|Year : 2022 | Volume
| Issue : 3 | Page : 125-131
Effect of two cleansing materials on hardness and surface roughness of conventional and three-dimensional printed denture base materials
Gehan El-Olimy1, Amel Salem2
1 Department of Dental Materials, Faculty of Dentistry, Tanta University, Tanta, Egypt
2 Department of Prosthodontic, Faculty of Dentistry, Tanta University, Tanta, Egypt
|Date of Submission||31-May-2022|
|Date of Decision||04-Jul-2022|
|Date of Acceptance||22-Jul-2022|
|Date of Web Publication||14-Sep-2022|
(BDS, MSc, PhD) Departments of Dental Materials, Faculty of Dentistry, Tanta University, Tanta, Gharbiya
Source of Support: None, Conflict of Interest: None
The aim of this study was to compare the effects of two different cleansing materials on the hardness and surface roughness of conventional and three-dimensional (3D) printed denture base materials.
Materials and methods
A total of 140 specimens were tested for surface hardness and surface roughness. The samples of each denture base type (n = 70) were randomly divided into seven subgroups each of them = 10 samples. The first subgroup was stored in distilled water. Second, third, and fourth subgroups were immersed for 18, 36, and 54 days in Corega denture cleanser, respectively. Fifth, sixth, and seventh subgroups were immersed for 18, 36, and 54 days in Aloe vera, respectively.
The roughness of the 3D printed denture base material was significantly lower than that of the conventional denture base material. While the hardness of the 3D printed denture base material was significantly higher than that of the conventional denture base material. For the two types of cleaning agents used, there was a nonsignificant difference in hardness of 3D printed and conventional denture base materials immersed in Corega or Aloe vera. There was a significant difference in the surface roughness of 3D printed and conventional denture base materials immersed in Corega and Aloe vera.
Within the limitations of this in vitro study, it was concluded that 3D printed denture base material exhibited significantly more favorable surface roughness and hardness compared to the conventional denture base material. Disinfection by immersion using Corega produced higher surface roughness values than using Aloe vera. While Corega and Aloe vera caused nonsignificant damage to the hardness of the conventional and 3D printed denture base materials.
Aloe vera gel for disinfecting 3D printed and conventional denture base materials is suggested to maintain a smooth surface of the denture base. Printing denture bases is recommended because of its high hardness and low roughness could be achieved.
Keywords: three-dimensional printed denture, base materials, cleansing materials, hardness, roughness
|How to cite this article:|
El-Olimy G, Salem A. Effect of two cleansing materials on hardness and surface roughness of conventional and three-dimensional printed denture base materials. Tanta Dent J 2022;19:125-31
|How to cite this URL:|
El-Olimy G, Salem A. Effect of two cleansing materials on hardness and surface roughness of conventional and three-dimensional printed denture base materials. Tanta Dent J [serial online] 2022 [cited 2023 Jan 31];19:125-31. Available from: http://www.tmj.eg.net/text.asp?2022/19/3/125/356081
| Introduction|| |
Edentulism is a highly prevalent condition globally . Although there has been an increase in rehabilitation with Osseo integrated implants, complete dentures are still a common treatment for the rehabilitation of complete edentulism in poor socioeconomic status . Poly methyl methacrylate will still be the well-liked material of choice for the fabrication of complete denture prostheses . Enhancements in science and innovation have given digital methods for denture base creation, including computer-aided design/computer-aided manufacturing. The benefits of computerized strategies include time consuming and fewer stages decreasing errors possibility. With computer-aided manufacturing, the denture could be fabricated by subtractive or additive manufacturing. Additive manufacturing by three-dimensional (3D) printing includes adding layers of denture base material, incrementally light activated, to construct the denture base . There are currently new 3D-printed materials from different dental producers for denture base construction. While the mechanical properties of conventional denture base have been researched and reported, the evidence of the performance of 3D printed denture base is insufficient , Proper denture hygiene is crucial for maintaining oral health. Deficient cleaning of removable dentures enhances the aggregation and adhesion of denture biofilm. It has been generally revealed that denture biofilm is a reservoir for pioneering microorganisms that can cause Candida-related denture stomatitis or even systemic infections ,. Denture cleaning material may be a synthetic or natural. From the natural denture cleansers, Aloe vera is a successful, available, economical one, and the oldest therapeutic plant ever . It was utilized as a viable therapeutic plant against Candida albicans . Ideal denture cleansers should have antibiofilm activity without negative impacts on the properties of the materials utilized for the fabrication of denture bases . Rough denture surfaces are more liable to retain biofilms with difficulty of removing them . Testing surface hardness and roughness are routinely utilized for analyzing the surface mechanical properties of denture base materials ,. Because cleanliness strategies have been shown to alter the mechanical properties of acrylic denture base materials, the aim of this study was to compare the effects of two different cleansing materials on hardness and surface roughness of conventional and 3D printed denture base materials.
