World Trends in Dental Ergonomics Research: A Bibliometric Analysis

Dental ergonomics provides an overview of dentists’ work efficiency. The objective of this study was to obtain quantitative information and produce a visualization of the network of scientific publications on the topic of ergonomics and dentistry using bibliometric analysis. Data mining was conducted using the Scopus database and Boolean expressions (ergonom* AND dentist*) on 14 April 2023. Data extraction and analysis were performed using Open Refine version 3.5.2., VOSviewer version 1.6.17., VOSviewer thesaurus, Microsoft Excel, and Tableau Professional version 2020.1.2. A total of 682 documents were identified, with the United States having the largest number of documents and citations (89 documents, 1321 citations). Work, Dentistry Today, and the International Journal of Environmental Research and Public Health were the top three sources. Ergonomics and musculoskeletal disorders (MSDs) are two of the very prominent keywords, with research topics covering prevalence, causes, factors related to causes, prevention, assessment, rehabilitation, evaluation, and intervention. There was no research on ergonomic interventions that collaborated with human factors and ergonomics (HFE). We conclude that the trending topic of dental ergonomics research topics around the world is centered on MSDs. The future research challenge is to apply HFE science to improve the health, safety, efficiency, and quality of dentists’ work.


Introduction
The focus of ergonomics is on humans and their interactions with products, equipment, facilities, procedures, and the environment in which humans live and work every day.Ergonomics seeks to prevent work-related musculoskeletal disorders through identifying, evaluating, and controlling the risk factors in the physical workplace [1].The dental profession involves repetitive movements combined with forceful movements, awkward postures, and inadequate recovery time.This profession requires precision and has high visual requirements due to the narrow working area, i.e., the oral cavity.Therefore, dentists are at high risk of developing work-related musculoskeletal disorders (WMSDs) [2].WMSDs are a subcategory of musculoskeletal disorders (MSDs).The Occupational Safety and Health Association (OSHA) defines musculoskeletal disorders (MSDs) as disorders of the skeletal muscles, nerves, tendons, ligaments, joints, cartilage, or vertebral discs, which occur slowly over time due to repeated wear and tear or microtrauma [3,4].
WMSDs are a significant problem for dentists and have been discovered early in their careers, even among dental students.Yusof et al., in their research, found that there were significant differences in posture among clinical students in their third, fourth, and fifth years of study.Body pain and the development of MSDs in fourth-year students were caused by poor posture in the legs, while in fifth-year students, they were caused by poor posture in the forearms.Students tend to work in awkward postures that are

Materials and Methods
This research was carried out in two stages.The first stage was an exploratory stage of searching for research topics using several keywords with Boolean expressions in the Scopus database.The purpose of this preliminary research was to find research topics with keywords that could provide the most data information (Table 1).A preliminary research topic search was carried out on 5 April 2022 using Boolean sentences in the Scopus electronic database.To search for phrases in Scopus, double quotes are used ("), wildcards (*), and Boolean operators (OR, AND, NOT).The purpose of double quotes is to tell Scopus that these are "loose phrases", meaning that the words must be together.The use of wildcards (*) is to represent a number of characters, and Boolean operators are used to expand or narrow search parameters when using databases or search engines.The default search field in Scopus uses TITLE-ABS-KEY because the Scopus database is an abstract indexer only [32,33].
Table 1.Data mining with several topics in preliminary research.

