WO2009137947A1 - Method for the production of a device for the targeted regeneration of bone tissue - Google Patents

Abstract

Disclosed is a method for producing a device for the targeted regeneration of a particular patient's bone tissue (1), said device consisting of a two-dimensional, flexible membrane (6). In said method, a three-dimensional structure of an actual state of the bone tissue (1) that is to be regenerated is recorded. A three-dimensional structure of a desired state of the bone tissue (1) that is to be regenerated as well as the shape and position of a bone graft (5) for regenerating the bone tissue (1) are then determined, and a three-dimensional boundary surface between the bone graft (5) or the bone tissue (1) and the connective tissue (13) is determined. A two-dimensional shape of the two-dimensional, flexible membrane (6) is then determined on the basis of the accurate three-dimensional boundary surface such that said three-dimensional boundary surface is created once the membrane (6) has been attached to the particular patient's bone tissue (1).

Description

 Method for producing a device for the targeted regeneration of bone tissue

Technical Field This invention relates to a method of making devices for the targeted regeneration of bone tissue.

State of the art

To restore and reconstruct face and jaw defects, various regeneration aids are used in plastic surgery and especially in maxillofacial surgery. The use of autologous, ie endogenous, bone or other bone substitute materials and osteoinductive implants is routinely used today for example in the jaw reconstruction and the treatment of minor bone defects and is an indispensable part of the practice.

If, for example, after the loss of a tooth due to the lack of mechanical stress for the local degeneration of the jawbone in the area of the alveolus, a repair of the bone defect, respectively the augmentation of the jawbone, will often be indicated before inserting a dental implant. As bone grafts, appropriately prepared pieces of autologous bone tissue can be used in such a situation, which are fitted and fixed in the defect. It is obvious that such a procedure on the one hand burden the patient and on the other hand consuming and therefore expensive.

For smaller bone defects on the alveolar ridge, therefore, gentler membrane techniques are preferably used. In this case, a dimensionally stable semipermeable membrane forms a hollow space in the size of the bone defect and prevents faster growing Soft tissue grows into the gap until the slower growing bone has completely filled the defect. Unless it is a bioresorbable membrane, the membrane is removed after completion of bone ingrowth, usually after three to six months.

Unless otherwise stated below, the term bone-craft is intended to subsume all bone and bone replacement materials used in facial and jaw reconstruction.

Three-dimensional dimensionally stable membranes or shells can be produced by means of a three-dimensional model of the bone tissue, or directly on the basis of an electronic model using modern CAD-CAM methods, for example using rapid prototyping systems. In contrast, the use of flexible membranes is preferred by the practitioner for the repair of minor bone defects on the jawbone or alveoli, for example in the root area of one or more missing teeth. Before attaching the bone-craft and the membrane, the artificial tooth root, the actual implant, fixed in the remaining jaw bone, with a part of the implant is then in bone-craft, so that the implant is finally anchored stable in the old and new bone tissue , In order to avoid further damage to the jaw and injury to the nerve, the bore for the anchoring element of the implant must be carried out very precisely in terms of position and depth. This is preferably achieved by means of a spatially fixed to the adjacent teeth rail, which serves as a jig. During the regeneration phase, the anchoring optionally protrudes through an opening in the membrane. When bone replacement is used as a bone craft, it must be spatially fixed in the gap to ensure the desired shape during osteoinduction, osseointegration and, ultimately, the entire remodeling of the regenerating bone tissue. On the other hand, the filling material has to be separated from the surrounding connective tissue in order to prevent it from growing into the gap prevent. For larger defects, as already mentioned above, three-dimensional shells or grids are used, for smaller gaps or alveoli, however, flexible membranes are suitable, which are preferably fixed to the surrounding bone tissue. Preferably, flexible membranes are made of biocompatible materials, and a variety of such materials are known in the art and in the art. Optionally, resorbable materials may also be used. During the procedure, the shape of the two-dimensional membrane must be adapted to the bone defect to be filled and its edge areas, so that the membrane rests against the adjacent bone tissue with sufficient overlap, the adjacent teeth, or tooth roots or implants, can be spared and, if necessary, adequately fixed, and the desired three-dimensional shape of the Bone graft is guaranteed. Until now, the membranes have been prepared by the doctor on site, whereby the measurement of the distances and the cutting of the membrane during the procedure takes 10 to 20 minutes. On the one hand, this leads to an increased physical exertion of the patient due to the longer operation time due to the anesthesia, on the other hand, the wound healing worsens the longer the wound is open. Economically speaking, the longer operating time leads to higher costs for the patient. Cumulative on several operations, the not inconsiderable loss of time also leads to a lower utilization of medical staff and infrastructure. Some dentists lack the necessary eye-sense and the manual skill to cut the membranes quickly and accurately with the available aids. These doctors must be trained in a time-consuming manner.

