WO2009024838A2

WO2009024838A2 - Impression and model components

Info

Publication number: WO2009024838A2
Application number: PCT/IB2007/053378
Authority: WO
Inventors: Bulent Dayangac
Original assignee: Bulent Dayangac
Priority date: 2007-08-23
Filing date: 2007-08-23
Publication date: 2009-02-26
Also published as: WO2009024838A3

Abstract

This invention is related to the impression and model component in order to determine easily and extremely sensitively the place of metal superstructure of implant supported prostheses (screw, cement and bar retained restorations).

Description

Description IMPRESSION AND MODEL COMPONENTS

[I] Technical Field:

[2] This invention is related to the impression and model components in order to determine easily and highly sensitively the place of metal superstructure of implant supported prostheses (screw, cement and bar retained restorations).

[3] Prior Art:

[4] Today, implants are placed in jawbone in case of full, partial or single tooth loss and excellent mouth rehabilitation is achieved by placing fixed or mobile prosthesis on them.

[5] Implant supported prostheses has a metal superstructure in order to mount them in their place in the mouth. To manufacture metal superstructure, a model prepared by taking impression from the patient is required. For said model, impression is taken from the patient with closed tray or open tray techniques.

[6] Closed tray impression technique:

[7] To take mouth impression;

[8] Impression pick-up (impression cap) is placed using snap-on mechanism on the abutment screwed on the implant. Snap-on mechanism operates in such way that rabbet part whose plastic impression pick-up diameter is smaller than the abutment stretches and covers around the abutment.

[9] Mouth impression and position of impression pick-up in the mouth are obtained through placing impression tray filled with rubber based impression material into the mouth and polymerizing the same. When the impression is removed from the mouth, impression pick-up remains inside the impression because polymerized impression material holds the impression pick-up by means of groove and extensions located on the impression cap.

[10] Modelling according to the impression;

[I I] Analog which is a replica of the abutment in the mount is placed on the impression pick-up via snap-on mechanism. Plaster is poured into the impression in such way to include analog and left to harden. After hardened plaster is removed from the impression and thus a mouth model with abutment analog is provided.

[12] Casting cylinder (wax-up coping, burn-out cap, burn-out cylinder) is placed on abutment analog using snap-on mechanism or directly. Metal superstructure form is provided by waxing up the casting cylinder, that is wax figure of metal superstructure with casting cylinder in it is obtained. Wax figure is removed from abutment analog and invested, and casting is conducted conventionally. Thus, metal superstructure is manufactured. [13] Furthermore, in certain systems impression is taken by screwing transfer coping instead of abutment into implant. Impression is removed from the mouth, transfer coping is unscrewed from implant and implant analog is screwed to the same. Transfer coping on which implant analog is screwed is then repositioned in the slot inside the impression and plaster is poured in. After hardening, plaster is removed from the impression. Hence, implant analog is inside the plaster model and transfer coping is on this model. Transfer coping is removed from the plaster model and abutment is screwed in the same place. Casting cylinder is placed on the abutment via snap-on mechanism or directly and metal superstructure is provided using the casting method as described above.

[14] There also exist systems in which transfer cap is placed on the transfer coping and said transfer cap remains in the impression. In those systems, transfer coping is required to be placed in the transfer cap remaining in the impression after transfer coping is unscrewed from the implant and implant analog is screwed instead.

[15] Open Tray Impres sion Technique :

[16] To take mouth impression;

[17] Plaster model is produced by taking mouth impression of the patient. Individual impression tray specific to the patient (custom made impression tray) is prepared on the said model. Hole is made on the custom made impression tray by being aligned to the implant. Impression pick-up is screwed on the implant using integral positioning screw (implant guide pin). Individual impression tray is filled with rubber based impression material and then applied into the patient's mouth in such way to the screw head protrude from the hole.

[18] Modelling according to the impression;

[19] After polymerization of the impression material, screw is loosened and the impression is removed from the mouth. Implant analog (implant replica) is screwed into the impression pick-up remaining in the impression and plaster is poured in. After plaster harden, screw is loosened and removed from the impression. Thus, plaster model in which implant analog is present is provided. Abutment is screwed into the implant analog and casting cylinder is placed on the abutment and metal superstructure is manufactured via casting method as described above.