Boolean Search Sentences Number of Documents
(TITLE-ABS-KEY (ergonom*) AND TITLE-ABS-KEY (dentist*)) 634 (TITLE-ABS-KEY ("musculoskeletal disorder*" OR "MSDs*") AND TITLE-ABS-KEY (dentist*)) 372 (TITLE-ABS-KEY ("work fatigue*" OR "burnout*") AND TITLE-ABS-KEY (dentist*)) 317 (TITLE-ABS-KEY ("work pressure*" OR "work stress*" OR "work anxiety*") AND TITLE-ABS-KEY (dentist*)) 43 Based on the results of data mining with several topics in our preliminary research, the topics of ergonomics and dentistry were selected, which provided the largest number of documents.During this research, data mining was carried out on the Scopus database using Boolean expressions (ergonom* AND dentist*) on 14 April 2023.The search results were exported into a Comma-Separated Value (CSV) file in Microsoft Excel [34].Microsoft Excel software was also used to analyze all information from recruited sources.To work on visualization and bibliometric construction, VOSviewer software version 1.6.17 was used, and to clean the data, Thesaurus_text in VOSviewer and Open Refine software version 3.5.2were used.
In the thesaurus step, keywords that have the same meaning (synonyms/hyponyms) were combined or deleted.The document distribution visualization tool was Tableau Professional software version 2020.1.2(Salesforce Inc., Singapore).The bibliography analysis attributes in VOSviewer software 1.6.17include co-authorship, co-occurrence, citation, bibliography coupling, co-citation of authors, organizations, and countries [35].The bibliometric analysis flow can be seen in Figure 1.

Publication Frequency by Year
There were 682 research publications on ergonomics and dentistry in Englishlanguage journals from 1965 to 2023 in the Scopus database.Figure 2

Publication Frequency by Year
There were 682 research publications on ergonomics and dentistry in English-language journals from 1965 to 2023 in the Scopus database.Figure 2

Contribution of Countries to the Field of Dental Ergonomics
A bibliometric coupling analysis was used to evaluate the number of articles published based on the authors' country of origin (Figure 3).There were 90 countries with at least one article and zero citations.The United States occupied the highest position for ergonomic dentistry publications with 89 articles.The ranking of countries based on the number of articles can be seen in Table 2.

Contribution of Countries to the Field of Dental Ergonomics
A bibliometric coupling analysis was used to evaluate the number of articles published based on the authors' country of origin (Figure 3).There were 90 countries with at least one article and zero citations.The United States occupied the highest position for ergonomic dentistry publications with 89 articles.The ranking of countries based on the number of articles can be seen in Table 2.

Contribution of Countries to the Field of Dental Ergonomics
A bibliometric coupling analysis was used to evaluate the number of articles published based on the authors' country of origin (Figure 3).There were 90 countries with at least one article and zero citations.The United States occupied the highest position for ergonomic dentistry publications with 89 articles.The ranking of countries based on the number of articles can be seen in Table 2.   Citation analysis was carried out on country analysis units with a maximum limit of 25 countries in one article, a minimum of one article, and one citation per country (Table 3).The results of this analysis were that out of 90 countries, 69 met these limits.Of the 20 countries with the highest citation weight, the United States was again in first place with 1321 citations for its 89 articles.The exciting thing was that Greece, with just three documents, obtained 287 citations and was ranked sixth.Source analysis was performed using VOSviewer 1.6.17with bibliographic coupling.This was based on the number of documents or articles and carried out on the sources unit, with a threshold of each journal having at least one article and zero citations.The aim of providing zero citations is that all sources can be presented through this application (Figure 4).The results showed that 323 Scopus-indexed sources published the 682 articles obtained via data mining, and the most extensive collection of connected sources consisted of 174 articles.In Table 4, it can be seen that Work was the top source, with 19 articles, followed by Dentistry Today (18 articles), the International Journal of Environmental Research and Public Health (14 articles), and the Journal of The American Dental Association (12 articles).Source analysis was performed using VOSviewer 1.6.17with bibliographic coupling.This was based on the number of documents or articles and carried out on the sources unit, with a threshold of each journal having at least one article and zero citations.The aim of providing zero citations is that all sources can be presented through this application (Figure 4).The results showed that 323 Scopus-indexed sources published the 682 articles obtained via data mining, and the most extensive collection of connected sources consisted of 174 articles.In Table 4, it can be seen that Work was the top source, with 19 articles, followed by Dentistry Today (18 articles), the International Journal of Environmental Research and Public Health (14 articles), and the Journal of The American Dental Association (12 articles).

