Method for installing a dental implant

Dental implants for supporting and positioning artificial teeth or prosthetic devices are provided. The dental implant is adapted to be installed and ultimately oseointegrated into a predrilled osteotomy site of either the maxilla or mandible. The dental implant has a generally cylindrical body with an apical threaded portion which is screwed and secured into the bone. The cylindrical body also includes an internal threaded bore extending from the second end into the cylindrical body along the longitudinal axis of the cylindrical body. An integral hexagonal shaped protrusion, when viewed along the bore of the cylinder, is preferably provided and extends from the end of the implant proximal the gingiva of the patient. The internal bore of the cylinder extends concentrically through both the annular base and the hexagonal protrusion. The hexagonal protrusion will mate with as corresponding shaped female recess in an abutment which supports and positions artificial teeth or other prosthetic devices above the gingiva or alveolar mucosa which is located above the bone. The abutment rests on both the annular base and the hexagonal projection This mating relation prevents the abutment from rotating around hexagonal projection and thereby maintains the orientation of the abutment and corresponding artificial teeth or prosthetic devices within the mouth.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to dental implants. More particularly, 
this invention relates to endosseous dental implants having external or 
internal locking means for engaging an artificial dental appliance a 
dental restoration or prosthesis. 
2. Description of Prior Art 
There are basically three different types of endosseous implants blades, 
screws, and cylinders. Blade, screw and cylinder implants all require that 
a hole or slot first be made in the maxillary or mandibular jawbone prior 
to the implant being inserted In the case of a screw-type implant, a 
threaded hole is either tapped in the bone to accept the threaded screw 
implant, or alternatively a self-tapping threaded implant is screwed 
directly into the prepared bone. The tops of both these screw-type 
implants are typically provided with either a hexagonal male projection or 
an internal female hexagonal arrangement which is adapted to mate with a 
correspondingly shaped engaging male or female mating surface in a screw 
driving tool which is used to actually insert the implant into the bone. 
Following insertion of the screw type implant, the male projection or the 
female aperture of the implant can be utilized to matingly engage a 
corresponding female aperture or male projection in a prosthetic component 
to firmly seat the component and prevent rotation of the prosthetic 
component with respect to the implant. In this way, the prosthetic 
component is secured into position with the above screw type implant. A 
representative example of a screw-type implant is disclosed in U.S. Pat. 
No. 4,713,004 to Linkow et. al. which discloses an implant having inner 
and outer screw threads along its elongate body portion and a hexagonal 
projection at its upper end which is adapted to be engaged for rotation 
with a wrench type tool. 
The prior art cylinder-type implants differ from the screw-type implants in 
several respects. First, the cylinder-type implants do not have external 
threads. Second, the cylinder-type implants typically have an open 
internal threaded central bore extending partially into the implant for 
the purpose of securing a prosthetic component. Third, the cylinder-type 
implants are not provided with hexagonal members extending from the tops 
thereof, because a threading tool is not necessary to install the 
cylinder-type implant as with a screw implant. In implanting a 
cylinder-type implant, an unthreaded hole is drilled into the bone, with 
the inner diameter of the hole being equal to or slightly less than the 
outer diameter of the cylinder to be installed. The cylinder is then 
carried to the surgical site by utilizing a carrying post which is 
threaded into the internal threaded central bore and which projects 
therefrom. The cylinder implant, with the carrying post extending 
therefrom, is then press fit into the hole and is gently tapped into place 
by tapping the carrying post with a small mallet (thereby protecting the 
implant itself). In the ideal case, a snug, tight fit is provided between 
the cylinder and the surgical osteotomy hole 
The choice of whether to use a screw-type or a cylinder-type implant is 
strictly up to the dental surgeon and has previously been substantially 
dependent upon the quality, quantity, and geometry of bone underlying the 
gingiva at the implant site. The cylinder-type implant is often preferred 
where the bone of the mandible or maxilla is soft or less dense. Since the 
bone of the maxilla is typically softer than bone matter of the mandible, 
cylinders are often the implants of choice when used in the maxilla. 
