METHOD OF INSTALLING A DENTAL IMPLANT

Abstract: A dental implant (10) and method of installing the same which includes the insertion of a root member (18) into the jaw bone (22). The root member is inserted into a predrilled socket in the support bone. A prefabricated oversized implant head (30) is reduced in size and secured to the root member (18) by use of a screw (34). The implant (10) is completed with a thin overlay (36).

Description: Description Method Of Installing A Dental Implant Technical Field This invention relates to oral prosthetic implants and more particularly to a method of installing a dental implant involving the reduction in size of an oversized implant head. Background Art A variety of dental implants have been developed to provide replacements for natural teeth or as abutments for bridgework. Typically these implants are of two-piece construction. One method of installing an implant involves first inserting a root portion into the bone in a subgingival manner. The implant is then left in position for a period long enough to allow bone tissue to form around the implant and anchor it in position. Because the root is inserted sub- gingivally, the forming bone is protected from any weakening or damage that might have occurred if the implant had protruded into the mouth where it could be knocked and the root jarred. Once the root is securely anchored, a removable implant head is attached that provides a support onto which a tooth-shaped overlay can be secured. One difficulty encountered with prior art implants is the fragile nature of the resulting artificial tooth. Such a prior art device is seen in FIG. 1. The dental implant 10 is located between two natural teeth 12 and 14. The implant 10 is formed using a typical submergible post-type dental implant system. The implant 10 includes a root 16 that may be of one, or two, piece construction having an anchor 18 and an implant head 20. The root is secured to the jaw bone 22 and the implant head 20 is generally either protected against jarring by use of a healing cap during bone growth or secured to the anchor at a later stage after bone growth is completed and the root is firmly anchored. The implant head 20 of prior art systems generally has a top tapered portion 24 to which a dental restoration 26 is attached. The implant head 20 of Figure 1 is illustrative of the implant heads used in prior art systems. See e.g.. U.S. Patent Nos. 4,547,157; 4,645,453; 4,687,443; 4,713,003; 4,744,753; 4744,754; 4,744,755; and 4,744,756. The head is small in volume relative to the volume of the tooth shaped dental restoration 26. The restoration is conventionally formed from porcelain or a similar material and is therefore inherently fragile. The larger the volume of the restoration, the greater the tendency for the tooth to crack and deteriorate. There are prior art dental prostheses that are formed from metal bodies with a ceramic overlay baked on the body. It is generally accepted that the best metallic material to use for such restorations is titanium. Titanium is recognized as the most bio-compatible metal for such uses. The methods of forming such prostheses however involve casting the metal to provide a body of appropriate shape. One such method is disclosed in U.S. Patent 4,744,756 in which a metal body is attached to an implant head to provide a larger support for a porcelain-type overlay. Casting is required in order that the body fits the root element and is suitably shaped to support an overlay. However, the casting apparatus required for the formation of such pieces for titanium is generally not available in a dental surgery. Consequently the metal bodies must be cast off premises. This has two consequences. First, it can cause unnecessary delay and increased the expense of the procedure. Second, metals cast using these techniques tend to be brittle and weaker than machine metals and thus have a high risk of damage during use, implementation and transportation before implantation. The use of gold or palladium is possible to overcome some of these problems, however, because of the cost of such metals, the use of oversized gold or palladium bodies is not commercially feasible. It is desirable therefore to provide an improved method for installing an oral prosthetic implant. Disclosure of Invention This invention provides an improved method of installing dental prostheses. This invention provides a method for installing dental prostheses for which all the necessary steps for installation can be carried out by a dental surgeon using equipment available for use in the everyday course of trade. Other objects, advantages and features of the invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings. One embodiment of this invention involves a method of installing a dental implant which includes the insertion of a root member into the bone and the reduction in size of an oversized implant head prior to securement to the root member. The root member is inserted into a pre- drilled socket in the support bone. The root is left in place and the bone is allowed to grow back and secure it in position. The oversized implant head is a prefabricated machined titanium head adapted for connection to the root member. The implant head is reduced in size until it is suitably shaped to receive an overlay. The implant head is then secured to the root element. The implant head may be substantially tooth-shaped. The implant head is preferably made of titanium because titanium does not present problems of rejection by the body. The titanium must be sufficiently workable to