An acid-resistant and antibacterial lithium silicate glass-ceramic for surface and its preparation method and application

Abstract

The present invention belongs to the technical field of oral prosthetics, and particularly relates to a lithium silicate glass-ceramic with acid-resistant and antibacterial surface, and a preparation method and application thereof. In order to provide a lithium silicate ceramic that maintains surface aesthetics, acid corrosion resistance and antibacterial ability, the present invention uses atomic layer deposition method to prepare a titanium oxide acid-resistant layer on the surface of the lithium silicate glass-ceramic. By replacing the Si-O-H bond on the surface of the lithium silicate ceramic with Si-O-Ti bond, it is tightly connected to the ceramic surface, improving the surface acid corrosion resistance. The preparation of the antibacterial layer is to use the template method to prepare a titanium oxide layer with pore channels, which is loaded with carbon nitride-platinum composite antibacterial nanoparticles. Under visible light conditions, reactive oxygen species are released to kill the entering pathogenic bacteria, realizing the construction of a dual-functional glass-ceramic with acid resistance and antibacterial properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of oral prosthetics, and particularly relates to a lithium silicate glass-ceramic with acid-resistant and antibacterial surface, a preparation method thereof and an application thereof. Background Art

[0002] With the improvement of economic level, people's requirements for dental aesthetics are also increasing day by day. All-ceramic crowns are popular among dentists and patients due to their ideal biocompatibility and excellent aesthetic properties. Among various types of dental ceramic restorations, lithium silicate glass-ceramics (LDGC) based on the SiO2-Li2O material system are increasingly widely used in dentistry. Lithium silicate glass-ceramics have good optical and aesthetic properties and can meet the requirements of most ceramic inlays and single crowns. Lithium silicate ceramics are composed of a crystalline part and an amorphous part. Compared with the crystalline part, the hardness of the amorphous part is relatively low, and the ability to resist liquid corrosion is poor. Research shows that exposure to acidic conditions will lead to the release of ions in lithium silicate ceramics, partial degradation of the ceramic surface, increased roughness and plaque accumulation. The oral cavity is an environment that communicates with the outside world. Due to bacterial infections, excessive gastric acid secretion and the intake of acidic beverages, the restorations are often in an acidic environment. At the edge line where the glass-ceramic is bonded to the tooth, bacteria are easily colonized, which further produces acid to corrode the restoration and the teeth at the bridging site, damaging the restoration and causing dental caries at the same time. Therefore, the restoration should have antibacterial ability while being acid-resistant. In order to improve the service life of lithium silicate ceramics, reduce the occurrence of caries at the contact site, and improve the corrosion resistance of the surface and kill the adhered bacteria are of great significance.

[0003] In recent years, the modification of lithium silicate glass-ceramics has mainly been achieved by additionally adding zirconia crystals with higher strength to improve the overall strength. However, pre-adding crystals to increase the overall density will increase the risk of microcracks during the cutting process, and with the increase in the number of crystals, the problem of dissolution of the amorphous and crystalline parts can only be alleviated to a certain extent, and cannot completely prevent it. Limited by the preparation method, it is currently impossible to obtain a lithium silicate ceramic that maintains surface aesthetics, acid corrosion resistance and antibacterial ability at the same time. Summary of the Invention

[0004] The present invention provides a lithium silicate glass-ceramic with acid-resistant and antibacterial surface, a preparation method thereof and an application thereof for the above problems.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides an acid-resistant and antibacterial lithium silicate glass-ceramic with a TiO2 layer deposited on its surface. A TiO2 layer with pore channels is deposited on the TiO2 layer. The pores of the TiO2 layer with pore channels are modified with Pt, and irregular sheet-like carbon nitride nanoparticles modified with Pt are loaded in the pores of the TiO2 layer with pore channels, that is, the irregular carbon nitride nanoparticles are fixed by Pt in the pores of the TiO2 layer with pore channels.

