News Column

Researchers Submit Patent Application, "Method and System for Designing and Producing Dental Prostheses and Appliances", for Approval

June 12, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Taub, Eldad (Reut, IL); Kopelman, Avi (Palo Alto, CA), filed on October 23, 2013, was made available online on May 29, 2014.

The patent's assignee is Cadent Ltd.

News editors obtained the following quote from the background information supplied by the inventors: "A dental treatment often begins with obtaining a three-dimensional (3D) model of a patient's teeth. The model may be a physical model of the dentition or a virtual 3D computer model. The model is used to assist in designing a dental treatment for the patient. After the treatment has been designed, the model is used to design the dental prosthesis or appliance to be applied to the teeth in order to execute the treatment. Such prostheses and appliances include, for example, bridges, crowns, and orthodontic braces.

"In some instances, a negative cast of the dentition is obtained at the dental clinic in which the patient is seen, and may include both arches, one arch, or part of an arch. The cast is sent to a dental laboratory, and a positive physical model of the dentition is made from the negative cast, typically by pouring plaster into the cast allowing the plaster to set. A dental treatment is then determined at the clinic using the model, and prostheses or appliances for mounting onto the patient's teeth are designed or selected in order to execute the treatment. The appliances are made at a laboratory and then dispatched to the clinic for mounting onto the patient's teeth.

"It is also known to obtain a 3D virtual representation of the teeth that is used to assist in devising a dental treatment and/or to design dental appliances. The 3D computer model may be obtained at the dental clinic using an optical scanner to scan the teeth directly or to scan a model of the teeth. The computer model is then used at the clinic for designing or selecting appropriate dental prosthesis and/or appliances to carry out the treatment. Instructions are then sent to a dental appliance laboratory for making the prosthesis or appliances, which are made at the laboratory and then dispatched to the clinic.

"Alternatively, a negative cast of the dentition of each jaw is obtained at a dental clinic that is dispatched to a dental appliance laboratory where a 3D positive model of the patient's teeth is made from the negative cast. The 3D model is then scanned at the laboratory so as to generate a virtual 3D model of the patient's teeth that is used to design appropriate dental prosthesis or appliances. The prosthesis or appliances are produced at the laboratory and then dispatched to the clinic.

"U.S. Pat. No. 6,632,089 to Rubbert et al., discloses a computer-based dental treatment planning method. A virtual 3D model of the dentition of a patient is obtained that is used to plan a dental treatment. Obtaining the 3D model as well as treatment planning can be performed at a dental clinic or at a remote location such as a dental appliance laboratory having access to the virtual model of the dentition. In the latter situation, the proposed treatment plan is sent to the clinic for review, and modification or approval by the dentist, before the requisite appliances are made at the laboratory."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "The present invention provides a system and method for designing and producing dental prostheses, such as for example crowns and bridges. The system comprises at least one dental clinic and at least one dental laboratory. The system also comprises a dental service center that is a separate entity with respect to the dental laboratory. The service center is equipped to generate a virtual 3D model (also referred to herein as a '3D numerical model', 'numerical model' 'virtual model', and the like) of a patient's teeth from data obtained either by scanning (typically optically) the teeth directly or by scanning a physical model of the teeth, the process being at least initiated at the dental clinic. Alternatively, the dental lab may generate the virtual model. The service center is also equipped to use the computer model to design a dental treatment and to select or design and to manufacture dental prostheses, or at least a part thereof. The details of the required prosthesis may then be sent to the clinic, and typically part of the manufacture of the prosthesis is handled by the service center. The dental lab may also be equipped to design at least a part of the prosthesis, typically a coping, for example by first defining the finish line on the 3D model. Alternatively, the dental lab may provide a prescription to the service center for the latter to design the coping. The clinic may then send instructions to a dental laboratory and/or to the service center, each of which is equipped to make a part of the dental prosthesis in accordance with instructions and data received and/or generated from any one of the dental clinic, dental lab or from the service center, and the manufactured prosthesis is then dispatched to the clinic.

"In a preferred embodiment, communication between the clinics, laboratories and the service center is over an electronic communications network such as the Internet or other suitable communications medium such as an intranet, local access network, public switched telephone network, cable network, etc.