Citation Analysis of Sources
This citation analysis used VOSviewer in the sources unit, with a minimum threshold of having one document and zero citations.The aim of providing zero citations is that all sources can be presented through this application (Figure 5).As a result of taking this approach, 323 sources indexed by Scopus were recruited, and the largest collection of connected sources consisted of 162 sources.Table 5 shows the results of an analysis of sources based on citations, where the Journal of The American Dental Association is the top source with a citation weight of 460, followed by BMC Musculoskeletal Disorders (421 citations), Work (338 citations), and Applied Ergonomics (262 citations).

Analysis of the Article
Our analysis of articles or documents aimed to discover which articles have had the greatest influence on research trends in relation to the topics 'ergonomics' and 'dentists' or, in other words, research trends in the field of dental ergonomics.For the analysis, VOSviewer was used with citation analysis as the type and analysis documents as the unit.The lower citation threshold was zero, which we used to obtain all article data in this research.VOSviewer displayed 682 articles and their information, including the authors' names, titles, source information (source name, volume, issue, page), and year of publication.
The article 'Prevalence of musculoskeletal disorders in dentists' published in the journal BMC Musculoskeletal Disorders in 2004 occupied the top citation position.Alexopoulos E.C., Charizani F., and Stathi I.C. wrote this article (Figure 6).The significant citation weight for the article shows the authors' enormous contribution to the development of dental ergonomics.In Table 6, the 15 most frequently cited articles are shown.

Analysis of the Article
Our analysis of articles or documents aimed to discover which articles have had the greatest influence on research trends in relation to the topics 'ergonomics' and 'dentists' or, in other words, research trends in the field of dental ergonomics.For the analysis, VOSviewer was used with citation analysis as the type and analysis documents as the unit.The lower citation threshold was zero, which we used to obtain all article data in this research.VOSviewer displayed 682 articles and their information, including the authors' names, titles, source information (source name, volume, issue, page), and year of publication.
The article 'Prevalence of musculoskeletal disorders in dentists' published in the journal BMC Musculoskeletal Disorders in 2004 occupied the top citation position.Alexopoulos E.C., Charizani F., and Stathi I.C. wrote this article (Figure 6).The significant citation weight for the article shows the authors' enormous contribution to the development of dental ergonomics.In Table 6, the 15 most frequently cited articles are shown.Co-authorship analysis examines interactions between authors in any scientific field.Co-authorship is a formal arena for collaboration between writers and experts and can even occur across and between scientific fields [36].Co-authorship analyses in the author analysis unit from 1733 authors identified 42 with a minimum of four articles [37].Next, an analysis was carried out using Microsoft Excel (Microsoft, Redmond, WA, USA).In Figure 7, based on the network visualization, three clusters have an extensive network, namely, Clusters 1, 2, and 3.The exciting thing is that the authors from Cluster 1 and Cluster 2, apart from writing together with authors in their cluster, are also shown to collaborate between the clusters.

Co-Authorship between Countries
Co-authorship analysis was carried out on country analysis units with a maximum limit of 25 countries in one article and a minimum of one article per country, with a zerocitation limit.We found that 90 countries met these limits, and the most extensive set comprised 35 connected countries (Figure 8).In Table 7, the ten countries with the top co-authorship are presented.

Co-Authorship between Countries
Co-authorship analysis was carried out on country analysis units with a maximum limit of 25 countries in one article and a minimum of one article per country, with a zerocitation limit.We found that 90 countries met these limits, and the most extensive set comprised 35 connected countries (Figure 8).In Table 7, the ten countries with the top coauthorship are presented.

Analysis of the Intellectual Structure
Our intellectual structure analysis aimed to determine which authors, articles, or sources have had the most significant influences on ergonomic dentistry research trends [38].

