CN111110925B

CN111110925B - Method for 3D printing of personalized periodontal tissue regeneration material

Info

Publication number: CN111110925B
Application number: CN201911330117.5A
Authority: CN
Inventors: 路瑞芳; 胡文杰; 王翠; 危伊萍
Original assignee: Peking University School of Stomatology
Current assignee: Peking University School of Stomatology
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2022-02-22
Anticipated expiration: 2039-12-20
Also published as: CN111110925A

Abstract

A3D printing method of an individualized periodontal tissue regeneration material is characterized in that preoperative Cone Beam Computed Tomography (CBCT) equipment is used for obtaining bone defect shape data of a periodontal bone defect patient, bone grafting shape data are determined according to the bone defect shape data, shape slice processing data and raw materials for 3D printing are determined according to the bone grafting shape data, then the individualized periodontal tissue regeneration material is printed out through a Fused Deposition Modeling (FDM) three-dimensional printer by using the shape slice processing data and the raw materials, and the method is beneficial to facilitating operation of doctors and achieving ideal surgical effects.

Description

Method for 3D printing of personalized periodontal tissue regeneration material

Technical Field

The invention relates to a periodontal soft and hard tissue regeneration reconstruction technology, in particular to a method for 3D printing of an individualized periodontal tissue regeneration material.

Background

The prevalence of periodontitis among people is as high as 90% or more, and is one of the leading causes of tooth loss in adults. Periodontitis is not obvious in early stage of diseases, patients often neglect tooth brushing, gingival bleeding and other symptoms, the treatment is often accompanied by serious periodontal tissue destruction and absorption, diagonal/vertical bone absorption and II-degree root bifurcation lesion (I-degree to IV-degree, the lesion degree is changed from light to heavy), and periodontal tissue regeneration is a feasible type of periodontal surgery, but the surgical effect is influenced by various factors.

Periodontal Tissue Regeneration (PTR) is the reconstruction of lost periodontal tissue due to periodontitis, with new cementum and alveolar bone formation, between which new periodontal ligament fibers connect them to form a functional periodontal attachment structure. Among periodontal tissues, only periodontal ligament cells have the potential to regenerate periodontal tissues. Guided periodontal tissue regeneration (GTR) is a procedure in which a membranous material is used as a barrier in periodontal surgery to prevent the gingival epithelium from growing along the root surface during the healing process, to prevent the contact between the gingival connective tissue and the root surface, and to provide a certain space to guide periodontal ligament cells having the ability to form new attachments to preferentially occupy the root surface, thereby forming new cementum on the root surface that has been exposed in the periodontal pocket, and to form regeneration of periodontal tissue by embedding periodontal ligament fibers. Non-absorbable membranes and absorbable membranes for GTR (constrained tissue regeneration).

Periodontal bone grafting (bone graft procedure) is a method of repairing an alveolar bone defect caused by periodontitis by using a graft material such as bone or a bone substitute, and aims to promote formation of new bone, repair a bone defect, restore an anatomical form of an alveolar bone, and obtain ideal periodontal tissue regeneration by the graft material. Is suitable for the diseases of the inferior bone pocket and II degree root bifurcation, and can be covered by the gingival tissue. Periodontal tissue regeneration has been a complex problem involving 3 different tissues of alveolar bone, periodontal ligament and cementum, and space maintenance, growth factors and the prevention of excessive growth of epithelial cells have been important issues for periodontal tissue regeneration.

Although guided periodontal tissue regeneration is a periodontal operation that is widely used, it is laborious and takes a long time to perform clinically. Generally, after a clinician finishes flap-turning debridement, the probes are required to measure the widths of the bucco-lingual direction and the near-far-middle direction of a bone defect and the depth of a bone pocket, and whether auxiliary bone grafting is required or not is judged according to the measured values. The bone grafting material is generally granular, loose particles are not easy to fix when the bone grafting material is filled, the filling is determined by factors such as the shape of a bone defect, the position of the bone defect, the experience of an operator, the filling force after the bone powder is implanted and the like (the bone powder filling force has influence on the bone formation amount after the bone is implanted in the prior art), the filling amount is uncertain under different conditions, the filling is easy to increase, or the bone shape is not well retained when the bone is filled, so that the bone grafting material is displaced.

