The present invention relates to the field of dental implantology, in particular the treatment of partial or complete loss of teeth from the dental arch using a single or multiple prosthesis intended to be attached and fixed to one or more dental implants.
A multiple prosthesis is intended to rest on the dental arch of the patient, generally by being fixed to several dental implants that are implanted in the maxillary or mandibular bone of the patient, in order to form several prosthetic teeth. A single prosthesis is intended to rest on the dental arch of the patient, generally by being fixed to a single dental implant that is implanted in the maxillary or mandibular bone of the patient, in order to form a single prosthetic tooth.
Regardless of whether the prosthesis is a single prosthesis or multiple prosthesis, it can be fixed on an implant or implants by way of at least one fixation screw. This screw can be captive or fitted in a cylindrical cavity formed in the prosthesis or formed in an abutment framework for a prosthesis. If necessary, the prosthesis can be withdrawn, for example for repair, by unscrewing the fixation screws.
A known type of prosthesis consists of a prosthesis produced by layering, that is to say by application of several successive layers of materials (such as ceramic, varnish, etc.). This layering is generally carried out using a brush. To ensure that the prosthesis being produced is dimensionally adapted to the jaw of the patient, it is placed on a master model containing at least one implant analog. The master model is a representation of the patient's jaw that is to be restored by means of the prosthesis to be produced. The prosthesis being produced is fixed by screwing in the implant analog, as is illustrated in FIG. 10 of the document US 2003/044753 A1.
The document US 2003/044753 A1 describes a prosthesis which is to be layered and which, together with a post, forms an inseparable assembly. This inseparable assembly can be attached and fixed to an implant analog by means of a fixation screw, of which the stem passes through the post and of which the head presses the post axially against the implant analog. The base of the post has a hexagonal recess receiving a complementary hexagonal cylindrical portion provided at the top of the implant analog. The recess and the cylindrical portion of non-circular shapes cooperate to prevent any rotation of the post with respect to the implant analog, such that the prosthesis is maintained in the correct position, with respect to the adjacent teeth, during the layering.
Between each layer, the prosthesis being produced is passed into the furnace in order to fix the layer of material previously applied.
To avoid oxidation of the one or more screws during each pass into the furnace, it is expedient to withdraw the one or more fixation screws and separate the prosthesis in production from the master model. Oxidation of the screws weakens their mechanical stability and entails a risk of accidental breakage.
However, the withdrawal of the screws proves to be lengthy and awkward to perform without damaging the freshly deposited layer of material. Moreover, the withdrawal of the screws is sometimes impossible when they are held captive in the cylindrical cavity of the prosthesis being produced.
Another type of prosthesis is also known which is composed of a multiple prosthesis comprising an abutment framework. The prosthesis is obtained by adding generic teeth to the abutments of the abutment framework, then by covering the abutment framework and the generic teeth with resin that is injected into a hollow impression, of which the inner shape corresponds to the outer shape of the prosthesis that is to be produced. To ensure that the prosthesis being produced is dimensionally adapted to the jaw of the patient, the abutment framework is placed on a master model containing at least one implant analog. The master model is a representation of the patient's jaw which is to be restored by the prosthesis that is to be produced. The abutment framework is fixed by screwing in said at least one implant analog. During the injection of the resin, the latter covers the abutment framework and part of the generic teeth, while at the same time filling the available volume between the master model and the assembly formed by the abutment framework and the generic teeth.
During the injection of resin, the latter covers the screw heads. Once the resin has solidified, it therefore has to be drilled in order to obtain access to the screw heads, so as to be able to unscrew then with a view to separating the prosthesis from the master model. The location of this drilling is decided somewhat roughly by the prosthetist, who relies on differences in shades (induced by differences in resin thickness) to best estimate the place to start drilling a hole. Withdrawal of the screws once again proves to be a very lengthy procedure.
A problem addressed by the present invention is to make it easier and quicker to place on the master model, and to remove from the master model, a prosthesis produced by layering or an abutment framework for the production of a prosthesis by injection of resin, while at the same time limiting the risks of accidental damage to the prosthesis.
To achieve these objects and others, the invention proposes a connection device between a dental prosthesis, or an abutment framework for a dental prosthesis, and a master model, extending longitudinally between a first end and a second end in which:
Such a connection device permits fixation of the prosthesis (or of the abutment framework) on the master model by a simple engagement which is obtained by a rapid and simple movement of relative translation (or the combination of several) between the prosthesis (or the abutment framework) and the master model. The engagement is reversible, such that the separation of the prosthesis (or of the abutment framework) from the master model is likewise reduced to a rapid and simple movement of relative translation (or the combination of several) between the prosthesis (or the abutment framework) and the master model.
There is no longer any need for screws requiring installation by screwing and removal by unscrewing, which fact greatly accelerates production. Therefore the engagement is done tensioned and produces accordingly a restraint effort of the prosthesis on the master model, said restraint effort being sufficient for the production of the prosthesis (by stratification or coating) but low enough to allow a separation of the prosthesis from the master model without risk of prosthesis degradation.
