Analysis of International Journal of Clinical Preventive Dentistry Research Trends Using Word Network Analysis

Original Article Int J Clin Prev Dent 2018;14(3):184-189 ㆍ https://doi.org/10.15236/ijcpd.2018.14.3.184 ISSN (Print) 1738-8546 ㆍ ISSN (Online) 2287-6197 Analysis of International Journal of Clinical Preventive Dentistry Research Trends Using Word Network Analysis Kyung-Hui Moon 1, Sun-Joo Yoon 1, Hye-sook Kwon 2 1 Department of Dental Hygiene, Jinju Health College, Jinju, 2 Department of Dental Hygiene, Gimcheon University, Gimcheon, Korea Objective: The purpose of this study was to analyze the structure of the research trends of the International Journal of Clinical Preventive Dentistry (IJCPD) through analysis of the word network. The keywords of 371 theses from Issue 1 of 2005 to Issue 1 of 2018 in the IJCPD were extracted and used as data. Methods: The collected data were analyzed using Excel 2016 and Cyram Inc. NetMiner Version 4.4.1. analysis and analysis were conducted on all IJCPD issues. Also, word network analysis per period was also conducted. Results: Of the 676 words acquired from the IJCPD the most frequently used word in the 13-year period was health. Further, discussions on caries, tooth, halitosis, and fluoride were the most active. In clinical preventive dentistry, the upper degree words were tooth, caries, health, fluoride, and halitosis., and the upper betweenness words were tooth, health, caries, plaque, halitosis. Also, the core degree keywords per period was found to be tooth, caries and fluoride in period 1; tooth, health and dentifrice in period 2; and health, caries and index in period 3. Conclusion: The most commonly used word in clinical preventive dentistry studies in the IJCPD over a 13-year period was health and the word was found to be tooth. Results of conducting analysis per period showed that studies were gradually expanded to various fields. It is expected that meaningful research from various aspects can be conducted based on the research trend analysis results of IJCPD using word network analysis. s: word network analysis, International Journal of Clinical Preventive Dentistry (IJCPD), research trend Introduction Corresponding author Sun-Joo Yoon Department of Dental Hygiene, Jinju Health College, 51 Uibyeong-ro, Jinju 52655, Korea. Tel: +82-55-740-1830, Fax: +82-0303-0008-1840, E-mail: wavelove2000@hanmail.net https://orcid.org/0000-0001-8002-9767 Received August 31, 2018, Revised September 4, 2018, Accepted September 18, 2018 Preventive dentistry is an academic discipline that studies the principles and methods for preventing oral diseases in individual patients [1]. International Journal of Clinical Preventive Dentistry (IJCPD) was launched in 2005 (ISSN [Print] 1738-8546; ISSN [Online] 2287-6197); it is published quarterly in March, June, September, and December every year. The official title of the journal is International Journal of Clinical Preventive Dentistry (IJCPD) and the abbreviated title is Int J Clin Prev Dent. Copyright c 2018. Korean Academy of Preventive Dentistry. All rights reserved. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 184

Kyung-Hui Moon, et al:analysis of IJCPD Research Trends Using Word Network Analysis IJCPD consists of original research reports, clinical articles, reviews, case reports, and other materials on preventive dentistry and related subjects that contribute to promoting oral health and development of clinical knowledge and skills related to preventive dentistry [2]. Research papers of various topics related to clinical preventive dentistry are being published in the IJCPD. The number has increased from five papers in 2005 to 20 in 2010 and 41 in 2015. It was proposed as a registration candidate for the National Research Foundation in 2010 and selected as a registered journal in 2014. The journal has since maintained its status up until now. Recently, various research fields have started using network analysis methods to analyze academic knowledge structures [3]. Network analysis is a method for objectifying all data and quantitatively analyzing their relationships. Such network analysis makes it easy to visualize various connection networks and carry out dimensional investigation, making