BACKGROUND OF THE INVENTION

Field of the Invention

[0001 ] The present invention has to do with surgical tools used for inserting a dental implant into a maxillary or mandibular socket. More specifically, the invention has to do with a new tool for inserting the implant without applying an undesirable lateral or moment force to the implant and thereby the host bone.

The Related Art

[0002] Primary stability is the result of mechanical locking between a dental implant and host bone. Currently, a dental hand piece is used to insert an implant into a maxillary or mandibular socket. In many cases, a surgeon uses a torsion wrench for the final turns of the implant. The torsion wrench provides the surgeon with greater tactile feedback than a hand piece.

[0003] The use of a torsion wrench is limited in that the wrench handle rotates in a plane parallel to the socket opening, thus, applying a lateral force to the implant. The lateral force generates a moment about the implant which causes excess pressure on the buccal wall and on the inferior/superior portion of the lingual/palatal wall, respectively. The additional pressure caused by the torsion wrench can lead to undesired changes to the socket geometry, implant displacement, and in severe cases, buccal wall failure or lingual/palatal wall perforation. Each of these cases leads to diminished primary stability and increased chances of implant failure. Surgeons apply apical pressure to the torsion wrench with their non-dominant hand to reduce lateral and moment forces applied to the implant. Excess apical force to stabilize the torsion wrench may lead to apical perforation into the maxillary sinus or the mandibular canal. Apical pressure may also cause diminished primary stability.

SUMMARY OF THE INVENTION

[0004] The tactile implant driver of the invention, also referred to herein as a "tool" or a "driver", improves on the torsion wrench design by transferring rotational motion from outside of the mouth to the implant, thereby eliminating excess movement inside the mouth. This is achieved according to the present invention by using a face gear or spur pinion or a gear and pinion bevel system to transfer torque from a plane parallel to or at an angle to the buccal wall to a plane perpendicular to the implant and the host bone socket opening. Torque is applied by twisting a handle of the tool to power the pinion located in the tool head. The handles are attached to the pinion via a drive shaft extending through the tool body. The drive shaft may be comprised of a flexible rod or a rigid rod which may or may not include one or more than one universal joint as explained in more detail below. The pinion drives a gear having a rotational axis which is perpendicular or approximately perpendicular to the rotational axis of the pinion and which is optionally connected to an adaptor on the bottom face of the tool head. The face gear or adaptor is designed to fit snugly around a dental implant screw carrying system (SCS). The dental implant screw carrying system can also be called a screw driver and the "screw" is the implant. When an adaptor component is used it may be, for example, designed to model the "MegaGen 91 1 Kit" ratchet wrench in order to adapt to existing universal SCSs but it can be designed to model other ratchet tools. My tactile implant driver transfers torque to the surgical site in a manner which eliminates detrimental lateral and moment forces caused by prior art torsion wrenches.

[0005] In a preferred embodiment, the tactile implant driver of the invention has a body comprising three sections. The proximal end of the proximal section has a rotatable handle 48 disposed thereon, the handle being affixed to a flexible drive shaft. The handle may optionally contain torsion control and/or ratchet mechanisms. The middle section preferably has an ergonomically shaped body, optionally at an angle to the distal section as explained below. Small port holes may be provided along the length of the proximal and middle sections to facilitate sterilization. The distal section contains the tool head which has smooth features and is sized to allow easy insertion into a surgical site. The distal section also may contain a cap to allow for placement of the gear and shaft during tool assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Fig. 1 is a partially transparent perspective view of a first embodiment of the driver of the invention illustrating the internal mechanical components.

[0007] Fig. 2 is a view of the first embodiment from the same perspective as Fig. 1 without partial transparency.

[0008] Fig. 3 is a perspective view of the underside of the first embodiment of the driver.

[0009] Fig. 4 is a side elevation view of the first embodiment of the driver in partial section.

[0010] Fig. 5 is an end view of the first embodiment of the driver in section viewed from the left end of Fig. 4. [001 1 ] Fig. 6 is a side elevation view of the first embodiment of the tool with a universal SCS and a dental implant affixed thereto.

[0012] Fig. 7 is a perspective view of a second embodiment of the driver.

[0013] Fig. 8 is a partially transparent view of the second embodiment taken from the same perspective as Fig. 7.