Analysis of the Intellectual Structure
Our intellectual structure analysis aimed to determine which authors, articles, or sources have had the most significant influences on ergonomic dentistry research trends [38].

Analysis of the Authors' Keywords
The aim of analyzing the authors' keywords is to find the correlation between keywords and the articles' topics, in this case, so that readers will find it easy to search for various dimensions of research on the themes of 'ergonomics' and 'dentistry'.The analysis was performed using the VOSviewer application, namely, a co-occurrence analysis of the authors' keywords with a minimum threshold of five keyword occurrences.There were 758 keywords detected, and 34 met the threshold specified above.
Figure 9 shows an overlay visualization of author keywords in six clusters with a total link of 482 and a total link strength of 1644.'Ergonomics' in Cluster 2 is the keyword most frequently used by the author, with 147 co-occurrences linked to 33 other words and a total link strength of 278.The keyword in second place is 'musculoskeletal disorders (MSDs)', found in Cluster 2 with 124 co-occurrences, links with 32 other authors' keywords, and a total link strength of 274.The remainder of the ten most used keywords by the authors are 'dentists' (88 co-occurrences with 31 links and a total link strength of 177), 'dentistry' (65 co-occurrences with 25 links and a total link strength of 113), 'dental students' (35 co-occurrences with 23 links and a total link strength of 78), 'posture' (28 co-occurrences with 20 links and a total link strength of 69), 'risk factors' (19 co-occurrences with 19 links and a total link strength of 54), 'dental ergonomics' (16 co-occurrences with 14 links and a total link strength of 22), 'occupational hazards' (16 co-occurrences with 19 links and a total link strength of 42), and 'prevalence' (16 co-occurrences with 15 links and a total link strength of 37).
keywords, and a total link strength of 274.The remainder of the ten most used keywords by the authors are 'dentists' (88 co-occurrences with 31 links and a total link strength of 177), 'dentistry' (65 co-occurrences with 25 links and a total link strength of 113), 'dental students' (35 co-occurrences with 23 links and a total link strength of 78), 'posture' (28 cooccurrences with 20 links and a total link strength of 69), 'risk factors' (19 co-occurrences with 19 links and a total link strength of 54), 'dental ergonomics' (16 co-occurrences with 14 links and a total link strength of 22), 'occupational hazards' (16 co-occurrences with 19 links and a total link strength of 42), and 'prevalence' (16 co-occurrences with 15 links and a total link strength of 37).
Table 8 lists the authors' keywords based on research subjects, research methods, occupational health and musculoskeletal disorders, ergonomics, and knowledge and education.The purpose of the grouping is to determine world research trends in the field of dental ergonomics [38].Table 8 lists the authors' keywords based on research subjects, research methods, occupational health and musculoskeletal disorders, ergonomics, and knowledge and education.The purpose of the grouping is to determine world research trends in the field of dental ergonomics [38].

Analysis of the Co-Citation Network of Cited Authors
Co-citation represents two articles that are cited together by at least one article published later.In other words, if two articles are cited together by at least one article, then those two articles are called co-citations.The number of articles that cite the two articles mentioned together is called the frequency or strength of the co-citation [40].These initial two articles have high co-citation power if more and more articles are published that cite these two articles.Co-citation patterns will change over time.Bibliographic coupling existed earlier than co-citation, and co-citation analysis is considered more recent in reflecting domain structure [41].
In this research, analysis of the co-citation network of authors cited using the VOSviewer application covered 14,317 authors.Setting the threshold of the minimum number of citations for an author as 20 citations, 164 authors were identified.For each of the 164 authors, the VOSviewer application calculated the total strength of co-citation relationships with other authors.Table 9 presents the 15 authors with the greatest co-citations and total link strengths.

