WO2015050331A1

WO2015050331A1 - Gear-shaped dental implant having multiple longitudinal teeth

Info

Publication number: WO2015050331A1
Application number: PCT/KR2014/008757
Authority: WO
Inventors: Ill Mo Rhew
Original assignee: Ill Mo Rhew
Priority date: 2013-10-04
Filing date: 2014-09-19
Publication date: 2015-04-09
Also published as: KR101452477B1

Abstract

Gear-shaped press-fit dental implants having multiple longitudinal teeth(20) filling circumferential surface(10a) of their bodies(10) are disclosed. While the longitudinal teeth(20) are bringing advantages replacing those of threads, such as much enlarged bone-to-implant contact, improved interlocking with bone tissue and reinforced bone penetration, the method of the implant placement 'press fit' gives freedom for asymmetrical designs. Multiple crosscuts(20a) machined into the longitudinal teeth(20) further enlarge the press-fit implant surface, and transform the undesirable shear type of stress to the surrounding bone tissue into preferable compressive stress.

Description

GEAR-SHAPED DENTAL IMPLANT HAVING MULTIPLE LONGITUDINAL TEETH

This invention concerns a dental implant, specifically a gear-shaped press-fit type dental implant having multiple longitudinal teeth, used as an artificial tooth root for holding a dental prosthesis.

Dental implants designed to be placed into jaw bones (endosseous implants) are classified into three categories (1) blade-form implants (2) cylinder-type implants (or press-fit implants) (3) screw-type implants. Figure 1 (Thomas D et al. Dental Implants: Are They for Me. University of Connecticut Health Center. http://dentalimplants.uchc.edu/about/types.html) depicts these three different types of dental implants placed into a jaw bone.

Press-fit implants and screw-type implants are collectively referred to as "root-form implants" because they look more like tooth roots compare to blade-form implants. These root-form implants are the major implants being used on the scene of contemporary implant dentistry. Particularly, screw-type implants are dominating the market.

In order to help the technical value of present invention to be understood, related background subjects will be described in categories in following paragraphs.

(1) Blade-form implants (figure 2)

Up until the arrival of Branemark implant (the first screw-type implant from Sweden) in the U.S. in 1980s, implant dentists in the Unites States had been mainly placing blade-form implants. Branemark implants’ significant research data and success rates have rapidly changed the type of implants since then, and the blade-form implants have fallen out of favor for a number of different reasons. Concerning the high failure rate of blade-form implants at that time, Dr. Raymond Choi, DDS, an assistant clinical professor of the TMJ/Facial Pain Clinic at the University of Southern California and private practitioner said “Their protocol at the time was you placed the implant, you finished the restoration fairly quickly. And the one of the criticisms from the people placing conventional implants(root-form implants) was that because of early movement, you’d get fibril integration instead of osseointegration (direct adhesion of bone to implant without any intervention of soft tissue between them). Therefore, the implant was set for failure in the future. However, there is an existing niche for blade-form dental implants. I come across so many situations, especially in the posterior mandible, where we’re lacking the bone width for the implant. To move forward, the practitioner must do extensive, invasive bone grafting so that there is a wide enough area to receive conventional implants. That usually is a procedure declined by patients quite often because of additional surgery, cost, and the time involved. A lot of people who would like to get implants are shut out because of the need to do this grafting. For those patients, a blade-form implant could be a tremendous option since the blade can work in narrow ridges.”

Nick Caplanis, DMD, MS, president of the American Academy of Implant Dentistry said “Implantologists should know that blade implant is and has always been a viable implant to treat patients especially those with certain bone deficiencies that could not otherwise have a root-form dental implant, or for the patients that, for one reason or another, can’t or don’t want pursue an augmentation bone graft procedure to build the bone back up to accommodate a dental implant or conventional dental implant.” (January 29, 2013 DrBicusbid.com)

Blade-form implants could be a great option for narrow and/or short jaw bone ridges. But, since they have been out of favor for a long period of time, the fact that only few practitioners can use it without specific additional education is one weakness of them, and, incompatibility of their prosthetic components with conventional implants (or root-form implants) is another weakness of this type of implants.

(2) Press-fit implants Vs Screw-type implants (figure. 3, 4)

Screw-type implants have helical threads which help the implants to advance smoothly into dense bones with their penetrating ability. Particularly, self-tapping threads, which are sharper than regular ones, have better penetration. The threads of screw-type implants, also, provide good interlocking with bone tissue and enlarged surface areas on which the bone tissue could adhere. The surface areas of screw-type implants, having threads, could be 30~500% larger than those of implants without threads.

However, screw-type implants have a disadvantage, compare to press-fit implants, which is a higher chance of stripping interior walls of the holes predrilled into jaw bones when they are advancing into, particularly, low density jaw bone sites such as the sites on upper posterior jaws. The screw-type implants have another disadvantage, the limitation of their acceptable design. The cross-sections transverse to the axis of a screw-type implants should always be round and symmetric, because they require rotation for insertion into holes.

