A photocured printing biomimetic gradient zirconia ceramic / resin composite material and a preparation method thereof

Abstract

The present application relates to a kind of light-cured printing biomimetic gradient zirconia ceramic / resin composite material and its preparation method.It is with zirconia ceramic / photoinitiator resin composite slurry as standard, by 3D printing preparation is obtained;Zirconia ceramic / photoinitiator resin composite slurry includes according to weight parts, yttrium stabilized zirconia 45~55 parts, 1,6-hexanediol diacrylate 15~20 parts, pentaerythritol tetraacrylate containing stabilizer MEHQ 5~10 parts, ethanol 3~5 parts, dispersing agent 2~3 parts, initiator 0.1~0.5 parts;Biomimetic crown model is spider web hexagon-squid bone S-shaped composite structure.The present application combines the biomimetic crown model of spider web hexagon-squid bone S-shaped composite structure, zirconia ceramic / photoinitiator resin composite slurry and the product prepared by 3D printing has the composite mechanical properties of dentin / enamel, keeps lower elastic modulus, improves the toughness of light-cured printing biomimetic gradient zirconia ceramic / resin composite material.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of light-cured printing bionic gradient zirconium oxide ceramic / resin composite material and its preparation method, belong to oral prosthetic technology field. BACKGROUND

[0002] All-ceramic restoration is widely used in clinical dentistry, but most of the all-ceramic crowns used in clinical practice are single-component ZrO2 ceramic materials, which leads to mismatch between the mechanical properties of the restoration and the natural tooth, and easy to cause uneven abrasion of the opposite tooth. In addition, the elastic modulus difference between the veneer and core porcelain of the double-layer all-ceramic crown, and the core porcelain and dentin is large, which is easy to cause stress concentration at the interface, thus leading to the occurrence of residual tooth tissue damage phenomenon. Therefore, it is urgent to protect the residual tooth tissue and improve the mechanical properties and service life of the full crown. In recent years, the method of combining ceramic and resin has become an effective strategy to solve the stress concentration of all-ceramic crown.

[0003] 3D printing is a free design and precise manufacturing of material structure, which provides a new opportunity for the optimization of mechanical properties of composite materials, and has great application prospect in the field of oral prosthetics. Liu et al. prepared an epoxy resin composite material with high bending strength by impregnating epoxy resin into a preformed, porous, surface functionalized three-dimensional alumina ceramic skeleton, which is due to the effective transmission of external stress by the interconnected isotropic 3D framework. Li et al. manufactured a glass / rubber interpenetrating phase composite material with a reasonably designed structure by 3D printing technology, and its fracture toughness is higher than that of traditional structure composite. Recently, this method has also been applied to the manufacture of dental composites. Sun et al. produced a zirconia / resin interpenetrating composite material, and through experiments, they proved that the zirconia / resin interpenetrating composite material has significantly improved mechanical properties compared with pure ceramic, thus showing excellent energy absorption and avoiding catastrophic damage, which can be attributed to the bicontinuity of the two phases. The hard inorganic phase provides high fracture strength, and the soft organic phase maintains structural integrity and can provide high energy absorption.

[0004] In the commonly used zirconia crown in clinical practice, the mismatch between the elastic modulus of the crown and the dentin can easily lead to damage to the residual tooth tissue, and the elastic modulus of zirconia is much higher than that of dentin, so reducing the elastic modulus has become a new problem in the development of zirconia crown. For example, VITA ENAMIC combines a dominant ceramic network structure and a reinforced polymer network structure, reducing the elastic modulus to 30 GPa. However, these traditional methods cannot precisely design and manufacture the structure of the composite material, which limits the further optimization and improvement of its mechanical properties.

[0005] Therefore, it is urgent to develop a new type of low elastic modulus zirconia ceramic / resin composite material that matches the human dentin. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a photocuring printing biomimetic gradient zirconia ceramic / resin composite material and a preparation method thereof.

[0007] The technical scheme of the present application is as follows:

[0008] A photocuring printing biomimetic gradient zirconia ceramic / resin composite material is prepared by 3D printing of zirconia ceramic / photoinitiating resin composite slurry taking a biomimetic crown model as a standard;

[0009] The zirconia ceramic / photoinitiating resin composite slurry comprises, by weight fraction, yttrium stabilized zirconia 45-55, 1,6-hexanediol diacrylate 15-20, pentaerythritol tetraacrylate containing stabilizer MEHQ 5-10, ethanol 3-5, dispersant 2-3, and initiator 0.1-0.5.

[0010] The biomimetic crown model is a spider web hexagon-squid bone S-shaped composite structure.

[0011] According to the present application, preferably, the zirconia ceramic / photoinitiating resin composite slurry comprises, by weight fraction, yttrium stabilized zirconia 50, 1,6-hexanediol diacrylate 17.5, pentaerythritol tetraacrylate containing stabilizer MEHQ 7.5, ethanol 4, dispersant 2.5, and initiator 0.25.

[0012] According to the present application, preferably, the yttrium doping amount in the yttrium stabilized zirconia is 2-4 mol%, and D50=200 nm.

[0013] According to the present application, preferably, the dispersant is an ammonium salt solution of acrylate copolymer BYK-154.

[0014] According to the present application, preferably, the initiator is photoinitiator TPO or photoinitiator (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide.

[0015] According to the present application, preferably, the zirconia ceramic / photoinitiating resin composite slurry is prepared by the following method:

[0016] According to the ratio, yttrium stabilized zirconium oxide and dispersant are added into ethanol solution to obtain zirconium oxide solution; then the zirconium oxide solution is stirred in a magnetic water bath at 55-65 DEG C for 0.5-1.5 h, and dried at 125-135 DEG C for 80-100 min to obtain modified zirconium oxide powder; then 1,6-hexanediol diacrylate, pentaerythritol tetraacrylate containing stabilizer MEHQ and initiator are added into the modified zirconium oxide powder, mixed at a speed of 90000-110000 rpm / s for 4-5 min, and then stirred magnetically at a speed of 450-550 rpm / s for 20-30 h to obtain zirconium oxide ceramic / photoinitiating resin composite slurry.

