Surgical guide for zygomatic bone implants

Abstract

A guide for guided surgery on zygomatic bone implants for dental prostheses includes a half-bushing and a complementary half-bushing which are connected by a pair of bars. The half-bushings and the bars define a common longitudinal median axis between them; the half-bushings have a U-shaped or semicircular cross-section with mutually opposite concavities directed toward the median axis; the half-bushings and the bars form a seat in which it is possible to insert a work member, such as a burr and a subsequent implant, which can move only along the median axis and rotates about an axis of rotation that coincides with the median axis.

Claims

1. A device for guided surgery on zygomatic bone implants for dental prostheses, the device comprising: at least one guide comprising a first half-bushing and a second half-bushing which are complementary and connected by a pair of bars; wherein: the first and second half-bushings and the bars define a common longitudinal median axis between them; the first half-bushing is spaced apart from the second half-bushing in a direction along the median axis with the pair of bars therebetween such that the first and second half-bushings do not overlap each other when viewed from a direction perpendicular to the median axis; the first and second half-bushings have a U-shaped or semicircular cross-section with mutually opposite concavities directed toward the median axis; and the first and second half-bushings and the bars are arranged such that an implement used during the guided surgery, when received by the first and second half-bushings, is movable only along the median axis and is rotatable about an axis of rotation that coincides with the median axis.

2. The device according to claim 1, wherein the second half-bushing has a guide slot in which the implement is receivable.

3. The device according to claim 2, wherein the guide slot comprises a pair of tabs which extend from the second half-bushing in a direction along the median axis toward the first half-bushing.

4. The device according to claim 1, further comprising at least one stabilization flange by which the device is fixable to a bone part.

5. The device according to claim 4, wherein the device is fixable in a palate region and zygomatic fossa via the at least one stabilization flange.

6. The device according to claim 4, wherein the device is fixable to the bone part via self-tapping locking screws or pins inserted in maxillary holes.

7. The device according to claim 4, wherein: the at least one guide comprises at least two guides; and the at least one stabilization flange mutually connects the at least two guides.

8. The device according to claim 1, wherein the implement comprises at least one of a burr and an implant.

Description

(1) Further characteristics and advantages will become better apparent from the description of preferred but not exclusive embodiments of the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

(2) FIG. 1 is a perspective view of the surgical guide according to the present invention;

(3) FIG. 2 is a front view of the guide;

(4) FIG. 3 is a side view of the guide;

(5) FIG. 4 is a schematic perspective view of two double guides, of which one is arranged in the position for use;

(6) FIG. 5 is a front view which shows schematically the placement of two guides;

(7) FIG. 6 is a bottom view of the palate, showing two guides in position;

(8) FIG. 7 is a view, similar to the preceding one, showing the application of a burr;

(9) FIG. 8 is a view of the step of insertion of an implant;

(10) FIG. 9 is a view of an inserted implant;

(11) FIG. 10 is a view of the implants inserted and of the removed guide;

(12) FIG. 11 is a schematic view of the virtual placement of the implants performed by the software.

(13) With reference to the cited figures, the surgical guide according to the invention, designated generally by the reference numeral 1, has a half-bushing 2, in a crestal maxillary position with vestibular concavity, adapted to determine both the working depth, i.e., the vestibulo-palatal penetration, referenced by the segment 3, and the direction of perforation that a burr 100 must follow.

(14) The guide 1 also includes two lateral bars 4 that unambiguously direct the sliding of the burrs 100 and of the implant 101 in space, and a complementary half-bushing 5, which is opposite to the crestal bushing 2 and have a concavity directed medially; the half-bushing 5 is arranged at the zygomatic region.

(15) The complementary half-bushing 5 acts as a guide for the surface direction and orientation of the burrs 100 and of the implant 101.

(16) The mutually opposite half-bushings 2 and 5 have a U shape or semicircular shape with the concavity directed toward the longitudinal median axis of the guide formed between the bars which extend parallel thereto.