[20] Furthermore, in certain systems transfer copings and transfer pick-ups used in the closed tray method are also used in this method. Weakened area on the transfer caps is punctured and integral positioning screws are screwed into the implant by passing through this hole and the channel in the transfer coping. As described above, impression is taken in such way that screw heads protrude from the custom made impression tray and the same procedures are followed.

[21] Technical problem: [22] In the prior art; impression is taken by using the combinations of

[23] - Impression pick-up + abutment analog,

[24] - Transfer coping + implant analog or;

[25] - Transfer cap + transfer coping + implant analog.

[26] During the combinations, abovementioned parts were screwed to each others and unscrewed and then screwed again or inserted in each other, then removed and then inserted again or removed from the impression and then repositioned inside the impression. During these procedures some mistakes were possibly be made. For instance, during screwing, unscrewing, screwing again, torque force could not be standardized, therefore screw might be sometimes wound excessively and sometimes less than required.

[27] Moreover; as a result of

[28] - slipping into foreign objects into the gap during inserting parts to each other and removing parts from each other, or

[29] - folding very thin rubber extensions during the procedure of removing from the impression and repositioned into the impression;

[30] position of the implant in the plaster model or abutment analogs on the plaster model might be different from the position in the mouth. Thus, it is highly possible to manufacture an incompatible metal superstructure because of obtaining a faulty plaster model.

[31] Dental technician obtains wax figure of the metal superstructure to be used in the casting by placing casting cylinders on the abutments in the plaster model and waxing up. In prior art, dental technician removes this wax figure and then invests it and performs casting procedure.

[32] Especially in the long bridges and full mouth restorations, deformations may occur during removing and investing the wax figure and metal superstructure may not fit with the desired accuracy.

[33] Open tray impression is a technique developed in order not to remove the impression pick-up or transfer coping from the impression. Necessity of such method can be showed as a proof of existence of the problems listed above. However, in the further steps of the open tray impression technique; screwing, unscrewing and screwing again procedures are performed sequentially.

[34] In most of the systems according to the prior art, snap-on mechanism is used on the shoulder of the implant in order to fit properly casting cylinders on the abutment analogs and to keep them fixed during wax-up. When metal superstructure is cast, this snap-on mechanism is required to be removed using finishing instruments because metal is not elastic. No matter how carefully was this process performed, it was impossible to be performed sensitive by hand. However, marginal fit should be perfect for the success of an implant for a long time. Casting cylinder of the systems in which snap-on mechanism is not used are placed directly on the abutment analog. However, in this case any attachment was not used; therefore, casting cylinders could not be kept fixed on the abutment during wax-up, so incompatibility could be seen in metal superstructure.

[35] Primary and secondary, if any, objects of the invention

[36] Object of the invention is to provide the impression and model components in order to determine precisely the position of implant during taking impression from the mouth in which implant is placed and producing model.

[37] Detailed Description of Embodiment according to the Invention related to Cement retained Restorations

[38] Impression and model components provided for attaining the objects of the invention are shown in the accompanying drawings wherein;

[39] Figure 1- is a perspective view of abutment according the invention.

[40] Figure 2- is a cross-section view of embodiment of hybrid cylinder with wide-spaced ledge according to the invention.

[41] Figure 3- is a cross-section view of embodiment of hybrid cylinder with narrow- spaced ledge according to the invention.

[42] Figure 4- is a cross-section view of peripheral ledge embodiment of hybrid cylinder according to the invention.

[43] Figure 5- is a perspective view of the guide piece according to invention.

[44] Figure 6- is a perspective view of die pin according to invention.

[45] Figure 7- is a cross-section perspective view in which die pin guide piece and hybrid cylinder according to invention are inserted in each other.

[46] Figure 8- is the cross-section view of position of the abutment according to the invention in the mouth.

[47] Figure 9- is the cross-section view of the hybrid cylinder which is inserted into the abutment in the mouth.

[48] Figure 10- is the cross-section view of the impression which is taken after the hybrid cylinder according to the invention is inserted in the abutment.

[49] Figure 11- is the cross-section view of the hybrid cylinder according to the invention while being disengaging from the abutment when the impression is removed from the mouth.

