Dentistry – Prosthodontics – Dental implant construction
Reexamination Certificate
2001-10-11
2003-09-30
O'Connor, Cary E. (Department: 3732)
Dentistry
Prosthodontics
Dental implant construction
C433S173000, C433S174000
Reexamination Certificate
active
06626671
ABSTRACT:
BACKGROUND OF THE INVENTION
The use of dental implants having a roughened surface has been disclosed in a number of patents including U.S. Pat. No. 6,102,703, U.S. Pat. No. 6,095,817, U.S. Pat. No. 6,048,204, U.S. Pat. No. 5,989,027, U.S. Pat. No. 5,947,735, U.S. Pat. No. 5,876,453 and U.S. Pat. No. 5,571,017. It is believed that the roughened surface facilitates osseointegration of the implant and surrounding bone and also aids in mechanical retention of the implant at the time of placement. The term ‘roughening’ and its cognates is intended to refer to surface texture on the order of about a hundred of microns or less. Surface roughening is not intended to refer to larger features of an implant such as the thread.
A number of different methods of roughening and/or coating the surface of an implant are known. One such method involves the use of a titanium plasma spray (TPS). The titanium plasma spray coating significantly increases the surface area of the implant. TPS both roughens and coats the implant.
Another method of roughening an implant involves blasting the implant with a resorbable blast material such as a calcium phosphate medium. The surface of the implant may then be passivated.
Other treatments using forms of hydroxyapatite for coating and/or roughening an implant without any subsequent passivation are also known.
Yet another method of roughening an implant involves acid etching the implant. One or more acids, for example, a combination of hydrochloric acid and sulfuric acid, may be used to etch an implant and thereby roughen the implant.
Other methods of surface roughening include blasting the implant with a blast material such as sand, glass, aluminum blast material including aluminum oxide (Al
2
O
3
) or titanium oxide (TiO
2
). Alternative blast media including calcium carbonate, sodium bicarbonate or other blast media that can be dissolved readily in a solution, typically an acidic solution. The solution should be able to substantially remove 100% of any particulate matter from the roughened surface.
Ion etching, chemical milling, laser etching and spark erosion techniques have also been used to roughen surfaces of implants.
Any of the above methods may include a passivation step and/or a cleaning step following roughening of the implant.
One type of implant to which roughening is applied is the self-tapping dental implant. Typically, self-tapping implants are formed by machining a one or more cavities in an implant body near the distal end of the implant. The cavities provide cutting edges which cut surrounding bone as the implant is threaded into the bone. The cavities also hold bone material that has been cut by the implant.
Roughening of the outer surface of the implant, however, can lead to rounding of the cutting edges of the implant, decreasing the cutting efficiency of the edges and increasing the torque required to insert the implant. A number of different techniques have been disclosed to avoid this problem. U.S. Pat. No. 5,885,079 and U.S. Pat. No. 5,571,017 disclose roughened implants having distal ends which are not as rough as the middle portion of the implants. U.S. Pat. No. 5,1947,735 discloses an implant having cutting edges which are substantially free of roughening. The cutting edges are masked during the roughening process.
There remains a need for methods of making self-tapping implants which are roughened and yet have sharp cutting edges.
All U.S. patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
The invention in various of its embodiment is summarized below. Additional details of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
The abstract provided herewith is intended to comply with 37 CFR 1.72 and is not intended be used in determining the scope of the claimed invention.
BRIEF SUMMARY OF THE INVENTION
In at least one embodiment, the invention is directed to a method of preparing a dental implant made from a material. In accordance with the method, a dental implant blank having a proximal and a distal end and a surface is provided. A desired portion of the surface of the dental implant blank is roughened and/or coated. Subsequent to roughening or coating, material is removed from at least a portion of the dental implant blank to form a dental implant. One or more cutting flutes may be formed during the removing step. In some embodiments of the invention however, the implant blank is machined without the cutting flute configuration. Each cutting flute comprises a cutting surface, a collector surface and a cutting edge. The cutting surface and collector surface are relatively smooth compared with the cutting edge. Desirably, the one or more cutting flutes are at the distal end of the implant.
The roughening or coating step may be accomplished by any suitable treatment process including titanium plasma spray processing, acid etching, blasting with a resorbable blast material, such as a medium having calcium phosphate, blasting with a non-resorbable blast medium or any combination of the above treatment processes. Following roughening, the dental implant blank may be passivated and/or cleaned to remove any particulate matter or any other undesirable matter. The dental implant may also be coated with a suitable coating such as hydroxyapatite.
In at least one embodiment, the cutting flutes are machined into the roughened dental implant blank after the roughening or coating step. In some embodiments, after formation of the cutting flutes, the implant may again be roughened to increase the surface roughness within the cutting region.
In some embodiments of the invention a sleeve may be threaded onto the apical or distal end of the implant. Preferably, the sleeve is threaded onto the distal end following the initial roughening treatment. The cutting flutes may then be machined into the implant through the sleeve. By machining the cutting flutes through the sleeve the potential formation of metal burrs is prevented.
In at least one embodiment of the invention, after the cutting flutes have been machined into the implant the sleeve may be removed and the implant may be roughened again to increase the surface roughness of the cutting flute region.
Alternatively, the sleeve may remain on the implant through the second roughening step to act as a masking feature. Following the second roughening step the sleeve may then be removed.
Desirably, the dental implant blank includes a neck portion at the proximal end and the roughened and/or coated portion of the dental implant blank extends from the distal end of the dental implant blank toward the proximal end of the dental implant blank, terminating distal to the neck portion. More desirably, the roughened portion and/or coated portion terminates one or two threads down from the neck portion or 1.5 mm to 3 mm down from the neck portion. The invention also contemplates the roughened and/or coated portion extending to the neck portion of the dental implant blank.
Optionally, the method further comprises the step of disposing a restorative object on the dental implant.
In another embodiment, the invention is directed to a method of preparing a dental implant. In accordance with the invention, a dental implant blank having a roughened and/or coated portion is provided and material removed from at least a portion of the roughened and/or coated blank to form a dental implant. Desirably, the neck portion of the implant blank is smooth. The dental implant blank may be roughened using a titanium plasma spray, a resorbable blast medium, such as calcium phosphate or any other suitable technique. The blank may be coated using hydroxy apatite or any other suitable coating. Desirably, material is removed to form at least one cutting flute in the distal end. Also desirably, the cutting flute comprises a cutting surface terminating in a rough cutting edge and a collector surface with the cutting surface and collector surface smoother than
Huotari Jeremy M.
Klardie Michael R.
Swanson Peter B.
Tremmel Thomas A.
Dorsey & Whitney LLP
Lifecore Biomedical, Inc.
O'Connor Cary E.
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