide a further guidance to the cutting tool thereby increaing the accuracy of the proce of removal of tooth tructure. Uing the dentit tool by imultaneouly contacting the two guiding edge and following the path in thi configuration allow a guidance of the cutting tool in two dimenion and a guidance of inclina tion of the cutting tool. Preferably, the method comprie the further tep of: determining a tooth retoration part having an inner hape So a to fita remaining part oftooth tructure of aid tooth, and having an outer hape o a to fit together with remaining neighbouring teeth; producing aid tooth retoration part. An advantage of the method according to the invention i that the hape of the remaining part of tooth tructure of the prepared tooth i known in advance due to the guided removal of tooth tructure. Thi improve further treatment, uch a preparing a temporary or final inlay, onlay, bridge, crown or veneer in advance baed on the three-dimenional data. Thi reult in that le office viit are required, a the dentit can both prepare the tooth and mount the tooth retoration part onto the prepared tooth in one ingle viit. Thi way of work ing doe not only ave time and thu cot, alo the inconve nience for the patient i trongly decreaed. Furthermore the chance that a prepared tooth get contaminated, and the reulting complication, are reduced to a minimum. Preferably, aid predetermined part i determined by: firtly determining a tooth retoration part having an outer hape So a to fit together with remaining neighbouring teeth, and having an inner hape compatible with aid outer hape; econdly determining a hape of remaining tooth tructure o that aid tooth retoration part having aid inner hape fit aid hape of remaining tooth tructure; thirdly determining aid predetermined part a being the part of tooth tructure to be removed o a to have aid hape of remaining tooth tructure left. Starting with determining a tooth retoration part intead of a conventionally, preparing the tooth, ha an advantage. A tooth retoration part can be determined having an outer hape o a to optimally fit together with remaining neigh bouring teeth. Procedure for determination of uch an outer hape are known to the peron killed in the art. An inner hape i then determined, which inner hape i compatible with aid outer hape. Criteria for being compatible depend on the material that i to be ued and mainly concern trength parameter, production parameter and parameter relating to the mounting of the retoration part onto the tooth and/or teeth. Preferably the inner hape i determined in uch a manner that a minimum amount of material i required to produce the tooth retoration part. Thi at it turn reult in that the remaining tooth tructure, required to fit to thi inner hape, i a large a poible, namely, the more material of a retored tooth i tooth retoration material, the le material of that retored tooth i tooth tructure. Then the predetermined part can be determined a being the part of tooth tructure to be removed o a to have aid hape of remaining tooth tructure left. Thu firt determining the tooth retoration part, reult in that a minimum of tooth tructure i to be removed from the tooth and maximum conervation of the original tooth tructure. A it i bet to maintaina much of the original tooth tructure, thi i an advantage. In a further tep, the determined tooth retoration part having the determined outer and inner hape, can be pro duced. Thi reult in that le office viit are required, a the dentit can prepare the tooth and mount the tooth retoration part onto the prepared tooth in one ingle viit, having the advantageou a decribed above. Preferably aid removal of tooth tructure i to be per formed in a plurality of tage in which aid guiding mean i provided to guide aid cutting tool in a firt tage of aid plurality of tage, and at leat one further guiding mean i provided to guide aid cutting tool in at leat one further tage, the method further compriing the tep of: determining aid at leat one further guiding mean (7) each compriing at leat two further guiding edge of which a further firt and a further econd guiding edge are paced apart from each other by a ditance of at leat 0.5 mm, aid further firt and aid further econd guiding edge being pro vided for imultaneouly contacting aid dentit cutting tool thereby guiding aid dentit cutting tool in Such a manner a to enable a guided removal of at leat partially aid predeter mined part of tooth tructure; producing at leat one further overlay each having one of aid at leat one further guiding mean. Producing a plurality of overlay intead of jut one over lay provide a further flexibility in the method for producing the dentit tool. Different overlay