DEVICE FOR MAKING DENTAL PROSTHESES MODELS

Abstract: In a device for making dental prosthesis models, at least two stems (4) are perpendicularly fitted to a base plate (2) and a pre-shaped plate (6) can be removably joined onto a frame (3) by a joining member (5) fixed to the frame (3). The frame-plate assembly can engage with the stems (4) both under the base plate (2) and over the base plate (2) and an impression holder (13) that is removably fixed to the base plate (3). When the frame (3) is under the base plate (2), a series of holes are made in the preshaped plate (6), these holes being adapted for receiving dowel pins (8). When the frame (3) is instead positioned over the base plate (2) and impression holder (13), and the pins extend downward, the negative impression is filled with a suitable quick hardening doughy material so as to form a dental prosthesis model (30) with a support structure made by said pre-shaped plate (6) along with said pins (8).

Description: DEVICE FOR MAKING DENTAL PROSTHESES MODELS TECHNICAL FIELD The present invention lies in the technical field concerned with the manufacture of dental replacement or prothesis models, made of a suitable material. In this field there are known devices that include a base plate onto which a special doughy sticky material is applied so as to fix removably thereto the impression holder, holding the impression of the patient's dental arch. BACKGROUND ART In the EP-A-0 030 312 there is described a base plate with two vertical stems fitted thereto. The two stems act as vertical guides for an overlying frame that features a recess accessible from the side. Horizontal ribs are made in this recess for engagement with complementar grooves made on a pre-shaped plate. Vertical displacements are obtained by means of a vertical screw fixed to the base plate in such a way that it can rotate. The screw can be easily turned by means of a knob. The plate, with the related frame, is positioned over the impression holder that is fixed to the base plate. Then, using a known tool, substantially comprising a radiation emitter joined to a drill, the operator turns the emitter to the regions of the impression to be drilled and intermittently activates the drill, thus making holes in the plate. The plate is then disconnected from the frame and special dowel pins are fitted in the holes previously made. The negative impression is then filled with a quick hardening doughy material and the plate is positioned, by means of the frame, over the negative impression, taking care that the pins are turned toward the inside of the impression. After the doughy material has become hard, the dental model remains fixed to the plate inasmuch as the pins are blocked in the hardened material. upon disengagement of the plate from the frame, the plate is properly shaped, in accordance with a geometrical profile similar to the dental arch, so that it can outline the model. This operation is carried out by grinding and is aimed to allow a good handling of the dental arch while performing further operations, e.g. by means of the well known articulator. The above device is rather complex and the operating phases for obtaining a model require specialized personnel, with a higher global cost for the prosthesis. Another drawback that results from using the just described device is the necessity of shaping the plate. Actually such operation constitutes a big burden for the process as far as both time and cost are concerned, particularly considering the high expense for specialized personnel. DISCLOSURE OF INVENTION The main object of this invention is to propose a device that is made in such a way as to simplify considerably the preparation of a prosthesis dental models by means of pre-shaped plates. A further object of the invention is to propose a device that is easy to use and precise and that is particularly convenient under the economic view. The above mentioned objects can be achieved by means of the device for making dental prosthesis models, that comprises a base plate and an impression holder which are removably fixed to the upper face of the base plate by means of doughy sticky material . The device also includes at least two stems, perpendicularly fitted to the base plate and protruding downward and upward, so that their upper ends go beyond the impression holder. A frame can engage the stems by means of through holes and a first joining member is fixed to the lower face of the frame so that a pre-shaped plate can be joined onto the frame. The frame is in turn positioned under the base plate and in engagement with the stems, in such a manner that the pre-shaped plate can udergo operating phases for making a series of holes therein, wherein a plurality of dowel pins 8 are to be fitted. The frame is then positioned over the base plate and impression