Pericortical Dental Implant And Inserter Therefor

Abstract

A pericortical implant for the retention of various dental prosthetic replacements in the form of a two-part clamp adapted to be placed about either the mandible or maxilla of the patient and having a mounting post for reception of the dental prosthesis. An inserter device including a force-applying screw for moving one clamp half with respect to the other and having extendible arms for temporarily retaining the clamp halves in position is provided for rapid application of the clamp.

Description

This invention relates broadly to dental prosthetic devices and more particularly to a pericortical dental prosthetic devices and more particularly to a pericortical dental implant and an inserting tool therefor. The pericortical dental implant is in the form of a clamping device specifically adapted for attachment to either the mandible or maxilla wherein the clamp may be securely fastened to the bone structure to serve as a permanent base for the reception and mounting of an artificial tooth or in conjunction with other clamps to mount a partial or full denture.

In the field of prosthodontics, the ultimate objective is to provide one or more artificial teeth which are firmly mounted within the mouth which will remain firm under the normal oral activities of the patient and which will appear natural to the sight.

The use of full or partially removable dentures is the common approach with most edentulous or partially edentulous patients. These dentures are not actually implanted but are merely fitted to the gums and may be held thereon as by adhesives or close interfitting with the gum. Many oral activities such as are frequently associated with eating of food substances such as corn and sticky candy may cause the denture to become dislodged. Discomfort and inconvenience in proper denture hygiene are other common complaints lodged by denture wearers.

When only one or two teeth are to be replaced, it is conventional to use a permanent bridge which consists of an artificial tooth supported by inlays that are cemented to the healthy natural teeth adjacent thereto. This bridge generally provides a reasonably firm support for the artificial tooth, however it usually requires the removal of portions of the adjacent healthy teeth in order to provide the necessary structure for supporting the anchoring inlays and is not, therefore, entirely desirable in all cases.

Due to the problems arising during utilization of dentures or bridges, experimentation and research have progressed in recent years in regard to the implanting of dental prosthetic appliances within the tissue of the gum so as to provide an anchor for dentures. The attempt to replace missing dentition by various implant means has been practiced with fairly limited success for somewhat over 100 years. Recent studies have indicated that there are presently over 35 million partially or completely edentulous people in the United States, 25 percent of whom cannot utilize their maxillary or mandibular dentures with comfort or ease. Studies also indicate that in Great Britain there are over 17 million partially or completely edentulous people and a similar percentage who have problems with dentures. Due to discomfort of dentures in such patients, many have not completely adapted to wearing these appliances and remain edentulous. The present invention overcomes the problems of denture fit and comfort.

PRIOR ART IMPLANTS

Many implant methods have been utilized in the past and are presently being employed to replace missing dentition, either in part or totally. It was not until Venable et al., in 1937 reported on the use of certain electropassive metals that were tolerated by human tissues that the field of implant research was truly placed on a scientific footing. Their work not only explained previous complications, but also lead to the development of the present day metals which are biologically inert when imbedded in tissue, examples being stainless steel and Vitallium.

Success of implants was also enhanced by the availability of antibiotics which, when used prophylactically to prevent infection, made intraoral procedures possible.

Indications for the use of implant dentures are:

1. cases of marked atrophy of the alveolus and jaw;

2. cases in which dentures cannot be worn because of painful mucosa;

3. cases of soft tissue hypertrophy and flabby ridge caused by denture irritation; and

4. cases with poor masticating function.

The individual replacement of missing teeth utilizing metals such as gold, silver and platinum is one of the oldest methods and these have failed primarily due to electrolytic reactions which develop when saliva comes in contact with the metal, producing bone resorption and loosening of the implant. Submucosal implants in the form of "collar buttons" have been inserted directly beneath the mucosa. These implants frequently loosen when secondary inflammation and infection occur, resulting in the loss of the retention of the dental prosthesis. Another method that has enjoyed only a marginal degree of success is the supraperiosteal implant. These implants generally in the form of polyethylene, silicone, nylon and acrylic resins are placed beneath the mucosa but above the periosteum. The major problem with this type of implant is the high frequency of foreign body reaction followed by rejection of the implanted substance. This rejection, coupled with the formation of areas of pressure necrosis, has been cited as the principal failure of the supraperiosteal implants.