As aforementioned, the cylinder implant is installed by pushing the body 
portion thereof directly into the surgical site drilled into the bone. The 
top of the cylinder implant is located at approximately the surface of the 
bone and includes an internal threaded bore extending, into the cylinder 
body as noted above. This internal threaded bore receives anchoring 
fasteners such as screws to hold a prosthetic component or restoration in 
place above the cylinder implant 
An abutment, which can take many forms and shapes is then placed on top of 
the cylinder or screw type implant. The abutment serves as a core to 
provide for retention and/or stability of a replacement tooth or dental 
prosthesis. The abutment is typically colineal with the central internal 
threaded bore of the cylinder when the abutment is in place on top of the 
cylinder. The replacement tooth or prosthesis typically also has an 
aperture colineal with the bore of the cylinder and the abutment. In such 
situations, a screw extending through the prosthetic device and the 
abutment is used to secure the abutment and the prosthetic device to the 
implant. In other cases, the prosthetic restorations are cemented onto the 
abutment core. 
Heretofore, where the bone closest the gum of the patient is soft, the 
surgeon utilizing the cylinder-type implant has not had the benefit of any 
screw-implant engagement with the bone of the patient. Moreover, prior to 
the teachings of the parent application hereto, the surgeon has not had 
the advantage of a shaped projection member, mating with a corresponding 
aperture in the abutment in order to obtain a secure and relatively 
permanent fit and orientation between the cylinder and the dental 
replacement structure. 
SUMMARY OF THE INVENTION 
It is therefore an object of this invention to provide a hybrid implant 
that combines the advantages of a cylinder implant and the advantages of 
the screw-type implant. 
It is another object of the invention to provide a hybrid implant which is 
constructed to utilize the wide variety of prosthetic devices already 
readily available with screw implants. 
Another object of this invention is to provide a dental implant which is 
rigidly securable within the socket or alveolar of a recently extracted 
tooth or prepared opening to provide a suitable foundation for a 
prosthesis such as a crown or replacement tooth. 
A further object of this invention is to provide a dental implant which 
does not threadably engage the socket or the open alveolar space of the 
extracted tooth or other opening in the region underlying the gingiva, but 
rather is inserted in this region by press fit or tapping impact. 
Yet another object of the invention is to provide a dental implant which 
threadably engages the hard bone which is at approximately the apical 
third of the implant body, but which does not threadably engage softer 
bone near the gingiva or alveolar mucosa of the patient, and which further 
includes an integral male projection member adapted to mate with a 
corresponding recess disposed within a dental prosthesis in order to 
resist rotation of the dental prosthesis relative to the dental implant. 
In accord with the objects of the invention, an endosseous implant (also 
referred to as the "hybrid" implant) comprising a rigid cylindrically 
shaped body having a threaded apical portion is provided. The cylindrical 
body and threaded apical portion are preferably comprised of commercially 
pure titanium and are adapted to be initially inserted into the bone of a 
patient as a conventional cylinder-type implant followed by a screwing 
(i.e. self-tapping) of the apical portion of the implant into the bone. 
The cylinder portion of the hybrid implant matches the standard 
cylinder-type implant, and preferably further includes an upper projection 
member that accepts the variety of prosthetic components heretofore used 
only with screw-type implants. The implant body may also include one or 
more recesses extending into or through the implant body to enhance the 
osseointegration of the cylinder body with, and the ultimate retention of 
the cylinder in the surrounding bone. 
The cylindrical body portion and, in some cases, the threaded apical 
portion of the implant are preferably first coated with a titanium plasma 
spray, and then with hydroxylapatite, to increase the surface area of the 
implant body and improve the biologic integration of the implant and the 
bone. Although the combination of hydroxylapatite and the titanium plasma 
is the preferred coating technique, other coating techniques using these 
materials, either individually or in combination, as well as other 
materials that enhance the biological osseointegration process may be 
used. 
A better understanding of the improved dental implant of the invention, and 
additional objects and advantages of the invention will become apparent to 
those skilled in the art upon reference to the detailed description and 
the accompanying drawings.