The oral cavity is a relatively narrow space in which the operation is very delicate. Periodontal defects are much more narrow, typically only a few millimeters, and the blockage of adjacent tissue makes manipulation very difficult. Accurate placement and retention of membranes in guided tissue regeneration is a very important element in determining the effectiveness of a treatment. Membranes used for GTR (guided tissue regeneration) are divided into 2 types, one is an absorbable membrane and one is a non-absorbable membrane. Regardless of the type of membrane, it is cut during the procedure to cover the root surface and the edges of the defect by 2-3mm, based on the measured data. The cut membrane needs to be attached to the adjacent tooth surfaces and cover the bone defect area, the bone bag is usually located on the adjacent surface, namely the membrane needs to be attached to the adjacent 2 tooth surfaces, and the shapes of the adjacent surfaces of different tooth roots are inconsistent, so that the trimming of a completely ideal membrane is theoretically very difficult. If the film is trimmed insufficiently, it does not provide a good barrier to the growth of epithelial tissue too quickly, and if the film is trimmed too much, it affects the coverage of the gums, and once exposed to the mouth, it is susceptible to infection. Even if a skilled clinician cuts the membrane by using the template, puts the membrane in the bone defect area for verification, then trims and verifies, the time of at least 10 minutes is spent when a basically suitable membrane is finally cut out, the time spent by an unskilled doctor is longer, and the patient is often allowed to have a rest in the closed mouth during the period of time, a large amount of microorganisms in the oral cavity can migrate to the bone defect area after debridement, so that the possibility of infection of the operative site is greatly increased, the operative time is prolonged, and the pain of the patient and the operation difficulty of the operative are increased. Moreover, because the membrane is directly attached to the defect area, the membrane is not fixed with the bone tissue below and the adjacent root surface, the membrane needs to be replaced once the membrane is touched during the process of gingival suture, and the operation difficulty of the operation is greatly increased.

Disclosure of Invention

Aiming at the defects or shortcomings in the prior art, the invention provides a method for 3D printing of an individualized periodontal tissue regeneration material, which comprises the steps of acquiring bone defect shape data of a periodontal bone defect patient by using preoperative Cone Beam Computed Tomography (CBCT) equipment, determining bone grafting shape data according to the bone defect shape data, determining shape slice processing data and raw materials for 3D printing according to the bone grafting shape data, and printing the individualized periodontal tissue regeneration material by using the shape slice processing data and the raw materials through a Fused Deposition Modeling (FDM) three-dimensional printer, so that the method is convenient for a doctor to operate and can realize ideal surgical effects.

The technical scheme of the invention is as follows:

a method of 3D printing of personalized periodontal tissue regeneration material, comprising the steps of: the method comprises the steps of acquiring bone defect shape data of a periodontal bone defect patient by utilizing a Cone Beam Computed Tomography (CBCT) device, determining bone grafting shape data according to the bone defect shape data, determining shape slice processing data and raw materials for 3D printing according to the bone grafting shape data, and then printing out an individualized periodontal tissue regeneration material by utilizing the shape slice processing data and the raw materials through a Fused Deposition Modeling (FDM) three-dimensional printer.

The raw material for 3D printing at least comprises a mixed raw material of polycaprolactone PCL and magnesium chloride, wherein the mixed raw material is used for implanting a bone defect entity in a bone tissue defect area, the polycaprolactone PCL serving as a bioabsorbable material is gradually degraded in a human body, and magnesium ions in the magnesium chloride are gradually released to promote proliferation and differentiation of bone cells so as to guide growth of surrounding bone tissues.