it possible to deduce the macroscopic flow in relational structures [3,4]. Accordingly, the purpose of this study is to implement network analysis methods in the clinical preventive dentistry field to analyze the research trends, based on papers published from the first issue since the founding of IJCPD up until the first issue of 2018. Such analysis will provide the directions and implications of research projects in the future. Materials and Methods 1. Subjects In order to search for the papers subject to this study, the Research Information Service System and the academic journal homepage (http://www.ijcpd.org) were used. This study used 371 out of 374 theses, published from issue 1 of 2005 to issue 1 of 2018 of the IJCPD, as subjects of analysis in which keywords were extracted and used as data. Three theses that were repetitive were excluded from the analysis. 2. Methods The collected data were analyzed using Excel 2016 and Cyram Inc. NetMiner Version 4.4.1. analysis was conducted to identify the research structure of IJCPD and analysis was conducted to identify core words. In addition, based on the studies of Jhang et al. [5], this study categorized the periods into five-year groups as period 1 from 2005 to 2009, period 2 from 2010 to 2014, and period 3 from 2015 to 2018 to analyze the research trends. The method is shown in Table 1. Results 1. analysis From the 676 words deduced from the IJCPD, 68 keyword groups in the top 10% frequency occurrence and with frequency of at least five times were formed. They are as shown in the below table (Table 2). The most frequently used word in clinical preventive dentistry research literature over 13 years was health, and it is evident that studies on caries, tooth, halitosis, and fluoride were the most active. Figure 1 is a graph of the top 45 words in terms of frequency of mention in clinical preventive dentistry studies and the word health appeared predominantly compared to other words. Figure 2 illustrates all of the word networks for IJCPD. In order to illustrate word networks, the 676 total words were reduced to 68 core keywords. Furthermore, the connections among words comprised of numerous links were reduced to the number of links, based on the top 10% in order to deduce good visualization results. 2. Word cloud analysis In order to intuitively identify the central topics of IJCPD through word network analysis, word clouds were visualized. Figure 3 illustrates these word clouds based on the most frequently appearing words in IJCPD. In the illustration, the size of the word is used as illustration criteria to represent its frequency of use. It shows that words such as health, caries, tooth, halitosis, fluoride, index, and dentifrice were the highest frequency words. 3. Centrality analysis 1) Analysis of total keyword degree and betweenness Table 3 shows the top 10 words through analysis. In clinical preventive dentistry, words at the center together with keywords are tooth, caries, health, fluoride, and halitosis. These words may be considered keywords of clinical preventive dentistry with the highest number of correlation with other keywords. The upper betweenness words are tooth, health, caries, plaque, halitosis, etc., Table 1. Theses subject to this study Research section 2005-2009 (period 1) 2010-2014 (period 2) 2015-2018 (period 3) No. of theses 74 174 123 No. of keywords 150 444 299 www.ijcpd.org 185

International Journal of Clinical Preventive Dentistry Table 2. Final 68 keyword groups with frequency of five times or more No. Frequency No. Frequency 1 Health 64 35 Streptococcus 7 2 Caries 50 36 Activity 7 3 Tooth 41 37 Application 7 4 Halitosis 35 38 Behavior 7 5 Fluoride 33 39 Chromatography 7 6 Index 30 40 Hypersensitivity 7 7 Dentifrice 27 41 Method 7 8 Care 20 42 Sugar 7 9 Plaque 19 43 System 7 10 Malodor 18 44 Tea 7 11 Toothbrush 16 45 Agent 6 12 Sealant 15 46 Control 6 13 Disease 14 47 Domain 6 14 Hygiene 14 48 Hardness 6 15 Saliva 14 49 Microhardness 6 16 Toothpaste 14 50 Remineralization 6 17 Gingivitis 13 51 Survey 6 18 Acid 12 52 Viscosity 6 19 Dentin 12 53 Water 6 20 Gingival 12 54 Whitening 6 21 Strength 12 55 SEM 5 22 Toothbrushing 12 56 Appliance 5 23 Child 11 57 Bacterium 5 24 Microorganism 11 58 Cement 5 25 Resin 11 59 Desensitization 5 26 Test 11 60 Enamel 5 27 Denture 10 61 Factor 5 28 Prevention 10 62 Fissure 5 29 Sodium 10 63 Flow 5 30 Education 9 64 Lesion 5 31 Mutans 9 65 Light 5 32 Program 9 66 Milk 5 33 Radiation 8 67 Phosphate 5 34 School 8 68 Pit 5 SEM: scanning electron microscope. and they are words that act as themes that connect words with other words. 