Description

This invention concerns a manufacturing method of a dental prosthesis, with specific reference to single-tooth prostheses.

A dental implant consists of a screw made of a biocompatible material, typically titanium, coated, if need be, with additional substances aimed at enhancing adhesion, osseointegration and resistence to bacterial attacks. The implant COTTSTSITS <jf ^~ aTi u per ptrrtTon d¾ ^~ s±gneTd ^~~ to—Bitrerg from the gingival arch that includes an internal thread to fix a connection device to which the dental crown will be secured.

Figure 1A shows one of the said connection devices L on which a stump M will be positioned, based on the conventional technique. The crown C will be then secured to the aforementioned stump M, as displayed in figure 1C. Both the stump M and the crown C are typically realized with materials that are suitable for dental uses. The procedure is first based on injecting some ceramic material within a mold, reproducing the shape of the stump and/or the crown, followed by baking in an oven, finishing off and polishing. The foregoing procedure is carried out in a dental laboratory, equipped with the necessary equipments and endowed with the required skills. Once this procedure has been completed, the realized prosthesis or the stump are glued to the connection device L and the whole work will be finally assembled with the dental implant, already positioned in the patient's oral cavity .

The procedure described above, besides being highly demanding in terms of high technical skills, is long and laborious and the patient is obliged to undergo several dental sessions, with significant time intervals between the moment when the deTT1Ti^ir^]yta ^~ iTrs ^~ the ^~ imp e ^" S's on— nd—the- moment when the dental technician realizes the prosthesis. Recently, new techniques have been spreading: the latter in turn are based on CAD/CAM system prosthesis design as well as on milling machine-assisted manufacturing, wherein the said milling machines are installed either in a dental laboratory or in a dental surgery. However, the realization of the stump M to be assembled with the connection device L still has to be carried out following the traditional system described above.

It would thus be desirable to enhance the realization procedure of a dental prosthesis in such a way that its manufacturing, or at least part thereof, is carried out directly in the dental surgery, with no need of a dental technician's specific skills. In this way, indeed, the manufacturing time could be significantly reduced, thus decreasing the number of dental sessions the patient has to undergo .

The problem addressed by the present invention is that of providing a procedure to meet the goal described above.

The said problem is solved through a manufacturing method of a dental prosthesis or a part thereof, as highlighted in the attached claims, whose definitions constitute integral part of this description.

An object of the invention is thus a manufacturing method ^~ o-f—a—dental—p-rcs-thes- s^—o —a—p-a-rt—t-he-reo-f-—e-a-s-y—a-n-d—th-a-fc does not require very high technical skills.

A further object of the invention is a coupling member between a milling machine and the connection device of a dental implant, as defined in claims 10 and 11.

Additional features and advantages of the present invention will emerge from the description of some realization examples carried out here below for illustrative, yet non limitative purposes, with specific reference to the following figures:

Figure 1A represents an exploded perspective view of the stump of a dental prosthesis as well as of a connection element with a dental implant, according to the current state of art;

Figure IB shows a perspective view of a small block of ceramic material for dental use; Figure 1C displays an exploded perspective view of an assembly made up of a connection element, a stump and a crown;

Figure 2 represents a perspective view of a connection element between a small block of ceramic material for dental use and a dental implant;

Figure 3 shows a perspective view of the assembly made up of a small ceramic block as well as of a connection element to a dental implant used in the manufacturing method of the -i-n-v-e-n-t-i-o-n-T-

Figure 4 displays a perspective view of a coupling member between the assembly described in figure 3 and a milling machine, exploitable in the inventive method;

Figure 5 represents a partial view of a milling machine for dental uses, applicable to the manufacturing method of the invention.

The invention concerns a manufacturing method of a dental prosthesis or a part thereof, that includes a milling step of a small block 1 made of a material suitable for dental uses, wherein the said block 1 is secured to a connection element for a dental implant.

According to a preferred embodiment, the method of the invention includes the following steps:

providing a milling machine 7 for dental uses,

supplying a block 1 made of a material suitable for manufacturing dental prosthesis provided with a hole 2, providing a connection element L for a dental implant, the said connection element L having a first connection portion 3 to the said dental implant and a second connection portion 4 to a dental prosthesis,

inserting the said second connection portion 4 of the connection element L into the hole 2 of the block 1 and securing the former to the latter, so as to form an assembly block 1 - connection element L, providing a coupling member 5 between the said first connection portion 3 and the supporting element 6 of the said milling machine 7,

connecting the assembly block 1 - connection element L of step d) to the coupling member 5,

assembling the coupling member 5 with the assembly block 1 - connection element L on the supporting element 6 of the said milling machine 7,

milling the said block 1, so as to obtain either a stump M or a dental prosthesis.

The milling machine 7 is of a conventional type.