[50] Figure 12- is the cross-section view in which die pin according to the invention is passed through the hybrid cylinder by means of the guide piece and inserted in the impression material.

[51] Figures 13- is the cross-section view of the hybrid cylinder and die pin according to the invention after the guide piece is removed. [52] Figure 14- is a cross-section view of the investment model on which hybrid cylinder according to the invention is present.

[53] Figure 15- is a perspective view of abutment analogue according to the invention.

[54] Figure 16- is a cross-section view of hybrid cylinder according to the invention and the abutment analogue placed in it.

[55] Parts included in the Figures are separately numbered and the numbers refer to the following:

[56] 1. Abutment

[57] 2. Hybrid cylinder

[58] 3. Ledge (in the hybrid cylinder)

[59] 4. Groove (on the abutment)

[60] 5. Retentive extensions (on the hybrid cylinder)

[61] 6. Die pin

[62] 7. Guide piece

[63] 8. Channel (in the guide piece)

[64] 9. Grip (on the guide piece)

[65] 10. Horizontal grooves (on the die pin)

[66] 11. Sharp pointed end (die pin)

[67] 12. Abutment analog

[68] Basically, the embodiment related to cement retained restorations according to the invention comprises;

[69] - a groove (4) around the abutment (1) and toward the inner part of the abutment (1) and;

[70] - a ledge (3) on interior surface of the hybrid cylinder (2) and located in such way to receive groove (4) on the abutment (1);

[71] in order to insert abutment (1) and hybrid cylinder (2) in each other (Figure 1-4).

[72] Groove (4) preferably is on the abutment (1), lmm above of the cervical margin and in the form of slot surrounding the abutment (1) (Figure 1).

[73] Hybrid cylinder (2) is a receiving piece of the abutment (1). Therefore, ledges (3) cross-section of which is almost a semi-circle is positioned at a level to receive the groove (4) on the abutment (1) (Figure 2-4). As a result of conical shape due to tapering diameter of the exterior surface of abutment (1) and the conical shape on the interior surface of the hybrid cylinder (2) receiving the former, ledge (3) and groove (4) are easily engaged to each other and disengaged from each other. To facilitate the operation of the snap-on mechanism comprising said engaging and disengaging procedures, hybrid cylinder (2) preferably is manufactured from an elastic material, e.g. a plastic derivative.

[74] There are peripheral retentive extensions (5) on the occlusal end of the exterior surface of the hybrid cylinder (2). Thus, hybrid cylinder (2) is allowed to remain in impression by disengaging from the abutment (1) while the impression is removed from the mouth. Furthermore, it is also possible to add sequentially more than one retentive extensions (5) in parallel in order to shorten the excessive length of hybrid cylinder (2) during usage. Hence, it is possible to use a hybrid cylinder (2) with abutments (1) in various sizes (figure 2-4).

[75] In implementation of the invention, investment is filled in the impression instead of plaster to produce master cast. However, die pin (6) is used in order not to break investment which is a weak material during removing from the impression (figure 6). Because of its structure, die pin (6) is much smaller than the interior diameter of hybrid cylinder (2). Therefore, guide piece (7) is used to orient die pin (6) in the hybrid cylinder (2) (figure 5-7). There is a longitudinal channel (8) in the centre of the guide piece (7) through which die pin (6) can pass (figure 5).

[76] To orient die pin (6) passing through the channel (8), first of all guide piece (7) needs to be fitted properly in the hybrid cylinder (2). To this end, guide piece (7) has the same exterior surface bevelling as the interior bevelling of the hybrid cylinder (2). The largest diameter of the hybrid cylinder is smaller than the narrowest diameter of the end of the ledge (3) inside the hybrid cylinder (2). Thereby, guide piece (7) fits into the hybrid cylinder (2) without being engaged with the ledge (3). After die pin (6) is passed through the channel (8) following central axis of the guide piece (7) and inserted into the impression material, this guide piece (7) can be removed from the hybrid cylinder (2) perpendicularly (figure 7). There is a grip (9) in the shape of cylindrical handle on the exterior part of the guide piece (7). This grip (9) enables easy removal of the guide piece (7) by means of a forceps from the hybrid cylinder (2).