The null hypotheses were; that there was no difference in hardness and surface roughness between conventional and 3D printed denture base materials. Both disinfection solutions used in this study, have no adverse effect on the surface hardness and roughness of the conventional and 3D printed denture base materials.
| Materials and methods|| |
Two types of denture base materials were studied in this research.
- Conventional heat cure denture base material poly methyl methacrylate (Acrostone; Acrostone Dental Manufacturer, Egypt)
- Resin for 3D printing (NextDent Denture 3D+, Soesterberg, the Netherlands).
Also, two kinds of denture cleansers were studied in this research.
- Aloe vera 100% gel concentrate (Vital care of No. Ltd, Dist. America) ingredients: water, propylene glycol, phenoxyethanol, carbomer, polysorbate 20, aminomethyl propanol, chorphenesin, fragrance, tetrasodium EDTA, aloebarbadensis, and leaf juice.
- Corega (Corega Denture Cleanser Tabs, GSK, Egypt). Corega cleansers contain four active ingredients which work in parallel to maintain denture hygiene: potassium caroate, tetra acetyl ethylene diamine, sodium carbonate peroxide, and sodium lauryl sulfoacetate.
Sample size calculation
Sample size calculation was done using the comparison of surface roughness. It was done based on comparing independent samples in the experimental study. The α-error level was fixed at 0.05. the power was set at 80%. To previously published research  the mean and SD of surface roughness after using the first cleaning agent was 0.23 ± 0.19 while it was 0.21 ± 0.10 after using the second cleaning agent. Accordingly, the minimum optimum sample size should be eight samples. The sample size calculation was done using G*Power version 188.8.131.52 (Universtat Kiel, Keil Germany).
A total of 140 specimens of dimensions 3 mm thickness, 10 mm width, and 10 mm length were tested for surface hardness and surface roughness. All denture base samples were constructed according to the manufacturers' instructions. The heat-polymerized acrylic samples were constructed utilizing the compression molding method. A square wax pattern block was prepared using a custom-made metallic mold. A square template made of wax was invested with gypsum, in denture flasks. Short cycle polymerization in a water bath at 72°C for 1.5 h, followed by 30 min boiling in 100°C water was performed. After curing and bench cooling, the specimens were deflasked.
A square block was designed by (Meshmixer Autodesk, California, USA) and saved as a standard tessellation language (STL) file; the 3D-printed samples were printed according to the obtained STL file. Using the STL, the 3D printing was conducted using (Epax 3D, North Carolina, USA).
All specimens were finished with no. 120, 200, and 800 silicon carbide grinding papers and polished with 1000 grade abrasive waterproof paper, rinsed with tap water, and air-dried. Specimens were polished using a slurry of water and pumice with a brush wheel followed by a slurry of tin oxide with a cloth wheel. All samples were polished with only one operator, to guarantee nearly the same pressure of the polishing tools on the samples.
All the specimens were stored in distilled water at room temperature for 2 days. The samples of each denture base type (n = 70) were randomly divided into seven subgroups. Each of them = 10 samples. Each subgroup was soaked into the same container.
- The first subgroup was stored in distilled water.
- The second, third, and fourth subgroups were immersed for 18, 36, and 54 days in Corega denture cleanser, respectively.
- The fifth, sixth, and seventh subgroups were immersed for 18, 36, and 54 days in Aloe vera, respectively.
The cleansers preparation
Corega solutions were prepared according to the manufacturer's instructions, by dropping one Corega tablet into 200 ml of warm water (40°C).
Aloe vera solutions were prepared by dissolving properly 2.5 g of Aloe vera gel in 200 ml warm water.
