KR101689535B1 - Composite Resin - Google Patents

Abstract

The present invention relates to a composite resin which has high processing cutting properties and easy processability based on a reduced content of silica, has sufficient strength, and uses materials not harmful to the human body, and a method for preparing the same. The method comprises the steps of: i) blending 2,2-bis-(4-(3-methacryloxy-2-hydroxypropoxy)phenylpropane (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA) and trimethylolpropane triacrylate (TMPTA) to provide a polymer compound; ii) forming silica by using barium aluminosilicate; iii) mixing the polymer compound obtained from step i), the silica obtained from step ii), a silane treating agent, a polymerization initiator and a preservative to provide a mixture; and iv) subjecting the mixture obtained from step iii) to defoaming and curing processes to obtain a composite resin. The composite resin has high processing cutting properties and easy processability based on a reduced content of silica, has high strength, and is obtained by a simple process so that production costs may be reduced.

Description

TECHNICAL FIELD [0001] The present invention relates to a composite resin,

The present invention relates to a composite resin and a method of manufacturing the same, and more particularly, to a composite resin using a material which is harmless to the human body and which is easy to process due to high cutting machinability by reducing the content of silica, will be.

In general, if a tooth is lost due to damage or deficiency due to dental caries or fracture, a great obstacle to pronunciation, writing, and aesthetics occurs. In addition, when the normal arrangement of the teeth starts to be shifted due to the movement of the adjacent teeth in the empty space without teeth, the food is caught between the teeth, resulting in tooth decay or appearance and bad breath. In particular, the damage or deficiency of the molar can not be properly eaten, so nutritional deficiency may occur. Damage or lack of the front teeth causes aesthetic problems. In addition, the probability of secondary caries occurring as a damaged or defective part is drastically increased.

Currently, patients who are caused by tooth damage or deficiency are given masticatory and aesthetic treatments through dental restoration or prosthetic treatment, which is an alternative to teeth. Dental restorations can be divided into direct repair and indirect repair according to the procedure. Direct dressing is used in small areas where oral restoration is possible, and curing methods also use chemical hardening and light curing. A variety of materials and curing methods can be used to manufacture representative prostheses for indirect dental implants.

Dental restorative procedures are the restoration of tooth replacement that is used as a substitute for teeth in the cavity formed by cutting out the affected part of the tooth that is required to be performed due to partial damage caused by the caries or fracture of the teeth. It is a drag repair material.

Dental restorative materials are used in a wide range of dental and orthodontic dental treatments, as well as general dental procedures for restoration of tooth integrity and fixation of the entire crown, Lt; / RTI >

These dental restorative materials are required to have various properties different from ordinary materials due to the special environment in the oral cavity. In other words, there are many problems such as wet environment close to 100% relative humidity, high occlusal pressure generated during chewing, rapid temperature change, close contact with living tissue, frequent side effects such as hypersensitivity, It should be manufactured considering the factors of the branch. In addition, reflecting the individual's high aesthetic desire due to recent development of mass media, color harmony with hemorrhoids should be considered.

In order to minimize the side effects of tooth loss, the prosthodontic procedure involves replacing the extracted tooth with an artificial substitute such as a fixed prosthesis (crown, bridge) or a removable prosthesis (a prosthesis that can be inserted or removed into the mouth, a denture or a partial denture) Production. The fixed prosthesis is a method of covering the surface of the adjacent natural teeth, the front and the rear, where the teeth have been lost, by about 1.0 to 1.5 mm, and covering the prosthesis. Because it is easy to pronounce like a natural tooth, has no foreign body, and has a high masticating effect, it tends to be restored with a crown or bridge without applying a partial denture if possible. Removable prosthesis is inevitably used when the last tooth, or a lot of teeth, is lost and a healthy abutment to be used for a fixed prosthesis is lacking. Although the treatment period is short and the cost is less, it has a great sense of foreign body and the chewing efficiency is greatly reduced to 1/4 to 1/10.

Dental prostheses are usually custom-made materials and are used as a replacement for tooth structures. Typical dental restorations include restorations, fillers, inlays, onlays, veneers, full and partial crowns, bridges, implants, posts, etc. . The prosthesis is made by a professional dentist, either by hand, or by a technician who is a well-trained professional manufacturer in a laboratory.