allow grinding of the implant head to the appropriate size. Brief Description Of Drawings For a more complete understanding of this invention, reference should now be made to the embodiment illustrated in greater detail in Figures 1-4 of the accompanying drawings and described by way of example only. In the drawings: Fig. 1 is a schematic sectional view through a prior art tooth implant; Fig. 2 is a schematic sectional view through an implant head suitable for use with the method of this invention; Fig. 3 is a schematic sectional view through a dental implant, inserted using the method of this invention; and Fig. 4 is a schematic view of a completed dental implant of this invention. Modes for Carrying Out the Invention The method of the present invention can be carried out in its entirety in a dental surgery. It is envisioned that the dental surgeon will have a collection of implant heads 30 similar to the one shown in Figure 2. Each implant head 30 has a central shaft 32 adapted for receiving a screw head for attachment to a root portion previously anchored to the jaw bone. The implant heads 30 will be substantially tooth shaped and in a variety of sizes to enable them to be reduced to a size and shape suitable for receiving an overlay with minimum grinding by the dental surgeon. Due to the wide variety of tooth shapes in the variety of people, some grinding will be inevitable but with prudent choice of gradation in tooth size, the grinding necessary will be kept to a minimum. Turning now to Figures 3 and 4, the completed restoration can be seen. A properly chosen implant head 30 has been reduced in size and attached to a root anchor 18. The anchor 18 is one of the known varieties of anchors and is implanted in the jaw bone 22 using one of the known appropriate methods. A screw 34 is employed to attach the implant head 30 to the root anchor 18 and a relatively thin overlay 36 provides the outer surface of the tooth. The overlay 36 forms only a small part of the total volume of the prosthetic tooth. This reduces brittleness and therefore increases the durability of the tooth. The prosthetic tooth shown in Figures 3 and 4 is installed in stages. First, the patient visits the dental surgeon's surgery to have the root 18 implanted in the jaw bone 22. At this or the subsequent visit, when the implant head is attached, the dental surgeon decides upon the size of the prefabricated implant head 30 to be worked with. This size obviously depends upon the size and shape of the patient's teeth. The implant head 30 is preferably titanium allow as the human body does not have a rejection reaction to titanium. Being a relatively soft metal it is also ideally suited to grinding. On a second visit once the root 18 is firmly anchored in position, the dental surgeon proceeds to grind the prefabricated implant head 30 until it is the required size. Using the surrounding teeth as a guide, the dental surgeon grinds the implant head 30 until it fits into the gap provided for the implant tooth yet still providing sufficient room for an overlay 36 to be attached. The prefabricated implant head used in this invention can be shaped to the most desirable configuration to accommodate the overlay 36. With conventional techniques, however, the implant head must be relatively small and it is often difficult to apply a crown to the resultant stump. Using the method of this invention the dental surgeon may reduce an oversized implant head 30 to provide an ideally shaped implant head to take an overlay or crown. Once the implant head has been ground to size, it is attached to the anchored root 18. This is achieved by a pin 34 screwed through both the implant head 30 and the root 18 has shown in Figure 3. Alternatively, the implant head 30 could have an integral screw thread for receipt by the root member. This method may, however, cause problems with orientation of ground implant head 30 which is likely to be highly asymmetrical. When the implant head is in position conventional crowning techniques can be used to attach tooth-shaped overlay 36 to the implant head. Each of the steps set forth above can be carried out in a dental surgery by a dental surgeon. This reduces the time and expense of sending implants off-premise to be cast. In addition, breakage of the implant head is virtually eliminated as the implant head being larger is far less brittle further reducing inconvenience to both the dental surgeon and the patient. The increased size of the implant head of this invention also reduces the thickness of a ceramic overlay required to provide a tooth surface. Thinner ceramics are less prone to cracking and the prosthetic tooth is therefor more durable. As can be seen from above, the method of this invention is very versatile and can be used with any of the known root implanting, crowning and capping techniques. It is convenient for the dental surgeon as well as speeding the installation process and increasing durability of the implant for the patient. The technique can be used for the same variety of implants as conventional prosthetic implants, ranging form single tooth implants to bridges. While one preferred embodiment of a tooth implant produced as a result of the method of this invention is illustrated, it will be understood, of course that the method of the invention is not limited to producing this embodiment. Those skilled in the art to which the invention pertains may make modifications to the method and other embodiments of the tooth-implant employing the principles of the invention, particularly upon considering the foregoing teachings.