EP 175731 5 A1 shows a method for producing three-dimensional, dimensionally stable shells from biocompatible materials by means of a suitable rapid prototyping method, namely a powder lamination method.

DE 101 38373 A1 shows a method in which, based on three-dimensional data of the actual state of a jawbone and the desired nominal state, a three-dimensional sionale, dimensionally stable shell is made. For this purpose, a three-dimensional model of the jaw bone is made in the desired state, and adapted to this model a membrane, which then remains without support in the corresponding three-dimensional shape and thus forms said shell. The production of a three-dimensional model is, of course, expensive, even if rapid prototyping methods are used.

Description of the invention

The object of the invention is to provide an advantageous process for the production of membranes for the directed regeneration of bone tissue with which, in particular, a shortening of the duration of the operation can be achieved.

These and other objects are achieved by a method according to the independent claim. Further advantageous variants are given in the dependent claims.

The method according to the invention is based on the use of three-dimensional data describing the position of the bone tissue and the teeth in the region of the bone defect in order to determine the ideal shape and size of the two-dimensional membrane, so that no separate and time-consuming manual measurement step is necessary.

As a drilling template for attaching the holes in the existing bone tissue, a rail is usually used, which is spatially fixed to the adjacent, still existing teeth. This splint must be made individually for the particular spatial position of the teeth to which it is attached and the desired position of the borehole. For this purpose, three-dimensional data about the spatial structure from jaw and teeth, which is usually done by optical imaging techniques, x-rays or computed tomography.

In the method according to the invention, these already present three-dimensional data are evaluated a second time to determine the most favorable size and shape of the membrane, depending on the desired shape of the bone-craft. Preferably, for this purpose, the position of the necessary attachment points of the membrane is determined on the jawbone, which in turn has an impact on the necessary overlap areas of the membrane with the existing bone tissue. Likewise, openings and recesses for implants and adjacent teeth which are already necessary in the membrane are preferably already determined. The two-dimensional data of the boundary between bone graft or future bone tissue and connective tissue determined on the basis of the three-dimensional data are subsequently converted into a two-dimensional shaping of the flexible membrane, whereby specific material properties of the membrane and further parameters can also be taken into account. Because of this two-dimensional shape, the membrane piece can finally be produced.

The completion of the membrane piece is preferably carried out by the manufacturer of the mounting rail. The surgeon then receives a kit comprising a custom-made splint / drill guide and, suitably, the individually fabricated membrane for covering the bone graft to be created, thus eliminating the need to separately cut the membrane in place by the surgeon. This results in a corresponding shortening of the duration of surgery.

Alternatively, the cutting of the membrane instead of the manufacturer of the splint can also take place later, for example in the practice of the oral surgeon. In this variant delivers the

Manufacturer of the rail / drilling jig the necessary information, for example, electronically, or in the form of a pattern. Since trimming does not occur during the operation ration must take place, but at any time before, and can also be performed by an appropriately trained assistant, resulting in this case, the desired shortening of the operation time.

MODE FOR CARRYING OUT THE INVENTION In the following, the invention will be explained further with the aid of drawings.

Figure 1 shows schematically a lower jaw in side view, with a positioned on two teeth rail with a drilling jig for producing a bore for an anchoring element to be implanted.

Figure 2 shows schematically a part of a mandible with a bone defect, (a) in plan view and (b) in a cross section through the jaw, with an implanted anchoring element, a bone graft for repairing the bone defect, and a device in the form of a membrane for Cover and shape the bone-craft and prevent ingrowth of connective tissue into the bone graft.