Milling machines of this kind are sold by firms like, for instance, Sirona or KaWo. The milling machine 7 includes a supporting element 6, on which the part to be milled is mounted, and a milling spindle 8, on which a suitable end mill cutter 9 is put. Milling machines of this type can work automatically, based on a CAD/CAM-elaborated working project.

The block 1 can be realized in any material suitable for manufacturing dental prosthesis. The said material is typically a ceramic material, like for instance disilicate or feldspathic ceramic, zirconium oxide, glass-ceramic, composite etc..

In certain embodiments, a nanocomposite ceramic material is used ^" The saTd material is a hybrid, cexarrrrc—wrth—dua-1- network structure, microfine structure (86% by weight) and reinforced through a poly-acrylate network; it combines the advantages of ceramic together with those of composite resins .

These kinds of materials are directly produced in their definitive state and consequently do not need additional baking processes; they can thus be used to realize dental prostheses with definitive morphology and are millable in the dental surgery, starting from the block 1.

Vice versa, when using the other ceramic materials listed above, additional steps of sintering or superficial coloring with heating processes are required, increasing the number of scheduled dental sessions. The neck K (figure 1C) , representing the visible part of the stump M obtained after milling the small block IB, instead, can be manually polished by the dental technician in a dental laboratory. Bin certain embodiments, the block 1 has a cylindrical shape and presents a longitudinal through hole 2.

The connection element L, displayed in figure 2, includes a first connection portion 3 to a dental implant and a second connection part 4 either to an abutment or to a crown with definitive anatomy. The first connection portion 3 has a varying shape, depending on the used dental implant type. "The s ^~ h ^~ a ^~ p ^~ e srown in—f'igurres—rA— nd—2—rs—me-rei—i-nd-jre-a-t-i-v-e— Different types of connection elements L, also called "link" or "abutment", are thus available on the market.

The second connection portion 4 has a slightly conical shape and comprises a longitudinal relief 10, serving as a reference positioning mark either for the stump or for the crown to be glued.

A flange 11 is located between the first 3 and the second 4 connection parts, so that its lower portion matches with the dental implant, whereas its upper section acts as end limit for the block 1.

The fixing of the second connection portion 4 of the connection element L into the hole 2 of the block 1 is carried out through gluing, Typically used glues are, for instance, self and light-cured ionomer cements. With reference to figure 4, the coupling member 5 comprises a first matching portion 12 with the first connection portion 3 of the connection element L as well as a second coupling portion 13 with the supporting element 6 of the milling machine 7.

The first matching portion 12 includes a seat 14 to contain the first connection portion 3 of the connection element L. The foregoing seat thus has a shape that is substantially equivalent to the seat of the dental implant the connection ^" element L is de ^~ S ^" t ^" rn ^" e-d ^— trcr.—Fox ^-" t ^~ h ^~ i-s—re'a-SO-ητ—the—s-h-a-pes—bo-t-h- of the seat 14 and of the second coupling portion 13 shown in the figure are only indicative and vary depending on the type of connection element L (varying, in turn, based on the type of dental implant) and of milling machine 7 that are used, respectively.

A cavity 16 is located on the edge of the first matching portion 12. The cavity 16 is used to position the assembly block 1 - connection element L, matched with the coupling member 5, with the proper rotation on the supporting element 6 of the milling machine 7, thus acting as a reference mark.

The coupling member 5 can be realized as a single piece, wherein the shape of the second coupling portion 13 depends on the milling machine type, whereas the shape of the seat 14 depends on the brand as well as on the type of dental implant that has been used. The block 1 will be secured to the coupling member 5 by a through screw tightened, in turn, with a nut that will block the assembly and will fasten it from the back part of the coupling portion 13. With this respect, a kit including a series of coupling members 5, depending on the brands both of the implant and of the milling machine, and a set of blocks 1, varying based on the implant's brand and measure and with different colors, could be provided.

^" The first rnlaTcTTitg poriTion Γ2 rrrc±ud ^" e"s—a—cavi-ty—1-6—aio-n-g- its edge. The cavity 16 is used to position the assembly block 1 - connection element L matched and screwed with the coupling member 5 with the proper rotation into the milling machine plate, as the cavity gets stuck on a pivot located on the milling machine plate.

The method this invention refers to thus allows to obtain a stump, a crown or a complete dental prosthesis through milling, directly in the dental surgery equipped with the milling machine. The CAD-designed abutment will have a well-known, precise shape; following the very same project crown manufacturing will also be possible, in such a way that the latter will match the abutment precisely and all this can be achieved in only one dental session. In this way, the manufaturing and the installation of a dental prosthesis within a patient's mouth are heavily simplified and the patient's discomfort is reduced correspondingly, due to the lower number of dental sessions he has to undergo .

Clearly enough, only a few particular embodiments of the present invention have been described so far: a skilled person will be able to make all the necessary changes to adapt it to particular applications, with no prejudice of the scope of protection of this invention.