WO1994000073A1

WO1994000073A1 - Apparatus for guiding implants

Info

Publication number: WO1994000073A1
Application number: PCT/GB1993/001214
Authority: WO
Inventors: Robert David Eden; Malcolm Peter Jackson Young
Original assignee: University Of Manchester Institute Of Science And Technology
Priority date: 1992-06-20
Filing date: 1993-06-08
Publication date: 1994-01-06
Also published as: AU4343293A; GB9425696D0; GB9213194D0; GB2284354A; GB2284354B

Abstract

An apparatus for guiding implants comprises a securing device (11; 41; 72, 73) for securing the apparatus to the patient at the region of the patient receiving the implant. The apparatus further comprises a drill guide (18; 42; 74) which is movable relative to the securing device (11; 41; 72, 73).

Description

APPARATUS FOR GUIDING IMPLANTS

TECHNICAL FIELD

This invention relates to apparatus for guiding implants and particularly but not exclusively to apparatus for guiding implants in dental, orthopaedic, veterinary, and prosthetic surgery.

BACKGROUND ART

With dental implants it is usual to surgically place a titanium cylinder with an internal screw thread within the bone of the upper or lower jaw as required. A bridge superstructure is then screw retained by these cylinders . In order to locate the titanium cylinder the mucosa (or intra oral) skin is peeled back to reveal the base of the jaw. A pilot drill is subsequently utilised to drill a narrow starting "hole" within the bone. A paralleling pin is placed within this pilot hole. A second pilot hole is drilled into the bone a short distance from the first. Further pilot holes may be drilled as required. The holes are later widened to receive the titanium cylinders. As the bridge superstructure is rigid it is important that the titanium cylinders are disposed in a parallel fashion if the bridge structure is to be fitted properly. Also if the holes are non-parallel this may lead to overload once the bridge is in position and consequently to implant failure. It is therefore very important that the pilot holes are arranged in a parallel manner.

At present the success of this technique depends to a very large extent on the skill of the dental surgeon. Even the most skilled surgeons find it difficult to orientate the pins exactly in parallel.

The present invention has been made from a consideration of this problem.

DISCLOSURE OF THE INVENTION

According to a first aspect of the present invention there is provided an apparatus for guiding implants comprising securing means for securing the apparatus to the patient at or adjacent the region of the patient receiving the implant, the apparatus further comprising guide means for guiding a drill, wherein the guide means is movably mounted in order to facilitate relative movement between the securing means and the guide means.

According to a second aspect of the present invention there is provided a kit comprising the following:- (a) an apparatus for guiding implants comprising securing means for receiving an elongate member extending from the patient at or adjacent the region of the patient receiving the implant, the apparatus further comprising guide means for guiding a drill, wherein the guide means is mounted for movement along a path defined by the apparatus in order to facilitate relative movement between the securing means and the guide means; and

(b) a second apparatus comprising means for altering the path for the guide means as defined by the apparatus.

According to a third aspect of the present invention there is provided a method of drilling a hole using the apparatus as hereinbefore defined in which the securing means is secured to the patient, the guide means is located at or adjacent the region of the patient receiving the implant and the guide means is used to guide the bit of a drill into said region of the patient.

The apparatus and method of the present invention offer a number of advantages.

The apparatus stabilises the bur and handpiece - A - during the preparation of the implant receptor site. Placement of the implant is difficult in the posterior region, where visual and mechanical access is poor. The use of Goretex Guided Tissue Regeneration (G.T.R.) techniques allow implantologists to accept dehiscences and fenestrations in many cases. Previously a bone platform was cut and a reduction of bone height to gain width was necessary. The apparatus of the present invention will reduce bur slip on engaging slopes or uneven surfaces, and this in combination with Goretex G.T.R. techniques will enable implantologists to engage slopes securely.

In any drilling operation, enlarging the initial pilot hole leads to bur slip and a tendency to ovalise the implant receptor site in the bone. Congruence of fit provides critical implant immobilisation and reduces the distance across which osteoblastic activity is necessary to promote osseointegration. The apparatus of the present invention will increase congruence of fit by steadying the burs during the enlargement of the pilot hole to the required size for the implant placement.