The surface part of the raw material for 3D printing comprises polylactic acid-polyglycolic acid polymer, the polylactic acid-polyglycolic acid polymer is used for forming a membrane structure combined with the surface of the implanted entity, and the printing area of the membrane structure exceeds the bone defect edge by 2-3 mm.

The coronal part implanted with the mixed material of polycaprolactone PCL and magnesium chloride of the bone defect entity is provided with a plurality of bulges, and the bulges are connected with a film structure of polylactic acid-polyglycolic acid polymer covered on the coronal part through mechanical latch hooks.

The film structure is covered and attached to the adjacent root surface, and the shape of the film structure is determined according to the depression and the shape of the adjacent surface of the tooth.

The membrane structure is multilayer structure, the one side of membrane structure and the contact of gum tissue is smooth structure in order to prevent the income of gum epithelium, thereby the one side of membrane structure and the contact of bone tissue is coarse texture in order to increase the area of contact of membrane and bone tissue through mechanical lock hook and increase stability.

The membrane structures are respectively printed as buccal membrane structures and lingual membrane structures on adjacent surfaces of teeth to avoid tooth contact point blocking; the root bifurcation on the buccolingual side is of an integrated structure at the position which is not easy to be blocked.

The personalized periodontal tissue regeneration material is subjected to the following sterilization treatment: soaking in anhydrous ethanol and 0.5% NaOH water solution for not less than 24 hr, and soaking in deionized water for not less than 30 min.

The personalized periodontal tissue regeneration material is soaked in a growth factor solution after disinfection treatment to promote bone tissue growth.

The implanted bone defect solid is a porous structure to induce the growth of osteocytes and periodontal ligament cells.

The invention has the following technical effects: the 3D printing method of the personalized periodontal tissue regeneration material can avoid the influence of adverse human factors on bone grafting, the implanted form of the material can be accurately analyzed through a three-dimensional model before operation, the consistency of the gaps of the implanted material in the operation is facilitated, the influence of the sight line, the filling force and the like of an operator is avoided, and the addition of growth factors such as BMP (bone morphogenetic protein), PRP (Platelet Rich Plasma) and the like is facilitated. The invention adopts a 3D printing mode, can print the barrier membrane in advance according to the shape of the bone defect before operation, is combined with an integrated bone grafting material or is independently applied to the bone defect area, and utilizes the bone shape to fix the printed membrane, thereby simplifying the operation process and supporting the realization of the standardization and the accuracy of the operation.

The invention has the following characteristics: 1. the surgery stage is simplified and standardized, soft and hard tissues needing periodontal reconstruction before surgery are well designed, and the surgery is convenient and fast to apply to clinical operation. Is better suitable for the regeneration of periodontal tissues of bone defects, particularly wall bone defects II and III, and can complete fine operation in narrow spaces such as periodontal bone inferior sacks, root bifurcation lesions and the like. 2. The existing bone grafting materials are all granular and are not easy to be systematically combined, the absorbable 3D printing material is adopted to print out the implant in vitro, and the Mg released after the 3D material is absorbed²+ can promote the proliferation and differentiation of bone cell and is favorable to the growth of bone tissue around. 3. The external filling force, the internal structure, the growth factors and the like can be added according to a certain proportion, so that a good filling effect is achieved, and the influence of human factors on the operation effect is reduced. 4. Printing a thin film on the surface of the printed defect space by polylactic acid, wherein the thickness of the thin film exceeds the edge of the neck defect by 2-3mm, and the thickness of the thin film is controlled within 50 microns to prevent the root of the gingival epithelial tissue from growing into the thin film. The surface of the implant with the printed tissue implanted into the bone defect comprises a convex structure and forms mechanical retention with the polylactic acid film facing the bone tissue surface, the implant can be implanted in different times (the buccal and lingual sides) at the position where the operation is difficult, such as the adjacent surface, and the like, and the retention is realized by the friction force of the surface, thereby facilitating the operation of doctors.