[77] There exist horizontal grooves (10) located vertically to the central axis of the die pin

(6) in order to allow it to attach to the investment. In addition, die pin (6) can be easily inserted into the impression material as its end (11) is sharp pointed. Besides, sharp pointed end (11) has a smaller diameter in comparison to the body of the die pin (6); thereby, pointed end is only inserted into the impression.

[78] The models are provided using the components described above according to the procedures listed in the following;

[79] - In the first visit, two identical impressions are taken from the patient, thus two hybrid cylinders (2) are used (101).

[80] - Abutment (1) is screwed to the implant during taking the impression (figure 8).

Length of the abutment (1) and hybrid cylinders (2) are modified by cutting or without cutting their crest beforehand according to the interocclusal distance (102).

[81] - One of the hybrid cylinders (2) are placed on the abutment (1) via snap-on mechanism (figure 9) [82] - The first impression is made with the rubber-based impression material (103)

(figure 10).

[83] - Repeating this procedure, the other hybrid cylinder (2) is placed on abutment (1) via snap-on mechanism and second impression is taken using again rubber based impression material (104).

[84] - When the impressions are removed from the mouth, hybrid cylinders (2) remain in the impression due to retantive extensions (5) on them (105) (figure 11).

[85] - Guide piece (7) is placed on the hybrid cylinder (2) in the first impression and sharp pointed end (11) of the die pin (6) is inserted in the impression material passing through the channel (8) at the centre of this piece (106) (figure 12).

[86] - Die pin (6), thus, is provided to pass through the centre of the hybrid cylinder (2)

(107).

[87] - Guide piece is removed (figure 13).

[88] - Die pins (6) are placed on the appropriate places for the natural teeth (108).

[89] - An investment which has a high strength to resist fracture is poured in the impression, (some investment products have compressive strength of 40-50MPa similar to dental stone) (109).

[90] - After hardening, investment is removed from the impression, end of the die pin (6) is cut, thereby a investment model with hybrid cylinder (2) and natural teeth is produced (110) (figure 14).

[91] - In this model, wax figure of the metal superstructure is obtained by waxing up the hybrid cylinder (2) (111).

[92] - Areas other than metal superstructure in the investment model are sawed. (112).

[93] - Sprues, reservoirs and sprue former are attached to the wax figure (113).

[94] - Investment part on which wax figure of the metal superstructure is present is placed in a ring and then invested again (114).

[95] - Casting procedure is performed according to the conventional methods (115).

[96] - Ledge (3) comprising snap-on mechanism in the hybrid cylinder (2) is removed by grinding (116).

[97] In addition, in case the number of the natural teeth in the 109th step, plaster can be filled in the natural teeth area and investment can be filled in the implant area.

[98] In the 110th step, to provide investment model; optimal values for the groove (4) and ledge (3) comprising snap-on mechanism between abutment (1) and hybrid cylinder (2), extension at the occlusal tip of exterior surface of the hybrid cylinder (2) can be determined by the simple tests conducted by the Universal testing machine.

[99] It is possible to use hybrid cylinder wide spaced ledge in order to grind easily the ledges (3) which are part of snap-on mechanism mentioned in the 116th step (figure X). Excessive grinding of the ledges (3) does not prevent operation of system as remaining surfaces keep their places. [100] - Abutment analog (12) is placed in the hybrid cylinder (2) in the second impression in order to manufacture plaster model in which dental technician orients the metal superstructure and then performs the following procedures (figures 15-16). Plaster model with abutment analog (12) on it is fabricated by pouring plaster inside the impression. [101] Detailed Description of 1st Embodiment of the Invention related to the Screw

Retained Restorations [102] Impression and model components provided for attaining the objects of the invention are shown in the accompanying drawings wherein;

[103] Figure 17- is cross section perspective view in which the hybrid cylinder and the impression cap according to the invention are mounted on the abutment. [104] Figure 18- is the cross-section perspective view of the hybrid cylinder according to the invention.

[105] Figure 19- is the perspective view of the hybrid cylinder according to the invention. [106] Figure 20- is the cross-section perspective view of the impression cap according to the invention.