holder, and in engagement with the stems with the dowel pins being turned toward the negative impression previously filled with quick hardening doughy material. BRIEF DESCRIPTION OF DRAWINGS The characteristic features of the invention are better outlined in the following description, with reference to the accompanying drawings, wherein: Fig. 1 is an exploded view of the device that is the subject of the present invention; Fig. 2 is a side view, with a partial cross section view, of the device shown in Fig. 1, with the frame and plate assembly being situated at the lower position; Fig. 3 shows a side view, with a partial cross section view, of the device shown in Fig. 1 and Fig.2, with the frame and plate assembly being situated at the upper position; Fig. 4 shows a prospective view of a dental prosthesis model, still fixed to the pre-shaped plate; Fig. 5 shows an exploded view of the subject device made in accordance with another embodiment; Fig. 6a and Fig. 6b respectively, show an exploded view and a plan view of a further embodiment of the invention; Fig. 7 shows an exploded view of a further embodiment of the sugbject device; Fig. 8 is a side view, with a partial cross section view, of the device shown in Fig. 7 with the frame and plate assembly being situated at the lower position; Fig. 9 shows the frame-plate assembly with the pins fitted to the plate; Fig. 10 shows a side view, with a partial cross section view, of the device shown in Fig. 7, with the frame and plate assembly being situated at the upper position; Fig. 11 shows a prospective view of the dental prosthesis model of Fig. 10, still fixed to the pre- shaped plate. MODES OF CARRYING OUT THE INVENTION With reference to Figs 1 to 4, reference numeral 1 indicates the device that is the subject of the invention. The subject device basically includes a base plate 2, with parallelepipedal shape, and a frame 3. A special sticky material 12 is applied to the upper face 2a of the base plate, so that an impression holder 13 can be removably fixed thereto. The impression holder 13, of known type, holds the dental arch impression 23. A plurality of stems 4 slidingly pass through matching holes 4a of the base plate 2. In the example shown in Fig. 1, there are four stems located each one at a respective corner of an ideal trapezoid that circumscubes the impression holder 13. In the frame 3 there are made holes 3a that match the holes 4a made in the base plate. A joining member 5, also fixed to the lower face 3c of the frame 3, comprises a cylindrical shank 52 and a series of conical bosses 53 which protrude from a relief that is preferably made integral with the same frame 3. Numeral 6 indicates a pre-shaped plate the outline of which circumscribes the outling of the dental arch. On the upper surface 6c of the plate 6 there is also made a recess 16; on the bottom of the recess 16 there are a cylindrical hole 6a and a series of conical holes 66. The recess 16, cylindrical hole 6a and conical holes 66 correspond to and match with the relief, shank 52 and conical bosses 53 of the joining member 5. Due to this configuration, the pre-shaped plate 6 can be removably jointed to the frame 3, according to a pre-set arrangement. Magnetic means 10 are fixed to the lower face 2a of the base plate 2 and specularly also to the upper sur ace 3b of the frame 3. The magnetic means are located at the corner of the base plate 2 and frame 3. These magnetic means 10 include magnetic plaques which are fixed to a face, and respective plaques of ferromagnetic material which are fixed to the remainder of the two faces. The present device can be used in a simple, quick and precise manner, as it is described hereinafter. The operator joints the pre-shaped plate 6 to the frame 3 by means of the joining memeber 5, and then locates the assembly thus obtained under the lower face 2b of the base plate 2. To do this the stems 4 must pass through the corresponding holes 3a of the frame (see Fig. 2). Because of the trapezoidal arrangement of the stems a wrong joining for the base plate 2 and the frame 3 is avoided, while a perfect centering and blocking between these two elements is achieved by means of the magnetic means 10 fixed to both of them. The pre-set arrangement of the pre-shaped plate 6 in respect of the impression holder 13 is therefore assured. At this point, the operator places a radiation emitter 20 in correspondence with the region of the impression, hold by the holder 13, that he wants to have drilled and activates a drill 22 by means of a known tool, in intermittent manner. The drill 22 is positioned under the pre-shaped plate 6, so that it can make holes in this latter (see Fig. 2). Upon completition of the drill operation, the frame 3 - plate 6 assembly is disengaged from the stems 4 and special dowel pins 8 are fitted into the holes previously