After 5 min of soaking, the denture base material samples were removed from the cleansing solution and rinsed thoroughly with running water. The sessions of soaking were repeated 10 times daily. Between the immersion procedures, the specimens were saved in distilled water, at room temperature. The 18, 36, and 54 days simulate 6, 12, and 18 months of cleansing by the patient, respectively.
The surface microhardness of the specimens was determined using Digital Display Vickers Microhardness Tester (Model HVS-50, Laizhou Huayin Testing Instrument Co. Ltd, China) with a Vickers diamond indenter and a 20× objective lens [Figure 1]. A load of 100 g was applied to the surface of the specimens for 15 s. Three indentations, which were equally placed over a circle and not closer than 0.5 mm to the adjacent indentations, were made on the surface of each specimen. The diagonal length of the indentations was measured by a built-in scaled microscope and Vickers values were converted into microhardness values. Five measurements were taken for each pair and the mean was used for statistical analysis.
For the determination of surface roughness values, Surface Profile Gage (Positector, SPG, Deflesko Corporation, New York, USA) was used. It is a hand-held electronic instrument that measures the peak-to-valley height of the surface profile of the surfaces [Figure 2]. It consists of a PosiTector body and a built-in probe. The gage is turned on and its probe is carefully applied to the surface to be measured. Five readings were taken for each specimen and then averaged. The mean of the examined specimens was taken as the surface roughness of the material.
Before analysis of surface roughness and hardness data, normality was tested with the Shapiro–Wilk test, and homogeneity of variance was tested with Levene's test. Three-way analyses of variance (ANOVA) were conducted on the surface roughness and hardness data, followed by Scheffe S multiple range test for post-hoc comparisons. All statistical testing was performed using a confidence level of 95% (α=0.05).
| Results|| |
The results of the analysis of variance [Table 1] of hardness data revealed that denture base material, and intervals and their two-way interaction effects (denture base intervals) were statistically significant at P value less than 0.05. While cleaning agent and their two and three-way interaction effects (denture base×cleaning agent, cleaning agent×intervals, and denture base×cleaning agent×intervals) were statistically nonsignificant. The main effect of the denture base yielded an effect size of 0.262 indicating that 26.2% of the variance in the hardness was explained by denture base type [F (1,144)=51.03, P < 0.001]. The main effect of intervals yielded an effect size of 0.445 indicating that 44.5% of the variance in the hardness was explained by intervals [F (3,144)=38.528, P < 0.001]. There were statistically significant interactions (denture base material-intervals, P = 0.004). Indicating that there was a combined effect for denture base and intervals on the hardness.
It can be seen from [Table 2} at baseline, the hardness of the 3D printed denture base material was 44.26 ± 1.2, which was significantly higher than the conventional denture base material (42.62 ± 0.6).
|Table 2: Mean (SD) hardness values of conventional heat-cured acrylic denture base material and three-dimensional printed denture base material at baseline and after immersion in Corega and Aloe vera cleaning materials for different periods|
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A factorial ANOVA (three-way ANOVA) was conducted to compare the main effects of cleaning agents, denture base materials, and intervals as well as their interaction effects on surface roughness and hardness data. The results of the analysis of variance [Table 3] of surface roughness data revealed that denture base material, cleaning agent, intervals, and their two and three-way interaction effects were statistically significant at P value less than 0.05. The main effect of the denture base material yielded an effect size of 0.212 indicating that 21.2% of the variance in the surface roughness was explained by the denture base [F (1,144)=38.81, P < 0.001]. The main effect of the cleaning agent yielded an effect size of 0.175 indicating that 17.5% of the variance in the surface roughness was explained by the cleaning agent [F (1,144)=30.6, P < 0.001]. The main effect of intervals yielded an effect size of 0.401 indicating that 40.1% of the variance in the surface roughness was explained by intervals [F (3,144)=32.13, P < 0.001]. There were statistically significant interactions (denture base material-cleaning agent). P value of 0.005; denture base material – intervals, P value less than 0.001, cleaning agent – intervals, P value of 0.011 and denture base material×cleaning agent×intervals; P = 0.03). Indicating that there were combined effects for denture base material, cleaning agent, and intervals on the surface roughness.