Preferably, the second connecting segment can have a conical or frustoconical final segment which follows on from the cylindrical portion and of which the cross section decreases away from the first connecting segment. The master model generally has several implant analogs, of which the directions of extension are most often oblique with respect to each other. The conical or frustoconical final segment permits progressive centering of the cylindrical cavities on their respective connection device, with a certain radial play making it possible to compensate for the oblique character of the implant analogs with respect to each other.
Advantageously, the second connecting segment can have at least one radial slit.
Said at least one radial slit, extending longitudinally along the cylindrical portion and, if appropriate, along the conical or frustoconical final segment, makes it possible to confer a certain radial elasticity on the second connecting segment for easy engagement and removal, while at the same time affording a sufficient hold by engagement to avoid accidental separation of the prosthesis (or of the abutment framework) and the master model.
Preferably, to allow it to be fixed by its first end on an implant analog, the connection device can have a screwing socket with a non-circular cross section, accessible from the second end via the cylindrical portion and, if appropriate, via the conical or frustoconical final segment.
Advantageously, the connection device can be produced from a material having a melting point of greater than or equal to 80° C., so as to have a good geometric and mechanical stability during the injection of resin for the production of a prosthesis having an abutment framework.
Good results have been obtained using polyoxymethylene (POM) sold under the brand name Delrin® and having a melting point of about 175° C. Delrin® additionally has good dimensional stability in the normal temperature range of the injected resin.
The connection device according to the present invention allows a dental prosthesis to be received on a master model, said prosthesis having at least one open cylindrical cavity configured to receive the cylindrical portion of the first connecting segment by engagement.
The connection device according to the present invention likewise allows an abutment framework to be received on a master model, said abutment framework having several open cylindrical cavities. It is thus possible to produce a dental prosthesis in the form of a multiple dental prosthesis comprising said abutment framework.
Preferably, the open cylindrical cavity can be configured to receive a fixation screw for fixing the dental prosthesis on a dental implant. The cylindrical cavities already provided in the prosthesis are thus opportunely used to fit the prosthesis on the master model.
According to another aspect, the invention proposes a method for layering a dental prosthesis, characterized in that said method comprises the following steps:
Such a method proves very advantageous for limiting the risks of accidental damage and for reducing the production time significantly, especially when:
According to another aspect, the invention proposes a method for producing a multiple dental prosthesis having an abutment framework, characterized in that said method comprises the following steps:
Other subjects, features and advantages of the present invention will become clear from the following description of particular embodiments, with reference being made to the attached figures in which:
A first embodiment of a connection device 1 according to the invention is illustrated in
In these figures, the connection device 1 is formed in one piece and extends longitudinally between a first end 1a and a second end 1b in a longitudinal direction I-I. The first end 1a comprises a first connecting segment T1 intended to be received in an implant analog 2 (
The first connecting segment T1 has an outer thread 6 intended to be received by screwing in an internally threaded segment 2a or 2b formed in the implant analog 2 (
The second connecting segment T2 comprises a cylindrical portion 7 intended to be received by engagement in an open cylindrical cavity 8 formed in the dental prosthesis 4 (
The second connecting segment T2 has a frustoconical (or conical) final segment 9 following on from the cylindrical portion 7. The cross section of the frustoconical final segment 9 decreases away from the first connecting segment T1.
The second connecting segment T2 has three radial slits 10a to 10c extending longitudinally along the cylindrical portion 7 and along the frustoconical final segment 9.
As will be seen more particularly in
The cylindrical portion 7 has a circular cross section with a diameter D1 slightly greater than or equal to the diameter D2 of the cylindrical cavity 8 provided in the dental prosthesis 4 (
The radial slits 10a to 10c impart a degree of radial compressibility to the cylindrical portion 7, so as to promote the engagement of the latter with force in the cylindrical cavity 8.
The frustoconical final segment 9 ends with a diameter D3 smaller than the diameter D2 of the cylindrical cavity 8. The frustoconical final segment 9 thus engages easily in the cylindrical cavity 8 and allows the cylindrical cavity 8 to be pre-centered with respect to the cylindrical portion 7 before the cylindrical cavity 8 is engaged with force on the cylindrical portion 7.
The open cylindrical cavity 8 of the dental prosthesis 4 (
It should be noted that, in the figures, the cylindrical cavity 8 is shown in a simplified manner so as not to inhibit the reader's understanding. In practice, it may for example comprise an internal annular groove for receiving an elastic ring (circlip) intended to serve as a seat under the screw head.
The use of a connection device 1 according to the invention during a method of layering a dental prosthesis 4 is illustrated in
During this method, a master model 3 (
The practitioner then screws the first end 1a of six connection devices 1 into the internally threaded segment 2a or 2b of the implant analogs 2. If the practitioner uses connection devices 1 such as the one illustrated in
During the connection by screwing, the practitioner drives the connection devices 1 in rotation by means of a screwing tool with a hexagonal shape matching the screwing socket 11.