Drawings

FIG. 1 is a schematic representation of periodontal tissue with bone defect morphology as measured by CBCT prior to surgery in practicing the present invention. It can be seen from fig. 1 that the buccal side 3 of the mandibular first molar 1 has a degree II radiculotomy and a radiculotomy bone defect zone 4 appears at the vault of the radiculotomy 5, reference numeral 2 in fig. 1 denoting the lingual side.

Fig. 2 is a schematic view of the periodontal tissue of fig. 1 after bifurcated bone defect region 4 has been implanted with a 3D printed personalized periodontal tissue regeneration material of the present invention. In FIG. 2, 5 denotes a mixed bone graft material (black portion in FIG. 2) in which polycaprolactone PCL and magnesium chloride are mixed and printed integrally, and 7 denotes a film of polylactic acid-polyglycolic acid polymer (white portion in FIG. 2). Since the actual operation is performed on the buccal side, the buccal side of the tooth is relatively easy to operate, and after the flap is completely removed, the mixed bone grafting material (black display part) in which polycaprolactone PCL and magnesium chloride are mixed and printed integrally is implanted into the root bifurcation defect region together with the film (white transparent display part on the surface) of the polylactic acid-polyglycolic acid polymer.

Fig. 3 is a schematic view of another periodontal tissue with bone defect morphology measured by CBCT before operation in the practice of the present invention. It can be seen from fig. 3 that a bone defect exists on the mesial-proximal surface 8 of the mandibular first molar 1, and reference numeral 9 in fig. 3 denotes the mesial-proximal surface bone defect region.

Fig. 4 is a schematic view of the periodontal tissue after the first step of implanting the 3D-printed mixed bone graft material 10 of the present invention into the mesial-proximal bone defect region of fig. 3. The mixed bone grafting raw material 10 is a mixed bone grafting raw material formed by mixing polycaprolactone PCL and magnesium chloride. Thus, the first step of implanting only the mixed bone graft material 10 can avoid the adjacent tooth from blocking the implant material.

Fig. 5 is a schematic view of periodontal tissues after buccal-lingual side implantation of a separately printed poly (lactic-co-glycolic acid) polymer film 11 in a second step on the basis of fig. 4. The polylactic acid-polyglycolic acid polymer film 11 covers the surface of the mixed bone grafting raw material 10.

Detailed Description

The present invention will be described with reference to examples.

The invention combines the preoperative CBCT three-dimensional projection technology, designs the personalized integrated implant material for periodontal guided tissue regeneration according to the form of the bone defect of the affected tooth, achieves the purpose of filling the required bone tissue and the membranous tissue for preventing the growth of the gingival epithelium at one step after debridement, can be well combined and retained with the periodontal tissue defect area, maintains the space and prevents the entry of the epithelium, can add growth factors into the material according to the needs, directly sews up the gingiva after filling, simplifies the operation process and improves the operation efficiency. The invention can provide an integrated bone grafting material, degradable magnesium particles are printed by 3D, the implanted form can be accurately analyzed by a three-dimensional model before operation, the gaps of the implanted material are consistent, the bone grafting material is not influenced by the sight line of an operator, the filling force and the like, and the bone grafting material is more beneficial to adding growth factors such as BMP, PRP and the like. The membrane structure on the surface is combined with the implanted bone material in a mechanical latch hook mode, and can be implanted in times or in a mode of separate printing on the cheek-tongue side, so that the blocking of the adjacent bone defect coronal contact point is avoided.

