Abstract:
A temporary dental prosthesis ( 60 ) which can be placed before, after or simultaneously with the placement of permanent implant i securely and accurately fixed to mounting assemblies ( 58 ). Each mounting assembly ( 58 ) has a combination implant/abutment member ( 10 ) screwed into a bore formed in the cortical bone with a smooth convex basal portion ( 12 ) received in a complimentary shaped recess formed at the entrance of the bore. A coping ( 30 ) is received on the head ( 16 ) of the combined implant/abutment member ( 10 ) and retained there by a pin ( 50 ) having a threaded portion ( 56 ) received in a threaded bore ( 24 ). The copings ( 30 ) and pins ( 50 ) are received in oversized bores formed in a blank temporary prosthesis and resin is injected around the copings and pins to secure the copings to the prosthesis at locations corresponding to the positions of the combined implant/abutment members ( 10 ).

Description:
This appln is a 371 of PCT/US98/26149 filed Dec. 8, 1998, which claims benefit of Provi. No. 60/069,088 filed Dec. 10, 1997. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to dental implants and more particularly to a temporary prosthesis and method for using. 
     BACKGROUND OF THE INVENTION 
     The natural teeth of an individual may be lost as a result of dental disease or trauma, making it desirable to replace such teeth with one or more prosthetic devices. An example of a prosthetic device is a dental implant which is surgically positioned within the mandibular of maxillary alveolar bone. 
     One type of dental implant has a first implant member for placement in an osteotomy site in the alveolar bone of a patient. Following healing, a head member, commonly called an abutment, is mounted in or on the first implant member and a tooth simulating prosthesis or crown is then mounted on the abutment, or in the case of edentulous individuals, a bridge supporting abutment is mounted in the first implant member. A successful system of this type is disclosed in U.S. Pat. No. 4,738,623. In that patent, a first implant or root member having a first or outer end formed with a female socket circumscribed by a shoulder and having a suitable anchoring means, such as outwardly extending fins, is placed in an osteotomy site or implant receiving cavity in the alveolar bone with suitable surgical instruments and techniques. The first implant member is inserted into the cavity with the upper portion of the member a selected distance below the opening of the cavity, that is, below the crest of the bone, e.g., two or three millimeters. A healing plug is inserted into a female socket of the first implant member and particles of a natural and/or synthetic bone growth stimulating grafting material are then packed within the cavity around the shoulder of the implant member and the wound is then allowed to heal for four to six weeks or longer until osseointegration has been completed. 
     Following healing, the dentist surgically accesses and removes the plug and replaces it with an abutment. The abutment has a male portion received within the female socket and an intermediate, outer, generally hemispherical surface portion which may extend through the surface of the crest of the bone which had previously been reamed to form a complimentary configuration when forming the cavity. The hemispherical surface portion is non-irritating to soft tissue and promotes mucosal healing. A prosthetic device can be attached to the abutment. 
     During the healing process care must be taken to avoid the transmission of forces on the implant which could cause dehiscence of the integrating implant. In the case of an edentulous individual, this would mean that solid foods would have to be eschewed for the healing period of four to six weeks or longer. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a temporary prosthesis, mounting components and a method for installing the prosthesis which can be used during the healing time of surgically positioned implants or whenever it is advantageous to attach a device to a temporary fixed implant. Another object of the invention is the provision of an apparatus and a method for securing a surgical stent or other device for use in implant surgery or for other purposes. Yet another object of the invention is the provision of an apparatus and a method by which a failing prosthesis can be secured on a temporary basis, that is, for a limited period of time. 
     Briefly stated, in accordance with the invention, single stage, combination implant/abutment members are screwed into the cortical bone between existing or planned permanent implants. The implant/abutment members have a head portion positioned above the mucosa. A precisely formed plastic coping is placed on each head portion and then a direct pick-up by and attachment of the coping to a temporary prosthesis can be effected or alternatively, a transfer pick-up impression of the copings can be done. With the use of implant analogs, a stone model can be poured for fabrication of the prosthesis extraorally. The prosthesis, for example a full or partial arch prosthesis, is then supported on the implant/abutment members spaced above the permanent implant sites thereby preventing transmission of transmucosal forces from the temporary prosthesis to the integrating implants caused by movement of the temporary prosthesis or food bolus. As a result, the patient is able to eat a more solid and diversified diet immediately post operatively. By means of the invention a temporary prosthesis can be securely and accurately placed, if desired, on the same day as that of the permanent implant surgery. 