can be provided for guid ing a dentit cutting tool along different ide of the tooth to be prepared, o that for example a circumferential path can be defined by uing multiple overlay each defining a different egment of the circumferential path. Multiple overlay fur thermore allow to ue different dental cutting tool, which i neceary in ome cae. Different overlay can be provided for preparing a tooth in multiple tage, in which for example a firt tage i provided to Smoothen the upper part of the tooth, a econd and a third tage are provided to cut away the longitudinal and tranveral ide of the tooth, and a fourth and fifth tage are provided to round off the edge between the longitudinal and tranveral ide each at a different ide of the tooth. Preparing a tooth in tage allow each overlay to be deigned having guiding edge which are particularly deter mined for guiding the cutting tool in a particular way charac teried by the particular tage. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be decribed in more detail with repect to the drawing illutrating ome preferred embodi ment of the invention. In the drawing: FIG. 1 how a top view of an overlay with a guiding groove according to the invention; FIG. 2 how a ide view of an overlay with a guiding groove placed onto a patient' teeth. FIG. 3 how a cro ection of part of an overlay with guiding mean according to one embodiment of the invention and a cutting tool; FIG. 4 how a cro ection of part of an overlay with guiding mean according to another embodiment of the invention and a cutting tool; FIG. 5 how a cro ection of part of an overlay with guiding mean according to the invention and a cutting tool;

8 5 FIG. 6 how a cro ection of part of an overlay with guiding mean according to a further embodiment of the invention and a cutting tool; FIG. 7 how a et of overlay to be ued by a dentit in preparing a tooth for mounting a crown or bridge. FIG. 8 how a cro-ection of the overlay hown in FIG. 7a. DETAILED DESCRIPTION In the drawing a ame reference number ha been allo cated to a ame or analogou element. The term lower, upper' etc. and derived directional term uch a "horizontal and vertical are baed on a normal configuration of an overlay a hown in the drawing, wherein the overlay fit onto teeth with their root extending vertically downward. The term dentit in thi text i not to be interpreted retrictive and can alo be read a dental techni cian, dental aitant, dental auxiliary, dental therapit, dental deigner etc. The invention provide a method for producing a dentit tool formed by an overlay 1 to be ued by a dentit in remov ing tooth tructure. Furthermore, the invention provide an overlay 1 obtainable by thi method. FIGS. 1 and 2 how uch an overlay 1 arranged onto the teeth 2 of a patient. Preferably, the invention provide a method for producing the dentit tool and a tooth retoration part in Such a manner that the tooth retoration part will fit the tooth that i prepared uing the dentit tool. The dentit tool according to the invention i preferably ued by a dentit in preparing a tooth for a retoration uch a placing inlay and onlay, crown, bridge, and veneer. Such retoration require a retoration part to be produced in order to fit the tooth after the latter ha been prepared. Uing the dentit tool according to the invention reult in that the hape of the prepared tooth, which conventionally i only known after preparation, i determined in advance. Baed on thi knowledge, a retoration part can be produced in advance o that thi retoration part i available to the dentit even before he or he tart preparing the tooth, and can be mounted directly after preparation of the tooth. Thi reult in that the patient Suffer le inconvenience, in particular that the num ber of viit to the dentit are reduced. Furthermore the chance that a prepared tooth get contaminated, and the reulting complication, are reduced to a minimum. Preferably, preparing a tooth for further treatment i per formed onto a ubtantially healthy tooth. When a tooth i damaged or infected, the damaged and/or infected part of the tooth will have to be removed firt, and the tooth will have to be recontructed before preparing the tooth for further treat ment. Thi minimize the chance that an infection develop underneath a tooth retoration part. Thi alo maximize the lifetime of the tooth retoration part a the bai for the tooth retoration part, namely the tooth, doe not contain damaged part any more. Several method are known for acquiring three-dimen ional data from a patient dentition. Such data can be retrieved by proceing photograph taken from the patient dentition. Another method i making a phyical impreion of the dentition and then Scanning thi