In contrast, the press-fit implants have basically smooth non-threaded surfaces. Thus, their procedure for insertion into jaw bone holes are simpler, faster. And, there’s no chance of bone hole interior wall stripping and consequential initial stability loss problem, even when they are advancing into soft bone holes. (Carl E. Misch. Contemporary Implant Dentistry. Mosby, Inc. 2008:p29-30). And the press-fit implants have one more important advantage that they could accept asymmetric, non-round cross-section design because they don't require rotation for insertion.

However, the smooth surfaces of press-fit implants provide basically smaller surface areas for bone tissue to adhere on due to the absence of threads. Also, due to lack of penetration potential, which is provided by threads in case of screw-type implants, advancing press-fit implants into dense bones is challenging in many cases and it could be particularly worse when the implant bodies are in tapered shapes. The operators can, at times, meet embarrassing situations therein the press-fit implants move neither forward nor backward due to the excessive compressions created between the implants and the bone tissues. Mechanical interlocking, which could be provided by threads, cannot not be expected also for press-fit implants.

When occlusal loads are applied, thanks to the threads which virtually configured perpendicular to the direction of occlusal load, the screw-type implants mainly result in compressive force, which bone tissue can resist against well, at the implant-to-bone interface, but the press-fit implants mainly result in less preferable shear force at the implant-to-bone interface. Bone is strongest when loaded in compression and 65% weaker when loaded in shear.(Jennifer T. Steigenga et al. Dental Implant Design and Its Relationship to Long-Term Implant Success. Implant Dentistry 2003;12:p309).

Implant companies have been using a plethora of additional features to accentuate or replace the effect of threads. These features include vents, grooves, flutes, indentations, and perforations of various shapes. (Jennifer T. Steigenga et al. Dental Implant Design and Its Relationship to Long-Term Implant Success. Implant Dentistry 2003;12:p309). But, the results have not been very satisfactory and the screw-type implants are leading the contemporary dental implant market predominantly.

(3) Parallel walled cylinder body Vs Tapered body of root-form implants

It's easy for tapered body implants to get more initial stability, compared with parallel walled cylinder body implants, even when they are placed into soft jaw bones, thanks to wedging effect. But, when placing tapered body implants into dense jaw bones, advancing them up to the end of the predrilled hole would be challenging due to the excessive compression created by the wedging effect, particularly when the implants are non-threaded.

(4) One-piece implants

There are commonly three parts to what is described as an implant, the implant fixture which is inserted directly into bone, the abutment an interconnecting part crossing the gum and connecting the implant to the overlying prosthesis, and the prosthesis itself. In a one-piece implant, an abutment is merged with an implant fixture forming a body. Thus the features including screw holes and internal abutment connection parts in implant fixtures are removed and the implants can have higher strength even with smaller diameters.

The one-piece implant are useful for some sites, for example, the sites for lower incisors and upper second incisors, where narrow diameter implants are required due to narrow spaces. One-piece implants having angled abutment parts are sometimes needed for such sites also. Screw-type one-piece implants cannot incorporate angled abutment parts or, at best, can incorporate only minimum angled abutment parts because they require rotation when being driven into jaw bones and the rotation of the angled abutment parts would be interrupted by adjacent teeth. The press-fit type one-piece implants, which don't require rotation for insertion, can have an advantage of incorporating large angled abutment parts. But, since they still are press-fit type implants, they still keep the aforementioned disadvantages of press-fit implants, the smaller surface area, the less preferable shear type stress against bone tissue.

(5) Meanwhile, in a previous Korean patent application 10-2009-0062829 (title of the invention : Pressure-placement type of dental implant fixture formed with bone-incising blade) a fixture body , as depicted in figure 5, with its diameter reduces from the top part to the bottom end(1), and with one or more bone-incising blades provided from the top part to the bottom part on the outside of the fixture body(3), that can arguably be placed easily on a narrow alveolar bone expending it, has been disclosed.

However, it was not a new idea. As shown in figure 2 (Hubertus Spiekermann, Implantology, 1995, Thieme Medical Publishers, Inc., New York. See the second implant from the top left), it was a design that had been tried even before 1990. The bone-incising blades(3) of the previous patent application only have the function of expending bones, and the implant design does not overcome the comparative weaknesses of press-fit implants against the screw type implants, the aforementioned much smaller surface area, shear type stress to the surrounding bone and lack of longitudinal retentive element that could prevent the vertical loss of bone tissue around the implant fixture.

(6) Meanwhile, previous Korean patent 728815 (title of the invention : dental implant fixture), as depicted on figure 6, disclosed an implant fixture wherein the border between the rough and smooth surface(15) is formed to be inclined so that it can be placed easily on the sloped jaw bone crests without additional procedures.

But, the previous invention was devised mainly for screw-type implants, and the screw-type implants require rotation for insertion as mentioned above. Therefore, there could be a problem such as placing the implant to an undesired depth when it is required to be tuned more so as to match the inclination of implant's rough/smooth border and the inclination of jaw bone crest.

The object of present invention is providing press-fit dental implants having following new technical features so as to tackle the weaknesses of press-fit type implants and integrating the advantages of screw-type implants and blade-form implants into the press-fit implants.