The invention discloses a method for 3D printing of an individualized periodontal tissue regeneration material, which is implemented as follows:

1. the patient firstly shoots CBCT, the operator analyzes the type and the form of the bone defect according to the displayed image, judges whether bone grafting is needed according to the form of the bone defect (walls II and III, mixed bone bag, root bifurcation lesion bone defect and the like), and designs the ideal form after bone grafting reconstruction (especially how the bone bag bone wall defect side of the wall II can reach the ideal bone grafting form, namely, a maximum central entity of the material to be implanted is designed, a plurality of tiny bulges protruding out of the periphery of the maximum entity are designed on the coronal direction of the bone defect and can be connected with a mechanical latch hook of a membrane structure above the tiny bulges, a bone tissue defect area adopts polycaprolactone PCL and magnesium chloride as raw materials, the PCL is gradually degraded as a bioabsorbable material after being implanted into a human body and releases Mg to promote bone growth, meanwhile, the porous structure of the bracket can induce the growth of bone cells and periodontal ligament cells, and various growth factors can be added according to the needs, eventually promoting healing of the periodontal bone defect. And finally, slicing each form as biodegradable, and importing data into an FDM printer, wherein the printing thickness is 0.1-0.2 mm. The mechanism for printing the membrane on the coronal plane after the bone tissue is implanted comprises a printing material which is polylactic acid-polyglycolic acid polymer, combines the shape of the adjacent surface of the tooth and the shape of the bone defect, a printing area which is 2-3mm larger than the edge of the defect and covers and is attached to the adjacent root surface, and the shape of the membrane is designed according to the depression and the shape of the adjacent surface of the tooth in advance. The 3D printed bone defect and the membrane are connected in a mechanical locking hook mode to play a role in retention, and can also be implanted respectively according to needs (namely, the bone tissue is implanted firstly, and then the printed membrane is placed).

2. If the bone is a narrow and deep III-wall bone bag, a patient does not need bone grafting, a 3D printed polylactic acid film is designed according to the defect form, the thickness of the film is 0.1-0.3mm, the film is of a multilayer structure, and the surface contacting with gingival tissues is of a smooth structure, so that the gingival epithelium is prevented from growing in; the surface contacting with the bone tissue is a rough structure, so that the contact area of the membrane and the bone tissue is increased, and the stability of the membrane is improved. The printing material is polylactic acid-polyglycolic acid polymer, combines the shape of the adjacent surface of the tooth and the shape of the bone defect, the printing area exceeds the defect edge by 2-3mm and is covered and attached to the adjacent root surface, and the shape of the film is designed according to the recess and the shape of the adjacent surface of the tooth in advance.

3. After printing, the implantation of bone grafting materials and membranes is simulated through operation, and if tooth contact points and the like are blocked, the materials are printed on the buccal and lingual sides respectively.

4. And after printing, soaking the printing paper in absolute ethyl alcohol and 0.5% NaOH for 24 hours respectively, and soaking the printing paper in deionized water for 30 min.

5. When in use, the printed material can be soaked with growth factors with different concentrations after being sterilized according to the situation, so as to further promote the growth of bone tissues.

Referring to fig. 1 to 2, fig. 1 is a schematic view of periodontal tissues having a bone defect morphology measured by CBCT before operation in the present invention. It can be seen from fig. 1 that the buccal side 3 of the mandibular first molar 1 has a degree II radiculotomy and a radiculotomy bone defect zone 4 appears at the vault of the radiculotomy 5, reference numeral 2 in fig. 1 denoting the lingual side. In FIG. 2, 5 denotes a mixed bone graft material (black block in FIG. 2) in which polycaprolactone PCL and magnesium chloride are mixed and printed integrally, and 7 denotes a film of polylactic acid-polyglycolic acid polymer (transparent in FIG. 2). Since the actual operation is performed on the buccal side, the buccal side of the tooth is relatively easy to operate, and after the flap is completely removed, the mixed bone grafting material (black) in which polycaprolactone PCL and magnesium chloride are mixed and printed integrally is implanted into the bifurcation root defect region together with the film (transparent surface portion) of the polylactic acid-polyglycolic acid polymer.