[107] Figure 21- is the perspective view of the impression cap according to the invention. [108] Figure 22- is the perspective view of the die pin which is seated in the slot in the hybrid cylinder according to the invention. [109] Figure 23- is the cross-section perspective view of the lengthening part of the hybrid cylinder according to the invention. [110] Figure 24- is the cross section view in which the hybrid cylinder according to the invention is screwed to the abutment on the implant. [I l l] Figure 25- is the cross section perspective view showing the position of the hybrid cylinder and the impression cap according to the invention after they are seated on the abutment. [112] Figure 26- is the perspective view showing the hybrid cylinder and the impression cap according to the invention together with their notch and nail. [113] Figure 27- is the cross section perspective view of the impression which is taken after hybrid cylinder and impression cap according to the invention is seated on the abutment. [114] Figure 28- is the cross-section perspective view showing removal of the impression cap from the hybrid cylinder when the impression is removed from the mouth. [115] Figure 29- is the cross section perspective view in which die pin according to the invention is placed in the hybrid cylinder. [116] Figure 30- is the cross section perspective view in which the hybrid cylinder according to the invention is seated in the impression cap in the impression after the die pin is placed. [117] Figure 31- is the cross section perspective view of the hybrid cylinder, the die pin together with the lengthening part of the hybrid cylinder according to the invention.

[118] Figure 32- is the perspective view of the abutment analog.

[119] Figure 33- is the cross section perspective view in which the hybrid cylinder according to the invention is placed in the impression cap after the abutment analog is screwed.

[120] Parts included in the Figures are separately numbered and the numbers refer to the following:

[121] 13. Screwed abutment

[122] 14. Hybrid cylinder

[123] 15. Impression cap

[124] 16. Groove (on the hybrid cylinder)

[125] 17. Nail (on the impression cap )

[126] 18. Retentive extensions (on the impression cap )

[127] 19. Die pin

[128] 20. Horizontal grooves (on the die pin)

[ 129] 21. Lengthening part of the hybrid cylinder

[130] 22. Screwed abutment analog

[131] The embodiment of the invention related to screw retained restorations comprises principally;

[132] - a hybrid cylinder (14) to be placed on the screwed abutment (13);

[133] - a impression cap (15) to determine the direction and the position of the hybrid cylinder (14) in the impression material,

[134] - die pin (19),

[135] - lengthening part of the hybrid cylinder (21) (figure 23).

[136] Hybrid cylinder (14) is similar with the plastic casting cylinders currently manufactured and is an access part of the screw retained abutments (13). However, hybrid cylinder (14) differs from the casting cylinders as its height align with the top of the screw and it has a deep notch (16) on its upper edge allowing to be placed in the impression cap in the same position (figure 18-19).

[137] Impression cap(15) is a part that is fixed to top of the hybrid cylinder (14), has nail (17) on its inferior side surface and exterior diameter of which is larger than the hybrid cylinder (14) (figures 20-21). There present retentive extensions (18) both on the exterior top surface for retention and for being retained by forceps and also on the exterior side surfaces for retention.

[138] The basic function of the die pin (19) is to prevent investment from breaking and the secondary function is to provide screw slot in the casting (figure 22). Therefore, head of die pin (19) has a similar form with the screw and has an appropriate diameter to fit into the hybrid cylinder (14) properly. Die pin is cylindrical and made of high fusing alloy. There are horizontal grooves (20) for retention of the investment on it.

[139] Lengthening part of the hybrid cylinder (21) is developed in order that the dental technician performs wax-up procedure (figure 23). It is a tubular plastic part which can be seated the same place after the impression cap (15) is removed.

[140] Manufacturing models by using abovementioned components:

[141] - In the first visit, two identical impressions are taken from the patient (201).

[142] - Thus two hybrid cylinders (14) and two impression caps (15) are used (202).

[143] - In taking impression, hybrid cylinder (14) is screwed gently to the screwed- abutment (13) on the implant (203) (figure 24).

[144] - Impression cap (15) is placed on the hybrid cylinder (14). In this process, it is ensured that nail (17) on the internal side surface of the impression cap (15) is fitted properly into the notch (16) on the upper edge of the hybrid cylinder (14) (204) (figures 25-26).

[145] - First impression is taken with rubber based impression material (205) (figure 27).

[146] - Other hybrid cylinder (14) is screwed gently on the screwed- abutment (13) and the second impression is taken by repeating the same procedure (206).