(17) In other words, the opposite half-bushings 2 and 5 define the hole in which the burr and then the implant are inserted; the burr and the implant represent a shaft which, with the hole, constitutes a prismatic pair, providing a system with a single degree of freedom, i.e., the motion of the shaft, i.e., the burr 100 and the implant 101, can occur only along one direction, which in this case coincides with the axis of the prismatic cavity formed by the half-bushings 2, 5.

(18) With this system, the axis of the hole coincides with the axis of the burr 100 and with the axis of the implant 101.

(19) The half-bushing 2 arranged on the maxillary bone has a U-shaped cross-section and dimensions suitable to guide the work of the burrs 100 and the subsequent positioning of the implant 101.

(20) The complementary half-bushing 5 also has a guide 6 for the first burr 100, the pilot burr, as will be described hereinafter.

(21) The guide 6 is constituted, in this specific case, by a guide slot defined by a pair of tabs 61, which extend from the complementary half-bushing 5 in the direction of the half-bushing 2.

(22) The surgical guide according to the present invention is particularly studied to be used in a particular zygomatic implant guided surgery technique which provides, as a first step, the acquisition of a multilayer CT (computerized tomography). This CT is processed by software which allows to virtually position the implants in terms of orientation, position and measurements, as shown schematically in FIG. 11.

(23) A second software is used to read the position of the implants, in relation to the bone, decided by the surgeon, and at the same time to virtually build a surgical guide with bone anchoring which allows to reproduce, with the surgical burrs, the exact path and placement of the implants to be inserted, exactly as in the virtual project.

(24) In a first step, a pilot mill, preferably constituted by a 2.5 mm diamond mill, is used, for determining the center of the circumference of the future implant 101 and which will be the insertion point for the drill of the actual burr.

(25) A second burr, termed cortical burr, allows the erosion of the excess bone level and the forming of the bone hollow for the resting of the future implant. This burr is used by resting its nonworking drill in the spot provided by the pilot burr and by tilting it and pushing it on the bone, consuming the bone with its active part; the final position of the burr is determined by the stop produced by the maxillary half-bushing 2.

(26) The subsequent burrs are guided by the half-bushings 2 and 5 and by the lateral bars 4, which are constituted by two prismatic shapes with a polygonal base; the prismatic shapes have such an extension as to connect the two half-bushings and are arranged tangentially to the ends of the diameter of the implant and parallel to each other.

(27) These features allow to guide the burr 100 and to remove the guide 1 after inserting the implant 101 in the bone.

(28) Another feature of the guide 1 is constituted by its extension by means of stabilization flanges 11 in the palate region and the zygomatic fossa; its stabilization occurs by means of self-tapping locking screws or pins 7, which are inserted in maxillary holes 8 and zygomatic holes 9 provided for this purpose.

(29) The files that contain the projects of the customized guides are sent to a center that is specialized in laser melting processes, thus producing the actual titanium guides with a high level of precision.

(30) The surgical technique provides for sculpting a mucosal flap, performing a bone peeling process that is suitable to expose the maxillary and zygomatic anatomical structures, and to accommodate the guide according to the present invention, which is fixed to the bone by means of pins 7.

(31) Once the intimate bonding between the bone and the plate has been verified, one proceeds with the sequence of burrs with the goal of providing a bone hollow for guiding the subsequent insertion of the implant.

(32) The seating of the implant is precise because the bone hollow on the maxillary bone and the hole inside the cheekbone (implant neo-receptacle) allow a single placement in terms of direction and depth and this occurs because during all the surgical steps the operator is guided by the two half-bushings 2 and 5, applying thereon an adequate pressure both with the burrs and with the implant itself at the time of its insertion.

(33) The technique thus provided allows to use implants with preset diameter and length and even to prepare a temporary screw-on prosthesis in order to provide an immediate prosthetic load.

(34) An example of execution of the surgical technique based on the guide according to the present invention is described hereinafter.