Transosseous implants have also been used and these require burrowing into and through the bone and utilizing screw or pin fixation. The required drilling through the bone in this method often produces an intense postsurgical inflammatory response and accompanying bone resorption which may lead to the mobility of the implant when the same is subjected to the high stress of mastication, and consequently the following loss of the implant.

Some limited degree of success has been achieved by the use of endosseous implants which have taken various forms. The intraosseous use of implants in the form of magnets has met with little acceptance since the results have been questionable in view of the fact that the magnetic field is somewhat diminished by the overlying tissue coupled with the necessity of preparing a bed in the bone for the reception of the magnet which sometimes is followed by foreign body reaction. Here an intraoral incision is made in the gum tissue and a magnetic insert is placed within the tissue so as to be between the surface of the gum tissue and the lower jaw bone after the incision is closed. The artificial tooth is provided with a metallic plug cast therein which holds the tooth to the gum tissue due to the magnetic attraction exerted by the magnetic insert that has been implanted. The intraosseous use of screws, pins, vent posts and vent blades requires that the same be driven into the bone and then having severe pressures placed on them which results in the rapid dissolution of bone around the implant, followed by mobility of the implant and possible failure. An example of a ring-type implant of this form is shown in the Linkow U.S. Pat. No. 3,465,441, issued Sept. 9, 1969.

A final form of implant is the subperiosteal implant which is applied beneath the mucosa in the periosteum which rests on the bone but without intraosseous engagement. While these implants have met with limited success, there are factors which mitigate against total successful use thereof. Since these implants are dependent upon fibrous tissue to hold them against the bone, and since fibrous tissue possesses a degree of elasticity, the net result is mobility of the implant when stress is applied thereto, thereafter followed by rejection. Maxillary subperiosteal implants are contraindicated in as much as the normal force of gravity will frequently prevent retention. It is also contraindicated in the maxilla because of the gross amount of cancellous bone present therein which will not support a subperiosteal implant due to rapid resorption of such cancellous bone. If a mandibular subperiosteal implant is inserted on a mandible which has not fully resorbed to dense cortical bone, the implant will become mobile and fail secondary to resolution of the remaining cancellous bone which produced a space defect between the base of the implant and the residual bone. Additionally, periosteal implants usually required multiple surgical procedures (i.e., initial surgery for exposure of the mandible and obtaining an impression; followed by a healing period of up to 6 weeks, than a second surgical procedure consisting of reexposure of the mandible followed by implantation of the subperiosteal device).

OBJECTS OF THE INVENTION

The pericortical clamp of the instant invention herein disclosed obviates the difficulties inherent in the prior art methods disclosed above. The clamp provides a firm, fixed base which more easily, quickly, and effectively supports a total or partial dental prosthesis.

A primary object of this invention is to provide means for mounting a dental prosthetic replacement which means is in the form of a clamp adapted to be fastened securely to either the mandible or maxilla of the patient.

Another object of the invention is to avoid the disadvantages common in the prior art of implantation by providing a clamping device that prevents any movement of the implant either lateral, torsional or longitudinal and yet will not place undue pressure upon the bone surface.

Still another object of this invention is to provide an inserter construction specifically adapted to place the implant clamp on the mandible or maxilla of the patient in a quick and simple operation.

Another object of the invention is to provide an implant device and inserter which may be readily applied by any dental surgeon and which includes a clamping device having two separate disengageable sections.

Another object of the invention is to provide an implant device formed of two sections, a clamp and an inserter, the latter being a tool to be used in inserting and tightening the clamp on the bone and which is then disengaged therefrom, leaving the implant clamp on the bone and about which the wound is closed.

