Abstract
Keywords
Introduction
Additive manufacturing (AM), also known as three-dimensional printing (3DP), is a technique to create three-dimensional (3D) objects in a layer-by-layer manner. 1 While 3DP has been around since 1986, the technology became highly visible once medical researchers began exploring its role and applications in personalized medicine. More recently, 3DP has emerged as an essential patient care modality with applications across various surgical disciplines. 2
By providing a new armamentarium for complex craniomaxillofacial (CMF) reconstructions, 3DP has started gaining traction in CMF surgery. 3 3DP is becoming an increasingly important adjunct for surgical specialties since its introduction, allowing customized solutions in anatomical biomodels, surgical templates or guides, and even individualized implantable materials in reconstructive surgical procedures. 4 This patient-centric, individualized approach has led to a large volume of biomedical literature outlining various aspects of this emerging CMF technology and applications.5-7 Such expansion in the knowledge base necessitates literature analyses to interpret cumulative scientific knowledge and evolution robustly.
Various research scholars have utilized bibliometric analysis to explore emerging biomedical application trends and better understand cumulative scientific knowledge. 8 Such methods employ quantitative techniques to evaluate linkages between countries, institutions, authors, journals, and keywords. 9 Using bibliometric analyses, researchers can explore innovation patterns, trends, and better identify gaps; thus, supporting further research and decision-making.10-12 Bibliometric analyses have been extensively employed in various biomedical and engineering domains.13,14
Although various studies have been conducted worldwide to investigate the utilization of 3DP in CMF surgery, there are no bibliometric studies in this field to date. Therefore, we designed the current study to present a comprehensive review of global scientific research data to address the scarcity of quantitative analytical research on 3DP in CMF surgery.
Materials and Methods
Data Sources and Extraction
All data until 14-Feb-2023 were extracted from the core collection of the Web of Science (WoS) internet database. While designing the search, the following parameters were utilized, • Truncation symbol * was used to ensure retrieval of all spelling variations of the search term along with any potential prefix or suffix associated with the search term. • Boolean operators AND, OR, and NOT were used to define the search scope. • Parenthesis was used to outline the Order of Precedence built-in WoS to cluster synonyms together for a more comprehensive search.
The following search strategy utilized the abovementioned parameters to ascertain a comprehensive literature retrieval. • (“*3D printing*” OR “*Three dimensional printing*” OR “Additive manufacturing” OR “Rapid prototyping”) AND (“Craniomaxillofacial” OR “Craniofacial” OR “Cranial” OR “Maxillofacial” OR “Facial” OR “Maxillo-facial” OR “Cranio-facial” OR “Maxilla*” OR “Mandib*“) NOT (“Dental”).
The retrieved literature was restricted to CMF topics by excluding unrelated WoS inbuilt “Citation Topics Meso.” (1.14 Nursing or 8.93 Archeology or 1.47 Prostate Cancer or 1.65 Allergy or 1.105 Strokes or 1.129 Back Pain or 1.82 Gait & Posture or 6.178 Gender & Sexuality Studies or 1.264 Longevity or 1.323 Legionellosis, or 1.72 Obstetrics & Gynecology or 1.111 Liver & Colon Cancer or 1.196 Micro & Long Noncoding Rna or 1.213 Thyroid Disorders or 1.291 Testicular Disorders or 1.37 Cardiology - General or 1.44 Nutrition & Dietetics or 10.290 Art or 5.9 Particles & Fields or 6.269 Political Philosophy).
Data Refinement
Given the study’s objective, the retrieved data were restricted to original and review articles. All remaining publication types were excluded from analyses. Given that the study was intended to see global trends, the articles in regional languages were excluded from analyses, and data were limited to English-language publications.
Data Analysis
For data analysis, the “Bibliometric analysis technique toolbox” proposed by Donthu et al. 15 was optimized as follows.
Performance Analysis
The performance analysis outlined the contributions of research constituents in a descriptive manner. The research parameters included in this analysis included the evaluation of publication trends, journals, countries, institutions, authors, and funding agencies.
The analysis of trending was performed using regression analysis. A graphical trend line depicting the goodness of fit (R2) value, ie, explained variation/total variation, was used, with the trend line showing the highest R2 value being selected to represent the model with the best fit. The respective analysis method was presented alongside the trend analysis. Regression parameters inbuilt within Microsoft Excel, as detailed immediately below, were employed in the analyses: • Linear trend: y = m * x + b; where, m = SLOPE(y,x) and, b = INTERCEPT(y,x). • Logarithmic trend: y = (c * LN(x)) + b; where, c = INDEX (LINEST(y,LN(x)),1) and, b = INDEX (LINEST (y,LN(x)),1,2). • Power trend: y = c * x ˆb; where, c = EXP (INDEX (LINEST (LN(y),LN(x)),1,2)) and, b = INDEX (LINEST (LN(y),LN(x)),1). • Exponential trend: y = c * e ˆ(b * x); where c = EXP (INDEX (LINEST (LN(y),x),1,2)), b = INDEX (LINEST (LN(y),x),1) and, e = EXP (1).
Science Mapping
This analysis assessed the inter-relatedness between the research mentioned above parameters as follows.
Citation Analysis
This analysis was performed to identify the most influential papers in CMF surgery and based on the supposition that citations represent the scholarly connections between publications that result from 1 article citing another.
15
Therefore, we could examine the most significant publications concerning 3DP in CMF surgery with the analysis. Citation analysis also evaluated top journals, countries, high-yield authors, and highly cited articles.