[0007] The present invention also provides a preparation method of an acid-resistant and antibacterial lithium silicate glass-ceramic, comprising the following steps:

[0008] Step 1, pre-treat the lithium silicate glass-ceramic;

[0009] Step 2, prepare an acid-resistant and antibacterial composite structure:

[0010] Step 2.1, preparation of a TiO2 substrate on the surface of the lithium silicate glass-ceramic: Place the pre-treated lithium silicate glass-ceramic in the reactor of an atomic layer deposition system, and alternately introduce titanium isopropoxide and deionized water into the reaction chamber;

[0011] Step 2.2, preparation of a TiO2 layer with pore channels: Alternately introduce titanium isopropoxide and deionized water into the reactor, then alternately introduce trimethylaluminum and deionized water into the reaction chamber. Etch the obtained product in a lactic acid solution to remove aluminum oxide, and take it out of the reaction chamber to obtain a TiO2 layer with a dense bottom layer and a TiO2 layer with pore channels on the surface layer;

[0012] Step 2.3, loading carbon nitride nanoparticles: Load the carbon nitride nanoparticles into the pores of the TiO2 layer with pore channels by an impregnation method;

[0013] Step 2.4, depositing Pt to prepare a double-catalytic antibacterial surface layer: Place the product obtained in Step 2.3 in the reaction chamber, and alternately deposit trimethyl(methylcyclopentadienyl)platinum(IV) (MeCpPtMe3) and O3. At this time, the carbon nitride nanoparticles modified with Pt are encapsulated into the pores of the TiO2 modified with Pt to obtain the acid-resistant and antibacterial lithium silicate glass-ceramic.

[0014] Furthermore, the pre-treatment of the lithium silicate glass-ceramic in Step 1 specifically comprises the following steps:

[0015] Step 1.1, cut the lithium silicate glass-ceramic into samples with dimensions of 20×4×1.6 mm for standby, and polish its surface in a gradient manner using metallographic grinding sandpapers according to 400#, 800#, 1200#, 1600#, and 2000#;

[0016] Step 1.2: Ultrasonically clean the ground and polished lithium silicate glass ceramic with acetone, ethanol, and deionized water for 10 min respectively, and then dry it at 50 °C.

[0017] Furthermore, in Step 2.1, introducing titanium isopropoxide and deionized water into the reactor alternately, the specific steps are as follows:

[0018] Vacuum the reaction chamber and preheat it to 150 °C. At the same time, preheat the outlet temperature of titanium isopropoxide to 80 °C. After introducing titanium isopropoxide for 0.2 s, wait for 3 s, purify the reaction chamber with N2 with a purity of 99.999% for 15 s, then introduce deionized water for 0.04 s, wait for 3 s, and purify the reaction chamber with N2 with a purity of 99.999% for 15 s. The chamber pressure of the vacuum reaction chamber is 10 - 200 Pa; this process is repeated 100 times respectively.

[0019] Furthermore, in Step 2.2, the preparation of the TiO2 layer with pore channels, the specific steps are as follows:

[0020] Step 2.2.1: Vacuum the reaction chamber and preheat it to 150 °C. At the same time, preheat the outlet temperature of titanium isopropoxide to 80 °C. After introducing titanium isopropoxide for 0.2 s, wait for 3 s, purify the reaction chamber with nitrogen with a purity of 99.999% for 15 s, then introduce deionized water for 0.04 s, wait for 3 s, and purify the reaction chamber with nitrogen with a purity of 99.999% for 15 s. The chamber pressure of the vacuum reaction chamber is 10 - 200 Pa; this process is repeated 30 times respectively;

[0021] Step 2.2.2: Vacuum the reaction chamber and preheat it to 150 °C. At the same time, preheat the outlet temperature of trimethylaluminum to 80 °C. After introducing trimethylaluminum for 0.2 s, wait for 3 s, purify the reaction chamber with nitrogen with a purity of 99.999% for 15 s, then introduce deionized water for 0.04 s, wait for 3 s, and purify the reaction chamber with nitrogen with a purity of 99.999% for 15 s. The chamber pressure of the vacuum reaction chamber is 10 - 200 Pa. This process is repeated 30 times respectively, and then return to Step 2.2.1. After Steps 2.2.1 and 2.2.2, it is regarded as a complete operation, and this complete operation is repeated 20 times;

[0022] Step 2.2.3: Etch the obtained product in a lactic acid solution at 37 °C for 6 h to remove alumina, wash it with deionized water until neutral, and then dry it.

[0023] Furthermore, in Step 2.3, loading carbon nitride nanoparticles, the specific steps are as follows:

[0024] Step 2.3.1: Put melamine into a crucible, heat it to 550 °C at a heating rate of 5 °C / min, hold for 120 minutes, then grind the obtained carbon nitride particles, and select carbon nitride with a particle size of 3 - 5 nm using differential centrifugation;

[0025] Step 2.3.2: Prepare a 500 μg / mL carbon nitride solution, immerse the product obtained in Step 2.2 in the solution for 2 h to allow carbon nitride nanoparticles to adsorb into the TiO2 nanopores, and then take it out and dry it at 50 °C for 1 h.