Another object of the invention is to provide a fixed implant clamp which can be applied with minimum surgical dissection of soft tissue.

Still another object of the invention is to provide a firm, fixed implant base which can be attached to the maxilla.

Yet another object of the invention is to provide a dental implant device which is simple in construction, relatively cheap to manufacture and which is safe and efficient at all times and which may be removed at a later date if desired.

Other objects and advantages will become apparent from the following description of the exemplary forms of the invention illustrated in the accompanying drawings.

DESCRIPTION OF THE VIEWS

FIG. 1 is a perspective view of the pericortical dental implant clamp;

FIG. 2 is an exploded perspective view of the clamp in inverted position;

FIG. 3 is a side elevation showing the pericortical dental implant clamp secured to a human mandible;

FIG. 4 is an enlarged cross-sectional view taken along the line 4-4 of FIG. 3;

FIG. 5 is a perspective view of the inserter tool with portions broken away to show detail, showing a pericortical dental implant clamp attached thereto;

FIG. 6 is a perspective view similar to FIG. 5 but showing the inserter inverted and without a clamp in place;

FIG. 7 is a sectional view of the inserter taken along the line 7-7 of FIG. 5;

FIG. 8 is a top plan view of the inserter in the closed position;

FIG. 9 is a bottom plan of the inserter in the closed position with the extended or open position shown in phantom lines;

FIG. 10 is a cross-sectional view through the inserter taken along the line 10-10 of FIG. 8;

FIG. 11 is a partial exploded perspective of the front end portion of the inserter showing the manner in which the pericortical clamp is secured therein;

FIG. 12 is a perspective view similar to FIG. 11 showing the clamp in place in the inserter with the two halves thereof separated; and

FIG. 13 is a perspective view similar to FIG. 12 showing the clamp portions being brought together.

Referring to the drawings in greater detail wherein like parts are represented by like reference characters, the pericortical dental implant clamp of the present invention is shown generally at 10, and is formed in two pieces, the proximal half 11 and the distal half 12. The clamp half portions are preferably formed from a biologically inert metal suitable for implantation in the human body. Stainless steel, tantalum, or a cobalt-chromium alloy commonly sold under the trademark Vitallium, have been used as implant materials in recent years and would be acceptable for this particular application.

Each clamp half includes an upright vertical wall 13, 14 having a planer inner face. The distal half 12 is provided with a pedestal 15 extending inwardly from the bottom of the vertical wall and the pedestal has elongated grooves 16 on the side surfaces thereof. The front face of the pedestal is drilled and tapped as at 17. The proximal clamp half 11 is formed with straddle arms 18 and 19 extending therefrom in a manner such as to fit closely about the pedestal 15 of the distal half 12. Each of the straddle arms are tapered to an edge as at 19' and are formed on their inner surfaces with a rounded elongated tongue 20 as shown in FIG. 2. It will be evident that the straddle arms of the proximal half will engage about the pedestal 15 of the distal half with the tongue portions 20 being received within the grooves 16. As best seen in FIG. 2, each of the flat wall surfaces 13 and 14 are provided with relatively sharp bone-engaging spikes 21.

The proximal clamp half is formed with a smooth bore hole 22 adapted for alignment with the tapped hole 17 of the distal half. A machine screw 23 serves to connect the two clamp halves together in a selected position of engagement about a bone as shown in FIG. 4. The screw 23 passes through the hole 22 and into threaded engagement with the tapped hole 17 in the distal half 12. Another tapped hole 24 is placed centrally of the wall of the proximal half 11 for a purpose to be later described. A truncated conical mounting post 25 is secured centrally on the bottom face of the pedestal 15 by means of a mounting screw 26. (See FIG. 4). It will be understood that if desired the mounting post could be formed integrally with the pedestal although in the preferred embodiment the same is removable since various configurations of posts could be used if desired. For example, a square cross section post may be found desirable in certain applications. An artificial tooth structure T may be cemented onto the mounting post 25 with the use of conventional dental cements. Alternatively, other means for locking the tooth structure to the mounting post may be employed such as a resilient detent member within the recess of the artificial tooth adapted to snap into a groove provided on the surface of the mounting post (not shown).