[147] - When the first impression is removed from the mouth, the impression cap (15) remains in the impression due to retentive extensions (18) both on the top and side surfaces (207) (figure 28).

[148] - Hybrid cylinder (14) is unscrewed from the abutment (13) (208).

[149] - To prevent investment from breaking and to provide screw slot in the casting, die pin (19) is placed in the hybrid cylinder (14) (209) (figure 29).

[150] - Hybrid cylinder (14) on which die pin (19) is seated is placed on the impression cap (15) in the impression. In this process, it is ensured that nail (17) on the internal side surface of the impression cap (15) is fitted properly into the notch (16) on the upper edge of the hybrid cylinder (14) (210) (figure 30).

[151] - Die pins (19) are placed in the appropriate places for the natural teeth and an investment which has a high strength to resist fracture is poured in the impression (some investment products have compressive strength of 40-50MPa similar to dental stone) (211).

[152] - In case the number of the natural teeth is more, plaster may be poured into the natural teeth area and investment to be poured into the implant area (212).

[153] - After hardening, investment model is removed from the impression, thereby investment model on which hybrid cylinder (14) and natural teeth are present is manufactured (213).

[154] - After modifying the height of the lengthening part of the hybrid cylinder (21) according to the interocclusal distance dental technician places the same on the hybrid cylinder (14) (214) (figure 31). [155] - Wax figure of the metal superstructure is manufactured by waxing up and casting procedure is performed as described in the cemented abutments part (215). [156] - Investment residue on the metal superstructure is cleaned and die pin is removed from its slot (216). [157] - In the second impression taken in order to manufacture plaster model on which dental technician orients the metal superstructure and performs the following procedures, the impression cap (15) also remains in the impression as stated before

(217).

[158] - Hybrid cylinder (14) is unscrewed from the abutment (13) (218). [159] - Abutment analog (22) is screwed to the hybrid cylinder (14) (219) (figure 32). [160] - Hybrid cylinder (14) is placed in the impression cap (15) in the impression considering the nail (17) and notch (16) (220) (figure 33). [161] - After pouring plaster, a plaster model on which abutment analog (22) is present is manufactured (221). [162] Detailed Description of 2nd Embodiment according to the Invention related to the

Screw-Retained Restorations [163] Impression and model components provided for attaining the objects of the invention are shown in the accompanying drawings wherein; [164] Figure 34 - is the cross-section perspective view in which hybrid cylinder and hybrid cylinder cap according to the invention are mounted on the screwed-abutment by means of snap-on screw. [165] Figure 35 - is the cross-section perspective view of the hybrid cylinder according to the invention.

[166] Figure 36 - is the perspective view of the snap-on screw according to the invention. [167] Figure 37 - is the cross-section perspective view of the hybrid cylinder according to the invention. [168] Figure 38 - is the perspective view of the die pin to be screwed to the hybrid cylinder cap according to the invention. [169] Figure 39 - is the cross-section perspective view of the lengthening part of the hybrid cylinder according to the invention. [170] Figure 40 - is the cross-section perspective view in which hybrid cylinder according to the invention is seated in the abutment on the implant by means of snap-on screw. [171] Figure 41 - is the cross-section perspective view of the position of the hybrid cylinder according to the invention on the abutment after hybrid cylinder cap is mounted. [172] Figure 42 - is the cross-section perspective view of the impression taken after hybrid cylinder cap is mounted on the hybrid cylinder according to the invention. [173] Figure 43 - is the cross-section perspective view showing the removal of the hybrid cylinder according to the invention from the snap-on screw when the impression is removed from the mouth.

[174] Figure 44 - is the perspective view in which the die pin is screwed to the hybrid cylinder cap according to the invention.

[175] Figure 45 - is the cross-section perspective view of the hybrid cylinder according to the invention on the investment model.

[176] Figure 46 - is the cross-section perspective view of the hybrid cylinder and the lengthening part mounted on the same.

[177] Figure 47 - is the perspective view of the abutment analog.

[178] Figure 48 - is the perspective view of the intermediary screw.

[179] Figure 49 - is the cross-section perspective view in which abutment analog is screwed to the hybrid cylinder cap according to the invention by means of intermediary screw.