impreion with a CAD/ CAM 3D canning device. For what concern the preent invention, any appropriate method for acquiring three-dimen ional data can be ued. After acquiring the three-dimenional data of the tooth, thi data get proceed by a computer o a to determine an overlay 1 fitting the teeth 2 of the patient. To thi end, the inner hape of the overlay preferably correpond to the outer hape of the tooth to be prepared and to the outer hape of at leat part of a neighbouring tooth. Overlay hould fit the teeth in Such a manner that once the overlay i placed onto the teeth, it will only come off by applying a ufficiently high force to the overlay. During preparation of the tooth, Small force may be applied to the overlay, which preferably hould not modify the poition of the overlay on the teeth. Preferably, the overlay 1 extend over the teeth 2 o a to alo coverpart of the gingiva 3 for tability purpoe and protection purpoe. A the dentit will ue the overlay 1 for removing tooth material, it i advan tageou that the overlay 1 i located onto the tooth in a table way. A an example, an overlay 1 cloely fitting the tooth, two neighbouring teeth, and part of the gingiva 3, enure that a dentit can arrange and maintain the overlay in a table poi tion during removal of tooth tructure. When the overlay 1 cover a part of the gingiva 3, at leat thi part of the gingiva 3 will be protected during the proce of removing tooth Structure. It i to be noted that an overlay 1 according to the invention can cover multiple teeth at once and can be provided to be ued by a dentit in preparing a plurality of teeth uing one ingle overlay 1. Thi can be advantageou in the proce of preparing teeth for placing veneer. Such an overlay com prie guiding mean, a will be explained further, for each tooth that need to be prepared. The determined overlay 1 ha a thickne 4 that mainly depend on the required trength thereof, and thu alo the material it will be made of. An overlay 1 according to the invention can have a contant overall thickne 4. A ubtan tially contant overall thickne i preferred for an overlay to be ued by a dentit in preparing a tooth or teeth for placing veneer. An overlay to be ued for preparing a tooth for placing a bridge or a crown preferably comprie an upper, guiding part 5, and a lower, Supporting part 6. The Supporting part 6 of the overlay 1 will enure that the overlay 1 can be arranged in a table way onto the teeth 2, wherea the guiding part 5 of the overlay 1 will guide the dentit cutting tool and preferably will alo determine the maximal penetration depth of the cutting tool in the tooth. To thi end, the thickne of the guiding part 5 of the overlay 1 will preferably be determined cae by cae together with the determination of the guiding mean 7, a will be explained further. The thickne 4 of the Supporting part 6 of the overlay 1 can be more freely choen depending on the preference of the dentit and/or the pro grammation of the computer. After acquiring the three-dimenional data, thi data get alo proceed by a computer o a to determine a predeter mined part of tooth tructure to be removed from the tooth by the dentit. The predetermined part will be determined in view of the further treatment. If a particular hape of the prepared tooth i required for allowing further treatment, the predetermined part will be choen o that after preparation of the tooth, thi particular hape will remain. Determining the predetermined part depend on many parameter and will differ from cae to cae. Parameter are the location of the tooth in the mouth of the patient, amount and location of the damaged tooth tructure, ditance of the tooth to neighbouring teeth, etc. In a preferred embodiment, the computer will alo take into account the different part of the tooth Such a the enamel, denting, pulp, cementum, etc. in determining the predetermined part. According to the invention, the computeri programmed to determine the predetermined part of tooth tructure to be removed without aitance of a dentit except for what con cern the input of the initial data of the tooth. However alo according to the invention, the computer can be programmed to determine the predetermined part in cooperation with a

