This invention relates to dental implant fixtures, more particularly to cylindrical fixtures which have a smaller external diameter than has up to now been available, for use in thin sections of human jawbones. This application is additional to our co-pending application Ser. No. 283,977 filed 12/13/88.
Cylindrical-shaped dental implant fixtures are known; they are in two broadly-defined groups--some having screw threads on all or part of the exterior wall, and some without threads. All are fitted into a pre-drilled bore prepared in the patient's jawbone, those with screw threads being screwed in, like a machine screw. Of the latter, some are self-tapping, and in some cases the prepared bore is pre-tapped to receive the threaded implant. In all cases the thickness of the section of the patient's jawbone to be prepared limits the diameter of the prepared bore that can be drilled in it. It is general dental practice to leave at least one mm. thickness of jawbone wall on either side of the prepared bore. Up to now cylindrical dental implant fixtures have been available in diameters ranging from about 4.0 mm. down to about 3.3 mm. This has limited the thickness of human jawbones in which dental implant fixtures can be installed to not less that about 5.3 mm, effectively barring the availability of dental implant fixtures in many situations where periodontic restoration is otherwise indicated.
Placement of cylindrical implants in narrow jawbone ridges often is only possible if bone is removed; i.e.: cutting a way of the narrow ridge until a point of sufficient ridge-width to accept the implant is reached. Availability of a narrower implant will reduce, and in some cases eliminate the need for such a procedure.
Dental implant fixtures are fitted with bores to receive and support transition components which in turn support a prosthodontic restoration. In the case of a cylindrical-shaped fixture this bore is usually coaxial in the fixture; frequently it is internally-threaded. The thickness of the material of the fixture between the outer wall (minor diameter of the external thread) and the wall of the receiving bore at its major diameter cannot be reduced below the minimum strength requirements of the fixture and its related transition components. Up to now these requirements have contributed to restricting the above-mentioned smaller diameter to about 3.3 mm.