made in the plate 6. Then the negative impression held by the holder 13 is filled with a special quick hardening doughy material 70 and subsequently, the frame-plate assembly is placed on top of the impression holder 13, taking care that the stems 4 be made to pass through the holes 3a of the frame 3 while the dowel pins 8 extend toward the impression (see Fig. 3). After the doughy material has become hard, the prosthesis model 30 remains fixed to the pre-shaped plate 6, inasmuch as the pins 8 are blocked in the hardened material. In other words, the plat 6 and the pins 8 form a support structure to which the prosthesis model 30 is firmly fixed. The operator disengages the frame 3 from the stems 4 and lastly disjoints the pre-shaped plate 6 from the frame 3. The prosthesis model 30 remains fixed to the plate 6 and is ready and suitably shaped to undergo subsequent operations (see Fig. 4). In the example shown in Figs. 1 to 4 the stems 4 can slide in the holes of the base plate 2. These stems can profitably made fixed to the base plate and protruding upwards and downwards from the same plate, to allow the engagement thereof with the frame 3, for carrying out the phases described above. In the embodiment illustratively shown in Fig. 5, the base plate 200 of the device 1 is different from the previous one because the joining member 5 is fixed to the lower face 200b thereof. This allows the pre-shaped plate 6 to be joined directly to the base 200 to undergo the operation as shown in Fig. 2 for the previous embodiment. A second joining member, identical to the one made on the frame 3 of the previous embodiment, is also made on the frame 300, so that the pre-shaped plate 6 can be joined thereto when it is positioned over the impression holder 13 while performing phases similar to the ones illustrated in Fig. 3. The frame 300 also features an opening 303 with crosspieces, the outline of which is similar to the outline of the pre-shaped plate 6. The task of this opening is to facilitate the disengagement of the plate 6 from the second joining member 5b. The opening 303 allows the frame-plate assembly to be lighter and permits a better view for the operator to see the phases performace as described above. In the just described embodiment there are no magnetic means 10 and the stems 4 are made integral to the base plate 200. The stems do not protrude downward from the base plate and suitable feet 201 are associated to the base plate bottom. In the embodiment shown in Figs. 6a and 6b, there is a frame 300 with a through opening 403 that has an outline similar to, and extends for an area larger than the pre-shaped plate 6. According to this embodiment the second joining member 5b is located clear of the opening 403 with the relief 51 symmetrically situated in respect of the symmetry plane of the same frame. It must be noted that the cylindrical shank 52 and the boss 53 are turned toward the opening 403. The removable joining between the plate 6 and the joining member 5b allows the plate to remain positiond in the opening 403 (see Fig. 6b). According to the embodiments of Figs. 7, 8, 9, 10 and 11, the frame 500 illustratively bears only two stems 4 and has a poligonal looped rib whose inside border matches the outline of the plate 6 that can therefore be fitted thereinto, with a movement in direction H. The rib inner surfaces 40a, encircling the area 40, are slanting and the perimetral surfaces of the plate are also slanting in the same way, so as they match the corresponding surfaces 40a thus remainnig fixed therein. In this embodiment there are mounted the magnetic means 10. With the embodiment shown in Fig. 7 the dental prothesis model 30 can be obtained in a way similar to that already described for the previous embodiments. For a better understanding in Figs. 8, 9, 10 and 11, there are illustratively shown the necessary operating phases. Alternatively, the pre-shaped plate 6 may feature a series of through holes which are very near to each other. In this case, a self-adhesive film is applied onto at least one face of the plate. The operator pierces the film with a sharp pointed tool (that is used instead of the drill 22) in the regions of the through holes chosen, and the pins 8 are subsequently fitted thereinto. Such a kind of plate can be easily used again after having destroyed the prosthesis model 30. It is enough to draw the pins 8 out of the holes and apply a new film onto the face of the plate. INDUSTRIAL APPLICABILITY The main advantage of this invention is that the device is made in such a way that it is passible to create dental prothesis models on a pre-shaped plate 6, thus avoiding the heavy grinding operation on the plate necessary to give it the desired shape. A further advantage of the device is that it is ready and practical to use and, moreover, it is economical.