Discussion
The Scopus database was used as the source of bibliographic data in this research because it has wide coverage, has good data quality and accuracy, provides various bibliometric analysis features, and is a data source that is verified and academically recognized [42].Falagas et al. compared the strengths and weaknesses of PubMed, Scopus, Web of Science, and Google Scholar.PubMed and Google Scholar are free; while PubMed is optimal for biomedical research, Google Scholar's accuracy is inconsistent.Scopus, meanwhile, has 20% greater citation analysis coverage compared to Web of Science [43].Sing et al. compared three Web of Science databases, Scopus, and Dimensions.It was reported that almost all journals on the Web of Science can be found in Scopus and Dimensions.Meanwhile, Scopus indexes 66.07% more unique journals compared to Web of Science.Web of Science and Scopus coverage tends to be in the areas of life sciences, physical sciences, and technology, while Dimensions covers more social sciences and arts and humanities [44].
The results of the bibliometric analysis showed that up to April 2023, 682 articles about dentists and dental ergonomics indexed by Scopus could be identified.The number of articles per year varied greatly, where the most prominent decline in articles was in 1979, when only one article was published.More recently, articles on dental ergonomics have increased sharply, with 36 in 2020, 43 in 2021, and 40 by the end of 2022.In 2023, as of April, there were 10 articles.
This sharp increase stems from various studies providing scientific evidence of the high prevalence of MSDs in dentists and noting that these disorders have been found since the beginning of individual-focused dental studies [45][46][47].These disorders are caused by awkward body postures, unergonomic instruments, poor environmental and system planning, and inadequate work practices.On the other hand, there is still little scientific evidence on the effectiveness of ergonomic educational interventions for improving body posture following induction as a dental student.This raises research questions as to why the prevalence of MSDs in dentists is so high and why ergonomic education interventions aimed at implementing healthy work postures have not had a significant impact [48].
The application of dental ergonomics is important because when working, dentists repeatedly assume sitting, standing, and static positions.Static postures are often used by dentists, such as bending the body forward, bending the neck forward, tilting towards the patient's mouth, rotating the spine, and abducting the hands for a long time [49].Static positions cause excessive contractions in several tissues, increasing muscle tension and thereby causing pain in the musculoskeletal system and peripheral nervous system [50].In addition, the work involves high visual demands, which result in postural adaptations.In their work, dentists often assume a kyphotic posture, bending and turning the head to adjust their field of vision, with lumbar rotation and flexion.Therefore, the prevalence of MSDs in dentists is higher compared to that in other professions [51].
Other risk factors for MSDs include static and awkward neck and shoulder postures, repetitive movements with force in the hands and arms, poor lighting, the patient position not being appropriate to the dentist's position, individual characteristics (physical condition, height, weight, general health, gender, age), and stress [52].MSDs reduce an individual's range of motion, grip strength, normal sensation, and even coordination of the musculoskeletal system [53].MSDs in dentists begin with initial symptoms including pain, swelling, tenderness, numbness, and loss of strength [54].In research in Saudi Arabia, neck and back pain were the main problems for dentists, which could start to be corrected in the process of dental education.So, it is important for dental schools to improve dental ergonomics training for their students [55].
The main goal of dental ergonomics is to reduce the risk of MSDs and to minimize the amount of physical and mental stress so that the quality of dentists' work can be improved [56].In addition, in the development of dental ergonomics research, the subjects are not only dentists and dental students but should also extend to dental hygienists [57], dental assistants [58], and dental technicians [59].The progress of dental ergonomics cannot be separated from its history, where initially dentists worked in a standing position; however, since the 1960s, the four-handed dentistry system has been developed where dentists work in a sitting position [60].Four-handed dentistry is a dental ergonomic effort to minimize unwanted movements and speed up dental treatment procedures [61].
Lietz et al., in their systematic review, considered various studies of ergonomic interventions to prevent MSDs in dental professionals.Of the 11 studies, 5 studies used ergonomic interventions in the form of using magnifying glasses or prismatic glasses; 2 studies used ergonomic dental chairs; 1 study used ergonomic dental instruments; and 3 studies provided ergonomic interventions in the form of ergonomic training.The results of all the included studies showed the important role of ergonomic interventions that can provide an improved work posture, increase work performance, and reduce the severity of MSDs in dental professionals [62].