The preparation of two closely related implant sites may result in the convergence of the implant holes. The apparatus of the present invention will control accurately the preparation of close proximity implant sites by drill stabilisation. Presently poor implant angulations complicate superstructure procedures due to non-parallelism. To date existing technology has focused on correcting or compensating for poor implant angulations. The use of multi angle abutment posts or universal joints (eg. Robutment joint) has been employed to correct poorly angled implants. The apparatus of the present invention will provide parallel implants. The problems with implant angulation will be prevented in many cases. By using the apparatus of the present invention retrievability can be guaranteed and simplified.

All known screw related implant systems experience problems with loosening of retainer screws. Derotation of fixation screws occurs during function and in non fixed prosthesis during seating and removal . Screw loosening usually occurs at one site preferentially where derotation forces have been concentrated. The apparatus of the present invention will reduce screw loosening by providing parallel implants. Parallel implant bodies facilitate controlled distribution of load and reduce the tendency for derotation of fixation screws.

Angled implants lead to problems with the emergence profile of implant abutment posts from the mucosa. Aesthetics and oral hygiene are difficult where vertical emergence profiles are lost. The apparatus of the present invention will favour superstructures with vertically emergent profiles. Aesthetics and oral hygiene will improve.

Although poorly angled implants can be corrected by angled implant abutment posts the loading of these angled implants leads to stress concentration at the implant body and abutment post angle. Attempts to accurately control and distribute occlusal loads is further complicated by the angle of the implant body relative to the abutment post. The apparatus of the present invention will provide parallel implants. Stress distribution will be improved and occlusal equilibriations procedures will be simplified by eliminating the need to consider implant body and abutment angles.

In a preferred embodiment of the invention the securing means may be operative to receive an elongate member. The securing means may comprise a body having a bore extending therethrough. The apparatus may comprise an arm, which is preferably arcuate and may be connected to the body, the arm defining the path of travel of the guide means. The arm preferably comprises a handle. The handle may involve twisting the free end of the arm through ninety degrees. The body and the arm preferably comprise a material which is easy to clean. This material is also preferably sufficiently malleable to facilitate bending when desired. The preferred material is stainless steel.

The guide means may comprise a rider which is slidably mounted on the arm. The rider preferably comprises plastics material and may be made for example by injection moulding. This provides the advantage of being cheap to manufacture and also, providing minimal pick up of particles by the drill thus reducing the risk of wound contamination. A bush may be received over the bit of the drill and within the guide means. The bush if made of plastics reduces galling. This bush may comprise at least two releasably connectable parts. This facilitates stepwise drilling. Also this provides free running of the drill bit which will usually be made of stainless steel thus avoiding galling of the drill collar. The bushes and riders may be disposable so as to provide enhanced hygiene.

The apparatus can be manufactured in two pieces and is cheap to produce, easy to use and easy to clean. The apparatus also offers the advantage of being usable for both upper and lower jaws and either^~side of the jaw. The apparatus may easily be used by both left and right handed practitioners. The dimensional tolerance of the apparatus preferably offers from 5mm to 30mm reach.

In an alternative embodiment of the invention the securing means may be pivotally connected to the guide means. A step may be provided in the apparatus . The step may be removable and is preferably located at the pivot. The step is useful in making implants in a stepped jaw. The securing means may travel up and down a paralleling pin inserted in a drill hole. This pin may have a groove or a threaded portion therein, facilitating blood release from the drilled hole as the pin is located therein. The pin may comprise a screw fitting which locates into a previously fitted implant. The guide means thus guides the drill relative the angle of the securing means as the securing means travels up and down the paralleling pin.

The securing means may comprise a denture. Furthermore the apparatus may comprise a serated arm. Such a serated arm is pliable.