2) network degree analysis per period Table 4 divides the period from 2005 to 2018 into three periods to examine changes in degree through analysis of keyword network for each period. The core degree keywords for each season were tooth, caries, and fluoride for period 1; tooth, health, and dentifrice for period 2; and health, caries, and index for period 3. The core degree keyword that shows that concentrated studies were carried out for each period was tooth and it figured 0.078 in period 1, 0.067 in period 2 and 0.044 in period 3, showing that research expanded to various fields going into periods 2 and 3. Figure 2. Word Network of International Journal of Clinical Preventive Dentistry for 13 years. Figure 1. Top 45 words for frequency. 186 Vol. 14, No. 3, September 2018

Kyung-Hui Moon, et al:analysis of IJCPD Research Trends Using Word Network Analysis 3) network betweenness analysis per period Table 5 shows the results of selecting and analyzing the top 15 core keywords for betweenness in each period. Analysis results showed that the betweenness for fluoride (0.379) and tooth (0.348) were high in period 1; in period 2, tooth (0.307) had high betweenness with weight as mediating roles; and then the weight was dispersed to resin (0.124), health (0.119), and cement (0.117). In period 3, most of the keywords of halitosis (0.212), caries (0.180), and tooth (0.1676) did not show big differences in weight. Furthermore, most keywords with high betweenness per period were found to score high in degree as well. Discussion This study aims to analyze the structure of research trends in the IJCPD through word network analysis. Network analysis makes it easy to visualize various connection networks and carry out dimensional investigation, making it possible to deduce the macroscopic flow in relational structures [3,4]. Word network analysis identifies knowledge sharing relations through keywords based on the assumption that the keywords presented in a thesis best express the theme of that thesis [6]. Word network analysis assumes that all of the words that make up the basic text are used to express the meanings of texts and that the meanings of texts are comprised of those words. Among them, there are words that play key roles and they are called keywords [7]. Word network analysis is indicated variously such as keyword network analysis, language network analysis, text net- Table 3. Total keyword degree and betweenness No. Degree Figure 3. Word cloud based on high frequency words. 1 Tooth 0.206522 Tooth 0.33228 2 Caries 0.184783 Health 0.243156 3 Health 0.163043 Caries 0.19149 4 Fluoride 0.141304 Plaque 0.146616 5 Halitosis 0.141304 Halitosis 0.130505 6 Dentifrice 0.130435 Fluoride 0.101563 7 Plaque 0.108696 Dentifrice 0.091166 8 Toothpaste 0.086957 Index 0.067091 9 Index 0.076087 Toothpaste 0.050472 10 Toothbrushing 0.076087 Fracture 0.046688 Table 4. Core degree keywords per period No. Period 1 (2005-2009) Period 2 (2010-2014) Period 3 (2015-2018) Centrality Centrality Centrality 1 Tooth 0.078571 Tooth 0.067332 Health 0.070632 2 Caries 0.071429 Health 0.042394 Caries 0.055762 3 Fluoride 0.064286 Dentifrice 0.034913 Index 0.055762 4 Activity 0.035714 Caries 0.027431 Halitosis 0.052045 5 Halitosis 0.035714 Fluoride 0.027431 Dentifrice 0.048327 6 Index 0.035714 Sodium 0.024938 Tooth 0.04461 7 Plaque 0.035714 Cement 0.022444 Gingivitis 0.02974 8 Strength 0.035714 Plaque 0.022444 Dentin 0.026022 9 Mouthguard 0.028571 Toothbrushing 0.022444 Fluoride 0.026022 10 Sealant 0.028571 Toothpaste 0.022444 Child 0.022305 11 Varnish 0.028571 Halitosis 0.01995 Test 0.022305 12 PFRI 0.021429 Index 0.01995 Care 0.018587 13 Application 0.021429 Sugar 0.01995 Denture 0.018587 14 Bleaching 0.021429 Acid 0.017456 Desensitization 0.018587 15 Filler 0.021429 Chromatography 0.017456 Disease 0.018587 PFRI: plaque formation rate index. www.ijcpd.org 187