Materials used to make dental prostheses typically include gold, ceramics, amalgam, porcelain, PFM, PFG, composites, and the like. Until recently, tooth restoration and prosthesis was preferred to amalgam with low cost and long life span. However, since amalgam has the color of mercury originally, the aesthetics with the tooth declined, and toxicity to the human body and environmental pollution became a problem. Gold is used for large fillings or inlays, but as with amalgam, the gold restored substitute still had the problem of lacking aesthetics with the original tooth. As a result, dentists are turning to ceramic or polymer-ceramic composites where the color of the material matches the color of the original tooth.

Aesthetic prosthesis refers to all procedures that artificially create or cover teeth, most similar to natural teeth after removing some or all of the teeth. In addition to orthodontic treatment, esthetic prosthodontics can address these aesthetically important areas, for example when the frontal areas are unusual in shape, are misaligned, or are very dark or colored. Typical examples are laminate, PFG, Collarless (made from only the porcelain of the crown of the gums), complete ceramics, and bridges. Recent aesthetic dentistry is a progressive treatment that emphasizes not only the removal of pathological conditions within the oral cavity but also the aesthetic appearance of the oral cavity.

Traditional dental prosthesis manufacturing procedures require a minimum of two dental visits to the patient. Impression on teeth and dentition as a rubbery product on first visit. After that, the prosthesis is made of metal, ceramics, or composite material, and is made to fit comfortably to the oral condition of the patient after completion of the production. It takes a period of one to two days or longer to manufacture the dental prosthesis, and it is labor-intensive to require a high level of skill and skill because the technician is made by hand during the manufacture of the dental prosthesis.

Due to recent developments in technology, computerized automation equipment such as optics, digitization devices, mechanical milling machines and CAD / CAM have significantly reduced the manual work area of the technicians and the dental prosthesis manufacturing period. Such computerized automation equipment manufactures dental prostheses by cutting, milling and grinding them into nearly precise shapes and forms of the necessary restorations at a faster rate and lower labor requirements than conventional manual methods. The CAD / CAM devices are available from Ce.novation (Inocermic, Germany), Ceron (Degudent, Germany), Cerec 3D (Sirona, Germany), Cerec InLab (Sirona, Germany), Decim (Cad.esthetcs, Germany), Medfacturing (Bego Medical, Germany), Ekton (Germany), Everest (Kavo, Germany), Evolution 4D (D4D Technologies, USA) ), Pricident DCS (DCS, Switzerland), Perfactory (DeltaMed, Germany), Procera Biocare, Sweden), Pro 50 (Cynovad, Canada), Wol-Cram -CAM (ZFN, Germany), ZirkonZahn (Steger, Italy), and the like.

The manufacture of a dental prosthesis using a CAD / CAM apparatus typically involves the use of a "mill blank ", i.e. a solid block of material from which the prosthesis is cut or carved. The mill blank is typically made of a ceramic material. VITA CELAY (TM) porcelain blank, VITA Mark II Vitablocks ™ and VITAIN-CERAM ™ ceramic blanks (Vita Zahn, Germany) Fabrik), which are commercially available. Machinable mica ceramic blanks (e.g., Corning MACOR (TM) Blank and Dentsply DICOR (TM) Blank) are also commercially available.

In this regard, although U.S. Patent Application Publication No. US 2003/0031984 discloses a ceramic dental mill blanks, a ceramic dental mill blanks may be formed by a mill blank using CAD / CAM The materials are very hard and have the disadvantage of excessive wear on the tool and prolonged dental prosthesis manufacturing time, and the manufacturing cost due to excessive wear of the tool is relatively high.

U.S. Patent No. 6,899,948 discloses the use of nano-sized silica particles to improve visual opacity and mechanical strength. However, when nano-sized silica particles having an average size of 200 nm or less are applied, the dental composition lacks rheological properties and it is difficult to produce a fine and hardened wheat blank.

In the early 2000s, 3M, Germany introduced a resin block containing ceramic to enable the restoration of dental prosthesis through machining in a small dental cutting machine. However, since the resin component is 80% or more, it is difficult to precisely process it due to the high elasticity unique to the polymer.