[0017] According to the application, the size of the spider web hexagon-inkfish skeleton S-shaped composite structure is 11*11*3.8mm; the wall thickness of the spider web hexagon-inkfish skeleton S-shaped composite structure linearly and uniformly increases from 1.6mm to 2.2mm from top to bottom.

[0018] According to the application, the porosity of the photocuring printing biomimetic gradient zirconia ceramic / resin composite material is 25-40vol%;

[0019] Further preferably, the porosity of the photocuring printing biomimetic gradient zirconia ceramic / resin composite material is 33.56vol%;

[0020] The porosity = 1-volume fraction, the volume fraction refers to the percentage of the volume of zirconia ceramic relative to the total volume of the photocuring printing biomimetic gradient zirconia ceramic / resin composite material.

[0021] The preparation method of the photocuring printing biomimetic gradient zirconia ceramic / resin composite material, specifically includes the following steps:

[0022] (1) the zirconia ceramic / photoinitiating resin composite slurry is deposited into the trough of the 3D printer, and 3D printing is carried out according to the biomimetic crown model to obtain a zirconia ceramic support;

[0023] (2) the photoinitiating resin and zirconia layer of the zirconia ceramic support obtained in step (1) are separated, cured under the dental photocuring lamp for 3-5min, cleaned, and then subjected to debinding sintering; the zirconia ceramic support after debinding sintering is etched in the piranha solution for 25-35min, cleaned, and then 10-(phosphonooxy) methyl acrylate is coated on the surface of the zirconia ceramic support after etching, and dental fluid resin is injected into the pores under negative pressure, cured under the photocuring lamp for 8-12min, and then polished to obtain the photocuring printing biomimetic gradient zirconia ceramic / resin composite material.

[0024] According to the application, preferably, in step (1), in the 3D printing process, the bottom of the forming table is exposed to ultraviolet irradiation to solidify into the shape of the biomimetic crown model; the forming table is raised by the thickness of a single layer, allowing the zirconia ceramic / photoinitiating resin composite slurry to continue to flow in, flooding the area below the solidified layer, and the cycle continues until the entire zirconia ceramic scaffold is formed.

[0025] The parameters of the 3D printing are 5s11mW, and the thickness of a single layer is 37μm.

[0026] According to the application, preferably, in step (2), the debinding and sintering process is carried out in a muffle furnace according to the following temperature parameters,

[0027] Debinding: uniformly increase the temperature from 20℃ to 100℃ in 120min, uniformly increase the temperature from 100℃ to 300℃ in 900min, keep 300℃ for 1h, uniformly increase the temperature from 300℃ to 460℃ in 900min, keep 460℃ for 1h, uniformly increase the temperature from 460℃ to 550℃ in 900min, and keep 550℃ for 1h.

[0028] Sintering: uniformly increase the temperature from 550℃ to 1550℃ in 120min, keep 1550℃ for 2h, and uniformly decrease the temperature from 1550℃ to 20℃ in 155min.

[0029] According to the application, preferably, in step (2), the piranha solution is a mixed solution of sulfuric acid and hydrogen peroxide, and the volume ratio of sulfuric acid to hydrogen peroxide is 3:1.

[0030] According to the application, preferably, in step (2), the dental fluid resin is Te-Econom Flow resin.

[0031] The application has the following beneficial effects:

[0032] 1. The application takes advantage of the toughness of tooth enamel and the gradient change of tooth enamel and dentin, and adopts a comprehensive biomimetic strategy to design a biomimetic crown model with a spider web hexagonal-squid bone S-shaped composite structure, and the light-cured printed biomimetic gradient zirconia ceramic / resin composite material prepared under the model has the composite mechanical properties of dentin / enamel, and can also maintain a low elastic modulus. The gradient design of the biomimetic crown model can further play a stress buffering role, and improve the toughness of the light-cured printed biomimetic gradient zirconia ceramic / resin composite material.

[0033] 2. The application provides a zirconia ceramic / photoinitiating resin composite slurry, and the slurry obtained by the combination of the components and the preparation method greatly improves the model printing precision, and the model after debinding and sintering has no cracks and excellent mechanical properties.

[0034] 3. The application combines the biomimetic crown model of the spider web hexagonal-squid bone S-shaped composite structure, the zirconia ceramic / photo-initiated resin composite slurry and 3D printing to provide a light-cured printing biomimetic gradient zirconia ceramic / resin composite material and a preparation method thereof. The application realizes the preparation of the light-cured printing biomimetic gradient zirconia ceramic / resin composite material by using the digital light-cured printing technology. The light-cured printing biomimetic gradient zirconia ceramic / resin composite material prepared simulates the mechanical properties of the natural tooth from the tooth enamel to the dentin transition, so that the mechanical properties are between the maximum and minimum pore structures, the establishment of the buffer structure is realized, the effect of reducing the interface stress concentration is achieved, and the elastic modulus is obviously lower than that of the commercial zirconia. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is a total flow chart for the design of the biomimetic crown model.

[0036] In the figure, A is a biomimetic crown model of the spider web hexagonal-squid bone S-shaped composite structure constructed by the comprehensive biomimetic strategy; B is a design and manufacturing process of the gradient zirconia ceramic support with a volume fraction of 33.56%, the uniform zirconia ceramic support, the gradient zirconia ceramic / resin composite material and the uniform zirconia ceramic / resin composite material; C is a typical photo of the gradient zirconia ceramic support, the uniform zirconia ceramic support, the gradient zirconia ceramic / resin composite material and the uniform zirconia ceramic / resin composite material after sintering, and the sample size is 7.5*7.5*2.7mm 3 ; D is an SEM image of the interface between the zirconia ceramic and the dental resin in the zirconia ceramic / resin composite material.