DETAILED DESCRIPTION OF INVENTION 
With reference to the figures, a dental implant 100 is shown having a 
cylindrical body portion 112, an outwardly threaded apical portion 119 
integral and below the cylindrical body portion 112, and a locking 
projection 114 integral and above the cylindrical body portion 112. The 
outwardly threaded apical (bottom end) portion or element 119, has sharp 
external cutting threads 111 which do not extend beyond the envelope 195 
of the cylindrical portion 112; i.e. the outer diameter of threads 111 
does not exceed the diameter, "D", of the cylindrical portion 112 cutting 
threads (although different numbers of threads can be used), and is 
typically, although not necessarily, from about 1/5 to 1/3 the length of 
body 112. The threaded portion 119 preferably does not exceed one-half the 
length of body 112. A typical thread pitch might be about 0.04 inches, 
while the inner diameter of the threads might be about 3/5 the width of 
the outer diameter of the threads. Of course, the number, pitch, and inner 
and outer diameter of the threads can vary widely as desired, as can the 
ratio of the length of the threaded portion to the total length of the 
implant. 
As seen in FIGS. 2, 3, and 4, the threaded portion 119 of the dental 
implant 100 also includes an anchor bore or hole 201 which extends through 
the implant in a direction perpendicular to the long axis of the implant. 
The hole 201 is provided to permit bone to grow therein (i.e. 
ossointegration) which enhances the anchoring of the implant in the bone. 
Those skilled in the art Will appreciate that the hole 201 may not be 
required. Moreover, it will be appreciated that the location of the role 
Could be changed; e.g. such that it is located in the cylindrical body 112 
of the implant 100. 
The cylindrical body 112 is shown having a concentric annular polished 
collar or base 118 integrally attached at the upper end 108 of body 112. 
Extending through the annular collar 118 in a concentric fashion and into 
the cylindrical body 112 is a threaded central bore 116. Annular collar 
118 has a planar top surface 129 at the end of cylindrical portion 112 
opposite the threaded portion 119 of body 112. The diameter of body 112 
and coextensive annular base 118 typically ranges from 2.0-6.0 
millimeters, while the length of body 112, including threaded portion 119, 
typically ranges from about 5-20 millimeters. Other diameter and length 
combinations may be utilized. 
Affixed to the planar top surface 129 of collar 118 and integral therewith 
is the projection 114 which has a hexagonal cross-section and a threaded 
central circular passage 105 (FIG. 2) concentrically surrounding threaded 
central bore 116. Threaded bore 116 extends only part way down through 
body 112, e.g. 1/3 to 1/2, and has internal threads 109, which continue 
upward through the integral annular collar 118 and projection 114. The 
sides 117 of hexagonal projection 114, when viewed along the axis 130 of 
the threaded bore 116, extend downward from the top surface 115 of 
projection 114 to the top surface 129 of annular collar 118 in a generally 
perpendicular direction to both top surfaces 115 and 129 and provide 
engageable surfaces. 
A generally cylindrically-shaped abutment member 122 is also provided in 
conjunction with implant 100. Extending through abutment member 122 is an 
unthreaded central bore 123 which in axial alignment with the longitudinal 
axis 130 of threaded bore 116 in cylindrical body 112. Abutment member 122 
also has a recess 131 of hexagonal cross-section at its lower end which is 
concentric with its central bore 123. Recess 131 corresponds in shape and 
size to the projection 114 to enable a close mating fit therewith. Recess 
131 is preferably slightly larger in size than bore 123. With recess 131 
of abutment 122 seated on collar 118 and in mating contact with projection 
114, abutment 122 may be securely engaged with cylindrical body 112 as 
hereinafter described. In this engaged position, threaded bore 116 of body 
112 and unthreaded bore 123 through abutment 122 are concentric and 
coaxial with longitudinal axis 130. 
When the hexagonal cross-section projection 114 and correspondingly shaped 
recess 131 are engaged, abutment 122 is prevented from rotating with 
respect to body 112. Other mating configurations besides the hexagonal 
configuration shown can be used, provided that rotation of either element 
causes corresponding rotation of the other elements. Examples of such 
suitable shapes for the projection and recess are square, rectangle, star, 
triangle, oval and free formed. 
In order to securely engage cylindrical body 112 with abutment 122, an 
abutment screw 124 with external threads 125 is provided The external 
threads 125 threadably engage with and correspond to internal threads 109 
of bore 116, and abutment screw extends through the non-threaded bore 123 
of abutment 122 to engage the internal threads 109 of bore 116 in body 
112. An internally threaded bore 134, with threads 137, extends into the 
upper portion of abutment screw 124. The threaded bore 134 permits the 
engagement of a prosthetic device 165 which is coupled to a gold cylinder 
126 to the abutment 122 (and hence to the cylinder 112) by engaging the 
external threads 139 of screw 128 Which extends through the gold cylinder 
126. 