Referring to fig. 3 to 5, fig. 3 is a schematic view of another periodontal tissue having a bone defect morphology measured by CBCT before operation in the present invention. It can be seen from fig. 3 that a bone defect exists on the mesial-proximal surface 8 of the mandibular first molar 1, and reference numeral 9 in fig. 3 denotes the mesial-proximal surface bone defect region. Fig. 4 is a schematic view of the periodontal tissue after the first step of implanting the 3D-printed mixed bone graft material 10 of the present invention into the mesial-proximal bone defect region of fig. 3. The mixed bone grafting raw material 10 is a mixed bone grafting raw material formed by mixing polycaprolactone PCL and magnesium chloride. Thus, the first step of implanting only the mixed bone graft material 10 can avoid the adjacent tooth from blocking the implant material. Fig. 5 is a schematic view of periodontal tissues after buccal-lingual side implantation of a separately printed poly (lactic-co-glycolic acid) polymer film 11 in a second step on the basis of fig. 4. The polylactic acid-polyglycolic acid polymer film 11 covers the surface of the mixed bone grafting raw material 10.

As can be seen from fig. 1 to 5, satisfactory effects can be obtained by implementing the present invention.

It is pointed out here that the above description is helpful for the person skilled in the art to understand the invention, but does not limit the scope of protection of the invention. Any such equivalents, modifications and/or omissions as may be made without departing from the spirit and scope of the invention may be resorted to.

Claims

1. A method of 3D printing of personalized periodontal tissue regeneration material, comprising the steps of: acquiring bone defect shape data of a periodontal bone defect patient by using Cone Beam Computed Tomography (CBCT) equipment, determining bone grafting shape data according to the bone defect shape data, determining shape slice processing data and raw materials for 3D printing according to the bone grafting shape data, and printing out an individualized periodontal tissue regeneration material by using the shape slice processing data and the raw materials through a Fused Deposition Modeling (FDM) three-dimensional printer;

the raw materials for 3D printing at least comprise mixed raw materials of polycaprolactone PCL and magnesium chloride, the mixed raw materials are used for implanting bone defect entities in bone tissue defect areas, the polycaprolactone PCL serving as a bioabsorbable material is gradually degraded in a human body, and magnesium ions in the magnesium chloride are gradually released to promote proliferation and differentiation of bone cells, so that growth of surrounding bone tissues is guided;

the surface part of the raw material for 3D printing comprises polylactic acid-polyglycolic acid polymer, the polylactic acid-polyglycolic acid polymer is used for forming a membrane structure combined with the surface of the implanted bone defect solid, and the printing area of the membrane structure exceeds the bone defect edge by 2-3 mm;

the coronal part of the mixed material of polycaprolactone PCL and magnesium chloride implanted into the bone defect entity is provided with a plurality of bulges, and the bulges are connected with a mechanical latch hook formed by a film structure of a polylactic acid-polyglycolic acid polymer covered on the coronal part;

2. The method for 3D printing of personalized periodontal tissue regeneration material according to claim 1, characterized in that the membrane structure is fitted in close proximity to the root surface and its profile is determined according to the concavity and morphology of the tooth's proximal surface.

3. The method for 3D printing of personalized periodontal tissue regeneration material according to claim 1, wherein the membrane structures are printed as buccal and lingual membrane structures, respectively, on the adjacent surface of the tooth to avoid tooth contact point blockage; the root bifurcation on the buccolingual side is of an integrated structure at the position which is not easy to be blocked.

4. The method of 3D printing of personalized periodontal tissue regeneration material according to claim 1, wherein the personalized periodontal tissue regeneration material is subjected to the following sterilization treatment: soaking in anhydrous ethanol and 0.5% NaOH water solution for not less than 24 hr, and soaking in deionized water for not less than 30 min.

5. The method of 3D printing of personalized periodontal tissue regeneration material according to claim 1, wherein the personalized periodontal tissue regeneration material is soaked in growth factor solution after sterilization treatment to promote bone tissue growth.

6. The method of 3D printing of personalized periodontal tissue regeneration material according to claim 1, wherein the implant bone defect entity is a porous structure to induce the ingrowth of osteocytes and periodontal ligament cells.