The clamp 10 may be applied to either the mandible or maxilla of the patient and as shown in FIGS. 3 and 4 is placed on the mandible for mounting of an artificial tooth to take the place of a tooth that has been removed and is surrounded by natural teeth. The detailed procedure for placing of the clamp will be described later herein in greater detail, however generally the application requires surgical procedures in order to expose the mandible and requires some scraping of the periosteum in order to provide intimate contact between the wall faces of the clamp and the bone surface. The clamp is pushed down so that the face of the pedestal 15 is directly against the top surface of the bone and forces are applied to cause a tight gripping of the bone by the wall faces 13 and 14. It will be noted that the spikes 21 will imbed themselves into the bone in order to provide a tight purchase and to prevent slippage of the clamp. The spikes are designed to be of a length as not to interfere or impinge upon the neurovascular bundle which runs through the mandible or maxilla. After placement of the clamp, the normal restorative powers of the body cause rebuilding and growth of the tissues and, as shown in FIG. 4, the normal gum line G will extend around and above the clamp so as to completely cover the same. The post 25 may be adjusted slightly in the vertical direction after completion of the surgery in order to make proper correction of the bite and proper mating with the teeth on the opposite bone.

It is also contemplated that the clamp may be fabricated in various widths in order to accommodate two or even more mounting posts. Additionally, the mounting posts may be angled with respect to the pedestal for areas such as the retromolar areas where curvature of the ridge crest may dictate such use. Such angled posts may also be useful in achieving parallelism with a mesially or distally tilted tooth or implant abutment. Various combinations of one or more implant clamps may be used for proper mounting of complete dentures.

When a completely edentulous mandible or maxilla is to be fitted with a prosthesis, at least four mounting posts are required for proper support.

THE INSERTER

While the pericortical implant clamp 10 could be applied to the bone by hand and the screw 23 tightened with a conventional screwdriver, a novel inserting tool has been developed which greatly speeds application of the clamp and achieves a tighter and more secure purchase of the clamp on the bone. This inserter is a modification of the bone clamp application tool shown in my earlier U.S. Pat. No. 3,477,429. The improved inserter is shown in FIGS. 5 and 6 and is designated generally at 30. The various components of the inserter may be formed of stainless steel or other suitable metallic material that can easily be sterilized. The inserter consists of a generally cylindrical, although slightly tapered, barrel portion 31 having a flat end wall from which extend spring arms 32 and 33. These arms may be part of a one-piece U-shaped construction and due to their length and design, are resilient and may be biased outwardly at their free end in a manner described in greater detail later herein. The inner face of each of the spring arms is provided with a V-groove or guide track 34 for a portion of its length and terminating in a front shoulder stop 35.

The barrel has a through cutout 36 and the interior of the barrel defined within the cutout has a rear wall 37 and a front wall 38. The rear wall 37 is axially bored as at 39 and the front wall 38 is bored at 40 to provide an opening coaxial with the opening 39 for reception of a hollow jack shaft 41. The jack shaft is rotatable within the barrel and is retained from axial movement with respect to the barrel by means of retaining clips 42 and 43 received within annular grooves in the shaft. A knurled hand knob 44 is secured to the rear end of the jack shaft in order to provide a convenient surface for manual rotation of the shaft. The forward portion of the shaft is formed with screw threads 45.

A screwdriver 46 is received within the axial bore of the jack shaft 41 and may be slid forwardly and rearwardly in an axial direction but is frictionally held in position by means of a friction grommet 47 mounted within the jack shaft 41. The rear end of the shaft of the screwdriver is provided with a hand knob 48 having a knurled surface and being slightly smaller in diameter than the knob 44. The forward end of the screwdriver is provided with a conventional flat blade configuration as shown at 49.