9 7 dentit, where for example the dentit decide on ome parameter. Thi cooperation can be etablihed by viualiz ing data relating to the tooth onto a computer diplay and allowing the dentit at leat to enter one parameter relating to the preparation of the tooth. Preferably a preview of the tooth i viualized onto the computer diplay together with a pre view of a imulation of the prepared tooth, o a to allow a dentit to ee the impact of choen parameter onto the pre pared tooth. The latter feature provide a larger degree of freedom to the dentit and allow a le experienced dentit to conult a more experienced dentit about a cae, baed on the data in the computer. In thi manner, the method for produc ing a dentit tool according to the invention allow a le experienced dentit to decide on a further treatment and pre pare a tooth for further treatment with a ame quality a if he or he wa an experienced dentit. In another embodiment, the computer i programmed to determine the predetermined part of tooth tructure to be removed in everal phae. At the end of each phae, the computer propoe a imulated Solution to the dentit and requet for approval or correction of the propoed olution. Preferably the predetermined part will be determined in everal tep. In a firt tep, the outer hape of the tooth retoring part i to be determined o that the tooth retoring part fit with the remaining teeth and fit into the dental arch of the patient. Abite lift or other corrective amendment can be directly integrated into the deign of the outer hape. Then, baed on thi determined outer hape, an inner hape get determined that i compatible with the outer hape. In uch a manner, a tooth retoration part can be determined having an optimal outer hape, and an optimal contruction in the ene that it i trong enough and a minimum of material i needed. In a following tep, the hape of remaining tooth tructure i to be determined o that the inner hape of the tooth retoring part fit the remaining tooth tructure after removal of tooth tructure. In a final tep, the predetermined part of tooth tructure i determined a the part of tooth tructure to be removed to have the hape of remaining tooth tructure left. Thi way of working allow determining the outer hape of the tooth retoring part uing bet fit program. Convention ally, the dentit will not follow the tep in the ucceion a mentioned above. The dentit will work the other way around, a the dentit will need to know the hape of the prepared tooth to determine the innerhape of the retoration part, after which the dentit will determine an appropriate outer hape. Firtly determining the tooth retoration part, according to a preferred embodiment of the invention, reult in that a mini mum of tooth tructure i to be removed from the tooth and a maximum conervation of the original tooth tructure can be obtained. Once the predetermined part ha been determined, guiding mean can be determined. The purpoe of the guiding mean i to guide a dentit cutting tool, i.e. a drill, o that the cutting tool remove at leat a part of the predetermined part. To thi end, it will be undertood that in ome cae, the dimenion of the dentit cutting tool. Such a the length, diameter, cro ectional form, etc. will be determining for which movement i to be made with the cutting tool to remove a certain part of tooth tructure. It will alo be undertood that in many cae, it will not be ufficient to make one ingle movement for removing all the predetermined part. Via computer calcula tion and/or imulation, one or more movement can be deter mined for removing the predetermined part of tooth tructure. It i to be undertood that a movement in thi context doe not only relate to a two-dimenional poition, but relate to the movement of the cutting tool in all it apect uch a hori Zontal movement, vertical movement and tilt movement The guiding mean according to the invention comprie at leat two guiding edge 11, 12 (FIG. 3-6). Two of thee guiding edge 11, 12 are paced apart from each other with a ditanced of at leat 0.5 mm. The guiding edge 11, 12 are provided to imultaneouly contact the cutting tool thereby guiding the cutting tool at leat partially into a predetermined movement. It i to be undertood in thi con text that a urface having a length and having a width which are at leat 0.5 mm can be conidered a the aid at leat two guiding edge 11, 12. Namely, the two outer edge of the Surface are provided to imultaneouly contact the cutting tool, and are paced apart with a ditance d of at leat 0.5. Preferably the two guiding edge 11, 12 are paced apart from each other with a ditance d of at leat 1 mm, more preferably of at leat 2 mm and mot preferably of at leat 3 mm. Increaing the ditanced between the two edge 11, 12 will increae the guiding quality a it will be much eaier for a dentit to control the cutting tool onto larger guiding CaS. The guiding edge 11, 12 are provided in Such a manner a to be imultaneouly contacted by the cutting tool at two contacting point. A illutrated in FIG. 3, preferably thee contacting point 11, 12, conidered on the cutting tool, are longitudinally paced apart by the ditanced. When the cut ting tool i arranged Subtantially perpendicular to the guiding