The dental implant 100 (including cylindrical portion 112, projection 114, 
collar 118, and threaded section 119), and the abutment 112 and abutment 
screw 124 are all preferably made of commercially pure titanium. 
Additionally, as hereinbefore noted, the cylindrical body portion 112 and 
the threaded portion 114 of the implant 100 at their outer surfaces are 
sometimes provided with a thin coating 138 of hydroxylapatite, titanium 
plasma, or other materials which aid in the bio-integration of the body 
112 with the surrounding bone 162. 
In use, an artificial tooth or other prosthetic device 165 is placed around 
the gold cylinder 126 which has a non-threaded bore 127. A gold screw 128, 
with external threads 139, is extended through the non-threaded bore 127 
of gold cylinder 126, to threadably engage the threaded bore 134 of 
abutment screw 124 and to securely hold gold cylinder 126 and the 
prosthetic device 165 fixedly in place relative to the upper surface 141 
of abutment 122. Abutment 122 is fixedly engaged to the implant 100, and 
is therefore also fixed in position to bone 162 to which the implant 100 
is engaged as hereinafter described. As so arranged, rotation of 
prosthetic device 165 about axis 130 of implant 100 is prevented by the 
engagement of the hexagonal projection 114 of the implant 100 with the 
hexagonal recess 131 in abutment 122. 
In implanting the implant device 100 in a bone 162, a hole which is the 
same as or slightly smaller in diameter than the diameter of the 
cylindrical portion 121 of cylindrical section 112 is drilled into the 
bone 162 to establish an unthreaded bore 147 in bone 162. In addition, an 
unthreaded concentric bore 149, of slightly smaller diameter than bore 
147, is pre-drilled deeper into bone 162. With a temporary installation 
piece 120 (FIG. 1) with external threads 121 threaded into bore 116 of 
body 112, the implant device 100 is brought to the surgical sight. The 
temporary installation piece 120 provides a cap or protective covering for 
the projection 114 and the threaded bore 116 of the implant. The implant, 
with its temporary installation cap 120 in place, is inserted in the 
pre-drilled bore hole 147 in bone 162, for example by gentle tapping with 
a small mallet on temporary installation cap 120, until the bottom of the 
threaded portion 119 of the cylindrical section 112 is in a position 
adjacently above the smaller diameter bore 149. The implant 100 is then 
screwed into bore 149 of bone 162 via use of a wrench or other tool (not 
shown) Which matingly engages the installation cap. As the implant 100 is 
turned about axis 130 the sharp cutting threads 111 of the threaded 
portion 119 tap into the bone surrounding the narrower bore 149. 
Eventually, the bottom 198 of the non-threaded portion of the cylindrical 
section 112 will seat on a shelf 199 which is formed by the junction of 
the larger diameter bore 147 and the smaller diameter bore 149. The result 
of utilizing the hybrid implant invention which combines a primarily 
cylindrical portion 112 with an apical screw portion 119 is a sound 
threaded engagement of the implant with the harder bone at location 151 
apical the prosthesis 165 and the patient's gingiva or alveolar mucosa, 
and a secure frictional, laterally supporting engagement of the 
cylindrical portion 112 with the less dense bone closest to the gingiva or 
alveolar mucosa. 
With the implant 100 in place, the temporary installation cap 120 is 
removed. A cover screw 130 (FIG. 1) having external threads 131, a 
hexagonal recess 132 opposite threads 131, and a cover member 133 with a 
planar lower surface 140, is then threaded into bore 116 until the lower 
surface 140 of the cover member 133 contacts the upper surface 129 of 
collar 118, thus providing a temporary seal between cover member 133 and 
the top of bore 116 at the surface of projection 114. Hexagonal recess 132 
in cover screw 130 allows a hexagonal tool, i.e. a wrench, to be inserted 
therein to advance cover screw 130 in into bore 116. Alternately, 
hexagonal recess 132 may be replaced by a slot running across the top 
surface of body 133 allowing cover screw 130 to be advanced by the 
insertion and rotation of a blade-type tool. After the cover member 133 of 
cover screw 130 has sealingly contacted projection 114, the implant is 
left in the bone for a period sufficient to permit bio-integration to take 
place, thereby securing the implant in the bone 162. 