"At least a part of the manufacturing of the prosthesis is shared between the service center and one or more dental labs, according to predetermined criteria. Further, at least one of the service center and the at least one said dental lab is adapted for designing said prosthesis based on the 3D numerical model of the dentition, wherein said prosthesis comprises an inner surface and an outer surface, wherein to provide a 3D model of said prosthesis. The service center is adapted for manufacturing at least a first portion of said prosthesis based on said 3D numerical model. In particular, the service center is adapted for manufacturing at least an internal surface of said prosthesis, wherein said internal surface is designed for mounting onto a target site comprised in said dentition. The prosthesis typically comprises at least one coping and the aforesaid internal surface is an internal surface of said coping. At least one of the service center and the at least one said dental lab is adapted for designing an external surface of said coping based on said 3D numerical model.

"Preferably, the service center comprises a material removal machine for directly manufacturing said coping from a suitable coping material based on the design of said internal surface and said external surface of said coping. Alternatively, the material removal machine may be used for manufacturing a physical model of said coping from a suitable wax material or the like based on the design of said internal surface and said external surface of said coping. The service center and/or at least one dental lab, and/or an external facility, comprises means for producing a negative cast of said physical model, and means for producing said coping from said negative model using a suitable coping material.

"At least one said dental lab is adapted for manufacturing at least a second portion of said prosthesis based on said 3D numerical model. The dental lab is adapted for manufacturing at least an external surface of said prosthesis, wherein the external surface is designed for providing adequate clearance for the prosthesis relative to other teeth in said dentition adjacent to said prosthesis. Furthermore, the external surface is designed for providing adequate occlusion between the prosthesis relative to other teeth in said dentition opposite to said prosthesis.

"The external portion of the prosthesis may be manufactured by a process involving adding at least one layer of material to a suitable coping and subjecting the layer to a material removal operation so that the surface of the layer conforms to a predetermined geometry. A plurality of layers may be sequentially formed over said coping, such that a final said layer conforms to the external surface required for the prosthesis.

"Optionally, the fabrication of each layer, or of the layer (when the prosthesis only comprises a single layer), of the prosthesis may be performed using traditional methods. Such traditional methods are known in the art, and include, for example, building porcelain or any other suitable material layer by layer, starting with a first layer laid over the coping, and manually working these layers to fit within the space allowed for the prosthesis in the intra-oral cavity. To facilitate this, a physical (typically plaster or stone) model of at least a part of the intraoral cavity can be produced, typically by the service center and based on the 3D virtual model of the teeth, and this is sent to the dental lab.

"Additionally or alternatively, the fabrication of said layer or layers is at least partially automated, and at least one dental lab comprises a material removal machine for removing material from said layer, and suitable scanning means for determining the topology of said layer prior to the material removing operation. Computer means are also provided for calculating machining paths for said material removal machine, wherein such paths are based on the difference between said topology of said layer prior to the material removing operation and the required topology for the surface.

"The aforementioned predetermined parameters include a dimensional accuracy for the manufacture of a part of said prosthesis. In particular, when the dimensional accuracy for the manufacture of a particular part is required to be about 40 microns or less than 40 microns, for example the internal surface of the coping, the part is manufactured by said service center. Alternatively, when the dimensional accuracy for a particular part is required to be within substantially more than 40 microns, for example an external part of the crown, this part is manufactured by a dental lab.

"In one particular application of the invention, a scan of the intraoral cavity is taken at a dental clinic, and the virtual model data thus obtained is sent to a dental lab. Then, the dental lab defines the margin line of the preparation (in the virtual model) and designs the coping geometry. Alternatively, the virtual model is (also) sent to the service center, together with a suitable prescription from the dental lab, in which case the service center defines the margin line of the preparation (in the virtual model) and designs the coping geometry. In either case, the coping geometry is processed by the service center, which then produces a coping based on the design, either directly, or indirectly via a lost wax process, for example. The coping, together with a physical positive model of the dentition, or a part thereof comprising the preparation, is sent to the dental lab, wherein the technician there prepares the full prosthesis in a traditional manner, by sequentially adding one or more layers of porcelain or other suitable material to the coping, and shaping the layers to produce the outer form of the prosthesis, checking with the physical model that the prosthesis will fit in the space left for it and provide adequate occlusion. The prosthesis is then sent to the dental clinic to be fitted to the patient.