(35) First of all, a multilayer TC acquisition is performed and the file is loaded in the dedicated software, which provides the virtual placement of the implants, in terms of depth and angle, on a CAT in relation to the prosthetic design.

(36) The file is imported in another software in order to design the surgical guide according to the present invention, which is made to size with respect to the bone of the patient and on the basis of the placement of the implant decided in the preceding software.

(37) The file is sent to the manufacturer of the guide, which manufactures it by laser melting.

(38) The guide is tested on a real model, printed from the files of the CAT (guide project validation), current tolerance 0.2 tenths of a centimeter.

(39) The 0.3 to 0.6 mm multilayer CT is acquired which includes the maxillary bone and the cheekbones in full and is extended up to the complete eye socket; the CT is preferably performed with a barium-based prosthetic radiological guide.

(40) The DICOM file of the CAT is imported into the software for planning and matching the reference points of the files of the digitized radiological guide.

(41) The zygomatic implant is extracted from the library and is positioned in three dimensions with a maxillary/zygomatic orientation, according to the surgical-prosthetic project. The software includes an implant library with diameters and lengths of the implants to be inserted.

(42) The placement of the crestal half-bushing 2 is performed by exporting it from the bushings library. The maxillary half-bushing 2 and the complementary half-bushing 5 have different lengths depending on the length of the implant that will be inserted. These two members constitute the guide of the burr in a unique direction.

(43) The maxillary half-bushing 2, together with the remaining portion of the complementary half-bushing 5, constitute an ideal prism (hole) through which only and exclusively one trajectory is possible for a zygomatic implant (shaft). Specifically, the hole is divided into two equivalent halves, the maxillary half-bushing 2 and the zygomatic complementary half-bushing 5, which are arranged in a mutually opposite manner: the half-bushing 2 with a vestibular concavity and the complementary half-bushing 5 with the concavity directed toward the zygomatic bone plane.

(44) The lateral bars 4 are arranged from the half-bushing 2 to the complementary half-bushing 5. These bars, which have a prismatic shape, are tangent to two opposite points of the circumference of the implant and are mutually parallel. These bars act as an additional guide of the shaft (implant) during its travel from the half-bushing 2 to the complementary half-bushing 5 (hole).

(45) The slot with guiding pin for the first burr is imported.

(46) The slot, half-bushing, complementary half-bushing, lateral bars, zygomatic slot for the first burr are aligned with the designed zygomatic implants.

(47) One then proceeds with modeling the guide with bone support, ensuring the stability of the plate, creating a prismatic kinematic pair in which the fixed portion is the guide and the movable portion is the burr.

(48) The guide must have a bone support with an extension from the palate portion, continuing on the maxillary bone, up to the zygomatic portion, extending it to the rear portion of the fossa.

(49) In order to fix the guide to the bone portion, holes are used in a number which is variable according to the extension of the guide and are positioned on the maxillary and zygomatic portion thereof.

(50) The holes have a diameter that is capable of accepting a self-tapping screw in order to fix the guide integrally to the bone portion.

(51) The burr moves inside the bushings (shaft/hole) with a predefined degree of tolerance, for example H6/h6 ISO Table, defined as good precision, on a scale of four values: high, good, medium, coarse.

(52) Finally, the file is sent to the guide production location and is preferably manufactured in titanium by means of the laser melting method.

(53) In practice it has been found that the invention achieves the intended aim and objects, providing a guide that is studied particularly for guided surgery on zygomatic implants for dental prostheses.

(54) An important advantage of the guide according to the present invention is that it is removable after inserting the implant or implants in place.

(55) Also, with a single guide it is possible to insert one or more implants, such as in the example shown in FIGS. 4-10, in which two guides are shown, each of which is configured for the application of two implants.

(56) The materials used, as well as the dimensions, may of course be any according to the requirements and the state of the art.

(57) This application claims the priority of Italian patent application No. 102018000006998, filed on 6 Jul. 2018, the content of which is incorporated as reference.