Our assessment of the development of world trends in the field of dental ergonomics showed that the United States is ranked highest with 89 articles, followed by India (66 articles), Brazil (29 articles), Germany (25 articles), Saudi Arabia (22 articles), Sweden (22 articles), and the United Kingdom (22 articles).The United States is the country with the most articles written across countries and is the country with the highest number of citations.Nonetheless, the analysis of the most cited countries showed that not all countries with more articles have high citations.For instance, Greece is in the sixth position among the top 10 countries with the highest citations, with 287 citations obtained from its three articles, as can be seen in Table 3.Based on network visualization, five countries have cited articles from Greece, namely, Sweden (link strength: 10), Germany (link strength: 9), the United States (link strength: 7), Iran (link strength: 6), and India (link strength: 5), in order of link strength level.
The Journal of The American Dental Association (JADA) is the journal with the highest number of citations, and the next is BMC Musculoskeletal Disorders, receiving 460 and 421 citations, respectively.JADA is the leading open-access journal in the United States, which has been around since 1913 and has a Q2 ranking with an h-index of 128, with its subject areas specifically in dentistry and medicine.Since 2000, BMC Musculoskeletal Disorders has been an open-access journal, ranked Q2 with an h-index of 112 subject areas including orthopedics, sports medicine, and rheumatology [63].In third place is Work, with a total of 338 citations.Work has been in existence since 1990 with subject areas covering prevention, assessment, and rehabilitation.It is an interdisciplinary journal ranked Q2 with an h-index of 58.In the fourth place is Applied Ergonomics which has 262 citations, meanwhile, with a Q1 ranking and an h-index of 119 indicated that this open-access journal is aimed explicitly at ergonomists and professionals who apply human factors in designing, planning, and managing technical and social systems.This bibliometric analysis showed that journal age, open-access status, topic, quality, and impact factors were essential in determining the number of document citations [64].
"The prevalence of musculoskeletal disorders in dentists" was the most frequently cited article and reached the top ranking with 274 citations.This was written by Alexopoulos E.C. in 2004, from the Department of Public Health, Technological Educational Institute of Athens, Greece and the Occupational Health Department, Hellenic Shipyards SA, Athens, Greece.The contents of this article are the results of a survey of 430 dentists in Thessaloniki, Greece, using the Nordic questionnaire to determine the occurrence of MSD complaints in the last 12 months, chronic MSD complaints for at least one month, MSD complaints that caused an inability to work, and whether the respondents sought medical treatment.The survey results showed that 62% of dentists experienced at least one MSD complaint, 30% of dentists experienced chronic MSD complaints, 16% stated they had been absent from work, and 32% of dentists sought medical treatment.From these results, it was concluded that dentists are at risk of experiencing MSDs related to the physical load of their work [65].Ranked second was an article entitled "Preventing musculoskeletal disorders in clinical dentistry: Strategies to address the mechanisms leading to musculoskeletal disorders" written by Valachi B., a physiotherapist who is one of the founders of Posturedontics, Portland, Oregon.In this article, strategies for preventing the development of MSDs in dentistry are presented, which aim to shape body posture and work ergonomically [66].The third most cited article is "Reports of the body in dental student population" by Rising D.W., from the Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California, San Francisco.The research was conducted on 271 dental students in their fourth year, and the conclusion was that 70 percent of students had experienced MSD complaints since their third year as dental students [67].
In the author visualization of keywords up to 2023, the keyword "Human Factors and Ergonomics (HFE)" was not found, even though HFE has progressed very rapidly recently.HFE is a science that studies interactions among humans, tasks, and elements of work systems, with the aim of making humans better integrated in a system via adaptations to the environment for the individual.Dentists and other dental health professionals will function better in a more conducive environment.HFE interventions have the potential to improve the performance, health, and welfare of workers, including (1) physical ergonomics interventions (anthropometrics, anatomy, physiology, biomechanics); (2) organizational ergonomics intervention (organizational structure, policies, procedures); and (3) cognitive ergonomic interventions relating to mental processes (memory, reasoning, perception, motor reactions) [68,69].The research into the application of HFE in the dental education system and dental practice is a future challenge for the world.
This bibliometric analysis research allowed us to produce various quantitative descriptive images of country citations, journals, articles, authors, and author keywords on the theme of ergonomics and dentistry.However, there are several limitations in bibliometric analysis.One is that open access to scientometric data is required.Access to data with sufficient accuracy is a fundamental limitation of bibliometric analysis.The important information required includes metadata, author data, affiliations, and citations.Another limitation is the possibility that the downloaded data are incomplete or duplicate data.The main obstacle in bibliometric analysis is the complexity and diversity of bibliographic data, meaning researchers need to be careful in understanding the various dimensions of the data.The number of citations is directly proportional to time, meaning that older papers tend to receive more citations than new papers.