International Journal of Clinical Preventive Dentistry Table 5. Core betweenness keywords per period No. Period 1 (2005-2009) Period 2 (2010-2014) Period 3 (2015-2018) 1 Fluoride 0.379959 Tooth 0.307028 Halitosis 0.212442 2 Tooth 0.348047 Resin 0.124787 Caries 0.180394 3 Caries 0.260432 Health 0.119581 Tooth 0.167999 4 Retention 0.247328 Cement 0.117781 Index 0.151391 5 Stroke 0.243577 Fracture 0.107953 Health 0.141656 6 Periodontitis 0.238438 Dentifrice 0.08875 Dentifrice 0.133257 7 Health 0.234943 Plaque 0.084749 Test 0.075409 8 Status 0.233094 Amalgam 0.079277 Fluoride 0.072503 9 Index 0.21593 Corresponding 0.076185 Gingivitis 0.061043 10 Activity 0.188695 Caries 0.071219 Prevention 0.060638 11 Oleary 0.144913 Toothpaste 0.071192 Denture 0.059888 12 Plaque 0.142446 Preparation 0.069813 Desensitization 0.053186 13 Strength 0.084892 Denture 0.060552 Saliva 0.051228 14 Light 0.075283 Sealant 0.056035 Toothpaste 0.048581 15 PFRI 0.074409 Chromatography 0.049728 Sealant 0.047329 PFRI: plaque formation rate index. work analysis, and semantic connection network analysis [8] based on the researcher s preference. In a semantics identification case study shared among policy stakeholders through socio-cognitive network analysis, Park and Chung [9] summed up the existing studies of text (word) network analysis in Korea from 2009 to 2012 by research scope and subjects; definition of nodes; definition of relations; analysis methods; and analysis tools. Therefore, it is evident that research is being conducted using several analysis tools in various fields. Accordingly, this study extracted keywords from 371 studies published in the IJCPD from 2005 to 2018 to analyze data. Results of word analysis showed that, among the 676 words extracted from the IJCPD, there were 68 words that represented keyword groups based on top 10% high frequency and frequency of at least five times. The most frequently used word in clinical preventive dentistry studies over 13 years was health, and it is also evident that discussions on caries, tooth, halitosis, and fluoride were the most active. When illustrating the word clouds based on words that appear the most in clinical preventive dentistry studies through word network analysis, it is evident that words such as health, caries, tooth, halitosis, fluoride, index, and dentifrice have high frequencies. The most representative scale for network analysis is. Typical centralities are degree and betweenness, and they are measured by computing the number of continuing relations for objects in networks. Degree measures how many other objects are connected an object; betweenness is measured based on the role of a word as a medium or bridge constructing networks of one node to another node [3]. Based on analysis, words that form by connecting keywords in clinical preventive dentistry were tooth, caries, health, fluoride, and halitosis. These are the keywords of clinical preventive dentistry with the most number of connections with other keywords. The upper betweenness keywords are tooth, health, caries, plaque, and halitosis, and they are the words that act as mediums that connect different words. When examining the degree keywords per period by dividing the period between 2005 to 2018 into three periods, tooth weighed 0.078 in period 1; 0.067 in period 2; and 0.044 in period 3. It shows that the central axis inclined towards a somewhat narrow concept in the first period, but spread to different themes in periods 2 and 3. For betweenness per period, fluoride (0.379) and tooth (0.348) scored high in period 1; in period 2, tooth (0.307) weighed high with a major mediator role; and then the weight was dispersed to resin (0.124), health (0.119), and cement (0.117). In period 3, most keywords including halitosis (0.212), caries (0.180), and tooth (0.1676) did not show big differences in values. Also, it was evident that most keywords with high betweenness for each period ranked high in degree as well. The IJCPD was launched in 2005 and contains research results on clinical preventive dentistry spanning over 13 years. It is necessary to refer to the research trends in clinical preventive 188 Vol. 14, No. 3, September 2018