[0037] Figure 2 It is a total flow chart for the design of the zirconia ceramic support.

[0038] In the figure, A is a gradient model design flow chart of the zirconia ceramic support; B is a Boolean operation design flow chart of the gradient zirconia support model and the ordinary dental crown model.

[0039] Figure 3 It is a result chart of the optimization of each component before the printing of the zirconia ceramic / photo-initiated resin composite slurry.

[0040] In the figure, A is the shrinkage rate result of the zirconia ceramic / photo-initiated resin composite slurry with different zirconia contents; B is a green body schematic diagram of the light-cured printing biomimetic gradient zirconia ceramic / resin composite material obtained from the zirconia ceramic / photo-initiated resin composite slurry under different printing parameters; C is the SEM result of the surface of the zirconia ceramic support after the printing and the curing treatment (left) and the zirconia ceramic support after the printing and the uncuring treatment (right).

[0041] Figure 4Optimization results of debinding and sintering of photocured printing biomimetic gradient zirconia ceramic / resin composite;

[0042] In the figure, A is the result of thermal gravimetric analysis (TGA); B is the sintering curve optimized according to thermal gravimetric analysis (TGA); C is the XRD result.

[0043] Figure 5 Mechanical property results of photocured printing biomimetic gradient zirconia ceramic / resin composite;

[0044] In the figure, a is the compressive stress-strain curve of the uniform zirconia ceramic / resin composite of Comparative Example 1; b is the compressive stress-strain curve of the gradient zirconia ceramic / resin composite of Example 2; c is the comparison of elastic modulus between commercial zirconia, the gradient zirconia ceramic / resin composite of Example 2 and dental resin; d is the comparison of elastic modulus between the uniform zirconia ceramic / resin composites of Comparative Example 1 with different wall thicknesses; e is the comparison of compressive strength between the uniform zirconia ceramic / resin composites of Comparative Example 1 with different wall thicknesses; f is the comparison of toughness between the uniform zirconia ceramic / resin composites of Comparative Example 1 with different wall thicknesses; g is the comparison of elastic modulus between the gradient zirconia ceramic scaffold of Example 2, the uniform zirconia ceramic scaffold of Comparative Example 2, the gradient zirconia ceramic / resin composite of Example 2 and the uniform zirconia ceramic / resin composite of Comparative Example 1; h is the comparison of compressive strength between the gradient zirconia ceramic scaffold of Example 2, the uniform zirconia ceramic scaffold of Comparative Example 2, the gradient zirconia ceramic / resin composite of Example 2 and the uniform zirconia ceramic / resin composite of Comparative Example 1; i is the comparison of toughness between the gradient zirconia ceramic scaffold of Example 2, the uniform zirconia ceramic scaffold of Comparative Example 2, the gradient zirconia ceramic / resin composite of Example 2 and the uniform zirconia ceramic / resin composite of Comparative Example 1 (mean ± standard deviation; n = 5), *P < 0.05.

[0045] Figure 6 Finite element simulation results of zirconia ceramic scaffold and photocured printing biomimetic gradient zirconia ceramic / resin composite:

[0046] In the figure, a is the finite element simulation result of the uniform zirconia ceramic / resin composite material of Example 1 with a wall thickness of 1.6 mm; b and c are the finite element simulation results of the gradient zirconia ceramic / resin composite material of Example 2; d is the finite element simulation result of the uniform zirconia ceramic / resin composite material of Comparative Example 1 with a wall thickness of 2.2 mm; e and f are the finite element simulation results of the uniform zirconia ceramic / resin composite material of Comparative Example 1 with a wall thickness of 1.8 mm; g is the finite element simulation result of the elastic modulus of the zirconia ceramic / resin composite material of Example 2 and Comparative Example 5 with different volume fractions; h is the finite element simulation result of the compressive strength of the zirconia ceramic / resin composite material of Example 2 and Comparative Example 5 with different volume fractions; i is the finite element simulation result of the compressive strength and elastic modulus of the zirconia ceramic stent of Comparative Example 2, the gradient zirconia ceramic / resin composite material of Example 1, and the uniform zirconia ceramic / resin composite material of Comparative Example 1.

[0047] Figure 7 Figure of the biocompatibility test results of the photocured printed biomimetic gradient zirconia ceramic / resin composite material;

[0048] In the figure, a is the relationship between the unit volume energy absorption and the maximum transmitted stress of the photocured printed biomimetic gradient zirconia ceramic / resin composite material and other materials; b is the comparison of the mechanical properties of the gradient zirconia ceramic / resin composite material and human tooth enamel and dentin; c is the CCK-8 assay for evaluating cell proliferation shows no significant difference; d is a representative live / dead staining image of Group 1; e is a representative live / dead staining image of Group 2; f is a representative live / dead staining image of Group 3; g is a representative live / dead staining image of Group 4; live bacteria are stained green, dead bacteria are stained red, and when live bacteria and dead bacteria overlap closely, they present orange / yellow staining. DETAILED DESCRIPTION

[0049] The following detailed description of the embodiments of the present application is given on the premise of the technical solutions of the present application, and detailed implementation manners and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0050] The raw materials and equipment used in the embodiments are all conventional commercially available products. 3 mol% yttrium-stabilized zirconia, D50 = 200 nm, is available from Suzhou, China; 1,6-hexanediol diacrylate (HDDA) and pentaerythritol tetraacrylate (PETA) containing stabilizer MEHQ are available from Shanghai Aldrich Technology Co., Ltd., China; photoinitiator TPO is available from Shanghai Aldrich Technology Co., Ltd., China; photoinitiator (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide and ammonium salt solution of acrylate copolymer BYK-154 are available from Geretsried, Germany.