In recent years, ceramic filler is 80% in Korea, and it has good physical properties such as human-friendliness and strength enhancement. However, it also has difficulty in precision processing, and ceramics are contained as much as 80% , There is a disadvantage that productivity is low due to a severe cracking phenomenon of a thin part during micro-machining.

Korean Patent No. 10-0854955 Korean Patent No. 10-1382364

It is an object of the present invention to solve the above-mentioned problems, and an object of the present invention is to provide a composite resin having a high processing cuttability by reducing the content of silica and a process for producing the same.

Another object of the present invention is to provide a composite resin which has a reduced content of silica to facilitate processing but has a high strength, and a method for producing the same.

Still another object of the present invention is to provide a composite resin and a method of manufacturing the same that can reduce the production cost as the manufacturing method is simple.

In order to accomplish the above object, the present invention provides a process for producing a polyester resin composition, which comprises reacting 2,2-bis- (4- (3-methacryloxy-2-hydroxypropoxy) phenylpropane (Bis- GMA), triethylene glycol dimethacrylate a step of preparing a polymer compound by mixing glycoldimethacrylate (TEGDMA) and trimethylolpropane triacrylate (TMPTA) to produce a polymer; a step of preparing silica using barium aluminosilicate; A sample mixing step of mixing the polymer compound prepared in the step of preparing the polymer compound with silica, a silane treating agent, a polymerization initiator and an anti-corrosion agent prepared in the silica preparation step to prepare a mixture; And a defoaming and curing step of defoaming and curing the composite resin to produce a composite resin.

At this time, in the step of preparing the polymer compound, 40 to 60% by weight of 2,2-bis- (4- (3-methacryloxy-2-hydroxypropoxy) phenylpropane (Bis- (TEGDMA) and 15 to 35% by weight of trimethylolpropane triacrylate (TMPTA), based on the total weight of the composition.

In the silica production step, the Barium aluminosilicate D50 size is 2 to 3 μm and the Barium aluminosilicate D50 size is 600 to 800 nm.

In this case, the Barium aluminosilicate D50 has a size of 2.5 to 90 μm and the Barium aluminosilicate D50 has a size of 700 nm to 0 to 10 wt%.

The silane treating agent in the sample mixing step is characterized by 97% of 3- (methacryloyloxy) propyltrimethoxysilane (methacryloyloxy) propyltrimethoxysilane.

Further, the polymerization initiator in the sample mixing step is characterized by being composed of benzoyl peroxide.

In addition, the discoloration inhibitor in the sample mixing step is characterized by comprising 2- (2H-Benzotriazol-2yl) -p-cresol (2- (2H-benzotriazol-2 yl)).

At this time, in the sample mixing step, 90 to 110 parts by weight of silica, 1 to 3 parts by weight of a polymerization initiator and 0.05 to 0.2 parts by weight of a discoloration inhibitor are added and mixed in 100 parts by weight of the polymer compound.

Also, in the defoaming and curing step, the mixture prepared in the sample mixing step is defoamed and cured in a vacuum oven maintained at a temperature of 50 to 100 ° C for 5 to 150 minutes.

As can be clearly understood from the above description, the present invention has an advantage that the content of silica is reduced and the machinability is high.

In addition, it has an advantage that it is easy to process by reducing the content of silica but the strength is strong.

In addition, since the manufacturing method is simple, the manufacturing cost can be reduced.

FIG. 1 is a diagram illustrating a method of fabricating a composite resin according to an embodiment of the present invention, according to process steps.
2 is a photograph of an EUT used in a three-point bending test.
Fig. 3 is a photograph of the sample used in the cytotoxicity test.
FIG. 4 is a microscopic photograph of the cytotoxicity test results (experimental group 1). FIG.
5 is a microscopic photograph of the results of the cytotoxicity test (control group 1).
6 is a microscopic photograph of the cytotoxicity test results (control group 4).

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Therefore, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the following embodiments.

Throughout the description of the present invention, when a part includes an element, it is understood that the element may include other elements, not the exclusion of any other element unless specifically stated otherwise.