[0026] Furthermore, in Step 2.4, the deposition of Pt to prepare a dual - catalytic antibacterial surface layer is specifically carried out as follows:

[0027] The deposition of Pt is carried out by alternately depositing trimethyl(methylcyclopentadienyl)platinum(IV) and O3 at 150 °C. Trimethyl(methylcyclopentadienyl)platinum(IV) is maintained at 75 °C. The pulse, exposure, and purge times of trimethyl(methylcyclopentadienyl) are 0.5 s, 15 s, and 30 s respectively, and the pulse, exposure, and purge times of O3 are 0.5 s, 10 s, and 30 s respectively. This alternate deposition process is repeated 10 times.

[0028] The present invention also provides an application of the acid - resistant and antibacterial lithium silicate glass - ceramic in dental crown restoration materials.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] The acid - resistant and antibacterial lithium silicate glass - ceramic provided by the present invention prepares an acid - resistant titanium oxide layer on the surface by atomic layer deposition. By replacing the Si - O - H bonds on the surface of the lithium silicate ceramic with Si - O - Ti bonds, it is tightly connected to the ceramic surface, improving the surface acid - corrosion resistance. The preparation of the antibacterial layer uses a template method to prepare a titanium oxide layer with pore - like channels, which is loaded with carbon nitride - Pt composite antibacterial nanoparticles. Under visible light conditions, reactive oxygen species are released to kill the entering pathogenic bacteria, realizing the construction of an acid - resistant and antibacterial dual - functional glass - ceramic. This method can precisely control the thickness of the surface functional layer, and can make the glass - ceramic and the functional layer porcelain combine tightly, with good aesthetic performance and excellent acid - resistant and antibacterial capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a process schematic diagram of this method, where (A) is the deposition of titanium oxide and aluminum oxide on the surface of lithium silicate ceramic by atomic layer deposition; (B) is the acid dissolution to remove aluminum oxide; (C) is the impregnation method to load sheet - like carbon nitride nanoparticles; (D) is the deposition of platinum by atomic layer deposition as the active site of carbon nitride and tightly linking carbon nitride and TiO2 by chemical bonds.

[0032] Figure 2Figure showing the detection results of the aesthetic properties of two samples. Among them, (A) is a photo display of LDGC and Pt@g-C3N4 / TiO2-LDGC, and there is no obvious difference in their color and luster; (B) shows that the color difference ΔE between LDGC and Pt@g-C3N4 / TiO2-LDGC and the standard plate detected by a colorimeter has no obvious difference.

[0033] Figure 3 Figure showing the comparison results of the Young's modulus and hardness of two samples. Among them, (A) is the Young's modulus value of LDGC and Pt@g-C3N4 / TiO2-LDGC, and the Young's modulus of Pt@g-C3N4 / TiO2-LDGC is significantly improved; (B) is the hardness value of LDGC and Pt@g-C3N4 / TiO2-LDGC, and the hardness of Pt@g-C3N4 / TiO2-LDGC is significantly improved.

[0034] Figure 4 Figure showing the lithium element release amount results of two samples.

[0035] Figure 5 Figure showing the wear performance results of two samples.

[0036] Figure 6 Figure showing the results of bacterial survival. Among them, (A) shows the number of viable bacteria on the surface of LDGC by the dilution plate coating method; (B) shows the number of viable bacteria on the surface of Pt@g-C3N4 / TiO2-LDGC by the dilution plate coating method; (C) shows the bacterial survival on the surface of LDGC after visible light irradiation by bacterial live / dead staining; (D) shows the bacterial survival on the surface of Pt@g-C3N4 / TiO2-LDGC after visible light irradiation by bacterial live / dead staining. Detailed implementation manners

[0037] In order to further elaborate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0038] Example 1

[0039] A surface acid-resistant and antibacterial lithium silicate glass-ceramic of this example has a TiO2 layer deposited on its surface, and a TiO2 layer with pore channels is deposited on the TiO2 layer. The pores of the TiO2 layer with pore channels are modified with Pt, and the pores of the TiO2 layer with pore channels are loaded with irregular flaky carbon nitride nanoparticles modified with Pt, that is, the irregular carbon nitride nanoparticles are fixed in the pores of the TiO2 layer with pore channels by Pt.