First, multiple longitudinal teeth on the surface of press-fit implants which enable the implant to get as large surface area as threaded screw-type dental implants.

Second, multiple crosscuts machined into the longitudinal teeth which enable, like threads on screw-type dental implants, the press-fit implants to transform occlusal load into compressive force (the type of force preferred by bone tissue) rather than shear force and which act as a vertical retention element resisting the loss of surrounding bone and which also enlarge the surface area

Third, a pair of enlarged longitudinal teeth of those multiple longitudinal teeth which provide maximum amount of bone-to-implant contact when placed along jaw bone ridges, and thereby, which bring back the virtue of classical blade-form implants, the usefulness on narrow and/or short jaw bone ridges overcoming the limitations of the recipient sites.

Fourth, a one-piece press-fit dental implant the axis of its abutment portion meets the axis of fixture portion forming a certain angle while having the first and second technical features mentioned above.

Fifth, an inclined rough/smooth border wherein the plane containing the border is formed to be inclined to a plane transverse to the axis of the press-fit implant while having the first and second technical features mentioned above.

In order to give solutions to the aforementioned problems, the present invention discloses a gear-shaped press-fit dental implant comprising, a body(10), 6 to 50 longitudinal teeth(20) on a circumferential surface(10a) of the body(10), 1 or more crosscuts(20a) formed on the longitudinal teeth(20) and 2 or more plain portions(20b) on the longitudinal teeth(20).

The whole tooth depths of the longitudinal teeth(20) gets gradually smaller and disappear at the top portion of the implant body(10)

The whole tooth depths of the longitudinal teeth(20) gets gradually smaller or gets gradually smaller and disappear at the bottom portion of the implant body(10)

The cross section of the body(10) is in a generally round shape.

The body(10) may be in parallel walled cylinder shape, wherein the cross section is identical from the top to the bottom.

The body(10) may be fully tapered (tapered from the top to the bottom) or partially tapered.

The lower end of a body(10) is, preferably, hemispheric in shape.

The crosscut(20a) machined into the longitudinal teeth(20) is in a shape of 'V' , 'U' viewed on the longitudinal section of the longitudinal teeth(20).

The depths of the crosscuts(20a) on the longitudinal teeth(20), preferably, do not exceed the whole tooth depths.

The longitudinal tooth(20) has a cross section shape of triangle, trapezoid, rectangle, pentagon, and hexagon.

The plain portion(20b) on the longitudinal teeth(20) may have an identical cross-section size from its top to the bottom.

The plain portion(20b) on the longitudinal teeth(20) may have cross-section sizes diminishing as it gets closer to the bottom.

At least two lower ends of the longitudinal teeth(20) are located within 6mm distance from the lower end of the body(10).

At least two upper ends of the longitudinal teeth(20) are located within 6mm distance from the upper end of the body(10)

All the longitudinal teeth(20) may have one ore more identical features of cross-section shape, cross-section area, longitudinal length, and whole tooth depth.

One or more of the longitudinal teeth(20) may have one ore more of different features of cross-section shape, cross-section area, longitudinal length, and whole tooth depth from another or other longitudinal tooth(teeth)(20).

The implant may further include a horizontal micro-grooves portion(30) wherein one or more micro-grooves are formed horizontally on the circumferential surface(10a) between the upper end of the body(10) and the upper ends of the longitudinal teeth(20). The micro-grooves portion(30) is formed, preferably, within 6mm distance from the upper end of the implant body(10).

The implant may include an abutment connection part(40), located on the top center of the body(10), adapted to receive an abutment(not shown) into it.

The whole tooth depths of the longitudinal teeth(20), are preferably within a range of 0.2~1.5mm.

The implant may further include a pair of enlarged longitudinal teeth(25) which have greater whole tooth depth than other regular longitudinal teeth(20) and located symmetrically apart around the axis of the implant body(10).

The pair of enlarged longitudinal teeth(25) have same or greater thickness than the other regular longitudinal teeth(20).

The whole tooth depth of the enlarged longitudinal teeth(25) is, preferably, greater than 1.5mm. The extent of their whole tooth depth may be up to the distance to adjacent implants or teeth.

The implant may further include an integrated abutment part(50) joined onto the body(10) forming a one-piece implant.

The axis of the integrated abutment part(C') may meet the axis(C) of the body part(10) forming a certain angle.

The body(10) may further include a sloped top surface(11) adapted to place it in accordance with sloped bone ridges, wherein a horizontal micro-grooves portion(30) on the top circumferential surface of the body(10) may be employed together, preferably having the sloped top surface(11) confined in the micro-grooves portion(30).

The body(10) may further include a inclined rough/smooth border(15), the border between lower comparatively rough surface and upper comparatively smooth surface, wherein the plane containing the rough/smooth border(15) is formed to be inclined to a plane perpendicular to the axis of the body(10). The difference between the maximum height and the minimum height of the rough surface in the direction parallel to the axis of the implant is, preferably, in the range of 1 to 3 mm.

The gear-shaped press-fit dental implant having multiple longitudinal teeth in present invention has following effects.

