Endosseous dental implant system

An endosseous dental implant system comprises a root formed, mechanically retained base and an intimate, inter-locking threaded coronal attachment. The root formed base is comprised of a self-locking, externally threaded, tapered shell, and an anti-rotational internally threaded, countersunk plug which is permanently attached below the coronal surface of the shell, thus forming a single unit. Internally, the coronal portion of the shell has a downward tapered bevel for locking the anti-rotational coronal attachment to the base once attached via the internal threads of the permanently connected countersunk plug. Self-tapping threads are incorporated into the apex of the root formed base for easy insertion and immediate locking with the osteotomy. Downward from the coronal portion through the midsection of the root formed base is a specially designed stress distributing thread for uniform loading through the implant site. Finally, to simulate the physiological conditions, the implant system is manufactured from a material that closely replicates the natural dentition.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to artificial orthopaedic implant prosthesis, and 
particularly, but not exclusively, to dental implants. 
2. Description of the Prior Art 
Presently, dental implants to replicate the function of an extracted or 
lost tooth, do so by rigidly fixing a primarily metallic implant to a 
bone-implant site. Although these implants have provided the dental 
industry with a certain degree of success, the absence of the 
biomechanical periodontal ligament, which evenly distributes the occlusal 
loads to the entire implant site, has caused the bone to resorb over time 
in certain regions of the implant. 
Over the last twenty-five years many root formed dental implants have been 
designed to replace natural dentition and provide for both aesthetic and 
functional occlusion. Although these designs provided for certain distinct 
mechanical characteristics for attaching the adjoining bone to the 
implant, they do not address the replacement and functional significance 
of the extracted periodontal ligament. Since the periodontal ligament acts 
as an intermediate barrier between the natural dentition and the 
osteodontic site (which absorbs and uniformly distributes the occlusal 
loads), the omission of such a feature can be devastating to an implant's 
success. Presently, many groove, thread, and hole implant designs are 
available to mechanically fixture and permanently lock the implant to the 
bone without any consideration for the structural loading to the implant 
site and the significance of the periodontal ligament. 
In 1983, an attempt was made to provide an implant system that simulated 
the physiological function of the periodontal ligament by inserting an 
intermediate attachment between the coronal element and the artificial 
root made from an elastic polymer. Although, in principle the design 
provided for a method to absorb the normal occlusion, the design failed to 
uniformly distribute the stress to the underlying bone that the implant 
was attached to. Furthermore, due to the weak mechanical characteristics 
of the elastic material, failure of this intermediate component was 
inevitable. 
Since then, many attempts have been made using computer aided finite 
element analysis to evaluate the stress distribution of various implant 
geometries in order to find the ideal design, assuming rigid fixation to 
the attached bone. Although this data has provided significant insight to 
the structural behavior of many geometries that exist today, few new 
practical designs using this technology have been developed due to their 
manufacturing and surgical requirements. 
What is needed is a specific thread geometry to evenly distribute the 
occlusal loads throughout the entire length of the implant. 
The object of my invention is to emulate, with a dental implant, the 
anatomical conditions of natural dentition using a defined geometry and 
unique material, that can be easily manufactured and surgically placed. 
Another object of my invention is to provide the implant with an 
interlocking mechanism to drive and secure the implant into the jaw and 
act as a receptor for securing a prosthetic attachment. 
It is further the object of my invention to uniformly distribute the stress 
throughout the entire length of the implant, and prevent bone loss, buy 
using a specially designed mechanically locking tapered thread. 
These and other objects of my invention will be apparent from the following 
description taken with reference to the accompanying drawings. 
BRIEF SUMMARY OF THE INVENTION 
The endosseous dental implant comprises two separate components assembled 
and permanently linked together as a single unit. The two components 
consist of a specially designed externally threaded shell for a uniform 
distribution of stress to the implant site and an internally threaded 
anti-rotational plug for securing prosthetic attachments. 
Over the past several years many attempts have been made to develop a 
stress shielding design. The current designs have not proven to be 
clinically successful. What is disclosed is a unique design which has 
never been published, machined or manufactured. It introduces a series of 
cones in alternating helical design over the first six millimeters of the 
implant body. These cones are of two basic mechanical designs. The first 
cone is large in surface area and is at an angle of incidence relative to 
a perpendicular to the long axis of the fixture which first introduces 
tension. The first cone is located at the top or coronal portion of the 
implant. Tension, being the inverse of compression, will provide a 
significant decrease in the vector force distributed into the bone. By 
increasing the angle of incidence and the volume of the surface area, this 
design transfers the majority of the initial stress to the second cone. 