[0014] Fig. 9 is a side elevation view of the second embodiment of the driver with a universal SCS and a dental implant affixed thereto.

[0015] Fig. 10 is a partially transparent view of a third embodiment.

[0016] Fig. 1 1 is a perspective view of a fourth embodiment of the driver of the invention.

[0017] Fig. 12 is a partially transparent view of Fig. 1 1 .

[0018] Fig. 13 is a side elevation section view of the fourth embodiment.

[0019] Fig. 14 is a section view of a part of Fig. 13 taken along section line

14-14.

[0020] Fig. 15 is a perspective view of the proximal end of the tool of the invention.

[0021 ] Fig. 16 is a top elevation view of Fig. 15.

[0022] Fig. 17 is a section view of Fig. 16 taken along line 17-17.

[0023] Fig. 18 is a section view of Fig. 16 taken along line 18-18.

[0024] Fig. 19 is an elevation view of a face gear provided with a screw carrying mechanism and an implant.

[0025] Fig. 20 is a section view of Fig. 19 taken along line 20-20.

[0026] Fig. 21 is a section view of Fig. 19 taken along line 21 -21 . DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Referring to Figs 1 -6 illustrating the first embodiment of the invention, the tactile implant driver 1 is comprised of an elongated housing 2, a drive shaft 3 rotatably disposed in the housing 2, the housing 2 and drive shaft 3 having proximal and distal ends. The proximal end of shaft 3 is affixed to handle 4 by connector 13 and the distal end of shaft 3 is affixed to pinion 5. Handle 4 is affixed to connector 13 and may be an integral part thereof. The handle is rotatably disposed and adjacent to the proximal end of housing 2. Handle 4 and connector 13 may be a unitary, one-piece construction. Pinion 5 engages and drives a gear 6 which has an adaptor 7 affixed thereto. Gear 6 rotates about an axis that is perpendicular or approximately

perpendicular to the axis about which pinion 5 rotates. In this context, the term

"approximately" means the axis of rotation of pinion 5 may be at an angle greater than 90 degrees from the rotational axis of gear 6 and may be at an angle of up to 120 degrees but preferably only up to 105 degrees from the rotational axis of gear 6. The adaptor 7 may or may not be removably affixed to gear 6. The pinion 5 and gear 6 are housed in head 8. The head 8 being affixed to the distal end of housing 2. The adaptor 7 may or may not extend somewhat out of the bottom face of head 8. First screw carrying system 10 is removably inserted into adaptor 7. And screw carrying system 10 removably receives implant 1 1 ; shown in socket opening 30 of host bone 9.

[0028] In a second embodiment of the invention, illustrated in Figs. 7-9, a universal joint 25 is disposed between the head 8 and the handles 4 of the tactile implant driver to allow the surgeon more flexibility in the placement and use of the tool.

This embodiment permits the surgeon to transfer torque from a plane angular to the buccal wall to a plane perpendicular to the implant socket opening 30. Torque is applied by twisting the handle 4 to power the pinion 5. The handle 4 actuates the pinion 5 by means of a drive shaft having a proximal portion 23, a universal joint 25 and a distal portion 24. As can be seen from the drawings, the proximal and distal portions of the drive shaft are connected to one another by the universal joint 25.

[0029] Further in the second embodiment, the elongated housing disposed between the handles 4 and the head 8 has a bend at the universal joint. As illustrated in Fig. 9, the housing may be comprised of a proximal segment 20 and a distal segment 21 which are connected by means of bend segment 22. The bend segment 22 may be fused to segments 20 and 21 or it may permit movement of segment 20 relative to segment 21 , preferably, but not necessarily, movement in the plane perpendicular to the socket opening 30. In an alternative design of the fused embodiment, the housing may be comprised of a single piece which is simply bent at the universal joint.