edge, the ditance between the contacting point will be ubtantially the ame a the ditanced between the guid ing edge. FIG. 3 illutrate a cutting tool lying imulta neouly againt the two guiding edge 11, 12. The guiding edge 11, 12 in thi configuration define a urface along which the cutting tool can be guided. However the guiding edge 11, 12 can alo imultaneouly contact the cutting tool at two contacting point being located each at one ide of the cutting tool, a illutrated in FIG. 4. In thi configuration, the guiding edge 11, 12 define a guiding groove in which the cutting tool can be guided. The guiding groove 7 i preferably determined o a to define a path laying in the upper Surface of the overlay 1. The groove 7 i provided for guiding a dentit cutting tool along thi path, and to thi end, the groove 7 extend through the overlay o a to form a communication between the inide of the overlay and the outer environment. When more than one path i to be followed for removing the predetermined part, multiple guid ing groove 7 will have to be determined. A combination of thee two mentioned configuration i illutrated in FIG. 5. In thi figure, a firt and econd guiding edge 11, 12, being the two guiding edge that are paced apart, can be een on the left hand ide, which edge define a guiding Surface. A third guiding edge 13 can be een on the right hand ide, which edge define, together with the firt and econd guiding edge 11, 12, a path. Thi configuration therefore allow a cutting tool to be guided into both a horizontal movement and a tilt. A can be een in FIG. 5, the cutting tool preferably comprie a collar 14 mounted onto the cutting tool. Pref erably at leat one of the guiding edge 11, 12, 13 i provided to guide the collar 14 of the cutting tool thereby guiding the cutting tool into a predetermined vertical poition or height or depth. A can be een in the FIG. 5, the guiding groove 7 defining a horizontal path, furthermore define a predeter mined height8 for each horizontal location of the cutting tool, So a to guide the cutting tool along a horizontal path and in a predetermined tilt, and alo guiding the cutting tool in the vertical way. FIG. 6 illutrate a variant on the embodiment hown in FIG. 3, and how the guiding edge 11, 12, which are pro

10 vided to imultaneouly contact the cutting tool at two con tacting point being longitudinally ditanced from each other. In thi embodiment, tooth tructure can be removed that i located in between the two guiding edge 11, 12. In particular in preparing a tooth for placing veneer, thi embodiment will be ued. For mounting a crown or a bridge, the tooth i to be haped into a truncated pyramid having rounded edge. To thi end the outer and upper part of the tooth are to be removed. Thi removal of tooth tructure can be guided by the dentit tool according to the invention. Preferably the removal of tooth tructure for preparing a tooth for mounting a crown or a bridge i performed in everal tage hown in FIG. 7. In a firt tage, hown in FIG. 7a and FIG. 8, the upper part of the tooth get moothened. Thi can be done uing an overlay having guiding edge 11, 12 a illutrated in FIG. 6. However in practice, it i preferred that the upperpart get haped into a V-form. To thi end, the upper part preferably get Smoothened uing two guiding mean a illutrated in FIG.3, which guiding mean are located on both ide of the toothin Such a manner that aid guiding mean are provided guide aid cutting tool to cut aid upper part into a V-hape. In a econd and a third tage, hown in FIGS. 7b and 7c, the longitudinal and tranveral ide of the tooth get cut, o a to obtain a truncated pyramid form. The cutting of thee ide can be guided by overlay having guiding mean a illutrated in FIG. 3, 4 or preferably FIG. 5. Preferably one overlay comprie two Such guiding mean each defining a path extending in the Surface of the overlay, the path extending parallel to each other, each on one ide of the tooth. In a fourth and fifth tage, hown in FIGS. 7d and 7e, the edge of the pyramid get rounded. Rounding thee edge can be guided by an overlay a hown in FIGS. 1 and 2. Such an overlay comprie a path extending in the Surface of the overlay and defining a egment of a circle. Each ide of the path i defined by a guiding Surface having at leat two guid ing edge, a illutrated in FIG. 3. The height of the guiding part 5 of the overlay 1 i defined o a to guide the cutting tool in a predetermined vertical poition. In thi ucceion of tage, the firt tage could be executed a the lat tage intead of a the firt. However tet have hown that tarting with Smoothening the upper part of the tooth i advantageou in the proce of preparing the tooth. Once the overlay 1 and the