"Full flexibility in communication between the clinics, laboratories and the service center is provided, enabling for example, many different communications to be performed therebetween, including the following non-limiting illustrative examples:

"(i) scanned data of the intraoral cavity (from which a virtual model thereof is generated) is sent from the dental clinic to the dental lab and/or service center;

"(ii) 3D numerical data (i.e., the virtual model) of the intraoral cavity, created directly at the dental lab or service center, or indirectly from data transmitted to either location, is transmitted to the dental clinic for approval;

"(iii) approved 3D numerical data of the intraoral cavity, wherever created, is transmitted to the dental lab and/or to the service center;

"(iv) definition of the margin line by means of the dental lab or the service center is sent to the dental clinic for approval;

"(v) approved margin line definition is sent to the service center and/or dental lab from the dental clinic;

"(vi) definition of the 3D coping geometry by means of the dental lab or the service center is sent to the dental clinic for approval;

"(vii) approved 3D coping geometry, and/or approval thereof, is sent to the service center and/or dental lab from the dental clinic;

"(viii) prescription for the coping is sent from the dental lab to the dental clinic for approval, and approved prescription is sent to dental lab and/or service center.

"Herein, 'dental clinic' refers to the interface between a dental practitioner and a patient, and thus includes any physical entity, in particular a clinic, in which there is interaction between a dental patient and a dental practitioner. While 'dental practitioner' typically refers to a dentist, doctor, prosthodontist or orthodontist, it also includes herein all other caregivers that may interact with a dental patient during the course of a dental treatment. While 'dental patient' typically refers to a person requiring the dental services of a dental practitioner, it also includes herein any person regarding whom it is desired to create a 3D numerical model of the intra oral cavity thereof, for example for the purpose of practicing the same or for carrying out research.

"The term 'prosthesis' is herein taken to include any restoration and any onlays, such as crowns and bridges, for example, and inlays, such as caps, for example, and any other artificial partial or complete denture.

"The terms virtual model, 3D numerical model, and the like, are used interchangeably herein to refer to a computer simulation of a surface, comprising 3D topographic data referring to the surface, such a surface typically being dental surfaces of the intraoral cavity.

"In another aspect of the invention a system and method are provided for designing and producing dental appliances, such as for example braces. The system comprises at least one dental clinic and at least one dental laboratory. The system also comprises a dental service center that is separate from the dental laboratory. The service center is equipped to generate a virtual 3D model of a patient's teeth from data obtained either by optically scanning the teeth directly or by scanning a physical model of the teeth, the process being at least initiated at the dental clinic. Alternatively, the dental lab may generate the virtual model. The service center is also equipped to use the computer model to design a dental treatment and to select or design and to manufacture appliances to carry out the treatment. The details of the treatment and of the required appliances may be then sent to the clinic. The clinic may then send instructions to a dental laboratory which is equipped to make at least a part of the dental appliances in accordance with instructions received from either a dental clinic or from the service center, and the appliances are then dispatched to the clinic.

BRIEF DESCRIPTION OF THE DRAWINGS

"In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

"FIG. 1 shows a dental service system for designing and producing dental appliances in accordance with one embodiment of one aspect of the invention;

"FIG. 2 illustrates a portion of the intra oral cavity of a patient wherein it is desired to implant a prosthesis;

"FIG. 3 illustrates in cross sectional view a crown prosthesis having a coping and a multiple layered cap.

"FIG. 4 illustrates a service center according to the first embodiment of the invention.

"FIG. 5 illustrates a dental lab according to the first embodiment of the invention.

"FIG. 6 illustrates a physical model of the intra-oral cavity of FIG. 2.

"FIG. 7 illustrates in cross sectional view a crown prosthesis having a multiple layered construction.

"FIG. 8 illustrates the insertion path of a bridge prosthesis according to the invention. and

"FIG. 9 shows a method for designing and producing dental appliances in accordance with a second embodiment of the invention.

"The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:"

For additional information on this patent application, see: Taub, Eldad; Kopelman, Avi. Method and System for Designing and Producing Dental Prostheses and Appliances. Filed October 23, 2013 and posted May 29, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1188&p=24&f=G&l=50&d=PG01&S1=20140522.PD.&OS=PD/20140522&RS=PD/20140522

Keywords for this news article include: Dentistry, Cadent Ltd., Prosthetics, Medical Devices.

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