[0030] Fig. 10 illustrates a third embodiment of the invention. Two universal joints 38 and 39 are disposed between the head 8 and the handles 4 of the tactile implant driver to allow the surgeon even more flexibility in the placement and use of the tool. This third embodiment also permits the surgeon to transfer torque from a plane angular to or in parallel with the buccal wall to a plane perpendicular to the implant socket opening. Torque is applied by twisting handle 4 to power the pinion 5. The handle 4 actuates the pinion 5 by means of a drive shaft having a proximal portion 37, a proximal universal joint 39, an intermediate portion 35, a distal universal joint 38 and a distal portion 36. As can be seen from Fig. 14, the proximal portion 37 is connected to the intermediate portion 35 by the proximal universal joint 39 and the distal portion 36 is connected to the intermediate portion 35 by means of distal universal joint 38. [0031 ] Further in the third embodiment, the elongated housing disposed between the handle 4 and the head 8 has bends at the universal joints of the kind used in the second embodiment illustrated in Fig. 9. The housing may be comprised of segments as used in the second embodiment or the housing may be comprised of a single piece which is simply bent at the universal joints.

[0032] Figs. 1 1 -21 illustrate a fourth embodiment of the invention, driver 41 . The fourth embodiment has an elongated housing comprised of a proximal section 42, a middle section 43, preferably comprised of an ergonomically shaped body, and a distal section 44 optionally at an angle (as shown) from about 10 degrees to 15 degrees, preferably about 12.5 degrees to the central axis a-a, of the proximal section 42. The elongated housing may also be made from a single piece which is bent. Thus, the central axis a-a of proximal section 42 is at an acute angle a with the central axis b-b of distal section 44. Implant 1 1 is perpendicular to central axis b-b when the screw carrying system 49 is inserted in the implant. (See Fig. 13.) Proximal section 42 has a rotatable handle 48 disposed at the proximal end thereof. Small port holes 45 may be provided along the proximal and middle sections to facilitate sterilization. The distal end of the distal section is small and has smooth features to allow easy insertion into a surgical site. A removable cap 68 allows for placement of a face gear 47 and a flexible drive shaft 46 during device assembly.

[0033] Figs. 12 and 13 illustrate flexible drive shaft 46, components of face gear 47 and components of rotable handle 48. Referring also to Figs. 19 and 20, face gear 47 is made to removably receive second screw carrying system 49, or an optional adaptor, and implant 1 1 is made to removably receive the second screw carrying system. As illustrated in Fig. 21 , face gear 47 contains a square bore which removably receives a square shaft of the proximal end of the screw carrying system. The screw carrying system (also called a screw driver) is removably held in place by friction with the walls of bore 49 and the implant is removably held in place by friction when SCS distal portion 49a is inserted into implant 1 1 . Bore hole 49b is a standard bore hole in implant 1 1 .

[0034] Figs. 13 and 15-18 illustrate enhanced components in the proximal end of the fourth embodiment of the driver as compared with Fig. 12.

[0035] Fig. 14 illustrates in section the distal end of flexible drive shaft 46 which is affixed to a distal axle extension 64 which extends through bearings 65 and 66 and terminates as a spur pinion 67 having teeth 67a. The spur pinion 67 drives face gear 47. An upper portion 47a of the face gear 47 has a smaller diameter and extends into bearing 70. Upper portion 47a of face gear 47 may optionally be magnetized to provide recording stability to screw carrying system 49.

[0036] Rotatable handle 48 comprises a connector 51 which connects the handle to flexible drive shaft 46. Handle 48 and connector 51 may be a unitary, one- piece construction. In this embodiment, the rotatable handle optionally comprises flexible rods 52 which bend relative to stationary measurement scales referred to herein as torsion markings 53. Torsion markings 53 are located at both ends of handle 48. (See Figs. 15 and 16.) The flexible rods 52 have bulbous ends 52a.

[0037] Torque is initiated by rotating flexible rods 52 which bend relative to the torsion markings 53. The rods 52 are preferably rotated by pressing on their bulbous ends 52a. The degree of bending positively correlates to torque applied to the host bone by the dental implant. Maximum torque can be applied by applying rotational force to the handle on which the torsion markings are printed rather than to the flexible rods. The handle also may contain a reversible ratchet mechanism as discussed below and a switch 62 extending from the handle that controls the direction in which torsion can be applied.

[0038] Each line of the torsion markings 53 has a value in Newton

centimeters ("N-cm"). Optimal insertion torque typically ranges between 35 N-cm and 60 N-cm. Insertion torque is positively correlated to primary stability. Optimal insertion torque is commonly used as a clinical metric for primary stability. More dense bone is able to handle higher insertion torque without fracturing.