guiding mean are determined, the determined overlay 1 having the determined guiding mean can be produced. Thi can be done by any known mean uch a a CAD/CAM ytem, rapid prototyping or 3D printing. When multiple guiding mean have been deter mined, multiple overlay 1 can be produced each compriing one or everal guiding mean. The overlay 1 ha, a already mentioned above, a lower, Supporting part 6 and an upper, guiding part 5. A can be een in the figure, the guiding part 5 ha a certain thickne 8, which define the height 8 of the path and enable the cutting tool to be guided in the vertical way. Preferably the upporting part 6 and/or guiding part 5 comprie a vertical opening 9 from the ide to the guiding groove 7, provided to erve a an entrance into the guiding groove 7 for a dental cutting tool. In particular when a cutting tool ha a tip portion that ha a diameter that i larger than the diameter of the main portion of the cutting tool, for example a high-peed drill with a tip in the form of a ball, thi opening i advantageou. Entering Such a cutting tool into the guiding groove 7 via the upper part of the overlay would at leat partially widen the guiding groove 7 thereby at leat partially taking away it poibility to firmly guide the cutting tool along the predetermined path. Further more a ide entrance 9 i preferred over an entrance via the upper part a it will be eaier to enter the cutting tool in a controlled manner into the guiding groove 7. When a guiding groove 7 i determined to form a circular path in the horizontal plane, it will be preferred to plit up thi path into everal egment, and produce multiple overlay 1 each having a guiding groove 7 correponding to one egment of thi path. Thi will reult in a et of overlay 1 which can be ued by a dentit one after the other to remove tooth tructure following thi circular path. Each overlay 1 of the et of overlay 1 will guide the cutting tool along a particular ide of the tooth. In the embodiment where the predetermined part i not determined baed on the hape of the tooth retoration part, the latter can be determined baed on the data in the computer. Outer hape of the tooth retoration part can be determined in everal way, all known to the peron killed in the art. A bite lift or other corrective amendment can be directly integrated into the deign of the outer hape. A firt poibility i to hape the tooth retoration part o that it reemble the outer hape of the original tooth. A econd poibility i to hape the tooth retoration part o that it fit with neighbouring teeth. A third poibility i a combination of the firt and econd, and modi fie the hape of the original tooth to better fit with the neigh bouring teeth. Inner hape of the tooth retoration part will be determined baed on the imulation of the preparation of the tooth. A the tooth will be prepared in a guided manner, it i known in advance what the hape will be of the prepared tooth. The inner hape of the tooth retoration part will be choen o that it fit the hape of the prepared tooth. Preferably the method according to the invention further comprie the tep of producing a tooth retoration part. Similar to the determination of the predetermined part, a tooth retoration part can be determined by a computer with out any interaction of a dentit. However it will be preferred that the computer determine the tooth retoration part in cooperation with a dentit, for example in a way a decribed above. The computer can, in thi proce of determining a tooth retoration part, perform predetermined clinical check and alert the dentit in cae the tooth retoration part doe not meet the tandard norm. Thi will enable a dentit to deign a tooth retoration part in a fat and reliable manner. The production of the tooth retoration part can be done by any mean known to the killed peron uch a a CAD/CAM ytem. The invention claimed i: 1. Overlay for guiding a dental cutting tool to remove predetermined tooth tructure from a tooth to be treated, the overlay compriing: an inner Surface having a hape and dimenion corre ponding to an outer Surface of the tooth to be treated o that the inner urface i releaably fixable to the tooth to be treated; a firt guiding edge extending through a thickne of the overlay including through the inner Surface, the firt guiding edge having a contour correponding to hori Zontal, vertical, and tilt movement to be followed by a dental cutting tool; and a econd guiding edge extending through the thickne of the overlay including through the inner Surface and paced apart from the firt guiding edge by a ditanced, the econd guiding edgehaving a contour correponding to the horizontal, vertical, and tilt movement to be fol lowed by the dental cutting tool.