Claims: Claims What is claimed is: 1. A method for installing a dental implant suitable for forming part of an oral prosthesis comprising the steps: preparing a socket in the support bone for receipt of a root member; inserting said root member into said socket; allowing said socket to heal; reducing the size of a prefabricated oversized implant head adapted for connection to said root member; ceasing size reduction when said implant head to said root member. 2. The method as claimed in claim 1 wherein said oversized implant head has dimension greater than those of the oral prosthesis of which is to form a part. 3. The method as claimed in claim 2 wherein said oversized prefabricated tooth is substantially tooth-shaped. 4. The method as claimed in claim 1 wherein said oversized prefabricated implant head is made from a titanium alloy. 5. The method as claimed in claim 1 wherein said implant head is reduced in size by grinding.- 6. The method as claimed in claim 1 comprising the additional step of securing a tooth- shaped overlay to said implant head. 7. The method as claimed in claim 6 wherein said overlay is formed from porcelain. 8. The method as claimed in claim 1 wherein said suitably shaped implant head is configured to have an overhanging lip. 9. The method as claimed in claim 1 wherein said suitably shaped implant head provides substantially the bulk of the oral prosthesis of which it is to form part. 10. A prefabricated, grindable, oversized, tooth-shaped implant head adapted to be secured to a preinserted dental implant root member together forming a dental implant. AMENDED CLAIMS [received by the International Bureau on 27 January 1993 (27.01.93); original claim 1 amended; new claims 11-16 added; other claims unchanged (4 pages)] What is claimed is: 1. A method for installing a dental implant suitable for forming part of an oral prosthesis comprising the steps: preparing a socket in the support bone for receipt of a root member; inserting said root member into said socket; allowing said socket to heal; reducing the size of a prefabricated oversized implant head adapted for connection to said root member; ceasing size reduction when said implant head is of the desired size; and connecting said implant head to said root member. 2. The method as claimed in claim 1 wherein said oversized implant head has dimension greater than those of the oral prosthesis of which is to form a part. 3. The method as claimed in claim 2 wherein said oversized prefabricated tooth is substantially tooth-shaped. 4. The method as claimed in claim 1 wherein said oversized prefabricated implant head is made from a titanium alloy. 5. The method as claimed in claim 1 wherein said implant head is reduced in size by grinding. 6. The method as claimed in claim 1 comprising the additional step of securing a tooth- shaped overlay to said implant head. 7. The method as claimed in claim 6 wherein said overlay is formed from porcelain. 8. The method as claimed in claim 1 wherein said suitably shaped implant head is configured to have an overhanging lip. 9. The method as claimed in claim 1 wherein said suitably shaped implant head provides substantially the bulk of the oral prosthesis of which it is to form part. 10. A prefabricated grindable, oversized, tooth-shaped implant head adapted to be secured to a preinserted dental implant root member together forming a dental implant. 11. An oral prosthesis comprising: a root member adapted for insertion in a support bone; and an implant head for connection to said root member wherein said implant head has been reduced from dimensions greater than those desired to its desired size before connection to said root member. 12. The oral prosthesis of claim 11 wherein said implant head is substantially tooth- shaped. 13. The oral prosthesis of claim 11 wherein said implant head is made form a titanium alloy. 14. The oral prosthesis of claim 11 wherein said reduction in size was caused by grinding. 15. The oral prosthesis of claim 11 wherein said implant head has an overhanging lip. 16. The oral prosthesis of claim 11 further comprising a porcelain overlay over said implant head. STATEMENT UNDER ARTICLE 19 The Article 19 Amendment corrects a typographical omission in Claim l. The Amendment also adds new Claims 11-16. These claims are directed to various embodiments of an oral prothesis incorporating the type of implant head referred to in Claim 10.

Inventors: TANAKA ASAMI, TANAKA, ASAMI
Applicants: ASAMI TANAKA DENTAL ENTERPRISE, ASAMI TANAKA DENTAL ENTERPRISES, INC.
Application year: 1992
Main classification: A61C8
IPC codes: A61C8