BRIEF DESCRIPTION OF DRAWINGS

In order that the invention may be more readily understood specific embodiments thereof will now be described by way of illustration only with reference to the accompanying drawings in which:- Fig. 1 is a perspective view of one apparatus in accordance with the invention;

Fig. 2 is a plan view of the apparatus of Fig. 1;

Fig. 3 is a perspective view of the apparatus of Figs. 1 and 2 in which the guide means has been removed;

Fig. 4 is a perspective view of the guide means of Figs. 1 and 2;

Fig. 5 is a diagrammatic illustration of the apparatus of Figs. 1 to 4 when in use;

Fig. 6 is a diagrammatic view of a set of teeth to which a bridge superstructure has been affixed using the apparatus of the present invention;

Fig. 7 is an apparatus for bending the part of the apparatus of Figs. 1 to 5 that defines the path of travel of the guide means;

Fig. 8 is a second apparatus in accordance with the invention;

Fig. 9 shows the second apparatus of Fig. 8 which has been modified so as to comprise a handle; Fig. 10 is a side elevation of a third apparatus in accordance with the invention;

Fig. 11 is an underplan view of the apparatus of Fig. 10;

Fig. 12 is a side elevation of a further apparatus in accordance with the invention;

Fig. 13 are side elevations of three different paralleling pins which may separately be temporarily implanted for the guidance of a drill using the apparatus and method of the present invention;

Fig. 14 is a side elevation of a bush for insertion in the cylinders of the apparatus of the present invention;

Fig. 15 a to d show alternative lower parts of the bush of Fig. 14; and

Fig. 16 is a perspective view of a further apparatus in accordance with the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

Referring to Figs. 1 to 7 an apparatus for guiding implants 10 comprises a cylinder 11 having an open ended bore 12 passing therethrough. An arcuate arm 13 extends from the cylinder 11. The arm 13 comprises a twisted region 14 which twists through 90° towards the free end 15 of the arm 13 so as to provide a horizontal handle 16. The handle 16 enables the apparatus to be comfortably held between the thumb and forefinger. The arm 13 comprises a narrow waist 17 adjacent the twisted region 14. The cylinder 11 and arm 13 are made from stainless steel or other material compatible with sound dental practice.

A cylindrical nylon plastics brush rider 18 has an open ended bore 19 extending vertically therethrough. Two horizontal plates 20,21 are provided on the top and bottom of the rider 18. An inwardly directed flange 22,23 is provided at the free end of each plate 20,21.

The rider 18 is secured to the arcuate arm 13 by capturing the arcuate arm 13 between one side 24 of the rider 18 and the flanges 22,23. The rider 18 may slide along the arcuate arm 13 between the limits of the cylinder 11 and the waist 17 in the arcuate arm 13. In practice the riders 18 are disposable. Riders 18 may be loaded and removed at the narrow waist 17.

In use the dental surgeon drills a first pilot hole 25 in the jaw of the patient. A first parallel pin 26 or 61 is located in the first pilot hole 25. In the event that there is an existing implant, a parallel pin 61c may be screwed into that implant. The apparatus 10 is secured to the first parallel pin 26 or 61 or 61c by locating the cylinder 11 over the first parallel pin 26 or 61 or 61c. The rider 18 is moved along the arcuate arm 13 to the position where the dental surgeon wishes to make the next implant. The cylindrical collar 27 of the drill 28 is then located in the bore 19 in the rider 18 and a second pilot hole 29 is made while the operator holds the handle 16. It is noted that the diameter of the bore 19 receives the cylindrical collar with a snug fit which allows rotation thereof. By drilling the second pilot hole 29 using the apparatus 10 the second hole 29 will be parallel with the first pilot hole 25. A second parallel pin 30 may then be located in the second pilot hole 29. A subsequent pilot hole 31 as shown in phantom lines in Fig. 5 may be made by locating the cylinder 11 around the second parallel pin 30 and guiding the drill bit through the rider 18 as before. Thus a plurality of pilot holes all parallel with the first hole may be made in "leap frog" fashion using the apparatus 10.

Once the pilot holes have been made the holes may be enlarged to receive titanium cylinders. The initial pilot hole can be enlarged by guiding the device from a parallel pin 61b that has been inserted in an enlarged hole. The bridge superstructure may be screwed in position as shown in Fig. 5.