11 11 2. The overlay of claim 1, wherein the inner urface ha a hape and dimenion o that it i releaably fixable to at leat a part of a neighboring tooth of the tooth. 3. The overlay of claim 1, wherein the inner urface ha a hape and dimenion o that the inner Surface i releaably fixable to at leat part of a plurality of neighboring teeth, the inner Surface, when fixed to the neighboring teeth, Surround ing and adequately contacting the teeth o that the overlay doe not releae or move upon application of preure during guiding of the cutting tool in normal ue of the overlay. 4. The overlay of claim 1, wherein the ditance d i at leat 0.5 mm. 5. The overlay of claim 1, wherein the firt and the econd guiding edge are paced apart a fixed ditance at correpond ing contacting point along repective length of the firt and the econd guiding edge. 6. The overlay of claim 1, wherein the firt and the econd guiding edge are paced apart a fixed ditance for contacting the at leat one dental cutting tool at correponding contacting point of the firt and the econd guiding edge. 7. The overlay of claim 1, wherein the overlay i a mono lithic, ineparable tructure. 8. The overlay of claim 1, wherein the firt and the econd guiding edge extend in a horizontal direction Such that when the dental cutting tool i located at leat at one poition between the firt and the econd guiding edge and i oriented vertically, the overlay guide the dental cutting tool to follow only a horizontal movement of the horizontal, vertical, and tilt movements. 9. The overlay of claim 1, wherein the firt and the econd guiding edge extendina Vertical direction Such that when the dental cutting tool i located at leat at one poition between the firt and the econd guiding edge and i oriented hori Zontally, the overlay guide the dental cutting tool to follow only a vertical movement of the horizontal, vertical, and tilt movements.. A dental cutting tool compriing a configuration pro viding it with the capacity of engaging one or more guiding edge of the overlay of claim Set of overlay to be ued for guiding at leat one dental cutting tool in removing predetermined tooth tructure from a tooth to be treated, the et of overlay compriing two or more of the following overlay: a firt overlay having a hape and dimenion for guiding at leat one dental cutting tool to cutaway at leat a portion of an upper part of a tooth baed on a deired height of remaining tooth tructure after removal of the upper part of the tooth; a econd overlay having a hape and dimenion for guid ing at leat one dental cutting tool to cut away at leat a portion of a longitudinal ide of the tooth; a third overlay having a hape and dimenion for guiding at leat one dental cutting tool to cut away at leat a portion of a tranveral ide of the tooth; a fourth overlay having a hape and dimenion for guiding at leat one dental cutting tool to round off edge between the longitudinal and the tranveral ide of the tooth at one ide of the tooth; and a fifth overlay having a hape and dimenion for guiding at leat one dental cutting tool to round off edge between the longitudinal and the tranveral ide of the tooth at the other ide of the tooth oppoite the one ide of the tooth, wherein each of the overlay of the et of overlay ha an inner Surface having a hape and dimenion o that each of the overlay i releaably fixable to the tooth to be treated The et of overlay of claim 11, wherein the inner urface of at leat one overlay of the et of overlay ha a hape and dimenion o that the inner Surface i releaably fixable to at leat a part of a neighboring tooth of the tooth. 13. The et of overlay of claim 11, wherein the inner urface of at leat one overlay of the et of overlay ha a hape and dimenion o that the inner Surface i releaably fixable to at leat part of a plurality of neighboring teeth, the inner Surface, when fixed to the neighboring teeth, Surround ing and adequately contacting the teeth o that the at leat one overlay doe not releae or move upon application of preure during guiding of the cutting tool in normal ue of Such overlay. 