[0040] As Figure 1 shown, a preparation method of a surface acid-resistant and antibacterial lithium silicate glass-ceramic of this example includes the following steps:

[0041] Step 1, pre-treat the lithium silicate glass-ceramics. The specific steps are as follows:

[0042] (1) Cut the lithium silicate glass-ceramics into samples with dimensions of 20×4×1.6 mm for standby. Use metallographic grinding sandpaper to perform gradient grinding and polishing on the ceramic surface according to 400#, 800#, 1200#, 1600#, and 2000# to make the surface smooth.

[0043] (2) Ultrasonically clean the lithium silicate ceramics with acetone, ethanol, and deionized water for 10 min respectively to remove surface organic substances, and then dry them at 50 °C.

[0044] Step 2, prepare the acid-resistant and antibacterial composite structure on the surface:

[0045] Step 2.1, preparation of the TiO2 substrate on the surface of the lithium silicate glass-ceramics (as shown in (A) of Figure 1 ): Place the pre-treated lithium silicate glass-ceramics in the reactor of the atomic layer deposition system. Use titanium isopropoxide as the metal precursor and deionized water as the oxygen precursor. Alternately introduce titanium isopropoxide and deionized water into the reaction chamber. Specifically:

[0046] Vacuum the reaction chamber and preheat it to 150 °C. At the same time, preheat the outlet temperature of titanium isopropoxide to 80 °C. After introducing titanium isopropoxide for 0.2 s, wait for 3 s, purify the reaction chamber with N2 with a purity of 99.999% for 15 s, then introduce deionized water for 0.04 s, wait for 3 s, and purify the reaction chamber with N2 with a purity of 99.999% for 15 s. The chamber pressure of the vacuum reaction chamber is 10 - 200 Pa; repeat this process 100 times respectively.

[0047] Step 2.2, preparation of the TiO2 layer with pore channels (as shown in (A) of Figure 1 ): Alternately introduce titanium isopropoxide and deionized water into the reactor, and then alternately introduce trimethylaluminum and deionized water into the reactor. Take out the obtained product from the reactor and etch away the alumina in the lactic acid solution to obtain a bottom dense TiO2 layer and a TiO2 layer with pore channels on the surface layer, named TiO2-LDGC. The specific steps are as follows:

[0048] Step 2.2.1, vacuum the reaction chamber and preheat it to 150 °C. At the same time, preheat the outlet temperature of titanium isopropoxide to 80 °C. After introducing titanium isopropoxide for 0.2 s, wait for 3 s, purify the reaction chamber with nitrogen with a purity of 99.999% for 15 s, then introduce deionized water for 0.04 s, wait for 3 s, and purify the reaction chamber with nitrogen with a purity of 99.999% for 15 s. The chamber pressure of the vacuum reaction chamber is 10 - 200 Pa; repeat this process 30 times respectively;

[0049] Step 2.2.2: The reaction chamber is evacuated and preheated to 150 °C. Meanwhile, the outlet temperature of trimethylaluminum is preheated to 80 °C. After introducing trimethylaluminum for 0.2 s, wait for 3 s, then introduce nitrogen with a purity of 99.999% to purify the reaction chamber for 15 s. Then introduce deionized water for 0.04 s, wait for 3 s, and introduce nitrogen with a purity of 99.999% to purify the reaction chamber for 15 s. The chamber pressure of the vacuum reaction chamber is 10 - 200 Pa. This process is repeated 30 times respectively, then return to Step 2.2.1. After performing Step 2.2.1 and Step 2.2.2, it is regarded as a complete operation, and this complete operation is repeated 20 times;

[0050] Step 2.2.3: The obtained product is etched in a lactic acid solution at 37 °C for 6 h to remove aluminum oxide (as shown in (B) of [reference]), washed with deionized water until neutral, and then dried. Figure 1

[0051] Step 2.3: Loading carbon nitride nanoparticles (as shown in (C) of [reference]): The carbon nitride nanoparticles are loaded into the pores of the TiO2 layer with pore channels by the impregnation method. The specific steps are as follows: Figure 1

[0052] Step 2.3.1: Put 3 g of melamine into a crucible, heat it to 550 °C at a heating rate of 5 °C / min, and keep it for 120 minutes. Then grind the obtained carbon nitride particles, and use differential centrifugation to select carbon nitride with a particle size of 3 - 5 nm;

[0053] Step 2.3.2: Prepare a carbon nitride solution with a concentration of 500 μg / mL, immerse the TiO2-LDGC in the solution for 2 h to allow the carbon nitride nanoparticles to adsorb into the TiO2 nanopores, and then take it out and dry it at 50 °C for 1 h.