The second cone is a cone of compression. This cone starts with a much 
lower angle of incidence which is compensated for by significantly 
reducing the volume of the cone. Stress introduced into the surrounding 
medium is a function of the combination of both angle of incidence and the 
amount of interface contact or combined surface area relative to the 
surrounding medium. By alternating cones of tension and compression over 
the next six millimeters of implant length in such a way to decrease the 
surface area and decrease the angle of incidence of tension cones, and 
increase the surface area and increase the angle of incidence of the 
compression cones, the design evenly distributes and diverts the stress 
over a larger volume thereby minimizing the initial incidence of trauma at 
the first point of contact. The design also allows for a decreasing 
diameter and gradual introduction of the anchor threads which maximizes 
the physical properties of the material. 
This unique design and application will apply to all implant-bone 
interfaces in the dental and medical profession. This would include hips, 
knees, shoulders, and all orthopedic retaining prosthesis involving a 
bone-implant interface. 
The invention may be better visualized by now turning to following drawings 
wherein like elements are referenced by like numerals.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The invention will be described by using specific language with reference 
to the accompanied illustrated embodiments. However, it is understood that 
the scope of the invention includes any modifications or alterations which 
would be obvious to anyone skilled in the art to which my invention 
relates. Designated numbers will be used to describe each component in the 
preferred embodiment. 
An endosseous dental implant system comprises a root formed, mechanically 
retained base and an intimate, inter-locking threaded coronal attachment. 
The root formed base is comprised of a self-locking, externally threaded, 
tapered shell, and an anti-rotational internally threaded, countersunk 
plug which is permanently attached below the coronal surface of the shell, 
thus forming a single unit. Internally, the coronal portion of the shell 
has a downward tapered bevel for locking the anti-rotational coronal 
attachment to the base once attached via the internal threads of the 
permanently connected countersunk plug. Self-tapping threads are 
incorporated into the apex of the root formed base for easy insertion and 
immediate locking with the osteotomy. Downward from the coronal portion 
through the midsection of the root formed base is a specially designed 
stress distributing thread for uniform loading through the implant site. 
Finally, to simulate the physiological conditions, the implant system is 
manufactured from a material that closely replicates the natural 
dentition. 
As shown in FIG. 1 the endosseous dental implant 1, according to my present 
invention, is comprised of a self-locking externally threaded tapered 
shell 3 which is used to self-tap the root formed implant 1 into a 
pre-fabricated implant site in the bone. Interposed and a permanently 
attached within the shell 3 is an internally threaded, countersunk plug 8 
that acts as a host for all the coronal attachments. These two unique 
components, the externally threaded taper shell 3 and the internally 
threaded countersunk plug 8, are permanently attached below the coronal 
portion of shell 3 forming a single unit 1 by means of a welding process. 
By countersinking threaded plug 8 below the upper ridge of the implant 
shell 3 certain desired features can be provided to the implant, without 
increasing the overall height of the prosthetic attachments. 
The disclosed geometry evenly distributes the occlusal loads throughout the 
entire length of the implant. As depicted in FIG. 2, since the applied 
occlusal stress is highest in the coronal aspect of the implant, the 
implant geometry incorporates a functional thread pitch 11 and thread 
angle 12 to allow for a uniform load distribution throughout the entire 
length of the implant. The geometry progressively increases the stress 
axially from the coronal portion to the apex 14 or bottom end of the 
implant site by simultaneously tapering the minor diameter of the thread 
inward by an angle 4 while increasing the angle of the thread angle 12. 
See the difference in thread angle between positions 100 and 102. Changing 
these parameters, the thread's minor diameter and the thread's angle 12, 
allows for reduced compression and maximize the tension at the top of 
implant 1 and then gradually converts these structural characteristic 
downward to generate a uniform stress field in the implant site. 
Incorporated at the apex of the implant is a self-tapping thread 5 to pull 
the implant downward during its initial placement. To assist in this 
process and to lock the implant into place, the thread 5 will utilize a 
specially designed cutting flute to cut, form, and lock the implant into 
place. 