14. The et of overlay of claim 11, wherein at leat one of the overlay ha the firt and the econd guiding edge paced apart a fixed ditance for contacting the at leat one dental cutting tool at correponding contacting point of the firt and the econd guiding edge.. A dental cutting tool compriing a configuration pro viding it with the capacity of engaging one or more guiding edge of an overlay preent in the et of overlay of claim Sytem to be ued by a dentit to remove predetermined tooth tructure from a tooth to be treated, the ytem com priing: a dental cutting tool; and the et of overlay of claim The ytem of claim 16, wherein one or more overlay of the et of overlay comprie: an inner Surface having a hape and dimenion corre ponding to an outer Surface of the tooth to be treated o that the inner urface i releaably fixable to the tooth to be treated; a firt guiding edge extending through a thickne of the overlay including through the inner Surface, the firt guiding edge having a contour correponding to hori Zontal, vertical, and tilt movement to be followed by a dental cutting tool; and a econd guiding edge extending through the thickne of the overlay including through the inner Surface and paced apart from the firt guiding edge by a ditanced, the econd guiding edgehaving a contour correponding to the horizontal, vertical, and tilt movement to be fol lowed by the dental cutting tool. 18. Sytem to be ued by a dentit to remove predetermined tooth tructure from a tooth to be treated, the ytem com priing: a dental cutting tool; and an overlay compriing: an inner Surface having a hape and dimenion corre ponding to an outer Surface of the tooth to be treated o that the inner urface i releaably fixable to the tooth to be treated; a firt guiding edge extending through a thickne of the overlay including through the inner Surface, the firt guiding edge having a contour correponding to hori Zontal, vertical, and tilt movement to be followed by the dental cutting tool; and a econd guiding edge extending through the thickne of the overlay including through the inner Surface and paced apart from the firt guiding edge by a ditanced, the econd guiding edgehaving a contour correponding to the horizontal, vertical, and tilt movement to be fol lowed by the dental cutting tool. 19. The ytem of claim 18, wherein a portion of the dental cutting tool ha a thickne uch that the dental cutting tool imultaneouly contact the firt and the econd guiding

12 13 edge of the overlay a the dental cutting tool move along a path defined by the firt and the econd guiding edge. 20. The ytem of claim 18, wherein the dental cutting tool comprie a cutting portion and a collar, at leat one of the firt and the econd guiding edge of the overlay being configured to contact the collar o a to enable the dental cutting tool to be guided by the overlay with a predetermined depth. 21. The ytem of claim 18, wherein the inner urface of the overlay ha a hape and dimenion o that it i releaably fixable to at leat a part of a neighboring tooth of the tooth. 22. The ytem of claim 18, wherein the firt and the econd guiding edge are paced apart a fixed ditance at correpond ing contacting point along repective length of the firt and the econd guiding edge. 23. The ytem of claim 18, wherein the firt and the econd guiding edge are paced apart a fixed ditance for contacting the at leat one dental cutting tool at correponding contacting point of the firt and the econd guiding edge The ytem of claim 18, wherein the overlay i a mono lithic, ineparable tructure. 25. The ytem of claim 18, wherein the firt and the econd guiding edge extend in a horizontal direction Such that when the dental cutting tool i located at leat at one poition between the firt and the econd guiding edge and i oriented vertically, the overlay guide the dental cutting tool to follow only a horizontal movement of the horizontal, vertical, and tilt movements. 26. The ytem of claim 18, wherein the firt and the econd guiding edge extend in a vertical direction Such that when the dental cutting tool i located at leat at one poition between the firt and the econd guiding edge and i oriented hori Zontally, the overlay guide the dental cutting tool to follow only a vertical movement of the horizontal, vertical, and tilt movements.