|Table 3: Results of three-way analyses of variance for surface roughness|
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It can be seen from [Table 4] that at baseline, the surface roughness of the 3D printed denture base material was 0.143 ± 0.05 μm, which was significantly lower than the conventional denture base material (0.198 ± 0.019 μm). There was a significant difference in the roughness of 3D printed denture base material by comparing immersion in Corega and Aloe vera at 18, 36, and 54 days. Also, there was a nonsignificant difference in the roughness of conventional denture base material by comparing immersion in Corega and Aloe vera at 18 days, while there was a significant difference at 36 and 54 days comparing Corega and Aloe vera immersion.
|Table 4: Mean (SD) surface roughness values of conventional heat-cured acrylic denture base material and three-dimensional printed denture base material at baseline and after immersion in Corega and Aloe vera cleaning materials for different periods|
Click here to view
| Discussion|| |
This study compared the hardness and roughness of conventional denture base material and 3D printed denture base material. In addition, comparing the effect of Corega and Aloe vera cleaning agent on the hardness and roughness of conventional denture base material and 3D printed denture base material.
Poly methyl methacrylate conventional denture base material has been widely used as a denture base material due to its desirable properties of excellent aesthetics, low water sorption and solubility, relative lack of toxicity, ability to repair, and simple processing techniques . Many attempts have been made to overcome the drawbacks associated with the conventional method of denture fabrication and to improve the properties of conventional denture base material . The digital denture is one of the recent improvements. The digital path of denture fabrication involves the digitization of the information captured from the patient using specific software . Once the denture is digitally designed, it is saved as a STL file. Following that, the denture is manufactured using either an additive 3D-printing or subtractive (computerized numerical controlled milling) technique ,. Milling is popular for manufacturing dentures, but 3D printing provides significant advantages. It is more economical; it does not involve the wear of rotary tools, or the waste of raw materials, and permits the simultaneous manufacturing of multiple products ,.
Denture hygiene and disinfection have been recommended as an essential practice for preventing cross-contamination and the maintenance of healthy oral mucosa ,. Several agents are indicated for denture disinfection and maintaining the health of dentures, classified into mechanical and chemical agents . A disinfection method should be effective without detrimental effects on the properties of materials used for the fabrication of denture base . Properties that are affected by denture cleansers are hardness and surface roughness, hardness, and these are very important for the long-term success of any prosthesis .
Hardness is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion . Hardness influences the surface characteristics of denture base material as it facilitates the prosthesis finishing and maximizes its resistance to abrasion and scratching during service and cleansing . Dentures made of a material with low surface hardness can be damaged by mechanical brushing, causing plaque retention and pigmentation, which can decrease the life of dentures .
The surface roughness of the denture base is a contributing factor to the accumulation of plaque, the adherence of. albicans, and bacterial colonization . Because there is no mention of roughness measurement in the International Standards Organization 1567 for denture base materials, a surface roughness tester was used for roughness measurements by measuring peak to valley height and computing the numeric values representing the roughness of the profile as Ra. The Ra value describes the overall roughness of a surface and is defined as the arithmetic mean value of all absolute distances of the roughness profiles from the center line within the measuring length.
During clinical use of dentures, several disinfection solutions may be used for denture cleaning and stomatitis control. It appears that different materials act differently once exposed to various cleaning agents .
The null hypothesis that no difference in hardness and roughness would be found between conventional and 3D printed denture base materials was rejected because statistical differences were observed among these materials. The results of this study demonstrated that the 3D printed denture base material in this study (NextDent Denture 3D+) presented lower initial surface roughness values and higher initial surface hardness compared to those of conventional denture base materials. Previous studies that assessed the mechanical properties of 3D printing denture base materials and compared them with conventional denture base materials used for denture bases are scanty.
The higher surface hardness of the 3D printed denture base material in this study (Epax 3D), compared to the conventional denture base material, may be attributed to less human error in the automated processing and the resin's compositional effects on mechanical properties. The hardness between the 3D printed and conventional denture base materials in this study was like the findings in a study by Prpić et al. , which compared the hardness of three brands of conventional heat-polymerized, three brands of computer-aided design/computer-aided manufacturing, one 3D-printed, and one polyamide material fabricated denture base materials. In their study, the authors reported a varying range of hardness among conventional denture base materials. One of conventional denture base materials was significantly lower than the 3D-printed as in this study; however, another conventional denture base material was higher than the 3D-printed. Therefore, different denture base material brands may contribute to differences in mechanical properties such as hardness.