Multiple longitudinal teeth can bring equivalent or more advantages of threads to the press-fit implants. They could provide anti-rotational structure, good interlocking with the bones, much enlarged bone-to-implant contact area and good penetration into jaw bones while keeping the advantages of press-fit implants such as acceptance of asymmetric designs, removing the chance of internal bone threads stripping and consequential loss of initial stability.

Multiple crosscuts incorporated on the longitudinal teeth further enlarge the surface area of the implant and transform the shear force, the main type of stress to the bone tissue around press-fit implants, into compressive force which bone tissue can resist well.

When the longitudinal teeth are formed as sharp as self-tapping threads and extended up to the lower apex of the press-fit implant, they could remove one of the weaknesses of press-fit implants, the frequent troublesome advancements in the holes prepared into dense bones, with their reinforced penetration potential.

When the longitudinal teeth are tapered, wherein they get thicker or deeper as they get closer to the top, they could compact soft bone tissue during the process of the press-fit implant insertion resulting in good initial stability and enlarged bone-to-implant contact.

A pair of enlarged longitudinal teeth could make this root-form implant act as if it is a old legendary blade-form implant. This press-fit implant having a pair of enlarged longitudinal teeth makes the implant placement possible into narrow and/or short jaw bone ridges where the implant placement might have been possible only by utilizing blade-form implants. Furthermore, this implant has following comparative advantages surpassing blade-form implants.

First, drills and prosthetic components for conventional root-form implants, which are familiar to contemporary dental implant practitioners, can be utilized.

Second, old blade-form implants had too wide blades to get enough support from bones which made the implants have limited indications. For example, they could be used only on the sites where there were no adjacent teeth. But the enlarged pair of longitudinal teeth of present invention, thanks to the already sufficient surface area of the implant through multiple longitudinal teeth and crosscuts, don't need to be so wide. Thus, the implant having a pair of enlarged longitudinal teeth can be placed on the sites where there are adjacent teeth.

Screw-type one-piece implants could only accept zero to minimum degree angled abutment part since they require rotation for insertion into jaw bones. Rotation of the angled abutment part would be disturbed by adjacent teeth. But press-fit implants don't require rotation. Thus, the press-fit one-piece implant having angled abutment part in present invention, wherein multiple longitudinal teeth and crosscuts are covering the advantages of threads while keeping the advantage of no requirement for rotation as other press-fit implants, would be useful on the sites for, such as, lower incisors and upper second incisors where they have narrow spaces demanding angled abutments.

Because the press-fit implant having an inclined rough/smooth border doesn't require rotation for insertion also, it is easy to align both the direction of the inclined border and insertion depth of the implant simultaneously when placing it into a sloped bone ridge.

Figure 1 depicts three different types of endosseous implants.

Figure 2 depicts various conventional implants including a few blade-form implants.

Figure 3 depicts various conventional press-fit implants.

Figure 4 depicts various conventional screw-type implants including two one-piece screw-type implants (the tallest ones on each top and bottom line).

Figure 5 is a perspective view of an implant fixture formed with bone-incising blades according to a previous patent application.

Figure 6 is a frontal view of two implants having inclined rough/smooth borders according to a previous patent.

Figure 7 is a perspective view of an example embodiment of tapered body implant according to present invention.

Figure 8 is a cross sectional view of the implant in figure 7.

Figure 9 is a perspective view of an example embodiment of parallel walled cylinder body implant according to present invention.

Figure 10 is a cross sectional view of the implant in figure 9.

Figure 11 is a schematic depiction that shows the difference of longitudinal teeth on present invention and blades on conventional press-fit implants.

Figure 12 and figure 13 are a frontal and a cross sectional view of an example embodiment of the implant having a pair of enlarged teeth according to present invention.

Figure 14 is a frontal view of an example embodiment of one-piece implant having a pair of enlarged longitudinal teeth according to present invention.

Figure 15 is a diagram that depicts an example utilization of customized osteotome for site preparation for the implants shown in figure 12 and 14.

Figure 16 is a diagram that depicts an implant having a pair of enlarged longitudinal teeth of present invention being guided by a drilled hole during insertion process.

Figure 17 is a frontal view of an example embodiment of one-piece implant having an integrated angled abutment part according to present invention.

Figure 18 depicts an insertion of a conventional screw-type implant having sloped top with rotation into a sloped jaw bone ridge.

Figure 19 is a frontal view of an example embodiment of implant having a sloped top surface according to present invention.

Figure 20 is a frontal view of an example embodiment of implant having inclined rough/smooth border according to present invention.

Figure 21 depicts an insertion of the implant shown in figure 20 without rotation into a sloped jaw bone ridge.

Hereinafter, embodiments of present invention will be described in more detail with reference to attached drawings.

As shown in figure 7, the press-fit dental implant of present invention basically comprises a body(10), multiple longitudinal teeth(20) on a circumferential surface(10a) of the body(10), and multiple crosscuts(20a) formed on the longitudinal teeth(20). It may further include a horizontal micro-grooves portion(30) on the top circumferential surface(10a) of the body(10) and an abutment connection part(40) on the top surface of the body(10).

Hereinafter, each part will be described one by one, and the parts having identical functions and effects will be described with identical numbers even though they are on different example embodiments.