[0054] Step 2.4: Depositing Pt to prepare a dual-catalytic antibacterial surface layer: Place the product obtained in Step 2.3 into a reactor, and alternately deposit trimethyl(methylcyclopentadienyl)platinum(IV) and O3. At this time, the Pt-modified carbon nitride nanoparticles (g-C3N4) are encapsulated into the Pt-modified TiO2 pores to obtain the surface acid-resistant and antibacterial lithium silicate glass ceramic, named Pt@g-C3N4 / TiO2-LDGC (as shown in (D) of [reference]). The specific steps are as follows: Figure 1

[0055] The deposition of Pt is carried out by alternately depositing trimethyl(methylcyclopentadienyl)platinum(IV) and O3 at 150 °C. The temperature of trimethyl(methylcyclopentadienyl)platinum(IV) is maintained at 75 °C. The pulse, exposure, and purge times of trimethyl(methylcyclopentadienyl) are 0.5 s, 15 s, and 30 s respectively, and the pulse, exposure, and purge times of O3 are 0.5 s, 10 s, and 30 s respectively. This alternate deposition process is repeated 10 times.​​​

[0056] The surface aesthetics of the acid-resistant and antibacterial lithium silicate ceramic prepared in this example is no different from that of the pure lithium silicate ceramic, and it has good acid resistance. The internal carbon nitride loaded in the titanium oxide layer is an irregular nanosheet structure, where Pt nanoparticles are linked between the titanium oxide layer and the carbon nitride particles. Under visible light irradiation, it has excellent antibacterial ability, so it can be used as a dental crown restoration material.

[0057] Example 2

[0058] Perform thin film performance analysis on the acid-resistant and antibacterial glass ceramic prepared in Example 1:

[0059] 1. Colorimetry: Observe the acid-resistant and antibacterial glass ceramic on the surface and the glass ceramic in the unmodified group. There is no obvious change in the acid-resistant lithium silicate ceramic on the surface. Use a colorimeter to compare the color changes, and there is no significant difference.

[0060] 2. Identify the ceramic surface, and the results are as Figure 2 shown in (A). The prepared Pt@g-C3N4 / TiO2-LDGC surface nanolayer film is uniform and transparent, and there is no color difference from the control group; (B) is the color difference value between the sample and the standard plate detected by the colorimeter. There is no obvious difference in ΔE between LDGC and Pt@g-C3N4 / TiO2-LDGC.

[0061] 3. Nanoindentation to detect surface hardness and Young's modulus

[0062] The film hardness and elastic modulus are measured by a nanoindenter (Nanoindenter XP, MTS). The indenter is a diamond triangular pyramid Berkovich indenter with a tip radius of curvature of ~40 nm. The displacement resolution of the instrument is 0.01 nm, and the force resolution is 50 nN. Fix the prepared sample on the sample stage, set the applied force to 200 uN, and hold for 5 s. Measure the hardness and elastic modulus of each sample at least 9 times, and calculate the surface hardness and Young's modulus values of each group of samples. The results are as Figure 3 shown. It can be seen from Figure 3 (A) that the Young's modulus of Pt@g-C3N4 / TiO2-LDGC prepared by this method is significantly improved. It can be seen from Figure 3 (B) that the hardness of Pt@g-C3N4 / TiO2-LDGC prepared by this method is significantly improved.

[0063] 4. Place the control group and the Pt@g-C3N4 / TiO2-LDGC group in an acidic liquid environment with pH 2.5, and use inductively coupled plasma-mass spectrometry to detect the release amount of Li element. The results are as Figure 4As shown, compared with the control group LDGC, the release of Li element by Pt@g-C3N4 / TiO2-LDGC in the acidic environment of pH 2.5 is significantly reduced, indicating its good acid corrosion resistance ability.