     According to the preferred embodiment of the invention, the combination implant/abutment member is formed of biocompatible material, such as titanium or titanium alloy, with a hemispherically shaped basal portion adapted to be received in a complimentary formed seat in the cortical bone, a threaded post extending in one direction from the basal portion and a cylindrical head extending in an opposite direction from the basal portion. The cylindrical head is formed with at least one flat, and preferably a plurality of spaced apart flats, to facilitate rotary attachment of the members in the bores in the cortical bone. A tapered section is formed on the coronal portion of each head which serves as a coping seat and an axially extending bore is formed through the end face of the head portion with the outer portion of the bore being threaded and the inner portion of the bore being formed with a non-circular surface, e.g., hexagonal. The coping, formed of ceramic, metal or suitable moldable plastic, such as polycarbonate or acrylic, bondable to a prosthesis member, to be discussed, has an outer periphery generally frusto-conical in configuration with a first tapered bore extending from the larger end face and a second bore having a straight section of a selected length extending from the smaller end face and with a second tapered section formed at the end of the straight bore section extending to a junction with the first tapered bore. The first tapered bore is complimentary in angle and diameter to that of the coping seat on the head of the implant/abutment member for reception thereon. The second bore receives an elongated pin formed of biocompatible material such as the same material as that of the implant/abutment member having at one end a tapered portion complimentary in angle and diameter to that of the second taper of the coping which serves as a pin receiving seat and a threaded distal end for threaded reception in the threaded bore of the implant/abutment members. The main shaft portion of the pin has a diameter selected to closely fit in the straight bore of the coping and the other distal end is formed with a screw driving slot in the end face thereof. The length of the elongated pin is selected preferably to extend beyond the coping and at least partially through the temporary prosthesis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, advantages and details of the novel and improved temporary dental implant system and method of this invention appear in the following detailed description referring to the drawings in which: 
     FIG. 1 is a front elevational view of a combination implant/abutment member of a mounting assembly made in accordance with the invention, 
     FIG. 2 is a top plan view of the FIG. 1 member, 
     FIG. 3 is a cross sectional view of a coping receivable on the FIG. 1 member, 
     FIG. 4 is a front elevational view of a pin receivable in the FIG. 3 coping and attachable to the FIG. 1 member, 
     FIG. 5 is a perspective view of a broken away portion of a lower jaw showing a temporary full arch prosthesis mounted on combination implant/abutment members and spaced above permanent implant sites, 
     FIG. 6 is a cross sectional elevational view of a portion of a temporary prosthesis showing a mounting assembly implanted in a portion of a cortical bone which also shows permanent implant sites, 
     FIGS. 7 and 8 are bottom and top plan views, respectfully, of a temporary prosthesis blank, and 
     FIG. 9 is a bottom plan view, similar to FIG. 7, with transfer tape material placed in a tape receiving groove used to determine the location of the mounting assemblies fixed in the cortical bone. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIGS. 1 and 2, a combination implant/abutment member  10  comprises a smoothly curved convex basal portion  12 , preferably hemispherical, with a post  14  of a selected length, e.g., 0.276, 0.394 or 0.550 inches, extending from the basal portion in one longitudinal axial direction and formed with cortical bone threads and a cylindrical head portion  16  extending from basal portion  12  in an opposite axial direction. Head  16  is formed with four spaced flats  18  to facilitate driving of the member into a bore formed in the cortical bone to be described below. It will be understood that the number of flats provided is a matter of choice. A tapered coping receiving seating surface  20  having a selected angle alpha, e.g., 18 degrees, is formed at the coronal portion of member  10  and a bore is formed through end  22  extending along the longitudinal axis of member  10 . The outer portion  24  of the bore is threaded and the inner portion  26  is formed with a non-circular, i.e., hexagonal, portion to facilitate fastening in a bore by means of a latched dental hand piece screwdriver. Coping  30 , shown in FIG. 3, is formed of suitable moldable plastic material, such as polycarbonate or acrylic to which the temporary prosthesis will bond, and preferably has a frusto-conical outer surface  32  formed with a selected angle gamma, e.g., 4 degrees, and a bore  34  extending between the larger end face  36  and the smaller face  38 . A first tapered portion  40  extends from face  36  and has a taper angle alpha forming a surface having an angle and diameter complimentary to that of seating surface  20  of implant/abutment member  10 . A straight section  42  of bore  34  extends from face  38  to a second tapered surface  44  which extends to a junction with the first tapered surface  40 . Second tapered surface  44  is formed with a selected taper angle beta, e.g., 20 degrees, and serves as a pin receiving seat for pin  50 , shown in FIG.  4 . Pin  50  has an elongated cylindrical shaft  52  formed with a tapered seating surface  54  adjacent one end having a taper angle beta and a diameter selected so that surface  54  is complimentary in angle and diameter to seating surface  44  of coping  30 . A threaded distal end portion  56  is receivable in threaded bore section  24  of implant/abutment member  10  to be discussed below. The opposite end of pin  52  is formed with a suitable screw slot  59  or other driving mechanism. 