At the end of this connection step (step b)), the master model 3 is situated in the configuration shown in
During a step c), a dental prosthesis 4 to be layered is made available, such as the one illustrated in
The dental prosthesis 4 is of the bridge type and has a plurality of open cylindrical cavities 8 configured to receive a fixation screw for fixing the dental prosthesis 4 on dental implants disposed in the mouth of the patient.
During a step d), the dental prosthesis 4 is placed on the master model 3 by means of a movement of relative translation (arrow 12 in
During this step, the frustoconical final portions 9 provide a pre-centering of the cylindrical cavities 8 with respect to the cylindrical portions 7. This is all the more useful when the implant analogs 2 are oriented in oblique directions.
It will be noted that the relative movement between the dental prosthesis 4 and the master model 3 can comprise more than one translation when the implant analogs 2 are oriented obliquely with respect to each other. The main movement remains a movement of relative translation as illustrated by the arrow 12 in
The configuration as illustrated in
Once the layering is completed, the practitioner withdraws the dental prosthesis 4 from the master model 3 by means of a movement of relative translation between the dental prosthesis 4 and the master model 3 as illustrated by the arrows 14 and 15. To do this, the practitioner can insert a tool into the residual space 16 situated between the dental prosthesis 4 and the master model 3 in order to provide leverage and cause a separation of the dental prosthesis 4 and of the master model 3, which leads to removal of the cylindrical portions 7 of the connection devices 1 from the cylindrical cavities 8.
During this withdrawal step (step f)), the connection devices 1 remain integral with the master model 3 by virtue of their screwed connection. Another type of connection may nevertheless be used, such as a connection involving an interference fit (for example by means of bayonets), as long as this type of connection affords a retention of the connection devices 1 in the implant analogs 2 that is greater than the engaged connection of the cylindrical cavities 8 on the cylindrical portions 7.
At the end of the withdrawal step, the dental prosthesis can be passed into a furnace in order to fix the layer that has been applied during the step e).
The connection device 1 according to the invention can likewise be used in a method for producing a multiple dental prosthesis comprising a abutment framework 5. Such a method is illustrated in
During a step a1), a master model 3 (
During a step b1), the first end 1a of the connection device 1 according to the invention is screwed into the internally threaded segment 2a or 2b of the implant analogs 2 (
During a step c1), an abutment framework 5 (
During a step d1), the abutment framework 5 is placed on the master model 3 by causing the open cylindrical cavities 8 to engage on the cylindrical portion 7 of the connection devices 1. To do this, a movement of relative translation (arrow 17 in
The configuration illustrated in
Thereafter, during a step e1), the practitioner attaches generic teeth 18a to 18c in a hollow impression 19 corresponding to the outer shape of the dental prosthesis that is to be produced. The abutment framework 5 is then inserted into the hollow impression 19 according to the movement of translation illustrated by the arrow 20 (
This then results in the configuration illustrated in
During a step f1), resin is injected between the hollow impression 19 and the master model 3 in such a way as to cover the generic teeth 18a to 18c and the abutment framework 5. A dental prosthesis is thus obtained which, on one side, matches the dental prosthesis outline by virtue of the hollow impression 19 and, on the other side, conforms to the patient's jaw (on which the prosthesis is to be implanted) by virtue of the master model 3.
After the resin has solidified, the assembly fixed to the master model 3 and formed by the covered generic teeth 18a to 18c and the covered abutment framework 5 is extracted (during a step g1)) from the hollow impression 19.
Finally, during a step h1), the subassembly formed by the covered generic teeth 18a to 18c and the covered abutment framework 5 is withdrawn from the master model 3 by means of a movement of relative translation between said subassembly and the master model 3. This movement of translation can be effected by leverage with the aid of a component that the practitioner inserts between the subassembly, formed by the generic teeth 18a to 18c and the abutment framework 5, and the master model 3.
Whether for the production of a dental prosthesis 4 by layering or for the production of a dental prosthesis by injection of resin, the connection device 1 according to the invention allows a prosthesis 4 being layered or an abutment framework 5 to be attached and fixed with a satisfactory hold on the master model 3, without having to use screws which considerably lengthen the time the practitioner needs to complete the work. Moreover, the withdrawal of the master model 3 from the layered prosthesis 4, for passing the latter into the furnace, or of the subassembly formed by the generic teeth 18a to 13c and the abutment framework 5, is easy and quick for the practitioner to do.
The present invention is not limited to the embodiments that have been explicitly described, and instead it includes the different variants and generalizations contained within the scope of the below claims.
Number | Date | Country | Kind |
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1554076 | May 2015 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/IB2016/052553 | 5/4/2016 | WO | 00 |