[0039] A reversible ratchet mechanism is also optionally disposed in handle 48 and is illustrated in detail in Figs. 17 and 18. The ratchet mechanism allows the surgeon to turn the handle in small increments so that he/she can always see the position of the flexible rods 52 relative to the torsion markings 53. The ratchet mechanism is disposed in connector 51 and the elements of the ratchet mechanism are illustrated in detail in Figs 17 and 18. The ratchet mechanism is comprised of a ratchet anvil 54 affixed to drive shaft proximal axle extension 55. Bearing 56 facilitates rotation of proximal axle extension 55. Spring biased pawls 58 and 59, having flat springs 60 and 61 respectively disposed between the pawls and the interior of connector 51 , are used to control the direction in which the ratchet anvil 54 can turn. The positions of the pawls in Fig. 17 would allow the gear 54 to rotate in a clockwise direction and would prevent translation of torque to the implant in a counterclockwise direction. Switch 62 has a cam 63 at its distal end. In Fig. 17, rotation of the switch in a clockwise direction would reverse the rotatable direction of ratchet anvil 54.

[0040] To use the tactile implant driver of the first three embodiments of the invention, a surgeon first places a first screw carrying system 10 into the adaptor 7 at the head 8. The tip of the first screw carrying system 10 is then placed onto and engaged with a dental implant 1 1 which already has been partially inserted into a socket opening 30 of a host bone 9. Torque is then applied by twisting the handles 4. The surgeon holds the head 8 and housing 2 or the distal segment 21 or 31 with his or her non-dominant hand in order to align the first screw carrying system 10 coaxially with the implant 1 1 (see Fig. 6). As the surgeon continues to twist the handles 4, the implant 1 1 is driven into the host bone 9, i.e. the mandible or maxilla. The surgeon receives tactile feedback due to the resistance applied by the host bone 9 to the implant 1 1 and transmitted through the driver to the surgeon's fingers on the handles 4. Primary stability is not compromised because excess pressure is not applied to the buccal or lingual/palatal walls. The tactile implant driver limits excess pressure applied to the buccal and lingual/palatal walls while providing tactile feedback to the surgeon during dental implant placement.

[0041 ] When the third embodiment of the driver is used, the driver handle is elevated at a small angle from the head in order to allow a surgeon easily to position the head perpendicular to the implant socket opening. The proximal portion of the handle is angled supplementary to the intermediate segment angle of elevation, thus, becoming parallel or approximately parallel with the head. The second angle ensures that the handles can be comfortably rotated in a plane parallel to or approximately parallel to the buccal wall. The drive shaft functions through both angles using two universal joints.

[0042] When the fourth embodiment of the driver is used, a surgeon first places the second screw carrying system 49 into face gear 47. The SCS distal portion 49a of the second screw carrying system 49 is then placed onto and engaged with implant 1 1 which already has been partially inserted into socket opening 30 of host bone 9. Torque is then applied by rotating flexible rods 52 which bend relative to torsion markings 53. As noted above, torsion markings 53 are located at both ends of handle 48. The ratchet mechanism allows the surgeon to view the torsion markings at an optimal angle. Without the ratchet mechanism, the surgeon would have to completely rotate the handle in order to turn the implant and thus be unable to see the torsion markings. The ratchet mechanism allows the surgeon to turn the handle in small increments so that the torsion markings are always optimally visible. The ratchet mechanism works for implant insertion and extraction so that the surgeon can measure torsion in both directions. The degree of bending positively correlates to the torque applied to the host bone by implant 1 1 . Maximum torque can be applied by applying rotational force to the handles 48 on which the scale 53 is printed rather than to the flexible rods.

[0043] The surgeon holds the head (distal portion) and body of the driver with his or her non-dominant hand in order to align the screwdriver 49 coaxially with the implant 1 1 and the socket 30. As the surgeon continues to twist the rear handles, the implant 1 1 is driven into the mandible or maxilla. The surgeon receives tactile feedback due to the resistance applied by host bone to the implant and transmitted through the driver to the surgeon's fingers on the handles. Buccal, lingual/palatal and apical pressures are limited because rotational force is applied outside of the mouth and transferred to the implant while providing tactile feedback to surgeons during dental implant placement.