The end 45 of the jack shaft having threads thereon is threadedly received in a jack nut 50 located between the spring arms 32 and 33 and has an upstanding front flange 51 mounted at the front end thereof which has flat, parallel side portions that are engageable against the spring arms in order to prevent rotation of the jack nut. A pusher plate 52 is mounted between the spring arms and forwardly of the front flange of the jack nut and has guide shoulders 53 engageable on the top faces of the spring arms. The pusher plate is mechanically connected to the front upstanding flange 51 by means of a flexible braided cable 54 which also serves as a retention means for retraction of the proximal clamp half as later described. The braided cable is adapted to transmit rotation along its length and yet has a certain degree of flexibility as shown in FIG. 7. A cutout 55 is provided in the barrel 31 in order to house the rear end of the cable which terminates in a knurled hand knob 56. The forward end of the cable is formed with a screw-threaded portion 57 extending beyond the pusher plate and adapted for insertion and attachment into the threaded tapped hole 24 of proximal clamp half 11. A flat retainer member 58 is mounted on the cable in order to prevent retraction of the same through the upstanding front flange 51.

In order to open and to retract the spring arms 32 and 33 for insertion and retention of the clamp halves, means are provided on the lower portion of the inserter for mechanically forcing the spring arms into the dotted line clamp-receiving position of FIG. 9. For this purpose screw shaft 60 is mounted in the barrel parallel to the jack shaft 41 and is provided intermediate its ends with a thumb wheel 61 extending partially through the cutout portion 36 of the barrel in order to be readily grasped by the thumb of the operator. The shaft is retained in the barrel by means of a flat retainer 62 mounted on the shaft 60. A push rod 63 is mounted by means of a nut 64 on the threaded end of the screw shaft 60 and is located immediately below the jack nut 50. A pair of toggle links 65 and 66 are pivotally mounted to the forward end of the opening rod by means of a toggle link pin 67. The opposite ends of the toggle links are pivoted to the respected spring arms by means of link pivot pins 68 shown in FIG. 9. It will be understood that rotation of the thumb wheel 61 in one direction will cause the inserter opening rod 63 to move forwardly thereby acting on the toggle links 65 and 66 to expand or extend thereby spreading the spring arms 32 and 33 as shown in phantom lines in FIG. 9. This position of extension is also shown in FIG. 11 wherein it will be evident that the two clamp halves may be inserted with the tapered shoulder portion 19' thereof being received in the V guide tracks 34 of the spring arms with the front shoulder stop 35 serving as an end abutment for the clamp. Rotation of the thumb wheel 61 in the opposite direction will cause retraction of the spring arms so that the clamp halves are firmly held within the inserter but may be moved with respect to each other as shown in FIGS. 12 and 13. By application of rotary motion on the knob 56, the screw end 57 of the flexible cable 54 may be secured within the tapped hole 24 of the proximal clamp half 11. In this position, rotation of the knurled hand knob 44 in a clockwise direction will cause retraction of the jack nut 50 along with the pusher plate 52 and the proximal clamp half 11 as shown in FIG. 12. In this retracted position, the screwdriver 46 may be physically removed from the jack shaft 41. The screw 23 has such a cross section that the same can be inserted through the bore inside the jackshaft as later described.

In this position, the clamp and inserter are placed over the bare bone portion previously prepared and counterclockwise rotation is imparted to the hand knob 44 in order to move the jack nut forwardly and along therewith the proximal clamp half through action of the pusher plate 52 as shown in FIG. 13. Rotation is continued until such time as a firm, secure purchase is applied to the bone by the two clamp halves, and wherein the spikes 21 will become engaged within the bone. At this point the screw is inserted through the open end of the jack shaft and is followed by the screwdriver 46 which as shown in FIG. 7 can be turned to insert the screw through the hole 22 of the proximal clamp half and become threadedly engaged in the tapped hole 17 in the distal half 12. As soon as the screw is tightened to the desired degree, the screwdriver is manually retracted and the knob 56 turned to release the screw end 57 from engagement with the proximal clamp half 11. Thereafter, the knob 44 may be turned slightly to retract the jack nut and associated parts so that the thumb wheel 61 may be actuated to expand the spring arms into the dotted line position of FIG. 9 so that the inserter may be manually removed.