Conclusions
Dental ergonomics research has developed rapidly to the stage where the world's trending research topic is MSDs in dentists.This topic includes the prevalence of MSDs, along with their causes, factors related to causes, prevention, assessment, rehabilitation, evaluation, and ergonomic intervention.There has not yet been any research on ergonomic interventions that collaborate with human factors and ergonomics (HFE).The future research challenge is to apply HFE science to improve the health, safety, efficiency, and quality of dentists' work.

Figure 1 .
Figure 1.Research methods and flow.

Figure 1 .
Figure 1.Research methods and flow.

Figure 2 .
Figure 2. The trend of a count of titles for the year.The year and count of titles filter the view.The year ranges from 1965 to 2023.The count of the title filter ranges from 1 to 43.

Figure 3 .
Figure 3. Distribution of documents by country.

Figure 2 .
Figure 2. The trend of a count of titles for the year.The year and count of titles filter the view.The year ranges from 1965 to 2023.The count of the title filter ranges from 1 to 43.

Figure 2 .
Figure 2. The trend of a count of titles for the year.The year and count of titles filter the view.The year ranges from 1965 to 2023.The count of the title filter ranges from 1 to 43.

Figure 3 .
Figure 3. Distribution of documents by country.Figure 3. Distribution of documents by country.

Figure 3 .
Figure 3. Distribution of documents by country.Figure 3. Distribution of documents by country.

Figure 5 .
Figure 5. Bibliometric analysis of the number of source citations.

Figure 5 .
Figure 5. Bibliometric analysis of the number of source citations.

Figure 6 .
Figure 6.Network visualization in the analysis of the most frequently cited documents.There are two groups, namely, the first group includes colorful circles, dominated by Alexopoulos E.C. (2004) with the largest circle, and the second group includes transparent gray circles, dominated by Al Wazzan K.A. (2001) with the largest circle.This coloring difference indicates no relationship between the first and second groups.Regarding circle size, the higher the citation weight, the bigger the circle[35].

Figure 6 .
Figure 6.Network visualization in the analysis of the most frequently cited documents.There are two groups, namely, the first group includes colorful circles, dominated by Alexopoulos E.C. (2004) with the largest circle, and the second group includes transparent gray circles, dominated by Al Wazzan K.A. (2001) with the largest circle.This coloring difference indicates no relationship between the first and second groups.Regarding circle size, the higher the citation weight, the bigger the circle[35].
namely, Argesanu V.; one author from the Ergonomics Department, Faculty of Dental Medicine, Victor Babes University of Medicine and Pharmacy (Romania), namely, Anghel M.D.; one author from the Department of Mechanical Machinery, Equipment, and Transport, Polytechnic University of Timisoara (Romania); and two authors from the Department of Periodontology, Faculty of Dental Medicine, Victor Babes University of Medicine and Pharmacy (Romania), namely, Stratul S. and Rusu D.