[0051] Embodiment 1

[0052] As shown in Figure 1 A, the present application utilizes the characteristics of the toughness of enamel and the gradient change of enamel and dentin, and adopts a comprehensive biomimetic strategy to design a biomimetic crown model with a spider web hexagon-inkfish skeleton S-shaped composite structure.

[0053] A commercially available 3DMax (Autodesk, Inc., USA) is used to construct a biomimetic crown model with a spider web hexagon-inkfish skeleton S-shaped composite structure with a wall thickness of 1.4 mm to 3.0 mm, and the size of each model is 90×90×40 mm.

[0054] The inventors found that the model with a wall thickness of 1.4 mm was too thin to cause printing failure during the design of the zirconia ceramic bracket, and the mechanical properties of the model with a wall thickness of 3.0 mm were too strong, and the pores were too small to penetrate dental resin. Therefore, the wall thickness of the zirconia ceramic bracket with a spider web hexagon-inkfish skeleton S-shaped composite structure was designed to be a gradient model that linearly and uniformly increases from 1.6 mm to 2.2 mm from top to bottom, rather than a uniform model with uniform thickness, as shown in Figure 2 A.

[0055] Further, since the size of 90×90×40 mm is too large to be printed, the inventors perform a Boolean operation on the gradient zirconia bracket model and the ordinary dental crown model, and the final size is adjusted to 11×11×3.8 mm. The porosity of the zirconia ceramic / resin composite material is analyzed, and the best porosity is 33.56 vol.%, as shown in Figure 2 B.

[0056] Embodiment 2

[0057] A zirconia ceramic / photoinitiating resin composite slurry includes, by weight: yttrium-stabilized zirconia with a doping amount of yttrium of 3 mol% 50 g, 1,6-hexanediol diacrylate 17.5 g, pentaerythritol tetraacrylate containing stabilizer MEHQ 7.5 g, ethanol 4 g, BYK-154 2.5 g, and photoinitiator TPO 0.25 g.

[0058] Then, according to the ratio, yttrium stabilized zirconia and BYK-154 were gradually added into the ethanol solution to obtain a zirconia solution; then the zirconia solution was stirred in a magnetic water bath at 60°C for 1 h to promote the adsorption of the dispersant on the surface of the zirconia particles, and then dried at 130°C for 90 min after stirring to obtain 54 g of modified zirconia powder; then 1,6-hexanediol diacrylate, pentaerythritol tetraacrylate containing stabilizer MEHQ and photoinitiator TPO were added to the modified zirconia powder, and the mixture was mixed vigorously using a planetary degassing mixer BHJ-3 (Henan Beihong Industry Co., Ltd., China) at a speed of 100000 rpm / s for 4.5 min, and then magnetically stirred at a speed of 500 rpm / s for 24 hours to obtain a stable and uniform zirconia ceramic / photoinitiating resin composite slurry.

[0059] A method for preparing a photocured printed biomimetic gradient zirconia ceramic / resin composite material, specifically comprising the following steps:

[0060] (1) 81.75 g of zirconia ceramic / photoinitiating resin composite slurry was deposited into the trough of a DLP 3D printer (AUTOCERA-R, Beijing Shiwu Technology Co., Ltd., China), and 3D printing was performed according to the biomimetic crown model constructed in Example 1; during the printing process, the bottom of the forming table was exposed to ultraviolet irradiation, so that it was cured into the shape of a biomimetic crown model; the forming table was raised by a single layer thickness, allowing the zirconia ceramic / photoinitiating resin composite slurry to continue to flow in, flooding the area below the cured layer, and the cycle continued until the entire green body was formed; the parameters for 3D printing were 5 s 11 mW, the thickness of a single layer was 37 pm, and a gradient zirconia ceramic scaffold with a volume fraction of 33.56% was obtained, and the specific process is shown in Figure 1 B;

[0061] (2) After the gradient zirconia ceramic scaffold of step (1) is formed, the photoinitiating resin and the zirconia layer are separated, and the gradient zirconia ceramic scaffold is cured for 4 min under a dental light curing lamp, then the nascent gradient zirconia ceramic scaffold is cleaned in anhydrous ethanol bath, and any residual non-cured slurry is removed by ultrasonic stirring, followed by debinding and sintering; then the debound and sintered body is etched in 10 mL of piranha solution for 30 min, the etched body is ultrasonically treated in anhydrous ethanol for 10 min and dried, 0.1 g of 10-(phosphonooxy)methyl decyl acrylate (Bide Pharmatech Ltd., Shanghai, China) is coated on the surface of the etched gradient zirconia ceramic scaffold to form an interfacial bond, and 0.5 g of Te-Econom Flow resin is perfused into the pores under a pressure of 0 Mpa, the Te-Econom Flow resin is slowly immersed to prevent air bubbles from being trapped, after perfusion is completed, it is cured under a light curing lamp for 10 minutes to ensure complete polymerization, and finally after polishing with SiC sandpaper, a light-cured printed biomimetic gradient zirconia ceramic / resin composite material is obtained.

[0062] Example 3

[0063] A zirconia ceramic / photoinitiating resin composite slurry comprises, by weight: yttrium-stabilized zirconia with a doping amount of yttrium of 3 mol% 45 g, 1,6-hexanediol diacrylate 15 g, pentaerythritol tetraacrylate containing stabilizer MEHQ 5 g, ethanol 3 g, BYK-154 2 g, and photoinitiator TPO 0.1 g.

[0064] The preparation method of the zirconia ceramic / photoinitiating resin composite slurry is the same as in Example 2.

[0065] The preparation method of the light-cured printed biomimetic gradient zirconia ceramic / resin composite material is the same as in Example 2.

[0066] Example 4

[0067] A zirconia ceramic / photoinitiating resin composite slurry comprises, by weight: yttrium-stabilized zirconia with a doping amount of yttrium of 3 mol% 55 g, 1,6-hexanediol diacrylate 20 g, pentaerythritol tetraacrylate containing stabilizer MEHQ 10 g, ethanol 5 g, BYK-154 3 g, and photoinitiator (2,4,6-trimethylbenzoyl)diphenyl phosphine oxide) 0.5 g.