Throughout the specification of the present invention, it is to be understood that, if a step is located "on" or "before" another step, an indirect temporal relationship, such as a mixing step after each step, The same rights as in the case of < RTI ID = 0.0 >

The terms " about ", " substantially ", etc. used to the extent that they are used throughout the specification of the present invention are used in their numerical values or in close proximity to their numerical values when the manufacturing and material tolerances inherent in the meanings mentioned are presented, Is used to prevent unauthorized exploitation by an unscrupulous infringer of precise or absolute disclosures in order to aid in the understanding of the disclosure. The term " step " or " step of ~ " used throughout the specification does not mean " step for.

The present invention relates to a composite resin and a method of manufacturing the same, and the method of manufacturing a composite resin according to the present invention may include a polymer compound production step, a silica production step, a sample mixing step, and a defoaming and curing step.

Hereinafter, a method for producing a composite resin according to an embodiment of the present invention will be described in detail. The composite resin according to one embodiment of the present invention can be understood more clearly by the following manufacturing method.

2 is a photograph of an EUT used in a three-point bending test, FIG. 3 is a photograph of an EUT used in the cytotoxicity test, FIG. 4 FIG. 5 is a photograph of a cytotoxicity test (control group 1), and FIG. 6 is a microscopic photograph of a cytotoxicity test result (control group 4). FIG.

First, a step of preparing a polymer compound may be performed. (S100)

40 to 60% by weight of 2,2-bis- (4- (3-methacryloxy-2-hydroxypropoxy) phenylpropane (hereinafter referred to as Bis-GMA), triethylene glycoldimethacrylate (Hereinafter referred to as TEGDMA) and 15 to 35% by weight of trimethylolpropane triacrylate (hereinafter referred to as TMPTA).

The method of mixing Bis-GMA, TEGDMA and TMPTA can be carried out by stirring at room temperature using a spatula, or by using a stirrer. It is also possible to mix by using centrifugal mixer.

Since the Bis-GMA has a very high viscosity and is difficult to handle, the TEGDMA and TMPTA are properly mixed in terms of viscosity control and strength control. Since the viscosity is very high at a low temperature and the usability is very low, It is preferable to mix them in a state in which the viscosity is lowered.

Next, a silica production step for producing silica using barium aluminosilicate (S200)

The Barium aluminosilicate D50 has a size of 2 to 3 mu m and the Barium aluminosilicate D50 has a size of 600 mu m. To 800 nm.

In this case, it is preferable that the Barium aluminosilicate D50 size is 2.5 to 90 to 100% by weight and the Barium aluminosilicate D50 size is 700 to 0 to 10% by weight.

Next, a sample mixing step for preparing a mixture by mixing the polymer compound produced in the step of preparing the polymer compound with the silica, silane treating agent, polymerization initiator and anti-constipation agent prepared in the silica preparation step (S300)

The mixed polymer is mixed with silane-treated silica. In order to prevent the progress of the curing process, it is preferable to mix the materials such as the polymerization agent at the end, and the amount of the polymerization initiator is usually 1% by weight based on the polymer and 0.1% by weight in the case of the anti-coloring agent.

At this time, 97% of 3- (methacryloyloxy) propyltrimethoxysilane was used as the silane treating agent for silane treatment of the silica, and the polymerization initiator was benzoyl peroxide (2- (2H-Benzotriazol-2yl) -p-cresol) is used as the anti-fading agent.

 The mixing method is the same as in the above-described polymer compound preparation step, but the mixture is mixed using a high-speed centrifugal mixer or an impeller stirrer.

In addition, in the sample mixing step, 90 to 110 parts by weight of silica, 1 to 3 parts by weight of a polymerization initiator, and 0.05 to 0.2 parts by weight of a color fading inhibitor are added and mixed in 100 parts by weight of the polymer compound, It is preferable that the ratio of the polymer compound and silica is 1: 1.

Finally, the mixture prepared in the sample mixing step is defoamed and cured in vacuum to prepare a composite resin (S400).

The mixture prepared in the sample mixing step is maintained at a temperature higher than room temperature of 50 to 100 DEG C for 5 to 150 minutes to lower the viscosity of the mixture by using a vacuum oven capable of maintaining a strong vacuum state Defoaming and curing. At this time, if the temperature exceeds 50 to 100 ° C, curing may occur during defoaming.

[ Example  One]

Composite resins of experimental group 1 according to one embodiment of the present invention and control groups 1 to 4 constructed differently from one embodiment of the present invention were prepared.