The cross section transverse to the axis(C) of the body(10) is in generally round shape. Here, 'generally round shape' means virtually round shape including all oval shapes and polygons which could fit into holes having round cross sections made by drilling. The body(10) may have a parallel walled cylinder shape, where the size of the cross section is identical all along the implant, or a partially/fully tapered shape. In figure 7, the body(10) is in tapered shape. In figure 9, the body(10) is in parallel walled cylinder shape. The lower end of each implant here is in hemispheric shape. Although the implants with parallel walled cylinder body(10) basically have weaker initial stability compare to the implants with tapered body(10), a parallel walled cylinder body(10) implant having multiple longitudinal teeth(20) could have sufficient initial stability thanks to the enlarged surface and good interlocking with bone tissue provided by the longitudinal teeth.

Also basically, when the body(10) is tapered, advancement of the press-fit implant in a dense bone is often very challenging due to excessive wedging effect. But, when the longitudinal teeth(20) are formed sharp, the implant can be driven into the dense bone easily thanks to the improved penetration by the longitudinal teeth.

The bottom of the body(10) may be in flat, hemispheric or any other curved shape.

Multiple longitudinal teeth(20) are formed on the circumferential surface(10a) of the body(10) radially. The number of the longitudinal teeth(20) is in the range of 6 to 50 per implant. 1 or more crosscuts(20a) are formed on the longitudinal teeth(20), and as a result, 2 or more plain portions(20b) of longitudinal teeth(20) are formed. These longitudinal teeth(20) provide enlarged surface area, anti-rotational structure, good interlocking with bone tissue and improved penetration for the implant. The crosscuts(20a) act as a bone retention element to the direction parallel to the axis(C) and thus, prevent the vertical loss of surrounding bone tissue. Besides, when they are filled with newly grown bone tissue, the crosscuts(20a) turn occlusal load into compressive force, the more resistable type of force to the bone tissue, to the surrounding bone tissue.

The longitudinal teeth(20) are formed by carving in the circumferential surface(10a) of the implant body(10) longitudinally. The whole tooth depth of the longitudinal teeth(20) gets gradually smaller and disappear at the top portion of the implant body(10), thus, even when the top portion of the implant is exposed over crestal bone there will be no undercut or radial protrusion around the exposed portion, and then, plaque accumulation under undercuts or around protrusions, which can finally cause inflammation and bone resorption, will be prevented in advance.

Also, when the whole tooth depth doesn't disappear at the top portion of the body(10), where the implant meets cortical bone, the longitudinal teeth(20) will sectionalize the cortical bone radially worsening the already bad blood supply of the cortical bone compare to cancellous bone. Then the cortical bone can be more vulnerable to resorption or necrosis.

Because the longitudinal teeth(20) are formed by carving in the circumferential surface(10a) of the implant body(10) longitudinally, the diameter of addendum circle and the diameter of the circumferential surface(10a) are identical as can be seen on the left side implant in figure 11. But the diameter of the circle that connects the outer surface of the blades of conventional press-fit implant having blades is larger than the diameter of circumferential surface(10a) of the body(10) as can be seen on the right side implant in figure 11. Thus, the width of recipient bone site for conventional implant having blades should be as wide as can accommodate the diameter of implant body(10) plus blade width. But the width of recipient bone site which can accommodate only the diameter of implant body(10) is good enough for the implant of present invention.

Also as can been seen in figure 11, the longitudinal teeth(20) are easy to fabricate compare to the blades which are protruded over circumferential surface(10a) of the body(10).

The longitudinal teeth(20) can be made in a lain down form in order to maximize the surface area without enlarging the implant diameter as can be seen in figure 10.

So as to maintain minimal amount of mechanical strength of the body(10), the whole tooth depths of the longitudinal teeth(20) gets gradually smaller or gets gradually smaller and disappear at the bottom portion of the implant body(10)

With the help of multiple longitudinal teeth(20), a press-fit implant could obtain good primary stability even when it has a parallel walled cylinder body(10), and also it could penetrate into a dense bone without trouble even when it has a tapered body(10).

The longitudinal teeth(20) may have an identical size of cross section between the top and the bottom portions of the body(10), or a gradually enlarging cross section as they get closer to the top. In order to get gradually enlarging cross-section, they may have gradually increasing whole tooth depth or gradually increasing tooth thickness. The tapered longitudinal teeth(20), wherein the cross-sections are enlarging as they get closer to the top of the body(10), have bone compaction effect during the process of implant insertion resulting in improved initial stability and wider bone-to-implant contact.

The crosscut(20a) machined into the longitudinal teeth(20) is in a shape of 'V' , 'U' viewed on the longitudinal side of the teeth(20).

A longitudinal tooth(20) may have a cross section shape of triangle, trapezoid, rectangle, pentagon and hexagon.

At least 2 lower ends of longitudinal teeth(20) are located within 6mm distance from the lower end of the body(10), and they may be, preferably, extended up to the lower end of the body(10). As the lower ends of longitudinal teeth(20) get closer to the lower end of the body(10), the implant has better penetration.