The surface roughness between the 3D printed and conventional denture base materials in this study was like the findings in a study by Fernandez et al. . They reported that the 3D printed specimens demonstrated lower surface roughness than conventionally produced after polishing.
The second null hypothesis that both disinfection solutions used in this study could be used without adverse effects on the surface hardness of the conventional and 3D printed denture base materials was accepted. Because the hardness of the conventional and 3D printed denture base specimens were not affected by either Corega or Aloe vera. These findings were similar to the findings in a study by Machado et al.  which evaluated the effect of chemical disinfection solutions on the hardness of conventional denture base material.
While the third null hypothesis that both disinfection solutions Corega and Aloe vera could be used without adverse effects on the surface roughness of the conventional and 3D printed denture base materials was rejected. Because. Corega created more surface roughness than Aloe vera in both denture base samples.
| Conclusions|| |
Within the limitations of this in vitro study, it was concluded that 3D printed denture base material exhibited significantly more favorable surface roughness and hardness compared to the conventional denture base material, so printed denture bases are recommended because of the high hardness and low roughness that can be achieved. Disinfection by immersion using Corega produced higher surface roughness values than using Aloe vera. While Corega and Aloe vera caused nonsignificant damage in the hardness of the conventional and 3D printed denture base materials.
Financial support and sponsorship
Conflicts of interest
| References|| |
Tyrovolas S, Koyanagi A, Panagiotakos DB, Haro JM, Kassebaum NJ, Chrepa V, et al
. Population prevalence of edentulism and its association with depression and self-rated health. Sci Rep 2016; 6:1–9.
Da Veiga Pessoa DM, Roncalli AG, de Lima KC. Economic and sociodemographic inequalities in complete denture need among older Brazilian adults: a cross-sectional population-based study. BMC Oral Health 2016; 17:5.
Alla RK, Sajjan S, Alluri VR, Ginjupalli K, Upadhya N. Influence of fiber reinforcement on the properties of denture base resins. J Biomater Nanobiotechnol 2013; 04:91–97.
Braian M, Jönsson D, Kevci M, Wennerberg A. Geometrical accuracy of metallic objects produced with additive or subtractive manufacturing: a comparative in vitro
study. Dent Mater 2018; 34:978–993.
Lee J, Belles D, Gonzalez M, Kiat-amnuay S, Dugarte A, Ontiveros J. Impact strength of 3D printed and conventional heat-cured and cold-cured denture base acrylics. Int J Prosthodont 2021; 713:1–18.
Prpić V, Schauperl Z, Ćatić A, Dulčić N, Čimić S. Comparison of mechanical properties of 3D-printed, CAD/CAM, and conventional denture base materials. J Prosthodont 2020; 29:524–528.
O'Donnell LE, Smith K, Williams C, Nile CJ, Lappin DF, Bradshaw D, et al
. Dentures are a reservoir for respiratory pathogens. J Prosthodont 2016; 25:99–104.
Kashiwabara T, Yoshijima Y, Hongama S, Nagao K, Hirota K, Ichikawa T. Denture plaque microflora in geriatric inpatients and maxillary defect patients. Prosthod Res Pract 2007; 6:153–158.
Isadkar Y, Palaskar S, Narang B, Bartake A. Aloe vera as denture cleanser. J Dent All Sci 2018; 7:23.
Riyadh Abdulwahhab A, Jassim RK. The effect of Aloe vera extract on adherence of Candida albicans
and other properties of heat cure denture soft lining material. Int J Med Res Health Sci 2018; 7:94–103.
Peracini A, Davi LR, de Queiroz Ribeiro N, de Souza RF, da Silva CHL, de Freitas Oliveira Paranhos H. Effect of denture cleansers on physical properties of heat-polymerized acrylic resin. J Prosthod Res 2010; 54:78–83.
Berger JC, Driscoll CF, Romberg E, Luo Q, Thompson G. Surface roughness of denture base acrylic resins after processing and after polishing. J Prosthodont 2006; 15:180–186.