At the coronal end 13 of the externally threaded shell 3 are two internally 
tapered countersunk bores 19 and 20. Bores 19 and 20 incorporate 
self-locking tapers to snugly attach their respective corresponding mating 
male elements described below. Of these two bores uppermost bore 19 is 
used as a receptor for attaching all prosthetic components, while lower 
bore 20 will be used for fixing the implant's internally threaded 
countersunk plug 8. 
As seen in FIG. 1, assembled and permanently attached to the coronal 
portion 13 of the externally threaded shell 3 is the internally threaded 
countersunk plug 8. Plug 8, prior to assembly as seen in FIG. 3, is 
comprised of an anti-rotational locking spline 21 at the coronal end 22 of 
the plug 8, and a tapped internal thread 7 defined throughout the entire 
length of a tapered bore 9. The assembly of plug 8 requires that the 
locking spline 21, for structural advantages, be recessed below internally 
tapered bore 19 of externally threaded shell 3. Once assembled and 
permanently attached to shell 3 via a welding process, coronal end 22 of 
the countersunk plug 8 is used for driving the implant into its 
pre-fabricated implant receptor site in the bone and provides a means of 
locking to mating prosthetic attachments. 
These aforementioned components, externally threaded bone locking tapered 
shell 3 and the internally threaded prosthetic securing countersunk plug 
8, are assembled and permanently attached to each other to achieve the 
previously stated objects in a functional and manufacturable manner. The 
assembled implant is shown in partial cutaway side view in FIG. 4. Plug 8 
is fixed by welding, gluing or other means into shell 3. An abutment 32 is 
then aligned onto splines 21 on plug 8 as best shown in the top plan view 
of FIG. 5 of plug 8. Abutment 32 extends to integrally or separably 
provide a post 30 to which the tooth or prosthetic (not shown) is attached 
by conventional means. Conforming splines are defined internally in the 
mating end of abutment 32. Abutment 32 is then secured to plug 8 by means 
of a stainless steel socket-hex head bolt 34 disposed within bore 36 of 
post 30 and abutment 32. Bolt 34 screws into threading 7 defined in bore 9 
of plug 8. Post 30 or the prosthetics attached to post 30 may be custom 
molded and angled to conform to the specific bite of each patient 
according to conventional dental lab techniques. 
A second embodiment of the invention is depicted in FIGS. 7 and 8. In the 
second embodiment internally threaded countersunk plug 8 alters the 
connection between the abutment and implant 1 described above to address a 
very common problem in implant dentistry that has had no prior solution. 
Modified plug 8 comprises a straight slot taperlock connection which is 
machined on a one degree thirty minutes Mores taper to cold weld plug 8 to 
the shell 3 in only one position. The position is fixed by means of a flat 
23 defined on end 22 of plug 8. A corresponding flat is then defined 
internally on abutment 32 in place of splines 21 used in the embodiment of 
FIGS. 1-5. 
Prior art implants have had various types of structures to provide multiple 
reproducible locations to accommodate an angled fixture or post. This has 
created a clinical problem of relocating plug 8 in the oral cavity from 
the working model at the time of insertion of plug 8 and the final 
prosthesis. This complication leads to remakes and multiple appointments. 
By designing the connection to only fit in one direction this assures 
accurate repositioning and reproducible transfer during clinical 
procedures. 
An external cylinder is machined to a Mores Taper at one degree thirty 
minutes to secure the abutment during final seating. Angled fixtures or 
posts will be accommodated by casting to the post 30 shown in FIG. 8. The 
feature of the external cylinder with a straight slot or flat also solves 
the difficult manufacturing issue of creating a reproducible Mores taper 
in a hex or octagon design which has been unsuccessfully attempted by 
prior art manufacturers. 
Many alterations and modifications may be made by those having ordinary 
skill in the art without departing from the spirit and scope of the 
invention. Therefore, it must be understood that the illustrated 
embodiment has been set forth only for the purposes of example and that it 
should not be taken as limiting the invention as defined by the following 
claims. The following claims are, therefore, to be read to include not 
only the combination of elements which are literally set forth, but all 
equivalent elements for performing substantially the same function in 
substantially the same way to obtain substantially the same result. The 
claims are thus to be understood to include what is specifically 
illustrated and described above, what is conceptionally equivalent, and 
also what essentially incorporates the essential idea of the invention.