At least 2 tops of longitudinal teeth(20) are located within 6mm distance from the upper end of the body(10), and they may be extended up to the upper end of the body(10). When a horizontal micro-grooves portion(30), which will be described in following paragraphs, is formed, the upper ends of longitudinal teeth(20) are preferably located below the lowest groove of the horizontal micro-grooves portion(30).

All the longitudinal teeth(20) may have one or more of identical features of cross-section size, cross-section shape, length, and whole tooth depth.

All corsscuts(20a) may have an identical shape and size.

One or more crosscuts(20a) may have different shape and/or size from another or other crosscut(s)(20a).

All plain portions(20b) may have an identical longitudinal length.

One or more plain portions(20b) may have different longitudinal length from another or other plain portion(s)(20b).

The whole tooth depths of longitudinal teeth(20) are in the range of 0.2 to 1.5mm.

A horizontal micro-grooves portion(30) may be further included on the circumferential surface(10a) between the upper end of a body(10) and the upper end of the longitudinal teeth(20) having more than 1 micro-grooves. The lowermost located micro-groove of the horizontal micro-grooves portion(30) is, preferably, to be located within 6mm distance from the upper end of the body(10). These micro-grooves enlarge the surface of the implant top portion for more bone tissue contact, and act as a bone retentive element against the direction parallel to the axis(C) of the body(10), resulting in good preservation of marginal bone tissue preventing vertical loss.

An abutment connection part(40) is a part to receive an abutment (not depicted in figures) into/onto the body(10) formed on the center of top surface of the body(10) having a screw hole (not depicted in figures) running inside. This abutment connection part(40) is selectively adopted depending on the different example embodiments as described in following paragraphs.

Hereinafter, different example embodiments of present invention will be described in categories.

1. The gear-shaped press-fit dental implant having a pair of enlarged longitudinal teeth

As depicted in figure 12 and figure 13, a pair of longitudinal teeth(25), which are formed symmetrically apart around the axis(c) on the circumferential surface(10a) and have greater whole tooth depths than other regular teeth(20), may be further included. With the help of this enlarged pair of teeth(25), the press-fit implant can be placed into narrow and/or short jaw bone ridges without bone grafting like the classical blade-form implants.

Classical blade-form implants should have wide blades so as to get sufficient support from bones, thus they couldn't be placed on sites where there are adjacent teeth. But the implant of present invention, because it has sufficient surface area with the help of multiple regular teeth(20) and crosscuts(20a), could get enough support with much smaller, compare to the blade size of conventional blade-form implants, pair of enlarged teeth(25). Thus it can be placed on the sites where there are adjacent teeth. The pair of enlarged longitudinal teeth(25) also have corsscuts(25a) and plain portions(25b).

The whole tooth depths of a pair of enlarged teeth(25) are, preferably, greater than 1.5mm and smaller than the distance to adjacent teeth/implants. Therefore, when there are no adjacent teeth/implants, the depth of a pair of enlarged teeth(25) can be as great as the width of the blades of conventional blade-form implants.

Figure 15 is a diagram that depicts an example utilization of customized osteotome(6) to form a recipient site for the pair of enlarged longitudinal teeth(25). A hole(4) is formed on the bone ridge utilizing drills first, then the cylindrical center of the osteotome(6) body is aligned on the entrance of the hole(4) and tap in the osteotome(6) into the hole(4) with a mallet and remove the osteotome(6). Then the precise size of recipient slots(5) that receive the enlarged pair of longitudinal teeth(25) are formed.

In this aspect also, the implant of present invention is different from the conventional blade-form implants. For recipient site preparation, conventional blade-form implants require slots but the implants of present invention require holes(4). Forming slots precisely fitting the widths and lengths of blades by moving dental burs back and forth is a skillful work which requires a considerable amount of training and experiences. Therefore, obtaining good initial stability is unpredictable for conventional blade-form implants. Initial stability is like a password for osseointegration. Low success rates and requirement of long training are the reason why blade-form implants are fallen out of the market today. On the other hand, holes(4) for implant of present invention are prepared utilizing drills which have precise diameters that corresponds to the implant diameters and the slots which receive the pair of enlarged longitudinal teeth are also prepared precisely utilizing customized osteotomes(6), so that the operators having little experiences also can obtain tight fit, or good initial stability easily.

The root thickness(w') of a pair of enlarged longitudinal teeth(25) is, as shown in figure 13, as wide as or wider than the root thickness(w) of regular longitudinal teeth(20). By controlling the root thickness, the amount of implant support could be controlled in accordance with jaw bone ridge conditions.

2. The gear-shaped one-piece press-fit dental implant having a pair of enlarged longitudinal teeth

Figure 14 depicts an press-fit implant wherein an abutment part(50) is integrated onto an implant body(10), the same type of body(10) having a pair of enlarged longitudinal teeth as depicted in figure 12, forming an one-piece implant. This type of implant doesn't have an abutment connection part(40) inside, thus it could be made in smaller diameters without loosing the mechanical strength, and consequentially it could be placed into much narrower jaw bone ridges.

