Field of the Invention

The present invention pertains to the field of designing and producing dental implant bridges/bars in the field of dentistry. More particularly the invention relates to a process, where a 3D database is shared for the steps of designing, manufacturing and validating dental implant bridges and bars.

Furthermore, the present invention provides a process workflow, where a digital impression, containing at least two dental implants, is scanned directly from the patient's oral cavity and is used for the design and subsequent shaping of a dental superstructure.

Background of the Invention

The goal of a dental implant system is to restore the patient to normal function, comfort, aesthetic, speech and health regardless of the current oral condition. These implant systems are based on the implantation of dental implants, such as dental implants made of biocompatible titanium, or other biocompatible materials such as zirconia, through insertion into the patient's jawbone. The dental implants allow dental superstructures, such as dental bridges, to be securely anchored to the jaw. A good fit of the dental superstructure is of highest importance, to reduce mechanical stress and enable good function and comfort for the patient.

It is known that a process for manufacturing a dental superstructure often starts with obtaining a 3D model of the patient's intraoral cavity. Traditionally, the dentist takes a physical dental impression of the patient's teeth, using an elastomeric material. By placing impression couplings on the patient's dental implants, the impression will contain both a negative imprint of the patient's teeth and the impression couplings (fixed in the elastomeric material), providing the implant locations. By using the dental impression as a mould, positive imprint model with couplings at the implant positions can be obtained, commonly in a plaster or gypsum material. From here on, said positive imprint model will be referred to as plaster model.

A more recent workflow includes the manufacture of the positive imprint model from a digital 3D model of the patient's teeth. In this case, the dentist obtains a digital imprint of the patient's teeth directly at the clinic by using various intraoral scanning techniques, often non-contact optical techniques. Such a system is for example disclosed in US2011/105894.

From the scanned digital imprint data, software can create a digital 3D model of the patient's teeth and intraoral cavity. The data is sent to a dental service provider, where it is used for the manufacture of a positive imprint model, using computer-aided design/computer-aided manufacture

(CAD/CAM) manufacturing systems. Normally, the positive imprint model has holes that correspond to the implant positions, where analogues that correspond to the patient's implants can be attached. The manufacturing methods are commonly milling and sintering and the material of the model is often a polymer. From here on, said positive imprint model will be referred to as polymer model.

The resulting plaster or polymer model with the positive imprint of the patient's teeth will be used for the design and fitting of the dental prosthesis.

A prototype of the implant superstructure can now be build up on the plaster or polymer model. Recent methods do this digitally. By placing scan bodies on the analogues, to show the location and orientation of the implants, and scanning the plaster or polymer model, a digital 3D model of the plaster or polymer model is obtained. Using said scanning data, software can generate a 3D model of dental implants that fits on the scanned plaster/polymer model.

The superstructure prototype or digital design file and plaster or polymer model is now sent to the superstructure manufacturer, who scans the superstructure prototype and plaster model with fitted analogues. Machining instructions for manufacturing of the dental superstructure is generated, to produce a dental implant shaped in accordance (copy mills).

The dental superstructure is thus constructed either physically using the plaster or polymer model, or designed digitally from the scan of the physical plaster or polymer model with fitted analogues. The accuracy of the manufacturing process of the dental superstructure model will depend on the quality of the dental plaster or polymer model. If the model has been prepared using a physical dental impression of the patient's teeth, any errors that occurred during the multitude of steps in creating the plaster model, will have a direct impact on the accuracy and fit of the dental superstructure. Similarly, if the model has been created from a digital scan, any manufacturing errors or errors during the mounting of analogues will have a direct impact on the accuracy and fit of the dental superstructure.

Thus, there is a need for a new process, where the accuracy and fit of the dental superstructure is independent of the accuracy of the dental model.

Summary of the Invention

Accordingly, the present invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solves at least the above mentioned problems by providing a method for manufacturing a dental superstructure, such as a bridge or bar framework, comprising: (a) scanning the intraoral cavity of a patient with at least two implanted dental implants to obtain scanned data comprising at least dental implant interface information of said at least two implanted dental implants; (b) creating a 3D numerical model of the dental superstructure, said model matching said dental implant interface information of said at least two dental implants; and (c) real shaping of said dental superstructure based on said 3D numerical model.

Advantageous embodiments are envisioned in the dependent claims below.

Brief Description of the Drawings

These and other aspects, features and advantages of which the invention is capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the

accompanying drawings, in which

Fig. 1 illustrates an overview of the process of producing a dental bridge or bar using a fully digitalized process, according to one embodiment of the invention; and

Fig. 2 shows a flow chart of the method for producing dental bridges or bars using a fully digitalized process, according to one embodiment of the invention.

Description of embodiments

The following description focuses on an embodiment of the present invention applicable to a process workflow for producing a dental superstructure, such as a bridge or bar framework. A system according to one embodiment of the invention is disclosed in Fig. 1 and a flow chart according to one embodiment of the invention is disclosed in Fig. 2.

The process workflow comprises the steps of scanning 10 the oral cavity of a person, said person having at least two implants. In this way scanned data comprising at least dental implant interface information of said at least two implanted dental implants is obtained.

In one embodiment the number of implants in the oral cavity of the person is at least three, such as 3 or at least 4, such as 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or above. As a consequence dental implant interface information for the corresponding number of dental implants will be comprised in the scanned data.