The experimental group 1 was prepared in one embodiment of the present invention, the control groups 1 to 3 were set differently from the embodiment of the present invention, and the control group 4 was a conventional product.

The mixing ratios of the raw materials of the experimental group 1 and the control groups 1 to 4 are shown in Table 1 below.

ingredient Experiment 1 Control 1 Control group 2 Control group 3 Control group 4 Bis-GMA 25 20 15 20 12.5 TEGDMA 12.5 10 7.5 10 11.3 TMPTA 12.5 10 7.5 10 - Barium aluminosilicate 49 59 69 59 75 Other One One One One 1.2 Sum 100 100 100 100 100

As shown in Table 1, Experimental group 1 consisted of 5: 5 silica composed of Bis-GMA, TEGDMA, and TMPTA and Barium aluminosilicate, and control group 1 had a ratio of polymer compound to silica of 4: 6 In the control group 2, the ratio of the polymer compound and silica was 3: 7. In the control group 3, the ratio of the polymer compound and silica was 4: 6 as in the control group 1. However, Do. (Control group 1, Benzoyl peroxide was used as a polymerization agent, while in the case of control group 3, Cumene hydroperoxide was used.) Finally, control group 4 was a polymer compound composed of Bis-GMA and TEGDMA, and Barium aluminosilicate : 1 탆) and amorphous synthetic silica, and the ratio of the polymer compound and silica was 25: 75.

[ Example  2]

Three-point bending tests were performed on Experimental Group 1 prepared according to one embodiment of the present invention and Control Groups 1 to 4 configured differently from one embodiment of the present invention. Test items of the three-point bending test are width, thickness, supporting point distance, breaking load, and bending strength, and the test method is as follows.

First, the test equipment was tested using an external micrometer (293-240, Mitutoyo, Japan) and a universal material testing machine (3366, Instron, U.S.A).

Next, the test method is as follows. (Applicable test method for dental porcelain for cutting process)

First, prepare three samples provided by the manufacturer, and measure the thickness and width of the sample using the measuring equipment.

의 공식을 적용하여 굽힘강도를 계산한다. (P : 파단하중(N), L : 지지점 거리(mm), ω : 시료의 너비(mm), b : 시료의 두께(mm))Place the specimen so that it is at the center of the supporting point of the test apparatus, apply a load to the width side perpendicular to the long axis of the specimen at a crosshead speed of (1 ± 0.5) mm / min and measure the maximum load when the specimen is broken.

To calculate the bending strength. L is the supporting point distance in mm, ω is the width of the sample in mm and b is the thickness of the sample in mm.

analysis Experiment 1 Control 1 Control group 2 Sample 1 Sample 2 Sample 3 Sample 1 Sample 2 Sample 3 Sample 1 Sample 2 Sample 3 Fracture
Load (N) 202.4 195.5 182.9 186.0 169.3 181.0 199.1 147.4 159.2 flex
burglar
(MPa) 119.9 118.4 101.8 102.0 104.2 110.3 111.6 79.7 92.0

analysis Control group 3 Control group 4 Sample 1 Sample 2 Sample 3 Sample 1 Sample 2 Sample 3 Fracture
Load (N) 167.6 144.2 164.1 234.5 195.1 225.1 flex
burglar
(MPa) 100.2 81.7 101.2 124.6 106.8 133.2

Table 2 and Table 3 show the results of the three-point bending test for Experiment Group 1 manufactured according to one embodiment of the present invention and Control Groups 1 to 4 configured differently from the embodiment of the present invention.

[ Example  3]

A cytotoxicity test was conducted on Experimental Group 1 prepared according to one embodiment of the present invention and Control Groups 1 to 4 configured differently from one embodiment of the present invention. Test substances and materials, equipment, specifications and test methods for cytotoxicity test are as follows.