Figure 7 .
Figure 7. Co-authorship network visualization: in the red circle is the combined co-authorship of Clusters 1 and 3; meanwhile, in the green circle, the co-authorship of Cluster 2 is shown.Figure 7. Co-authorship network visualization: in the red circle is the combined co-authorship of Clusters 1 and 3; meanwhile, in the green circle, the co-authorship of Cluster 2 is shown.

Figure 7 .
Figure 7. Co-authorship network visualization: in the red circle is the combined co-authorship of Clusters 1 and 3; meanwhile, in the green circle, the co-authorship of Cluster 2 is shown.Figure 7. Co-authorship network visualization: in the red circle is the combined co-authorship of Clusters 1 and 3; meanwhile, in the green circle, the co-authorship of Cluster 2 is shown.The joint writing collaboration between Clusters 1 and 3 shows collaboration in scientific fields and institutions.From Clusters 1 and 3, eight authors were found from Social Medicine and Environmental Medicine, the Institute of Occupational Medicine, Goethe-University (Germany), namely, Groneberg D.A., Ohlendorf D., Holzgreve F., Wanke E.M., Fraeulin L. Maurer-Grubinger C., Hauck I., and Nowak J.In addition, from Cluster 1, several different author affiliations were found including one author from the Medical Center of the Johannes Gutenberg, Department of Orthodontics, University Mainz (Germany), namely, Erbe C.; one author from the Principles of Prevention and Rehabilitation Department (GPR), Institute for Statutory Accident Insurance and Prevention in the Health and Welfare Services (Germany), namely, Nienhaus A.; and one author from the Department of Dental Radiology, Institute of Dentistry, Goethe-University (Germany), namely, Betz W. In Cluster 3, two authors were found from the Institute for Occupational Health and Safety (IFA)-German Social Accident Insurance (DGUV), Germany, namely, Ditchen D. and Hermanns I. Joint authorship in Cluster 2 also demonstrates the degree of collaboration between scientific fields and institutions based on author affiliation.From Cluster 2, one author was found from the Mechatronics Department, Polytechnic University (Romania), namely, Argesanu V.; one author from the Ergonomics Department, Faculty of Dental Medicine, Victor Babes University of Medicine and Pharmacy (Romania), namely, Anghel M.D.; one author from the Department of Mechanical Machinery, Equipment, and Transport, Polytechnic University of Timisoara (Romania); and two authors from the Department of Periodontology, Faculty of Dental Medicine, Victor Babes University of Medicine and Pharmacy (Romania), namely, Stratul S. and Rusu D.

Figure 8 .
Figure 8. Bibliometric analysis of co-authorship by country.

Figure 8 .
Figure 8. Bibliometric analysis of co-authorship by country.

Figure 9 .
Figure 9. Overlay visualization map of author keywords from the 1990s to 2023.The color of the circles ranges from blue, which indexes articles with publication years around 2012, to green for 2014-2016, to yellow for 2018, to the latest year, 2023 [39].

Figure 9 .
Figure 9. Overlay visualization map of author keywords from the 1990s to 2023.The color of the circles ranges from blue, which indexes articles with publication years around 2012, to green for 2014-2016, to yellow for 2018, to the latest year, 2023 [39].

Table 2 .
The 20 countries with the most significant number of documents.

Table 3 .
The 20 countries with the highest number of citations.

Table 5 .
Top 15ranked sources with the most citations.

Table 5 .
Top 15ranked sources with the most citations.

Table 8 .
Grouping of author keyword visualization overlays up to 2023.

Table 9 .
Top 15 co-cited authors in ergonomic and dentist references.