The curvature of the arcuate arm 13 acts to avoid any teeth still present in the jaw. It may be, in rare cases, that the arcuate arm may need to be bent in order to achieve this. This may be achieved by way of an anvil type apparatus 32. This apparatus 32 comprises a plate 33 having two spaced-apart upstanding pins 34,35. In order to bend the arcuate arm 13; the arm 13 is located between the two pins 34,35 and the arm 13 is pushed towards one of the pins 34,35 thus bending the arm 13. Angle lines (not shown) may be provided on the plate for guidance.

Referring to Fig. 8 a second apparatus 40 comprises a securing cylinder 41 for engagement with a pilot pin as before and a guide cylinder 42 for the drill. However, instead of providing a movable rider 18 on an arcuate arm as previously described relative movement of the securing cylinder 41 and guide cylinder 42 is achieved by way of a pivotal connection. An arm 43,44 extends from each cylinder 41,42. The arms 43,44 are connected by a pivot 45.

In use the securing cylinder 41 is placed over a parallel pin and the arms 43,44 are moved about the pivot 45 so as to allow movement of the guide cylinder 41. Referring to Fig. 9 there is shown an apparatus 46 similar to that described with reference to Fig. 8 except in that a handle 47 is secured to the hinge. The handle 47 may be used to maintain the apparatus 46 in the correct position during use.

Referring to Figs. 10 and 11 an apparatus 48 is illustrated which is similar to that described with reference to Fig. 9 except in that the handle comprises a- step 49. This facilitates a 360° turning movement about the pivot 50. One of the arms 51 of the apparatus is shorter than the other arm 52. A recess 53 is provided in the longer arm which may receive the cylinder 54 of the shorter arm so that the arms may close together.

Referring to Fig. 12 a similar apparatus 55 comprises a stepped pivot joint 56. The stepped pivot joint 56 may comprise a cylindrical insert 57 having an open ended bore extending therethrough. A screw or bolt which in use acts as the hinge pin is passed through an aperture in one arm 58, through the bore of the insert and then through an aperture in the other arm 59. A bolt 60 is secured to the end of the screw or bolt which extends beyond this arm 59. This arrangement allows the apparatus to accommodate a step in the jaw bone of the patient. Fig. 13 shows a paralleling pin 61 which may be used to guide the apparatus of the present invention. This pin is similar to the conventional parallel pin 26 but is both longer and with a tapered shoulder. The paralleling pin 61b will fit a wider diameter hole and groove 62a is provided in the pin which extends from the base to the top of the pin. The groove 62a acts to channel the blood from the site of drilling out of the drilled hole as the pin is inserted .into the hole. The paralleling pin 61c is unconventional in that a threaded portion allows the pin to be screwed securely into an existing implant.

Figs. 14 and 15 show a bush which may be placed over the drill bit before it is received in the guide means 18,42 for the drill. The bush 63 may be made from any suitable plastics material such as PTFE. The bush 63 acts to prevent galling for example when a stainless steel drill is running in a stainless steel guide means resulting in pick up of material which could contaminate the wound. The bush also acts as a guide for the drill. The bush 63 may comprise two parts 64,65. When both parts 64,65 of the bush are located on the drill bit a shallow hole may be drilled. Once this initial drilling is complete the lower part 65 of the bush may be removed and a deeper hole may be drilled. The edge of' the lower part of the bush and/or upper part of the bush which is adjacent the other part of the bush may be bevelled in order to facilitate easy separation of the two bush parts. The lower part 65 of the bush can be connected to the upper part of the bush by way of a push fit or a snap fit. Lower parts of the bush are illustrated in Fig. 15 having either a push fit connection 15a or a snap fit connection 15 b to d. As an alternative to using a two or more part bush a series of differently sized bushes may be used.