After the lapse of a sufficient amount of time to enable bio-integration, 
cover screw 130 is removed from cylinder 112 by reverse rotation and 
unthreading to expose bore 116. At this time recess 131 of abutment 122 is 
placed in a rotationally fixed mating engagement with projection 114. 
Abutment 122 provides the base support for the subsequent attachment of 
gold cylinder 126 and a prosthetic device 165, above the gingiva or 
alveolar mucosa 170 which is above the bone in which the implant 100 is 
implanted. 
As hereinbefore described, abutment screw 124 is placed through the 
non-threaded bore 123 of abutment 122 so that threads 125 of the abutment 
screw 124 engage the threads of bore 116. As abutment screw 124 advances 
into bore 116, the recess 131 of abutment 122 securely engages the 
projection 114 which is integral with body 112. 
Gold cylinder 126, with its attached prosthetic device 165, is then seated 
on the top of the abutment screw 124 with its bottom portion in contact 
with abutment screw 124 and its frustoconical surface portion 147 in 
contact with the similarly shaped surface 141 of abutment 122. Gold screw 
128 is inserted through non-threaded bore 127 of gold cylinder 126 and is 
securely threaded into the threaded bore 134 of abutment screw 124. Gold 
screw 128 frictionally holds gold cylinder 126, and therefore the 
corresponding artificial tooth or prosthetic device 165, firmly in place 
on the top of abutment 122 and abutment screw 124. 
Abutment screw 124 is prevented from rotating by its frictional bearing 
contact with abutment 122, which is in turn prevented from rotating by the 
interaction of the close mating engagement of projection 114 and recess 
131. Since rotation of abutment 122 and abutment screw 124 is prevented, 
rotation of gold cylinder 126 is also prevented by the frictional bearing 
engagement of gold cylinder 126 with abutment 122 and abutment screw 124. 
In this way, the artificial tooth or other prosthetic device 165 attached 
to gold cylinder 126 is prevented from rotating around body 112 by a 
simple and effective arrangement which has not heretofore been available 
in the prior art. Also, the self-tapped threaded engagement of the apical 
portion of implant 100 with hard dense bone at a location remote from the 
gingiva or alveolar musoca, together with tight lateral support of the 
unthreaded cylindrical portion 112 by bone closer to the gingiva or 
alveolar mucosa, provides enhanced protection against movement of the 
implant. 
There has been described and illustrated herein a dental implant in 
accordance with the present invention. While particular embodiments of the 
invention have been described, it is not intended that the invention be 
limited exactly thereto, as it is intended that the invention be as broad 
in scope as the art will allow. Thus, while the preferred implant was 
described as having particular numbers of threads at a given pitch, and 
being of particular size, etc., those skilled in the art will appreciate 
that the threaded portion of the hybrid implant can take numerous forms, 
and hybrid implants can be prepared regardless of size. Further, while the 
preferred dental implant described and shown includes a hexagonal 
projection as taught by the parent application hereto, the invention is 
intended to encompass all implants having a cylindrical top portion and a 
threaded apical portion, regardless of whether a hexagonal projection is 
included or not. Thus, for example, the top portion of the implant might 
have a differently arranged projection extending therefrom. Alternatively, 
the top portion of the implant might have a female mating surface 
(hexagonal or otherwise) seated therein. All that is required is that 
there be some means available which permits the screwing of the hybrid 
implant into the osteotomy site in the bone, and some means for attaching 
the prosthesis to the hybrid implant. In a similar vein, it will be 
appreciated that while a particular abutment was described for permitting 
connection of the prosthesis to the implant, other abutments can be 
utilized which screw retained or cemented crowns to the implant. Also, 
while the method of inserting the hybrid implant into the osteotomy site 
suggested a certain order of steps, it will be appreciated by those 
skilled in the art that depending upon the particular arrangement of the 
hybrid implant, the annular abutment, and the tools used to screw the 
hybrid implant into the osteotomy site, different steps and/or a different 
order of steps could be utilized. For example, instead of removing the 
protective cap after screwing in the hybrid implant, the protective cap 
could be removed before, depending on the tool used for screwing in the 
hybrid implant, the arrangement of the top surface of the hybrid implant 
itself, as well as, in certain circumstances, the preparation of the site. 
It will therefore be appreciated that yet additional changes and 
modifications can be made to the invention as described without deviating 
from the spirit and scope of the invention as so claimed.