3. The gear-shaped one-piece press-ft dental implant having an angled abutment part

As depicted in figure 17, an integrated abutment part(50) of a one-piece press-fit implant may be formed to have its axis(C') meet the axis(C) of the body part(10) forming a certain angle(θ). Tight spaced recipient sites, such as the sites for lower incisors and upper second incisors, frequently require small diameter one-piece implants and sometimes require angled abutments additionally. This particular implant of present invention could fulfill both requirements at the same time.

Figure 17 shows the distinctive feature of the angled integrated abutment part(50), having its own axis(C'), compare to the integrated abutment part(50) depicted in figure 14 which share one axis(C) with the body part(10).

4. The gear-shaped press-fit dental implant having a sloped top

As depicted in figure 19, the body(10) may further include a sloped top surface(11) adapted to be placed in accordance with a sloped bone ridge. When a horizontal micro-grooves portion(30) is employed together, on the top circumferential surface of the body(10), the sloped top surface(11) is preferably confined in the micro-grooves portion(30). Since this also is a press-fit implant which doesn't require rotation, it is easy to match both the direction of slope and the insertion depth simultaneously.

To describe the comparative advantage of this particular example embodiment of press-fit implant to a screw-type implant having an identical sloped top surface, with reference to figure 18, the screw-type implant may require undesirable more turns frequently so as to place the sloped top surface(11) in accordance with a sloped bone ridge resulting in deeper or shallower implant placement than the planed insertion depth, but, the implant in this example embodiment is a press-fit type implant which doesn't require rotation, thus it is easy to match both the slope and the insertion depth simultaneously.

5. The gear-shaped press-fit dental implant having an inclined rough/smooth border

As depicted in figure 20, the body(10) may further include an inclined border(15) between rough and smooth surface adapted to be placed in accordance with a sloped bone ridge. When a horizontal micro-grooves portion(30) is employed together, on the top circumferential surface of the body(10), the inclined border(16) is, preferably, confined in the micro-grooves portion(30). Since this also is a press-fit implant which doesn't require rotation, as shown in figure 21, it is easy to match both the direction of slopes(or inclinations) and the insertion depth simultaneously.

To describe the comparative advantage of this particular example embodiment of press-fit implant to a screw-type implant having an identical inclined rough/smooth border, with reference to figure 18, the screw-type implant may require undesirable more turns frequently so as to place the inclined rough/smooth border(11) in accordance with a sloped bone ridge resulting in deeper or shallower implant placement than the planed insertion depth, but, the implant in this example embodiment is a press-fit type implant which doesn't require rotation, thus it is easy to match both the slope and the insertion depth simultaneously.

Here, forming inclination on the rough/smooth border(15) is intended, when placing a dental implant into a not to excessively inclined jaw bone ridge, to place the rough surface of the implant inside the bone without reduction of protruded bone part, which aims at bone crest flattening, or bone grafting.

The press-fit implant in this example embodiment may comprises a rough-surfaced lower part (the part below the number 15 in figure 20), having a predetermined roughness, and a smooth-surfaced upper part, having a roughness lower than the roughness of the rough-surfaced lower part, wherein the plane containing the rough/smooth border is formed inclined to the plane perpendicular to the longitudinal axis of the body(10). The plane containing the inclined rough/smooth border(15) may be planar or curved.

The dental implant(whether it is a screw type or a press-fit type) having an inclined rough/smooth border(15) designed to be used on sloped bone ridges, has following advantages.

First, higher part of the sloped bone ridge could be preserved and used to support an implant.

Second, expenses for bone grafting could be saved.

Third, time and efforts for both patient and practitioner could be saved.

Meanwhile, the height difference between the highest point and lowest point of the inclined rough/smooth border is, preferably, to be in the range of 1mm to 3mm. When the difference is less than 1mm, the effect would be virtually negligible, and when the difference exceeds 3mm, the amount of bone support loss could be beyond acceptance.

Heretofore, while particular embodiments of the invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made therein without departing from the invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

[Description of Numbers]

1 : a fixture body 2 : an abutment insertion hole

3 : a bone-incising blade 4 : a recipient hole

5 : a slot 6 : an osteotome

7 : gingiva 8 : alveolar bone

10 : an implant body 10a : circumferential surface

11 : a sloped top surface

15 : a inclined rough/smooth border

20, 25 :

longitudinal teeth

20a, 25a : crosscuts

20b, 25b : plain portions of longitudinal teeth

30 : a horizontal micro-grooves portion

40 : an abutment connection part

50 : an integrated abutment part

Claims

A gear-shaped press-fit dental implant, comprising:

a body(10);

6 to 50 longitudinal teeth(20) formed on the circumferential surface(10a) of the body(10) ; and