Figure 3 shows a membrane-shaped device for covering a bone graft, with openings for two implanted anchoring elements, in a flat state before assembly.

Following the reconstruction of the bone defect 1 1 with the aid of the bone graft 5, the artificial replacement tooth, which is composed, for example, of the abutment and the crown, is fastened on the anchoring element or implant 3 implanted in the jawbone 1 and serving as an artificial tooth root. The crown is individually made on the basis of three-dimensional data of the jaw and the surrounding teeth. To make a late To ensure tere exact positioning of the artificial tooth, and to prevent injuries to the lying in the jawbone 1 nerve 12, the holes 8 in the jaw bone I ₁ in which the anchoring elements are introduced, are very precisely positioned. For this purpose, placed on adjacent existing teeth 5 rails 9 are used on soft corresponding jigs 91 are arranged. 1 shows schematically such a rail 9, placed on two remaining teeth 2 of a lower jaw 1. With the help of the jig 91, the bore 8 is made in the jawbone. The splint 9 was made specifically for a patient due to the three-dimensional data of the jaw and the teeth in the actual state.

FIG. 2 schematically shows a part of a lower jaw 1 with a bone defect 1 1, (a) in a plan view and (b) in a cross section through the jaw 1. In the area of the bone defect an implant 3 is implanted. A membrane-shaped device 6 is attached to the jawbone such that the membrane 6 and the jawbone 1 form a cavity in which the bone defect 1 1 lies. The membrane 6 serves for covering and shaping the bone-craft and separating the blood flow between bone and connective tissue, so that only the surrounding bone tissue can grow into the bone-graft. The bone graft 5, which is usually selected from the following group, is introduced into said hollow space: synthetic, xenogenic, autologous bone grafts or mixtures thereof. As an example of synthetic bone grafts Straumann Bone Ceramic overall ^® was Nannt 20, a mixture of hydroxyapatite and tricalcium phosphate (beta-TCP). A well-known xe- nogenes bone graft is the product of Bio-Oss ^®, Geistlich, consisting of the mineral portion of bovine bone. The implant 3 protrudes through a recess 61 of the membrane 6. If it should be necessary due to the local conditions, the membrane 6 may also have lateral recesses 62 for the adjacent teeth 2. The membrane 6 should not exceed a size that is not necessary, but minimal overlap with the limiting bone tissue is necessary, inter alia to attach the edge of the membrane with pins 63 to the bone tissue. As a rule, the overlapping edge, also referred to as overlap, is not more than 3 mm.

As a suitable membrane material has, for example, a collagen-based membrane of the company Geistlich know, which is offered under the brand Bio-Gide ^® . However, all membrane materials used in dentistry according to the invention can be used.

A membrane element may also extend over a longer range. Thus, for example, Figure 3 shows schematically a corresponding membrane-shaped device 6 analogous to Figure 2, with openings 61 for two implanted anchoring elements, in flat, two-dimensional) learning state before assembly.

Instead of the surgeon, as usual, determining the necessary geometrical information for cutting the membrane 6 during the operation in order to subsequently cut the membrane from a corresponding membrane material blank, the three-dimensional data of

15 jaws and teeth used to determine the necessary two-dimensional shape of the membrane piece to be attached before the operation due to the desired three-dimensional shape of the bone graft, optionally with the corresponding necessary recesses 61, 62 for the implants and the surrounding teeth. Specific material properties of the membrane (elasticity, material, thickness, etc.) and other parameters

20 also be taken into account. The membrane 6 or a pattern of the membrane is then made simultaneously with the rail 9, and delivered to the attending physician as a ready-to-use set.

The necessary three-dimensional data for the production of the membrane are already present because these data are used to determine the correct position of the implant, the Production of the rail with drilling jig, and the production of the replacement tooth are needed anyway. Accordingly, no additional effort is involved in this regard in the inventive method. The time savings during the operation when using a prefabricated membrane can be between 5 to 1 5 min, which shortens the entire operation time, and thus the physical stress of the patient. Logistically, the shorter total duration results in better utilization of infrastructure and medical staff, which has a positive impact on cost efficiency.