The scanned data thus forms a digital impression. The digital impression comprises information with regard to at least two dental implants - their location and orientation. The digital impression is then used for designing and subsequent shaping of a dental superstructure, without the need for a physical replica of the dental superstructure or the adjacent elements of the patient's oral cavity.

In this way, the present invention alleviates at least the problems identified above by alleviating the need for a physical replica of the dental superstructure or the adjacent elements of the patient's oral cavity. Hence, the risk of loss of accuracy and accumulation of secondary faults in the shape and fit of the dental superstructure may be decreased. Also, if a positive impression of the patient's teeth is manufactured using the provided digital impression, the spatial accuracy can be increased in comparison with a traditional dental plaster/polymer positive impression. However, since such a model is not required for the design and validation of said dental superstructure, the model accuracy requirement may be lower, depending on which application the model is used for, allowing for simpler and more cost effective methods of

production.

The method includes obtaining a digital impression of the patient's teeth and existing prosthetic dental implants, by scanning the patient's intraoral cavity, using one or a combination of several intraoral scanning techniques. This procedure suitably takes place at a dental clinic with appropriate equipment for such a digital scan. The scanning data will provide a digital impression of the patients intraoral cavity as well as data for the at least two dental implants. The scan alternatively includes dental and palatal scans and bite registrations, for extensive information of the patient's intraoral cavity.

From said digital impression, a 3D model of the patient's teeth and intraoral cavity is generated 20 using appropriate software. The 3D model may be numerical. Such software is readily available and is known to the skilled artisan. Based on the patient implant requirements and the virtual 3D model of the patient's oral cavity, a suitable dental superstructure is designed to fit the virtual 3D model of the patient's oral cavity, and a 3D numerical model of the dental superstructure is created 30.

When creating the 3D numerical model of the superstructure, the 3D numerical model may comprise screw channel information corresponding to said at least two dental implants. The screw channel information is such that the finally obtained superstructure may be screw retained to the at least two dental implants, via insertion of a screw member into the screw channel and subsequent screw retention via screwing the screw member into cooperation with corresponding implant. The 3D numerical model may thus also comprise screw member seat(s) at the bottom of the screw channel(s), said screw member seat(s) matching location and direction of corresponding implant(s). The screw channel information of the 3D numerical model may also be angled or bent, such that a central axis of the screw member seat is angled in relation to at least one central axis of said screw channel.

By using computer-aided design/computer-aided manufacture

(CAD/CAM) manufacturing systems, said 3D numerical model data is used directly in the manufacturing process 40, without the need for a physical replica of the dental superstructure or the adjacent elements of the patient's oral cavity. The 3D numerical model data may be communicated to the

manufacturing process 40 via a computer network, such as an intra- or internet, from the numerical model data acquiring step 30. The manufacturing method for shaping the real superstructure may for example be milling, sintering or printing.

The fit of the manufactured dental superstructure is thus directly correlated to the information from the digital scan of patient's intraoral cavity. Furthermore, the quality assurance of the dental superstructure can directly validate that the coordinates of the at least two dental implants correlates between the digital scan of patient's intraoral cavity and the dental

superstructure.

Using digital data transfer techniques, said process has extensive flexibility in the location of dentist clinics and labs. With suitable software, the dentist could do all of the above steps locally at the dentist clinic, or by sharing the data using digital transfer, both alternatives being envisioned in Fig. 1, the scan data can be shared using digital transfer with a dental lab or

manufacturing facility, where the data processing can take place remotely.

The digital 3D information is shared with a dental superstructure manufacturer, where a CAD file is generated, from the 3D drawing of the dental superstructure, and used for the manufacture of the prosthesis 40. From the 3D numerical model of the dental superstructure, the real shaping 40 of said dental superstructure can take place.

According to a further aspect of the invention, a digital model of the positive impression of the patient's teeth can also be manufactured 50 using the provided digital 3D impression of the patient's intraoral cavity. This digital model may then be transformed into a real model 60, through the same CAD/CAM procedure. However, preferably the real model is milled or sintered in a plastic or plaster material, which easily makes possible to include analogues corresponding to the dental implants in said real model. This can be desired if the prosthesis requires an extra surface layer (such as porcelain), which will be added in a subsequent manual process, since then a real model could be needed to trim the bite of the person, i.e. to trim the occlusal, incisal or coronal parts of the superstructure and/or prosthesis in a quality assurance step 70. Traditional methods use such a physical positive model, of at least part of the dentition from the upper and lower jaw, to manually build up these extra surface layers to fit within the space allowed for the dental prosthesis in the intra-oral cavity. Since said model is not used for the validation of said dental coupling, the spatial accuracy can be lower than for a traditional dental plaster/polymer positive impression.

The present invention has at least the advantage over the prior art that it (i) enables higher spatial accuracy of the dental superstructure, limited only by the quality if the intraoral scan and manufacturing methods; and (ii) removes several sources of potential error from the manufacturing process, by eliminating the manufacture and subsequent rescanning of the "polymer/plaster model".

Although the present invention has been described above with reference to specific embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the invention is limited only by the accompanying claims and, other embodiments than the specific above are equally possible within the scope of these appended claims.

In the claims, the term "comprises/comprising" does not exclude the presence of other elements or steps. Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. The terms "a", "an", "first", "second" etc do not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.