1 or more crosscuts(20a) and 2 or more plain portions(20b) formed on the longitudinal teeth(20)

wherein the whole tooth depths of longitudinal teeth(20) get gradually smaller and disappear at the top portion of the body(10).
The gear-shaped press-fit dental implant according to claim 1,

wherein the whole tooth depths of longitudinal teeth(20) get gradually smaller or gets gradually smaller and disappear at the bottom portion of the body(10).
The gear-shaped press-fit dental implant of claim 1,

wherein the cross section of the body(10) is in generally round shape.
The gear-shaped press-fit dental implant of claim 1,

wherein the cross section area of the body(10) is identical from the top to the bottom.
The gear-shaped press-fit dental implant of claim 1,

wherein the body(10) is in fully or partially tapered shape.
The gear-shaped press-fit dental implant of claim 1,

wherein the crosscut(20a) is in a shape of 'V' and 'U' viewed on the side of the longitudinal tooth(20).
The gear -shaped press-fit dental implant of claim 1,

wherein the depths of the crosscuts(20a) are not exceeding the whole tooth depths of the longitudinal teeth(20).
The gear-shaped press-fit dental implant of claim 1,

wherein the longitudinal tooth(20) has a cross section shape of triangle, trapezoid, rectangle, pentagon, and hexagon.
The gear-shaped press-fit dental implant of claim 1,

wherein the plain portion(20b) on the longitudinal teeth(20) has an identical cross-section area from the plain portion(20b)'s top to the bottom.
The gear-shaped press-fit dental implant of claim 1,

wherein the plain portion(20b) on the longitudinal teeth(20) has gradually diminishing cross section area as it gets closer to the plain portion(20b)'s bottom.
The gear-shaped press-fit dental implant of claim 1,

wherein at least two lower ends of the longitudinal teeth(20) are located within 6mm distance from the lower end of the body(10).
The gear-shaped press-fit dental implant of claim 1,

wherein at least two upper ends of the longitudinal teeth(20) are located within 6mm distance from the upper end of the body(10).
The gear-shaped press-fit dental implant of claim 1,

wherein all the longitudinal teeth(20) have one or more identical features of cross-section shape, cross-section area, longitudinal length, and whole tooth depth.
The gear-shaped press-fit dental implant of claim 1,

wherein one or more of the longitudinal teeth(20) have different cross section shape from another or other longitudinal tooth(teeth)(20).
The gear-shaped press-fit dental implant of claim 1,

wherein one or more of the longitudinal teeth(20) have different cross section area from another or other longitudinal tooth(teeth)(20).
The gear-shaped press-fit dental implant of claim 1,

wherein one or more of the longitudinal teeth(20) have different longitudinal length from another or other longitudinal tooth(teeth)(20).
The gear-shaped press-fit dental implant of claim 1,

wherein one or more of the longitudinal teeth(20) have different whole tooth depth from another or other longitudinal tooth(teeth)(20).
The gear-shaped press-fit dental implant of claim 1,

further comprising a horizontal micro-grooves portion(30), having more than 1 horizontal micro-grooves, on the circumferential surface(10a) between the upper end of body(10) and the upper ends of longitudinal teeth(20).
The gear-shaped press-fit dental implant of claim 18,

wherein the horizontal micro-grooves portion(30) is located within 6mm distance from the upper end of the body(10).
The gear-shaped press-fit dental implant of claim 1,

further comprising an abutment connection part(40) on the top surface center of the body(10).
The gear-shaped press-fit dental implant of claim 1,

wherein the depths of the longitudinal teeth(20) are in the range of 0.2mm to 1.5mm.
The gear-shaped press-fit dental implant of claim 1,

further comprising a pair of enlarged longitudinal teeth(25), which have greater whole tooth depths than other regular longitudinal teeth(20).
The gear-shaped press-fit dental implant of claim 22,

wherein the pair of enlarged longitudinal teeth(25) are located apart on symmetrical position around the axis of the body(10).
The gear-shaped press-fit dental implant of claim 22,

wherein the pair of enlarged longitudinal teeth(25) are as thick as or thicker than other regular longitudinal teeth(20).
The gear-shaped press-fit dental implant of claim 22,

wherein the whole tooth depths of the pair of enlarged longitudinal teeth(25) are greater than 1.5mm, and smaller than the distance to adjacent teeth or implants.
The gear-shaped press-fit dental implant of claim 1,

further comprising an integrated abutment part(50) on the top of the body(10).
The gear-shaped press-fit dental implant of claim 26,

wherein the axis(C') of the integrated abutment part(50) meets the axis(C) of the body(10) forming a certain angle.
The gear-shaped press-fit dental implant of claim 22,

further comprising an integrated abutment part(50) on the top of the body(10) forming an one-piece implant.
The gear-shaped press-fit dental implant of claim 28,

wherein the axis(C') of the integrated abutment part(50) meets the axis(C) of the body(10) forming a certain angle.
The gear-shaped press-fit dental implant of claim 1, 20 or 22,

further comprising a sloped top surface(11) on the top of the body(10).
The gear-shaped press-fit dental implant of claim 1, 18, 20, 22, 26 or 27,

further comprising a rough-surfaced lower part having a predetermined roughness, and a smooth-surfaced upper part having a roughness lower than the roughness of the rough-surfaced lower part,

wherein a plane containing the rough/smooth border(15) is formed to be inclined to a plane transverse to the axis of the body(10).
The gear-shaped press-fit dental implant of claim 31,

wherein the difference between the maximum height and the minimum height of the rough surface in the direction parallel to the axis of the body(10) is in the range of 1 to 3mm.