The cell line is NCTC clone 929 (L929) (Korea Cell Line Bank, Korea), the culture conditions are 37 ± 2 ° C, 5 (v / v)% CO ₂ The culture media were RPMI-1640 (HyClone) supplemented with 1% penicillin-Streptomycin and 10% FBS, Natural Rubber Latex (Coltene / Whanledent, USA) as positive control, High Density Polyethylene Film (BJ66464 (20 μL), BG66370 (200 μL), BJ50630 (1000 μL), GILSON, Inc., USA), CO ₂ INCUBATOR (MCO-18AIC, SANYO Electric Biomedical Co., Ltd., Japan), a microscope (CKX41SF, OLYMPUS, Japan) and Centrifuge (VS-5000N, VISION Scientific Co., Ltd., Korea).

The test standard is the Common Criteria for Biological Safety of Medical Devices (Food and Drug Safety Notification No. 2014-115), ISO 10993-5 (2009), Tests for in vitro cytotoxicity.

For the test method, L929 cells are cultured in a 100-mm dish at 3.0 * 105 cells for 24 hours to make 80-90% confluent (the area of the sample should cover 1/10 of the total area). Remove the medium and mix with RRPMI-1640 medium + 20% FPS and 2% agar at a ratio of 1: 1. Add 10 mL of the medium to the dish containing the cells and allow to stand for 20 minutes. At this time, the final concentration of agar is 1%. If the medium is hardened, make 0.01% Neutral red, add 5 mL of the solution, keep it for 15 minutes, and remove the remaining solution. Then, positive control, negative control, and sample are placed on each dish and cultured for 24 hours and observed under a microscope.

The evaluation criteria should be within mild when positive and negative controls are correct, and the items of observation are shown in Table 4 below.

analysis Experiment 1 Control 1 Control group 4
Sample 1 Sample 2 Sample 3 Sample 1 Sample 2 Sample 3 Sample 1 Sample 2 Sample 3 cell
toxicity None None None Moderate Moderate Moderate None None None

Table 5 shows the results of the cytotoxicity tests on Experimental Group 1 prepared according to one embodiment of the present invention and Control Groups 1 to 4 configured differently from one embodiment of the present invention.

In conclusion, the composite resin and the manufacturing method thereof according to the embodiment of the present invention reduce the content of silica to increase the machinability, which is easy to process but does not have a strength and has a strength similar to the conventional one. There is an advantage that it can be used.

Although the present invention has been described in detail with reference to the embodiments using Experimental Group 1 and Control Groups 1 to 4, the present invention is not limited to the above-described embodiments, but may be modified into various forms, It will be obvious that the same may be varied in many ways by one skilled in the art. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

Claims (10)

40 to 60% by weight of 2,2-bis- (4- (3-methacryloxy-2-hydroxypropoxy) phenylpropane (Bis-GMA), triethylene glycoldimethacrylate (TEGDMA) 15 to 35% by weight of trimethylolpropane triacrylate (TMPTA) and 15 to 35% by weight of trimethylolpropane triacrylate (TMPTA) to prepare a polymer compound;
Barium aluminosilicate D50 having a size of 2.5 to 90 to 100% by weight and Barium aluminosilicate D50 having a size of 700 to 0 to 300 nm are prepared by using barium aluminosilicate, 10% by weight of silica to prepare silica;
90 to 110 parts by weight of the silica produced in the silica preparation step, 1 to 3 parts by weight of the polymerization initiator and 0.05 to 0.2 parts by weight of the discoloring inhibitor are mixed with 100 parts by weight of the polymer compound produced in the step of preparing the polymer compound, To prepare a mixture; And
And a defoaming and curing step of defoaming and curing the mixture prepared in the sample mixing step in a vacuum oven maintained at a temperature of 50 to 100 ° C for 5 to 150 minutes to prepare a composite resin. Gt; delete delete delete The method according to claim 1,
The silane treating agent in the sample mixing step may be,
(Methacryloyloxy) propyltrimethoxysilane) of 97% by weight or more and 3- (methacryloyloxy) propyltrimethoxysilane. The method according to claim 1,
The polymerization initiator in the sample-
Benzoyl peroxide. ≪ RTI ID = 0.0 > 8. < / RTI > The method according to claim 1,
In the sample mixing step,
(2H-Benzotriazol-2yl) -p-cresol). 2. The method for producing a composite resin according to claim 1, wherein the resin is selected from the group consisting of 2- (2H-benzotriazol-2yl) -p-cresol. delete delete A composite resin produced by the method of any one of claims 1, 5, 6 or 7.

Images