As an aid to rotation of the thumb wheel, a leverage assist pin 69 which is normally housed on the barrel as shown in FIGS. 5 and 7 may be inserted into one of a plurality of pin receiving holes 70 on the barrel. See FIGS. 6 and 9. This pin permits additional leverage to be applied to the thumb wheel when desired.

After insertion of the clamp, the mounting post 25 may be applied over the threaded portion 26 and the prosthetic replacement is subsequently emplaced. In a short period of time during the natural healing process, gum tissue will completely cover the exposed portions of the clamp and there will usually be no necessity for ever removing the clamp from the bone.

While I have shown and described a preferred embodiment of the invention, it is to be understood that the drawings and detailed disclosure are to be construed in an illustrative rather than a limiting sense since various modifications and substitutions of equivalents may be made by those skilled in the art within the spirit and scope of the invention.

Claims

What I claim as my invention and desire to protect by Letters Patent of the United States is:

1. A pericortical clamp to provide anchorage for artificial teeth and adapted for application to the mandible or maxilla, comprising a pair of clamp halves, each half having a relatively planar vertical wall, means interconnecting said clamp halves so that said walls are in adjustably spaced apart clamping relationship on either side of a bone, and post means on one of said clamp halves for mounting an artificial tooth.

2. A clamp as defined in claim 1, wherein said interconnecting means comprises a pedestal extending inwardly from one clamp half and a pair of straddle arms extending inwardly from the other clamp half and adapted to fit about the sides of the pedestal.

3. A clamp as defined in claim 2, wherein said post means is mounted on said pedestal.

4. A clamp as defined in claim 3, wherein said post means comprises a screw secured on said pedestal and a mounting post threadedly received on said screw.

5. A pericortical clamp as defined in claim 1, and further including a plurality of bone-engaging spikes mounted on the inner face of said vertical walls.

6. A clamp as defined in claim 2, wherein said pedestal and straddle arms are interconnected in slidably adjustable relationship by a tongue and groove interface.

7. A clamp as defined in claim 6 and further including adjustable screw means for retaining a predetermined adjusted relationship of said clamp halves.

8. A dental prosthetic appliance and inserter comprising a pair of relatively movable clamp halves having flat inner faces and adapted to be engaged about either the maxilla or mandible, means on one of said clamp halves for mounting an artificial tooth, an inserter having expandable arms adapted to temporarily retain said clamp halves therebetween during installation on a bone, means on the inserter for expanding and contracting said arms about said clamp halves, mechanical force transmission means for moving one of said clamp halves toward the other to clamp about the bone, and screw means adjustably retaining said clamp halves in position about said bone after removal of said inserter.

9. An appliance and inserter as defined in claim 8, and further including means on the inserter engageable with one clamp half to move said one clamp half away from said other clamp half.

10. An appliance and inserter as defined in claim 8, wherein said expandable arms are stiff spring members normally parallel to each other and said means for expanding and contracting the same comprises a pair of toggle links commonly pivoted at one end to a pusher bar and having their opposite ends pivotally mounted on one of said arms, and power means for advancing said pusher bar to expand said arms for the reception of said clamp halves.

11. An appliance and inserter as defined in claim 8, wherein said force transmission means comprises a screw jackshaft on said inserter, and nut means engageable with said screw jackshaft and in contact with said one clamp half.

12. An appliance and inserter as defined in claim 8, and further including screwdriver means on said inserter engageable with said screw means.

13. A method of applying a dental prosthetic appliance to either the mandible or maxilla comprising the steps of stripping the periosteum from about the implant site on the bone, placing a two-piece clamp over the bared bone portion, tightening said clamp into firm bone contact, and securing the prosthetic appliance to the clamp.