[0068] The preparation method of the zirconia ceramic / photoinitiating resin composite slurry is the same as in Example 2.

[0069] The preparation method of the light-cured printed biomimetic gradient zirconia ceramic / resin composite material is the same as in Example 2.

[0070] Comparative Example 1

[0071] A zirconia ceramic / resin composite material, the structure of which is as described in Example 1, the composition and preparation method of the zirconia ceramic / photoinitiating resin composite slurry being as described in Example 2, except that the wall thickness is different, and the product of the present comparative example is a uniform zirconia ceramic / resin composite material with different wall thicknesses, the wall thicknesses being 1.6 mm, 1.8 mm, 1.9 mm, 2.0 mm, and 2.2 mm, respectively.

[0072] Comparative Example 2

[0073] A zirconia ceramic scaffold, the structure of which is as described in Example 1, the composition and preparation method of the zirconia ceramic / photoinitiating resin composite slurry being as described in Example 2, step (1), except that the wall thickness is different, and the product of the present comparative example is a uniform zirconia ceramic scaffold with different wall thicknesses, the wall thickness being 1.6 mm.

[0074] Comparative Example 3

[0075] A photocured printed biomimetic gradient zirconia ceramic / resin composite material, the structure of which is as described in Example 1, the composition and preparation method of the zirconia ceramic / photoinitiating resin composite slurry being as described in Example 2, except that the printing parameters are different, and the product of the present comparative example is prepared under the conditions of 7 s 11 mW, 3 s 11 mW, 5 s 13 mW, and 5 s 9 mW, respectively.

[0076] Comparative Example 4

[0077] A zirconia ceramic scaffold, the structure of which is as described in Example 1, the composition and preparation method of the zirconia ceramic / photoinitiating resin composite slurry being as described in Example 2, step (1), except that the zirconia ceramic scaffold is not cured by a dental photocuring lamp.

[0078] Comparative Example 5

[0079] A photocured printed biomimetic gradient zirconia ceramic / resin composite material, the structure of which is as described in Example 1, the preparation method being as described in Example 2, except that the mass of yttrium-stabilized zirconia in the zirconia ceramic / photoinitiating resin composite slurry is different, and the mass of yttrium-stabilized zirconia used in the zirconia ceramic / photoinitiating resin composite slurry of the product of the present comparative example is 14 g, 22 g, 32 g, and 50 g, respectively.

[0080] Comparative Example 6

[0081] A kind of photocuring printing biomimetic gradient zirconia ceramic / resin composite material, structure as described in example 1, zirconia ceramic / photoinitiating resin composite slurry ingredient and preparation method as described in example 2, the difference is that the debinding sintering parameter is different, the product of this comparative example is respectively in the debinding process: 150 min from 20 ℃ to 150 ℃ at a constant speed, in 200 min from 150 ℃ to 250 ℃ at a constant speed, 250 ℃ keeps 1 h, in 300 min from 250 ℃ to 350 ℃ at a constant speed, 350 ℃ keeps 1 h, in 400 min from 350 ℃ to 550 ℃ at a constant speed, 550 ℃ keeps 1 h;

[0082] Sintering: under the condition of 120 min from 20 ℃ to 100 ℃ at a constant speed, in 900 min from 100 ℃ to 300 ℃ at a constant speed, 300 ℃ keeps 1 h, in 900 min from 300 ℃ to 460 ℃ at a constant speed, 460 ℃ keeps 1 h, in 900 min from 460 ℃ to 550 ℃ at a constant speed, 550 ℃ keeps 1 h, it is prepared.

[0083] Comparative example 7

[0084] A kind of zirconia ceramic / resin composite material, structure as described in example 1, zirconia ceramic / photoinitiating resin composite slurry ingredient and preparation method as described in example 2, the difference is that the debinding sintering parameter and wall thickness are different, the uniform zirconia ceramic / resin composite material with 1.6 mm wall thickness is prepared using the debinding sintering parameter described in comparative example 6.

[0085] Test example 1

[0086] 1, the shrinkage test of photocuring printing biomimetic gradient zirconia ceramic / resin composite material prepared in example 2 and photocuring printing biomimetic gradient zirconia ceramic / resin composite material prepared in comparative example 5, the results are shown in Figure 3 A.

[0087] As shown by Figure 3 A, the increase of yttrium stabilized zirconia content is related to the decrease of volume shrinkage after sintering, when the proportion of yttrium stabilized zirconia is 61.16%, the photocuring printing biomimetic gradient zirconia ceramic / resin composite material is best, and the incidence of model surface cracking is reduced.

[0088] 2, the green body schematic diagram of photocuring printing biomimetic gradient zirconia ceramic / resin composite material obtained under different printing parameters of example 2 and comparative example 3, as shown in Figure 3 B;The SEM results of zirconia ceramic scaffold of example 2 and zirconia ceramic scaffold of comparative example 4 are shown in Figure 3 C.

[0089] As shown by Figure 3B~C can be seen that the printing precision is best under the 5s 11mW power and immediate post-curing treatment, while under the 7s 11mW and 5s 13mW power, there is excessive growth of fine pores, under the 3s 11mW and 5s 9mW power, the zirconia layer and the resin layer are broken, and the zirconia layer is adhered to the vat film. And the printed photocured printing biomimetic gradient zirconia ceramic / resin composite material layer under the 5s 11mW parameter is more firmly bonded between the layers, which is the best printing parameter.

[0090] 3. Thermogravimetric analysis (TGA) was performed on the photocured printing biomimetic gradient zirconia ceramic / resin composite material prepared in Example 2 and the photocured printing biomimetic gradient zirconia ceramic / resin composite material prepared in Comparative Example 6, and the results are shown in Figure 4 A.