[0064] 5. Detection of wear performance: The friction coefficient was detected by an MFT-R4000 high-speed reciprocating friction and wear tester. The specimen to be loaded was fixed on the instrument loading table, and the longitudinal width of the loading table was 2 cm. A Si3N4 ball with a diameter of 5 mm was used as the loading head and aligned with the center position of the specimen test surface. The wear parameters were set by the software, with a constant force of 10 N, a frequency of 3.6 Hz, a temperature of 37 °C, a reciprocating sliding distance of 5 mm, and a movement time of 30 min. After each sample test, the counter-balance ball was replaced. The results are as Figure 5 shown, the friction coefficient of Pt@g-C3N4 / TiO2-LDGC is significantly reduced.

[0065] 6. Detection of the antibacterial ability of the control group and the Pt@g-C3N4 / TiO2-LDGC group. 1 mL of Streptococcus mutans solution was added dropwise to the control group and the Pt@g-C3N4 / TiO2-LDGC group respectively, irradiated with visible light of 100 mW for 0.5 h, then taken out after culturing at 37 °C for 24 h, evenly coated on an LB plate, and the sterilization effect was observed. The results are as Figure 6 shown in (A) and (B) below. Compared with the LDGC group, the number of viable bacteria on the surface of Pt@g-C3N4 / TiO2-LDGC is significantly reduced.

[0066] 7. Detection of the antibacterial ability of the control group and the Pt@g-C3N4 / TiO2-LDGC group. 1 mL of Streptococcus mutans solution was added dropwise to the control group and the Pt@g-C3N4 / TiO2-LDGC group respectively, irradiated with visible light of 100 mW for 0.5 h, then taken out after culturing at 37 °C for 24 h, and SYTO 9 (green) and PI (red) were used to stain the bacteria for live-dead staining to observe the survival of the bacteria. The results are as Figure 6 shown in (C) and (D) below. Pt@g-C3N4 / TiO2-LDGC can significantly kill Streptococcus mutans under visible light irradiation.

[0067] The above shows and describes the main features and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

[0068] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only includes an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A surface acid-resistant and antibacterial lithium silicate glass-ceramic, characterized in that, A TiO2 layer is deposited on the surface of the lithium silicate glass-ceramic, and a TiO2 layer with porous channels is deposited on the TiO2 layer. The pores of the TiO2 layer with porous channels are modified with Pt, and irregular flaky carbon nitride nanoparticles modified with Pt are loaded in the pores of the TiO2 layer with porous channels, that is, the irregular carbon nitride nanoparticles are fixed in the pores of the TiO2 layer with porous channels by Pt.

2. The preparation method of the acid-resistant and antibacterial lithium silicate glass-ceramic on the surface according to claim 1, characterized in that It includes the following steps: Step 1, pre-treat the lithium silicate glass-ceramic; Step 2, prepare a surface acid-resistant and antibacterial composite structure; Step 2.1, preparation of the TiO2 substrate on the surface of the lithium silicate glass-ceramic: Place the pre-treated lithium silicate glass-ceramic in the reactor of the atomic layer deposition system, and alternately introduce titanium isopropoxide and deionized water into the reaction chamber; Step 2.2, preparation of the TiO2 layer with porous channels: Alternately introduce titanium isopropoxide and deionized water into the reactor, then alternately introduce trimethylaluminum and deionized water into the reaction chamber, take out the obtained product from the reaction chamber, and etch away alumina in the lactic acid solution to obtain a bottom-layer dense TiO2 layer and a surface-layer TiO2 layer with porous channels; Step 2.3, loading carbon nitride nanoparticles: Load carbon nitride nanoparticles into the pores of the TiO2 layer with porous channels by the impregnation method; Step 2.4, depositing Pt to prepare a double-catalytic antibacterial surface layer: Place the product obtained in Step 2.3 in the reaction chamber, and alternately deposit trimethyl(methylcyclopentadienyl)platinum(IV) and O3. At this time, the carbon nitride nanoparticles modified with Pt are encapsulated into the pores of the TiO2 modified with Pt to obtain the acid-resistant and antibacterial lithium silicate glass-ceramic on the surface.

3. The preparation method of a surface acid-resistant and antibacterial lithium silicate glass-ceramic according to claim 2, characterized in that, In Step 1, the specific steps for pre-treating the lithium silicate glass-ceramic are as follows: Step 1.1, cut the lithium silicate glass-ceramic into samples with a size of 20×4×1.6 mm for standby, and polish its surface gradiently with metallographic grinding sandpaper according to 400#, 800#, 1200#, 1600#, 2000#; Step 1.2, ultrasonically clean the ground and polished lithium silicate glass-ceramic with acetone, ethanol, and deionized water for 10 min respectively, and then dry it at 50 °C.