Referring to Fig. 16 a further apparatus 70 in accordance with the invention is shown which is particularly suitable for drilling at least the first hole in the jaw in order to ensure that it is correctly oriented. The apparatus 70 comprises a deformable serated metal rail 71 the ends of which are embedded in the rear parts of a plastics denture 72,73. A plastics bush rider 74 is received over the rail 71, the bush rider 74 being similar to the bush rider 18 of Fig. 1. In use the denture 72,73 is placed in the mouth and the rail is deformed to be in register with the jaw bone where the implant is to be made. The serations allow the rail to be easily deformably in all directions and the rail is therefore very pliable. The rail may be moved in sites or the apparatus may be removed from the mouth prior to moving the rail. Once the rail is arranged correctly the bush rider 74 is located in position and the rail may be set by filling the serations with dental wax. The drill hole is then made. Subsequent drill holes may be made using this apparatus. Two or more bush riders 74 may be located on the rail if space permits .

Thus the present invention provides an apparatus which provides accurate parallelism. This facilitates easy fitting and removal of the bridge superstructure.

A large number of implant systems are currently in use throughout the world. It is considered that the apparatus of the present invention will be compatible with all systems. The apparatus of the present invention will be particularly useful when the bridge is to be screwed to the implant.

It is to be understood that the above described embodiments have been described by way of illustration only. Many modifications and variations are possible.

For example the implant apparatus and method described above can be used in any appropriate implanting surgery such as orthopaedic surgery for example in fitting fixation plates, in veterinary surgery and in prosthetic surgery for example in the fitting of prosthetic eyes, ears, noses and so forth o such as by the "Branemark" implant system.

Claims

1. An apparatus for guiding implants comprising securing means for securing the apparatus to the patient at or adjacent the region of the patient receiving the implant, the apparatus further comprising guide means for guiding a drill, wherein the guide means is movably mounted in order to facilitate relative movement between the securing means and the guide means.

2. An apparatus for guiding implants as claimed in claim 1, wherein the securing means is operative to receive an elongate member.

3. An apparatus as claimed in claim 1 or claim 2, wherein the securing means comprises a body having a bore extending therethrough.

4. An apparatus as claimed in any preceding claim, wherein the apparatus comprises an arm, said arm defining the path of travel of the guide means.

5. An apparatus as claimed in any preceding claim, wherein the apparatus comprises a serated arm.

6. An apparatus as claimed in claim 4 or claim 5, wherein the guide means comprises a rider which is slidably mounted on the arm.

7. An apparatus for guiding implants as claimed in any preceding claim, wherein the guide means comprises a body defining an aperture which is operative to receive with a snug fit the bit of the drill or a drill collar.

8. An apparatus as claimed in any of claims 1 to 7, wherein the dimensional tolerance of the apparatus offers from 5mm to 30mm reach.

9. An apparatus as claimed in claim 1, wherein the securing means is pivotally connected to the guide - means.

10. An apparatus as claimed in claim 9, wherein a step is provided in the apparatus.

11. An apparatus as claimed in claim 10, wherein the step is removably located at the pivot.

12. An apparatus as claimed in any preceding claim, wherein a bush is operative to be received over the bit of the drill and within the guide means.

13. An apparatus as claimed in claim 12, wherein the bush comprises at least two releasably connectable parts.

14. An apparatus as claimed in claim 1, wherein the securing means comprises a denture.

15. An apparatus for guiding implants as claimed in any preceding claim, wherein the implant comprises a pin, the pin may comprise a groove or a threaded portion.

16. An apparatus for guiding implants substantially as described herein with reference to the accompanying Figs. 1 to 5, 8 and 9, 10 and 11, 12 or 16.

17. A kit comprising the following:-

(a) an apparatus for guiding implants comprising securing means for receiving an elongate member extending from the patient at or adjacent the region of the patient receiving the implant, the apparatus further comprising guide means for guiding a drill, wherein the guide means is mounted for movement along a path defined by the apparatus in order to facilitate relative movement between the securing means and the guide means; and

18. A method of drilling a hole using the apparatus as claimed in any preceding claim in which the securing means is secured to the patient, the guide means is located at or adjacent the region of the patient receiving the implant and the guide means is used to guide the drill into said region of the patient.