[0091] As can be seen from Figure 4 A, a minimum weight loss of 1.71% occurs below 300°C, mainly due to the evaporation of excess alcohol and the bottom layer resin. Between 300°C and 460°C, the binder removal rate is 23.36%; the exothermic peak indicates that the mass loss is fastest at 416.9°C. Subsequently, between 460°C and 550°C, a mass loss of 10.66% occurs, with a peak loss at 506.9°C. Above 550°C, there is no further change, indicating that the photosensitive polymer is completely removed. Finally, the sintering curve parameters are optimized according to the thermogravimetric analysis (TGA) results as shown in Figure 4 B.

[0092] 4. The gradient zirconia ceramic / resin composite material prepared in Example 2, the gradient zirconia ceramic scaffold, and the uniform zirconia ceramic / resin composite material (1.8mm) prepared in Comparative Example 1, the uniform zirconia ceramic scaffold (1.6mm) prepared in Comparative Example 2 were photographed and displayed as shown in Figure 1 C.

[0093] Test Example 2

[0094] 1. Finite element simulation tests were performed on the photocured printing biomimetic gradient zirconia ceramic / resin composite material prepared in Example 2, the zirconia ceramic / resin composite material (1.6mm) prepared in Comparative Example 1, and the zirconia ceramic scaffold (1.6mm) prepared in Comparative Example 2 to predict the potential cracking tendency in the structure.

[0095] The specific method is: using ABAQUS instrument (Dassault Systemes Simulia Corp., USA), 1000N stress is applied on the Z axis of the photocured printed biomimetic gradient zirconia ceramic / resin composite material prepared in Example 2, the zirconia ceramic / resin composite material (1.6 mm) prepared in Comparative Example 1 and the zirconia ceramic scaffold (16 mm) prepared in Comparative Example 2 to simulate the maximum occlusal force value. The complete fixed boundary condition is carefully applied on the bottom surface, anchoring the bottom surface while compressing the top surface. Finite element analysis is used to carefully check the stress distribution at different locations, and the results are shown in Figure 6 .

[0096] As can be seen from Figure 6 , with the increase of the wall width, the stress dispersed on the zirconia ceramic scaffold will be smaller and smaller, indicating that the energy absorption effect is stronger. Under the action of the applied force, the stress is more dispersed on the upper part of the scaffold with larger thickness, absorbs larger stress, so the stress is smaller, and the stress in the middle part is the most concentrated, which is a transition structure from top to bottom. The gradient scaffold and the composite material in the zirconia ceramic scaffold gradually fracture along the compression direction, and these cracks expand to the thicker surface with the increase of strain. This leads to a slight increase in stress in the composite material, delays the failure process Figure 6 f, 6h), and the stress on the Z axis is uniformly distributed Figure 6 b, 6d). Under the same analysis step, the stress distribution of the gradient material is smaller than that of the uniform material, and the gradient material absorbs more energy, so it shows stronger elastic modulus and compressive strength than the uniform material Figure 6 b, 6f, 6d and 6h). The finite element simulation results are compared with the experimental data of elastic strength and modulus. The simulation results are consistent with the experimental results, proving that the elastic modulus and compressive strength of the gradient material are stronger than those of the uniform material, and the finite element results of the composite material are stronger than those of the single zirconia ceramic scaffold Figure 6 i).

[0097] Test Example 3

[0098] The photocured printed biomimetic gradient zirconia ceramic / resin composite material prepared in Example 2 and the photocured printed biomimetic gradient zirconia ceramic / resin composite material prepared in Comparative Example 3 are characterized.

[0099] 1. Microstructure analysis

[0100] The surface morphology of the photocured printed biomimetic gradient zirconia ceramic / resin composite prepared in Example 2 and the photocured printed biomimetic gradient zirconia ceramic / resin composite prepared in Comparative Example 3, and the microstructure of the zirconia and dental fluid resin interface in the photocured printed biomimetic gradient zirconia ceramic / resin composite prepared in Example 2 and the photocured printed biomimetic gradient zirconia ceramic / resin composite prepared in Comparative Example 3 were imaged using a field emission scanning electron microscope (G300 FE-SEM, Carl Zeiss, Germany). The specific method was as follows: the composite was sputtered with a gold layer for 5 min at a current of 10 mA, and SEM imaging was performed at a working distance of 8 mm and an acceleration voltage of 5 kV, and the results are shown in Figure 1 D and Figure 3 C.

[0101] From Figure 1 D, it can be seen that the bonding between zirconia and dental fluid resin is tight.

[0102] From Figure 3 C, it can be seen that under the printing parameters of 5s and 11mW, the bonding between the zirconia layers is the tightest.

[0103] 2. XRD analysis

[0104] The photocured printed biomimetic gradient zirconia ceramic / resin composite prepared in Example 2 and the zirconia ceramic / resin composite prepared in Comparative Example 7 were subjected to phase transition analysis (t-m) by X-ray diffraction (XRD, Ultima IV, Rigaku, Tokyo, Japan) in the 2θ range of 20° to 90°, using Cu Kα radiation at 40 mA and 45 kV, and the results are shown in Figure 4 C.

[0105] From Figure 4 C, it can be seen that the photocured printed biomimetic gradient zirconia ceramic / resin composite prepared in Example 2 contains tetragonal zirconia after sintering.

[0106] 3. Mechanical properties

[0107] The photocured printed biomimetic gradient zirconia ceramic / resin composite prepared in Example 2, commercial zirconia, dental resin, the zirconia ceramic / resin composite (1.6 mm) prepared in Comparative Example 1, and the zirconia ceramic scaffold (16 mm) prepared in Comparative Example 2 were subjected to compression and three-point bending tests using a microcomputer-controlled electronic universal testing machine (SUST Ltd., Zhuhai, China) at a loading rate of 0.05 mm / s. Five tests were performed on each sample, and the standard deviation was reported, and the stress-strain curve was obtained; the Young's modulus, toughness, bending strength, and compressive strength were derived from the stress-strain curve, and the toughness was calculated, and the results are shown inFigure 5 As shown.