[180] Parts included in the Figures are separately numbered and the numbers refer to the following:

[181] 23. Screwed abutment

[182] 24. Hybrid cylinder

[183] 25. Retentive extension (on hybrid cylinder)

[184] 26. Snap-on screw

[185] 27. Retentive area (snap-on screw)

[ 186] 28. Hybrid cylinder cap

[187] 29. Screw threads (in the hybrid cylinder cap)

[188] 30. Die pin

[ 189] 31. Screw threads (at the end of the die pin)

[190] 32. Horizontal grooves (on the die pin)

[191] 33. Lengthening part of the hybrid cylinder

[192] 34. Intermediary screw

[193] 35. Screwed abutment analog

[194] The embodiment of the invention related to screw retained restorations comprises principally;

[195] - A hybrid cylinder (24) to be seated on the screwed abutment (23) by means of snap- on system,

[196] - Screw comprising snap-on system (26),

[197] - hybrid cylinder cap (28),

[198] - die pin (30) to be screwed to the hybrid cylinder cap (28),

[199] - lengthening part of hybrid cylinder (33); (figure 34).

[200] Hybrid cylinder (24) is similar to the plastic casting cylinders currently produced by the manufacturers. However, length of the hybrid cylinder is shortened and a peripheral retentive extension (25) is made at the occlusal end of its exterior surface in order to enable the hybrid cylinder to remain in the impression while the impression is removed from the mouth. Hence, hybrid cylinder (24) is enabled to remain in the impression while the impression is removed from the mouth (figure 35).

[201] A specific snap-on screw (26) is developed in order to provide snap-on mechanism between the hybrid cylinder (24) and screwed abutment (23). A peripheral retentive area (27) just under the head of this screw is provided by tapering slightly side parts of the head of screw (figure 36). Thereby, snap-on mechanism is maintained between the hybrid cylinder (24) and the screwed abutment (23).

[202] Hybrid cylinder cap (28) is a part which is fixed to top of the hybrid cylinder (24) and has threads (29) on the end facing to the snap-on screw (26). It is seated on top of the edge of the hybrid cylinder (24) before taking the impression. When the impression is removed from the mouth, die pin (30) is screwed to the screw threads (29) which are present in the hybrid cylinder cap (28) (figure 37).

[203] Die pin (30) prevents investment from breaking and provide a screw hole. It is a cylindrical part having the same diameter with the screw. One of its ends has screw thread (31) in order to be screwed to the hybrid cylinder cap (28), the other end remains in the investment model and it has horizontal grooves (32) for retention of the investment on it. Die pin (30) is made of high fusing alloy.

[204] Lengthening part of the hybrid cylinder (33) is developed in order that dental technician performs wax up procedure. It is a tubular plastic part which can be seated top of the hybrid cylinder (24) after the hybrid cylinder cap (28) is removed (figure 39).

[205] Manufacturing models by using abovementioned components:

[206] - In the first visit, two identical impressions are taken from the patient. Thus two hybrid cylinders (24) and two hybrid cylinder cap (28) are used (301).

[207] - In taking the impression, one of the hybrid cylinders (24) is screwed gently to the abutment (23) on the implant by means of snap-on screw (26) in such way to provide snap-on mechanism (302). (figure 40)

[208] - Hybrid cylinder cap (28) is mounted on the hybrid cylinder (24) and the first impression is taken with the rubber based impression material (303). (figures 41-42)

[209] - Other hybrid cylinder (24) is screwed gently on the abutment (23) by means of snap-on screw (26) and the second impression is taken by repeating the same procedures (304).

[210] - When the first impression is removed from the mouth, hybrid cylinder (24) disengage from the snap-on mechanism due to the peripheral retentive extensions (25) on the occlusal end and remains in the impression (305) (figure 43). [211] - Die pin (30) is screwed to the hybrid cylinder cap (28) on the hybrid cylinder (24) (306) (figure 44).

[212] - Die pins are placed in the appropriate places for the natural teeth and an investment which has a high strength to resist fracture is poured in the impression (some investment products have compressive strength of 40-50MPa similar to dental stone) (307).

[213] - After hardening, investment model is removed from the impression. Thereby, the investment model on which hybrid cylinder (24) and natural teeth are present is manufactured (308) (figure 45).