Machado AL, Breeding LC, Vergani CE, da Cruz Perez LE. Hardness and surface roughness of reline and denture base acrylic resins after repeated disinfection procedures. J Prosth Dent 2009; 102:115–122.
Porwal A, Khandelwal M, Punia V, Sharma V. Effect of denture cleansers on color stability, surface roughness, and hardness of different denture base resins. J Indian Prosthod Soc 2017; 17:61–67.
Abuzar MA, Bellur S, Duong N, Kim BB, Lu P, Palfreyman N, et al
. Evaluating surface roughness of a polyamide denture base material in comparison with poly (methyl methacrylate). J Oral Sci 2010; 52:577–581.
Paulino MR, Alves LR, Gurgel BCV, Calderon PS. Simplified versus traditional techniques for complete denture fabrication: a systematic review. J Prosth Dent 2015; 113:12–16.
Infante L, Yilmaz B, McGlumphy E, Finger I. Fabricating complete dentures with CAD/CAM technology. J Prosth Dent 2014; 111:351–355.
Alp G, Murat S, Yilmaz B. Comparison of flexural strength of different CAD/CAM PMMA-based polymers. J Prosthodont 2019; 28:e491–e495.
Steinmassl O, Offermanns V, Stöckl W, Dumfahrt H, Grunert I, Steinmassl PA. In vitro
analysis of the fracture resistance of CAD/CAM denture base resins. Materials 2018; 11:401–405.
Shim JS, Kim JE, Jeong SH, Choi YJ, Ryu JJ. Printing accuracy, mechanical properties, surface characteristics, and microbial adhesion of 3D-printed resins with various printing orientations. J Prosth Dent 2020; 124:468–475.
Kattadiyil MT, AlHelal A. An update on computer-engineered complete dentures: a systematic review on clinical outcomes. J Prosth Dent 2017; 117:478–483.
Machado AL, Breeding LC, Vergani CE, da Cruz Perez LE. Hardness and surface roughness of reline and denture base acrylic resins after repeated disinfection procedures. J Prosth Dent 2009; 102:115–122.
Azevedo A, Machado AL, Vergani CE, Giampaolo ET, Pavarina AC, Magnani R. Effect of disinfectants on the hardness and roughness of reline acrylic resins. J Prosthodont 2006; 15:235–242.
Paranhos H de FO, Peracini A, Pisani MX, Oliveira V, de C, et al
. Color stability, surface roughness and flexural strength of an acrylic resin submitted to simulated overnight immersion in denture cleansers. Braz Dent J 2013; 24:152–156.
Machado AL, Giampaolo ET, Vergani CE, de Souza JF, Jorge JH. Changes in roughness of denture base and reline materials by chemical disinfection or microwave irradiation. surface roughness of denture base and reline materials. J Appl Oral Sci 2011; 19:521–528.
Vladimir Prpi´c D, Samir ˇCimi´c, DMD5, 1 Zdravko Schauperl, BSME, 2 Amir´Cati´c, DMD, 3 Nikˇsa Dulˇci´c, DMD 4 &, 1PhD. Comparison of Mechanical Properties of 3D-Printed CADConventional Denture Base Materials 2020.pdf.
Pavarina AC, Vergani CE, Machado AL, Giampaolo ET, Teraoka MT. The effect of disinfectant solutions on the hardness of acrylic resin denture teeth. J Oral Rehabil 2003; 30:749–752.
Radford DR, Sweet SP, Challacombe SJ, Walter JD. Adherence of Candida albicans
to denture-base materials with different surface finishes. J Dent 1998; 26:577–583.
Agarwal M, Wible E, Ramir T, Altun S, Viana G, Evans C, et al
. Long-term effects of seven cleaning methods on light transmittance, surface roughness, and flexural modulus of polyurethane retainer material. Angle Orthod 2018; 88:355–362.
Fernandez PK, Unkovskiy A, Benkendorff V, Klink A, Spintzyk S. Surface characteristics of milled and 3D printed denture base materials following polishing and coating: an in-vitro study. Materials 2020; 13:3305–3310.
MacHado AL, Giampaolo ET, Pavarina AC, Jorge JH, Vergani CE. Surface roughness of denture base and reline materials after disinfection by immersion in chlorhexidine or microwave irradiation. Gerodontology 2012; 29:521–528.
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]