4. The preparation method of an acid-resistant and antibacterial lithium silicate glass-ceramic for surface according to claim 2, characterized in that, In Step 2.1, the specific steps for alternately introducing titanium isopropoxide and deionized water into the reaction chamber are as follows: The reaction chamber is evacuated and preheated to 150 °C. At the same time, the outlet temperature of titanium isopropoxide is preheated to 80 °C. After introducing titanium isopropoxide for 0.2 s, wait for 3 s, purify the reaction chamber with N2 with a purity of 99.999% for 15 s, then introduce deionized water for 0.04 s, wait for 3 s, purify the reaction chamber with N2 with a purity of 99.999% for 15 s, and the chamber pressure of the vacuum reaction chamber is 10-200 Pa; this process is repeated 100 times respectively.

5. The preparation method of a surface acid-resistant and antibacterial lithium silicate glass-ceramic according to claim 2, characterized in that, In Step 2.2, the specific steps for preparing the TiO2 layer with porous channels are as follows: Step 2.2.1: The reaction chamber is evacuated and preheated to 150 °C. Meanwhile, the outlet temperature of titanium tetraisopropoxide is preheated to 80 °C. After introducing titanium tetraisopropoxide for 0.2 s, wait for 3 s, purify the reaction chamber with nitrogen with a purity of 99.999% for 15 s, then introduce deionized water for 0.04 s, wait for 3 s, and purify the reaction chamber with nitrogen with a purity of 99.999% for 15 s. The chamber pressure of the vacuum reaction chamber is 10 - 200 Pa. This process is repeated 30 times respectively. Step 2.2.2: The reaction chamber is evacuated and preheated to 150 °C. Meanwhile, the outlet temperature of trimethylaluminum is preheated to 80 °C. After introducing trimethylaluminum for 0.2 s, wait for 3 s, introduce nitrogen with a purity of 99.999% to purify the reaction chamber for 15 s, then introduce deionized water for 0.04 s, wait for 3 s, and introduce nitrogen with a purity of 99.999% to purify the reaction chamber for 15 s. The chamber pressure of the vacuum reaction chamber is 10 - 200 Pa. This process is repeated 30 times respectively. Then return to Step 2.2.

1. After performing Step 2.2.1 and Step 2.2.2, it is regarded as one complete operation. This complete operation is repeated 20 times. Step 2.2.3: The obtained product is etched in lactic acid solution at 37 °C for 6 h to remove alumina, washed with deionized water until neutral, and then dried.

6. The preparation method of an acid-resistant and antibacterial lithium silicate glass-ceramic according to claim 2, characterized in that, In Step 2.3, loading carbon nitride nanoparticles is specifically carried out as follows: Step 2.3.1: Put melamine into a crucible, heat it to 550 °C at a heating rate of 5 °C / min, and keep it for 120 minutes. Then grind the obtained carbon nitride particles, and use differential centrifugation to select carbon nitride with a particle size of 3 - 5 nm. Step 2.3.2: Prepare a carbon nitride solution with a concentration of 500 μg / mL. Immerse the product obtained in Step 2.2 in the solution for 2 h to enable carbon nitride nanoparticles to adsorb into the TiO2 nanopores. After taking it out, dry it at 50 °C for 1 h.

7. The preparation method of a surface acid-resistant and antibacterial lithium silicate glass-ceramic according to claim 2, characterized in that, In Step 2.4, depositing Pt to prepare a dual - catalytic antibacterial surface layer is specifically carried out as follows: The deposition of Pt is carried out by alternately depositing trimethyl(methylcyclopentadienyl)platinum(IV) and O3 at 150 °C. Trimethyl(methylcyclopentadienyl)platinum(IV) is maintained at 75 °C. The pulse, exposure, and purge times of trimethyl(methylcyclopentadienyl)platinum(IV) are 0.5 s, 15 s, and 30 s respectively, and the pulse, exposure, and purge times of O3 are 0.5 s, 10 s, and 30 s respectively. This alternating deposition process is repeated 10 times.

8. The application of the acid-resistant and antibacterial lithium silicate glass-ceramic for the surface as described in claim 1, characterized in that For dental crown restoration materials.

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