[0108] Depend on Figure 5 It can be seen that for homogeneous zirconia ceramic / resin composites, the elastic modulus, compressive strength, and toughness of the material gradually increase with changes in zirconia volume fraction and wall thickness. The elastic modulus of the 2.2mm wall thickness reaches 1352.67MPa (±11.18), which is 1.90 times that of the 1.6mm wall thickness (710.39MPa (±12.63)). The compressive strength of the 2.2mm wall thickness reaches 133.91MPa (±3.20), which is 1.43 times that of the 1.6mm wall thickness (93.37MPa (±3.04)). The toughness of the 2.2mm wall thickness reaches 10.73MJ / m³ (±0.52), which is 6.44MJ / m³ that of the 1.6mm wall thickness. 3 (±0.40) is 1.67 times. For gradient zirconia ceramic / resin composites, the elastic modulus of the gradient composite is 1012.50 MPa (±9.09), the compressive strength is 113.72 MPa (±2.62), and the toughness is 8.96 MJ / m. 3 (±0.34), all within the range of wall widths of 1.8 and 2.0. At the same volume fraction, compared to uniform zirconia ceramic / resin composites, gradient zirconia ceramic / resin composites exhibited an 8.5% increase in elastic modulus, a 7.5% increase in compressive strength, and a 3.2% increase in toughness. The mechanical properties of zirconia ceramic / resin composites continuously improved with increasing wall thickness, and the mechanical properties of the gradient structure were superior to those of the uniform structure.

[0109] 4. The photocured printed biomimetic gradient zirconia ceramic / resin composite material prepared in Example 2 was compared with foams, ceramics, metals and polymers disclosed in the article “Leary, M.; Mazur, M.; Elambasseril, J.; McMillan, M.; Chirent, T.; Sun, Y.; Qian, M.; Easton, M.; Brandt, M., Selective laser melting (SLM) of AlSi12Mg lattice structures. Materials & Design 2016, 98, 344-357”, the article “Li, S.; Li, Q. M., Response of functionally graded polymeric foam under axial compression. International Journal of Mechanical Sciences 2021, 210.”, the article “Wang, Z.; Li, Z.; Shi, C.; Zhou, W., Mechanical performance of vertex-based hierarchical vs square thin-walled multi-cell structure. Thin-Walled Structures 2019, 134, 102-110.”, the article “Parande, G.; Manakari, V.; Wakeel, S.; Kujur, M.; Gupta, M., Enhancing Mechanical Response of Monolithic Magnesium Using Nano-NiTi (Nitinol) Particles. Metals 2018, 8(12).” and the results are shown in Figure 7a; the mechanical property data of the photocured printed biomimetic gradient zirconia ceramic / resin composite material prepared in Example 2 were compared with human tooth enamel and dentin disclosed in the article “V. Imbeni, J.J. Kruzic, G.W. Marshall, S.J. Marshall, R.O. Ritchie, The dentin-enamel junction and the fracture of human teeth, Nat. Mater. 4 (2005) 229-232, https: / / doi.org / 10.1038 / nmat1323.” and the article “S. Algharaibeh, H. Wan, R. Al-Fodeh, A.J. Ireland, D. Zhang, B. Su, Fabrication and mechanical properties of biomimetic nacre-like ceramic / polymer composites for chairside CAD / CAM dental restorations, Dent. Mater. (2021) 1-12, https: / / doi.org / 10.1016 / j.dental.2021.10.016.”, and the results are shown in Figures Figure 7 b.

[0110] As can be seen from Figure 7 a, the photocured printed biomimetic gradient zirconia ceramic / resin composite material prepared in Example 2 of the present application exhibits similar energy absorption rate to the materials reported in other literatures. As can be seen from Figure 7 b, the mechanical properties of the photocured printed biomimetic gradient zirconia ceramic / resin composite material prepared in Example 2 of the present application are between dentin and enamel, which can reduce the stress concentration problem commonly seen in dentistry and protect the remaining dental tissue.

[0111] Test Example 3, cytotoxicity test

[0112] 1. Cell proliferation test

[0113] Human skin fibroblasts (HSF, Procell, China) were maintained in culture at 37°C, 5% CO2, 95% air in complete medium (89% DMEM high glucose medium, 10% fetal bovine serum and 1% penicillin / streptomycin). Before testing, the test materials were first washed with deionized water, PBS buffer and 75% ethanol in sequence, and sterilized under ultraviolet light for 2 hours. The 5 groups are as follows: the first group is HSF cell culture for 1, 3, 7 days; the second group is the comparative example 1 uniform zirconia ceramic / resin composite material (1.6mm), which is co-cultured with HSF cells for 1, 3, 7 days; the third group is a commercial zirconia block, which is co-cultured with HSF cells for 1, 3, 7 days; the fourth group is the example 2 photocured printing biomimetic gradient zirconia ceramic / resin composite material, which is co-cultured with HSF cells for 1, 3, 7 days; the fifth group is complete medium without any material and cells. Then the cytotoxicity of the above 5 groups of cells was determined using the Cell Counting Kit-8 detection kit according to the manufacturer's instructions. Specifically, after 1, 3 and 7 days of cell culture, the culture medium was completely replaced with 1ml DMEM containing 10% CCK-8 reagent, and the absorbance was measured by a microplate reader (SPECTRO star Nano, BMG Labtech, Offenburg, Germany) at 450nm wavelength. After 2 hours of co-culture, the absorbance was measured by a microplate reader (SPECTRO star Nano, BMG Labtech, Offenburg, Germany) at a wavelength of 450nm, and the results are shown in Figure 7 c.

[0114] As can be seen from Figure 7 c, the photocured printing biomimetic gradient zirconia ceramic / resin composite material prepared by the present application has no cytotoxicity.