Claims: CLAIMS 1. Device for making dental prosthesis models, comprising a base plate (2) and an impression holder (13) removably fixed to the upper face (2a) of the base plate by means of doughy sticky material (12), said device being characterized in that it includes: at least two stems (4) , perpendicularly fitted to the base plate and protruding downward and upward, so that their upper ends go beyond said impression holder (13); a frame (3) that can engage said stems (4) by means of through holes; a first joining member fixed to the lower face (3c of said frame (3) ; a pre-shaped plate (6) that can be joined onto said frame (3) that, in turn, is positioned under said base plate (2) and in engagement with said stems (4) , in such a manner that said pre-shaped plate (6) can udergo operating phases for making a series of holes therein; a plurality of dowel pins (8) , adapted to be fitted into said series of holes of said pre-shaped plate joined onto said frame that in turn is then positioned over said base plate (2) and impression holder (13), and in engagement with said stems (4), with said dowel pins (8) being turned toward said impression (23) previously filled with quick hardening doughy material (70). 2. Device for making dental prothesis models , comprising a base plate (200) and an impression holder (13) removably fixed to the upper face of the base plate by means of doughy sticky material (12), said device being characterized in that it includes: at least two stems (4), perpendicularly fitted to the base plate and protruding downward and upward, so that their upper ends go beyond said impression holder (13); a first joining member (5a) fixed to the lower face (200b) of the base plate (200), for engagement with a pre-shaped plate (6) destined to undergo operating phases for making a series of holes therein; a frame (300) that can engage with said stems (4) by means of through holes; a plurality of dowel pins (8) fitted into said series of holes, said pre-shaped plate along with said dowel pins (8) being designed to form the support structure of a dental prosthesis model (30) obtained when the said frame (300) is positioned in engagement with said stems (4) and over said impression holder (13), with said pins (8) fitted to said pre-shaped plate (6) and turned toward said impression (23) that has been previously filled with quick hardening doughy material (70). 3. Device for making dental prosthesis models, comprising a base plate (2) and an impression holder (13) removably fixed to the upper face (2a) of the base plate by means of doughy sticky material (12), said device being characterized in that it includes: at least two stems (4), perpendicularly fitted to the base plate and protruding downward and upward, so that their upper ends go beyond said impression holder (13); a frame (500) including a poligonal looped rib, said frame being able to engage said stems (4) by means of through holes; a pre-shaped plate (6) removably engaged with said frame (500) that, in turn, is positioned under said base plate (2) and in engagement with said stems (4), in such a manner that said pre-shaped plate (6) can udergo operating phases for making a series of holes therein; a plurality of dowel pins (8), adapted to be fitted into said series of holes of said pre-shaped plate joined onto said frame that in turn is then positioned over said base plate (2) and impression holder (13), and in engagement with said stems (4), with said dowel pins (8) being turned toward said impression (23) previously filled with quick hardening doughy material (70). 4. Device as in claim 1 or 3, characterized in that it includes magnetic means (10) fixed to the lower face (2b) of said base plate (2) and correspondingly to the upper face (3b) of sais frame (3, 500). 5. Device as in claim 1, characterized in that said joining member (5) includes a cylindrical shank (52) and at. least one conical boss (53), which protrude from a shaped relief (51) made integral with said frame C3), while in the upper surface of said pre- shaped plate (6) there are made a cylindrical hole (6a), at least one conical hole (6b) and a recess (16) matching said cylindrical shank, said conical boss and said relief respectively. 6. Device as in claim 1, characterized in that said first joining member (5a) includes a cylindrical shank (52) and at least one conical boss (53), which protrude from a shaped relief (51) made integral with the lower surface (200b) of said base plate (200) while in the upper surface of said pre-shaped plate (6) there are made a cylindrical hole (6a), at least one conical hole (6b) and a recess (16) matching said cylindrical shank, said conical boss and said relief respectively. 7. Device as in claim 2, characterized in that said second joining member (5b) includes a cylindrical shank (52) and at least one conical boss (53), protruding from a shaped relief (51) made integral to the said frame (300), while in the said pre-shaped plate (6) there are made a cylindrical hole (6a), at least one conical hole (6b) and a recess (16) matching said cylindrical shank, said conical boss and said relief respectively. 8. Device as in claim 2 characterized in that said frame (300) features a through opening (303) with a grid, said opening having an outline similar to the outline of the pre-shaped plate (6) . 9. Device as in claim 2, characterized in that the said frame (300) features a through opening (403) having an outline similar to the outline of said pre- shaped plate (6) and extension larger than the extension of said pre-shaped plate (6), while said second joining member (5b) includes a cylindrical shank (52) and at least one conical boss (53), protruding from a shaped relief (51) made integral to the said frame (300), and positioned clear of said through opening (403) symmetrically with respect to a symmetrical plane of said frame. 10. Device as in claim 9, characterized in that said cylindrical shank (52) and conical boss (53) are turned toward said through opening (403). 11. Device as in claim 3, characterized in that the surfaces (40a) which delimit the internal area (40) of the poligonal looped rib made in the frame (500) are slanting, and the perimetral outer surface of said pre-shaped plate (6) are also slanting in the same way so as to match the corresponding surfaces (40a).

Inventors: CONCETTI MAURO, RACCICHINI FRANCO, SABATINI MARCELLO, CONCETTI, MAURO, RACCICHINI, FRANCO, SABATINI, MARCELLO
Applicants: PROTESI DENTALE CONCETTI MAURO, LABORATORIO PROTESI DENTALE CONCETTI MAURO - RACCI
Application year: 1992
Main classification: A61C9
IPC codes: A61C9