[214] - Hybrid cylinder cap (28) is unscrewed from the die pin (30) (309).

[215] - After dental technician modifies the height of the lengthening part of the hybrid cylinder (33) according to the interocclusal distance, it is mounted on the hybrid cylinder (24). The following procedures are performed as described under the cemented abutments and the metal superstructure is manufactured (310) (figure 46).

[216] - In the second impression taken in order to manufacture plaster model on which dental technician orients the metal superstructure and performs the following procedures, the hybrid cylinder (24) also remains in the impression by disengaged from the snap-on mechanism as stated before (311).

[217] - Abutment analog (35) is screwed to the hybrid cylinder cap (28) by means of the intermediary screw and the plaster model on which hybrid cylinder (24) is present is manufactured (312) (figure 47-49)

[218] - The hybrid cylinder (24) is removed from the abutment analog (35) by unscrewing the hybrid cylinder cap (28) (313).

[219] In 31 lth step, optimal values for allowing hybrid cylinder (24) to remain in the impression by disengaging from the snap-on mechanism can be determined by the simple tests conducted by the Universal testing machine.

[220] In the 312th step, in case the number of natural teeth is more, plaster may be filled in the natural teeth area and investment may be filled in the implant area.

Claims

[1] A hybrid cylinder system enabling to fit the metal superstructure of the implant supported prosthesis in the embodiment related to the cement retained restorations; allowing abutment (1) and hybrid cylinder (2) to be inserted in each other; comprising:

- a groove (4) around the abutment (1) and to the inner part of the abutment (1) and;

- ledge (3) on interior surface of the hybrid cylinder (2) and located in such way to receive the grove (4) on the abutment (1); characterized with

- the groove (4) on the abutment (1) to be inserted in each other and to be removed from each other and the receiving ledge (3) in the hybrid cylinder (2) and;

- the retentive extensions (5) located on the occlusal end of exterior surface of the hybrid cylinder (2) to allow hybrid cylinder (2) to remain in the impression by disengaging from the abutment (1) during taking the mouth impression.

[2] A hybrid cylinder (2) system according to Claim 1 characterized with a die pin

(6) having the same exterior surface bevelling with the interior bevelling of the hybrid cylinder (2) in the impression, oriented through a channel (8) in the guide piece (7) largest diameter of which is smaller than the narrowest diameter of the end of the ledge (3) inside the hybrid cylinder (2) in order to prevent investment from breaking while manufacturing mouth model corresponding to the impression via investment.

[3] A hybrid cylinder (2) system according to claims 1 or 2 characterized with a die pin (6) having horizontal grooves (10) in order to attach to the investment.

[4] A hybrid cylinder (14) system enabling to fit the metal superstructure of the implant supported prosthesis in the embodiment related to the screw retained restorations; comprising

- A hybrid cylinder (14) to be placed on the screwed abutment (13);

- An impression cap (15) to determine direction and position of the hybrid cylinder (14) in the impression material; characterized with: to provide inserting of the abutment (13) and hybrid cylinder (14) in only one position;

- a nail (17) comprise a extension from the inner side of the impression cap (15) and; - a groove (16) on the hybrid cylinder (14) in which nail (17) on the impression cap (15) is seated, the retentive extensions (18) on the exterior side surface of the impression cap (15) to allow impression cap (15) remain in the impression material. [5] A hybrid cylinder (24) system enabling to fit the metal superstructure of the implant supported prosthesis in the embodiment related to the screw retained restorations; comprising

- hybrid cylinder (24) to be seated on the screwed abutment (23) by means of snap-on mechanism,

- a screw comprising snap-on mechanism (26),

- hybrid cylinder cap (28); characterized with:

- a hybrid cylinder (24) having retentive extensions (25) to hold impression material while removing from the mouth, and

- a hybrid cylinder cap (28) providing easy removal of the hybrid cylinder (24) from the screwed abutment (23);

-a snap-on screw (26) having a peripheral retentive area (27) just under the head of screw provided by tapering slightly side parts of the head of screw upwards, and

- a hybrid cylinder cap (28) to cover top of the hybrid cylinder (24), having a screw hole in its centre providing retention of screwed die pin (30) when hybrid cylinder (24) remains in the impression material together with the hybrid cylinder cap (28).