[0115] 2, cell viability staining

[0116] After 3 days of co-culture, the first to fourth groups were subjected to cell viability staining using a live / dead cell viability kit. Fluorescence images were captured in a dark room using a scanning microscope (D-35 578, Leica, Wetzlar, Germany), and the results are shown in Figure 7 d-g.

[0117] As can be seen from Figure 7 d-g, the photocured printing biomimetic gradient zirconia ceramic / resin composite material prepared by the present application has good biocompatibility for clinical application.

Claims

1. A photocured printed biomimetic gradient zirconia ceramic / resin composite material, characterized in that, is a zirconia ceramic / photoinitiating resin composite slurry is taken as a standard of a biomimetic crown model, and is prepared by 3D printing; The zirconia ceramic / photoinitiating resin composite slurry comprises, in parts by weight, yttrium stabilized zirconia 45-55, 1,6-hexanediol diacrylate 15-20, pentaerythritol tetraacrylate containing stabilizer MEHQ 5-10, ethanol 3-5, dispersant 2-3, and initiator 0.1-0.

5. The yttrium stabilized zirconia has a yttrium doping amount of 2-4 mol%, and D50=200 nm. The biomimetic crown model is a spider web hexagon-inkfish skeleton S-shaped composite structure, the size of the spider web hexagon-inkfish skeleton S-shaped composite structure is 11*11*3.8 mm, and the wall thickness of the spider web hexagon-inkfish skeleton S-shaped composite structure linearly and uniformly increases from 1.6 mm to 2.2 mm from top to bottom. The porosity of the photocured printed biomimetic gradient zirconia ceramic / resin composite material is 25-40 vol%.

2. The photocured printed biomimetic gradient zirconia ceramic / resin composite material according to claim 1, wherein, The zirconia ceramic / photoinitiating resin composite slurry comprises, in parts by weight, yttrium stabilized zirconia 50, 1,6-hexanediol diacrylate 17.5, pentaerythritol tetraacrylate containing stabilizer MEHQ 7.5, ethanol 4, dispersant 2.5, and initiator 0.

25.

3. The photocured printed biomimetic gradient zirconia ceramic / resin composite material according to claim 1, wherein, The dispersant is an ammonium salt solution of an acrylate copolymer BYK-154, and the initiator is a photoinitiator TPO or a photoinitiator (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide.

4. The photocured printed biomimetic gradient zirconia ceramic / resin composite of claim 1, wherein, The zirconia ceramic / photoinitiating resin composite slurry is prepared by the following method: According to the proportion, the yttrium stabilized zirconia and the dispersant are added to an ethanol solution to obtain a zirconia solution; then the zirconia solution is stirred in a magnetic water bath at 55-65 DEG C for 0.5-1.5 h, and dried at 125-135 DEG C for 80-100 min to obtain a modified zirconia powder; then 1,6-hexanediol diacrylate, pentaerythritol tetraacrylate containing stabilizer MEHQ and initiator are added to the modified zirconia powder, mixed at a speed of 90000-110000 rpm / s for 4-5 min, and then stirred magnetically at a speed of 450-550 rpm / s for 20-30 h to obtain the zirconia ceramic / photoinitiating resin composite slurry.

5. The photocured printed biomimetic gradient zirconia ceramic / resin composite of claim 1, wherein, The porosity of the photocured printed biomimetic gradient zirconia ceramic / resin composite material is 33.56 vol%.

6. The method of claim 1, wherein the photocurable printing biogradient zirconia ceramic / resin composite is prepared by the steps of: Specifically comprising the following steps: (1) The zirconia ceramic / photoinitiating resin composite slurry is deposited into a trough of a 3D printer, and 3D printing is performed according to the biomimetic crown model to obtain a zirconia ceramic scaffold; (2) separating the light-induced resin and the zirconia layer of the zirconia ceramic scaffold obtained in step (1), curing for 3-5 min under a dental photocuring lamp, cleaning, and then performing debinding and sintering; acid-etching the zirconia ceramic scaffold after debinding and sintering in an arowana solution for 25-35 min, cleaning, coating 10-(phosphonooxy) methyl acrylate on the surface of the acid-etched zirconia ceramic scaffold, and then pouring dental fluid resin into the pores under negative pressure, curing for 8-12 min under a photocuring lamp, and then polishing and grinding to obtain a photocured and printed biomimetic gradient zirconia ceramic / resin composite material.

7. The production method according to claim 6, wherein In step (1), in the 3D printing process, the bottom of the forming table is exposed to ultraviolet irradiation to solidify into a biomimetic crown model shape; the forming table is raised by a single layer thickness, allowing zirconia ceramic / light-induced resin composite slurry to continue to flow in, flooding the area below the solidified layer, and the cycle continues until the entire zirconia ceramic scaffold is formed. The parameters of the 3D printing are 5 s 11 mW, and the thickness of a single layer is 37 μm.

8. The production method according to claim 6, wherein In step (2), the debinding and sintering process is performed in a muffle furnace according to the following temperature parameters: Debinding: uniformly increasing the temperature from 20°C to 100°C in 120 min, uniformly increasing the temperature from 100°C to 300°C in 900 min, maintaining 300°C for 1 h, uniformly increasing the temperature from 300°C to 460°C in 900 min, maintaining 460°C for 1 h, uniformly increasing the temperature from 460°C to 550°C in 900 min, and maintaining 550°C for 1 h; Sintering: uniformly increasing the temperature from 550°C to 1550°C in 120 min, maintaining 1550°C for 2 h, and uniformly decreasing the temperature from 1550°C to 20°C in 155 min.

9. The production method according to claim 6, wherein In step (2), the arowana solution is a mixed solution of sulfuric acid and hydrogen peroxide, and the volume ratio of sulfuric acid to hydrogen peroxide is 3:1; the dental fluid resin is Te-Econom Flow resin.

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