Kyung-Hui Moon, et al:analysis of IJCPD Research Trends Using Word Network Analysis dentistry through keyword analysis and analysis to identify ways to diversify academic topics and methodologies in the relevant fields related to the nation s oral health policies. This study is meaningful in that it implemented word network analyses of dentistry studies to analyze trends in clinical preventive dentistry research. However, in examining the research trends of clinical preventive dentistry, the analysis per the third period was from 2015 to 2018 issue 1; this is not a five-year period, so the research results of subjects for comparative study cannot be generalized. In future studies, it is necessary to conduct comparative analytical studies using materials published over five-year periods each. Furthermore, not only should the research trends in clinical preventive dentistry be examined, but analyzing networks on how keywords relevant to clinical preventive dentistry are used in online media would also be meaningful research in the future. Conclusion This study implemented word network analysis methods in the clinical preventive dentistry research literature to extract keywords from 371 studies published from issue 1 of 2005 to issue 1 of 2018 in the IJCPD to identify research structure and to conduct analysis in order to identify keywords. The period from 2005 to 2009 was categorized as period 1; 2010 to 2014 as period 2; and 2015 to 2018 as period 3 to analyze research trends and to obtain the following conclusions. Of the 676 words acquired from the IJCPD the most frequently used word in the 13-year period was health ; it is evident that discussions on caries, tooth, halitosis and fluoride were the most active. In clinical preventive dentistry, the upper degree words were tooth, caries, health, fluoride, and halitosis, and the upper betweenness words were tooth, health, caries, plaque, and halitosis. Also, the core degree keywords per period were found to be tooth, caries, and fluoride in period 1; tooth, health, and dentifrice in period 2; and health, caries, and index in period 3. Tooth weighed 0.078 in period 1; 0.067 in period 2; and 0.044 in period 3, showing that studies expanded to various topics going to periods 2 and 3. 1. Of the 676 words acquired from the IJCPD the most frequently used word in the 13-year period was health, and it is evident that discussions on caries, tooth, halitosis and fluoride were the most active. 2. The upper words that are core words connected to keywords in clinical preventive dentistry are tooth, caries, health, fluoride, and halitosis, and the upper betweenness words that act as mediums that connect words were found to be tooth, health, caries, plaque, and halitosis. 3. Upon analyzing changes in degree through analyzing keyword networks per period by dividing the time between 2005 to 2018 into three periods, it was found that the core degree keywords in period 1 were tooth, caries, and fluoride ; in period 2 they were tooth, health, and dentifrice ; and in period 3 they were health, caries, and index. Tooth weighed 0.078 in period 1; 0.067 in period 2; and 0.044 in period 3, showing that research spread to various topics going into periods 2 and 3. 4. Upon analyzing core betweenness keywords per period, fluoride (0.379) and tooth (0.348) scored high in period 1 and tooth (0.0307) weighed highest in period 2 showing a high mediator role, but then the weight was dispersed to resin (0.124), health (0.119), and cement (0.117). In period 3, most keywords such as halitosis (0.212), caries (0.180), and tooth (0.1676) did not show major differences in values. Based on the above results, the most frequently used word in clinical preventive dentistry over 13 years in the IJCPD was health and it was found that the word was tooth. Further, results of analysis per period showed that keywords are gradually spreading to various research themes. It is anticipated that meaningful research in various fields will be conducted based on the results of IJCPD research trend analysis using word network analysis. References 1. Paik DI, Kim HD, Jin BH, Park YD, Shin SC, Cho JW, et al. Clinical preventive dentistry. 5th ed. Seoul: Komoonsa; 2011. 2. 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