As an alternative to the complete prefabrication of the membrane by the manufacturer, a pattern can also be supplied, on paper or in electronic form, which allows the surgeon to make the membrane himself faster, from the material of his choice. Preferably, in such a case, the completion of the membrane by an assistant, before the operation. The use of a pattern in the process according to the invention has the further advantage that, if necessary, a replacement membrane can be produced in the field without problems if the first one is damaged.

The method according to the invention is not limited to membranes for use in orthognathic surgery, but can also be used for other bone-craft in which membrane-shaped devices can be used, for example for smaller defects on the cranial bone.

The method according to the invention for producing a device for directional regeneration of a bone tissue (1) of a specific patient, consisting of a two-dimensional, flexible membrane (6), therefore comprises the following steps:

- Receiving a three-dimensional structure of an actual state of the bone tissue to be regenerated 1; - Determining a three-dimensional structure of a desired target state of the bone tissue to be regenerated I ₁ and the shape and position of a bone-Crafts 5 for the regeneration of the bone tissue 1;

Determination of a three-dimensional interface between the bone-craft 5 or the bone tissue 1 and the connective tissue 1 3; and

Determining the three-dimensional shaping of a membrane-shaped device 6 based on the three-dimensional boundary surface, converting this three-dimensional shaping into a two-dimensional cutting pattern and producing this two-dimensional cutting pattern.

After cutting and attaching the membrane 6 to the bone tissue 1 of the patient to be treated, the desired three-dimensional interface is accurately formed. When manufacturing the membrane 6, the positions of implants 3 and adjacent teeth 2 are advantageously taken into account and corresponding recesses 61, 62 are provided in the membrane. The two-dimensional membrane piece 6 can then be produced from the membrane material based on the defined two-dimensional shape information, for example by cutting by hand or preferably by laser cutting. Alternatively, the shape information may also be used to provide a cut pattern, in printed or electronic form, with which the membrane is then completed at a later time. It is also possible to print the pattern directly on a membrane blank with a suitable method. List of reference numbers

1 jawbone

1 1 Bone defect

1 2 nerve

1 3 connective tissue

2 tooth

3 anchoring element / implant

5 bone craft

6 device / membrane

61 recess for implant

62 recess for tooth

63 pin

8 hole

9 rail

91 drilling gauge

Claims

claims 1. A method for producing a device for the directed regeneration of a bone tissue (1) of a particular patient, consisting of a two-dimensional, flexible membrane (6), in which - A three-dimensional structure of an actual state of the bone tissue to be regenerated (1) is added; - Determining a three-dimensional structure of a desired target state of the bone tissue to be regenerated (1) and the shape and position of a bone-Crafts (5) for the regeneration of the bone tissue (1); - Determining a three-dimensional interface between the bone-craft (5) or the bone tissue (1) and the connective tissue (1 3); and - Determines a two-dimensional shape of the two-dimensional flexible membrane (6) due to the exact three-dimensional interface and a pattern of the two-dimensional, flexible membrane (6) is generated. 2. The method of claim I _1, characterized in that in the determination of the two-dimensional shaping of the positions of existing implants (3) and adjacent teeth (2) is taken into account, in particular for the determination of the arrangement of corresponding recesses (61, 62) in the membrane-shaped device (6). 3. The method according to claim 1 or 2, characterized in that subsequently the membrane-shaped device (6) is made of a sheet-shaped membrane blank, preferably by cutting. 4. The method according to claim 1 or 2, characterized in that subsequently a template for the production of the membrane piece is provided from a membrane, preferably a pattern in printed or electronic form. 5. The method according to claim 4, characterized in that the pattern is printed on a sheet-shaped membrane blank. 6. A device consisting of a two-dimensional, flexible membrane (6), for the directed regeneration of bone tissue (1), manufactured by a method according to any one of the preceding claims. 7. A set, including - a rail (9) with drilling jig (91) for drilling one or more holes (8) in a jawbone (1) of a particular patient for attachment of implants (3), wherein the rail (9) with drilling jig (91) is individually adapted to the jawbone (1) of the particular patient, and - A device for the directed regeneration of a bone tissue defect (1 1), consisting of a two-dimensional membrane (6), for attachment to the jawbone (1) of the patient, wherein the membrane-shaped device (6) is individually adapted to the jawbone of said patient.