     With reference to FIGS. 5 and 6, a schematic broken away portion of a lower jaw is shown with a plurality of combined implant/abutment members  10  implanted in cortical bone  1  along with proximately mounted permanent implants  2  having healing plugs  3  extending from abutment receiving sockets in the implants. The particular number, placement and type of implants  2  are a matter of choice. The time of placement of the permanent implants can be contemporaneous with the placement of implant/abutment members  10 , before or after, if desired. Implant members  2 , of any conventional type, are placed in the cortical bone using conventional implant surgical procedures, such as those discussed in U.S. Pat. No. 4,738,623, referenced above, the subject matter of which is incorporated herein by this reference. The location and number of implant/abutment members  10  are selected to provide solid, stable support for a prosthesis for a limited time period. 
     Implant/abutment members  10  are implanted by first forming bores into the cortical bone at the selected locations with a conventional surgical bur. Preferably, a generally hemispherical recessed seat is formed at the entrance to the bore with a larger diameter bur and then a single stage, implant/abutment member  10  is screwed into the bone utilizing flats  18  with either manual or power tools. A pin  50  is then mounted in each member  10  with threaded portion  56  received in threaded bore portion  24 . With reference to FIGS. 7-9, an elongated cord of flexible, relatively soft, impression material  70  is placed in a groove  62  extending between ends  64 , 66  of a suitable blank temporary prosthesis  60  on its bottom side and alignable with the cortical bone. Blank prosthesis  60  is formed of suitable plastic material, such as polycarbonate or acrylic. The blank temporary prosthesis  60  is then placed on members  10  with pins  50  attached thereto in the desired location relative to the cortical bone and pressed toward the mounting assemblies to make depressions  72  caused by pins  50 . The prosthesis blank is removed and marked at  74 . Cord  70  can then be removed and oversized bores formed through the prosthesis blank in alignment with the location of the previously disposed depressions  72 . 
     Pins  50  are then removed from members  10  and a coping  30  is then placed on each implant/abutment member  10  with tapered surfaces  40  received on tapered seating surfaces  20 . A pin  50  is then inserted in each respective coping and attached to member  10  by means of threaded portion  56  received in threaded bore portion  24  and with tapered surface  54  received on tapered surface  44  of coping  30 . Prosthesis  60  is then placed on mounting assemblies  58  with pins  50  and copings  30  received in respective oversized bores. Epoxy, or similar material, is injected in the oversized bores around the pins and copings filling in the bores. As the epoxy sets, excess material is trimmed away leaving the prosthesis securely fastened to mounting assemblies  58 , as shown in FIG. 6, spaced from the sites of permanent implants  2  so that no transmucosal force will be transmitted from the temporary prosthesis to or occlusal forces through the integrating permanent abutments  2  during the healing process. When the healing process is completed the pins can be unscrewed so that the temporary prosthesis, along with copings  30  can be removed. Implant/abutment members  10  can then be unscrewed and discarded and a permanent prosthesis can be installed supported on abutments placed in the now fully integrated permanent implants  2  in a known manner. 
     Pins  50  facilitate the removal and accurate placement of the prosthesis and the use of prefabricated copings  30  assure quality adaptation and minimize the clinician&#39;s chair time. 
     Although it is preferred to use pins  50 , the design of the implant/abutment member  10 , including the tapered mating surfaces  40  of the coping and  20  of the implant/abutment member, affords sufficient retention even if a pin is not used since sufficient resistance is provided by means of the internal walls of the threaded bore  24  and the tapered surfaces. 
     If desired, the temporary prosthesis can be formed by injecting or filling a shell or vacuum formed acrylic outline of the intended prosthesis with a suitable moldable material, such as acrylic, onto and around the seated copings of the combined implant/abutments. 
     It will be understood that a device also can be installed onto the combined implant/abutment(s) which may be used for non-prosthetic purposes, such as a support for anchorage in orthodontic or distraction osseogenesis purposes. 
     The invention minimizes dehiscence of integrating permanent implants caused by movement of a temporary prosthesis or food bolus while allowing a patient to eat a more solid and diversified diet immediately after placement of the temporary prosthesis on mounting assemblies  58 . The invention allows for chair side or laboratory fabrication of the temporary prosthesis before or subsequent to permanent implant placement or independent of other implant placements. 
     In addition to allowing secure and accurate placement of a temporary prosthesis on the same day as permanent implants, the invention also allows salvaging of failing dental prosthesis on an interim basis. Another use of the invention is for the secure and accurate placement of surgical stents (templates) used in association with the placement of the permanent implants. Yet another use is as a means to secure other devices to bone, for example, one could secure an appliance which in turn could be used to secure other devices for a variety of purposes, such as aesthetics or for orthodontic purposes. 
     In view of the above, it will be seen that the various objects of the invention have been met. Various additional changes and modifications of the above described invention will be readily apparent to those skilled in the art and it is the intention that any such change or modification be deemed to come within the scope of the present invention as set forth in the appended claims.