16
The parameters used for these evaluations were as follows. 1. TLCS (Total Local Citation Score) was used to show the count of citations to a paper within the retrieved data. 2. TGCS (Total Global Citation Score) was used to show the total number of citations to a paper within the retrieved data. 3. TLCR (Total Local Cited References) was used to show the number of citations in a paper’s reference list to other papers within the retrieved data. 4. TLCS/t represented the ‘Total Local Citation Score per year’ from paper publication to the end of the collection. 5. TGCS/t represented the ‘Total Global Citation Score per year’ from paper publication to the end of the collection. 6. TLCSx (Total Local Citation Score excluding self-citations) was used to show the count of citations to a paper within the retrieved data excluding author self-citations.
Co-Citation Analysis
This analysis is based on the assumption that publications cited together frequently represent a similar theme. Thus, this analysis helped to identify thematic clusters related to 3DP in CMF surgery.15,17
Bibliographic Coupling
With this analysis, it was assumed that 2 publications sharing common references are likely to represent a similar theme. 18 For this analysis, clusters were generated based on the citing article. In addition to observations from co-citation analysis, bibliographic coupling aided in providing visibility to recent and less-cited publications. Therefore, this analysis was used to identify the most up-to-date bibliographic information concerning 3DP in CMF surgery.
Keyword Analysis
This method was sorted to evaluate the content of publications employing the keywords used by researchers in the field of 3DP in CMF surgery. The analysis was based on the assumption that keywords that frequently appear together have a thematic relationship with one another. 15
Co-Author Analysis
Since co-authorship is a modality for intellectual collaboration among researchers, this analysis was intended to evaluate the interactions among scholars in the field of 3DP in CMF surgery. 15 The analysis was performed to evaluate collaboration between individual authors and different countries.
Data Visualization
The network data were visualized using JAVA-driven graphical user interface-based software VOS viewer version 1.6.19. Additional visualizations were created using Microsoft Excel via Office 365 and Histcite.
Results
The search strategy mentioned above retrieved a total of 1659 articles from 1994 up until 14-Feb-2023. Among these, 1387 articles met the inclusion criteria [original articles (n = 1268), review articles (n = 119)]. The majority of these articles were in English (n = 1367). A display of the article exclusion and eventual evaluable dataset is presented in Figure 1. Data refinement overview.
Performance Analysis
Annual Trends of Publications
Considering that study included only 1.5 months of data for 2023. The articles published in 2023 were not included in the trend analysis. Since 1994, ie, the year of the first retrieved publication, there has been an exponential increase in the number of publications each year. The annual trend of publications is displayed in Figure 2 as follows. Annual trend in the number of publications.
Journal Analysis
Top Ten Journals with Publications Related to 3DP in CMF Surgery.
aIF: Impact Factor; based on 2021 data retrieved from Clarivate journal citation report.
Country Analysis
Sixty-seven countries participated in published research articles on 3DP in CMF surgery. For analyses purposes, authors aggregated data from England, Scotland, Wales and Northern Ireland under United Kingdom based on archived information available from “The official site of the Prime Minister’s Office, United Kingdom”.
19
The global heatmap (Figure 3) indicated that there appears to be international participation in the research concerning 3DP in CMF surgery, except for a substantial number of countries in the African continent. On the other hand, the data of the top 10 countries participating in such research did indicate substantial regionalization in a handful of countries (Figure 4). The country-wise data revealed that most publications were from China (n = 296), followed by the USA (n = 274). Global heatmap outlining participating regions. Top ten countries participating in 3DP in CMF research.
Affiliation Analysis
The analysis of the institutes affiliated with the 3DP in CMF research reported that all institutes that constituted the top ten publications were affiliated with an academic university. An overview of these institutes is provided in Figure 5. Multiple institutes with the same number of publications were included under 1 group. The highest number of publications was carried out within Shanghai Jiao Tong University (n = 53). Egyptian Knowledge Bank (EKB), retrieved among the top ten institutes (number of publications = 26), being a library, was manually excluded from the analysis. Top ten institutes contributing to 3DP in CMF research. 13INSERM: L’Institut national de la santé et de la recherche médicale.
Author Analysis
In total, 5806 authors contributed to 1367 publications included in this analysis. Figure 6 outlines the top high-yield authors. Among these, authors with the same number of publications were included under 1 group. The analysis revealed that Ciocca L and Scotti R authored most papers (n = 18), followed by Moiduddin K (n = 17). Top high-yield authors with the respective number of publications.
Funding Analysis
Top 5 Funding Agencies.
Science Mapping
Citation Analysis
Among the total 1367 publications, 1156 reported a minimum of 1 citation. These data were presented as network overlay visualization per year using VOS viewer (Figure 7) utilizing 948 articles connected via different nodes. This analysis provided a visual representation of the most influential publications per year, with a unit of analysis being the cited reference. The node size in the visualization is proportional to the number of citations. The result indicated that older publications were cited more frequently than recent ones. Citation network.
Highly Cited Journals.
Citation Analysis per Country.
High-Yield Authors.
We analyzed the data to identify the top cited papers utilizing citation numbers in WoS Core as well as overall citation. We used the inbuilt function of ‘Highly Cited Papers’ to retrieve the top 5 highly cited articles. All 5 papers were between the years 2015-2017 (both inclusive). The results revealed that the review articles were cited more often than original research papers. Thematically these articles seemed to lean more towards “recent advances” in 3DP.
Co-Citation Analysis
For co-citation analysis, an arbitrary minimum number of citations was limited to 20 to achieve a comprehensible network analysis. The network map was adjusted to the strength of association between different clusters. The node size for different clusters was proportional to the number of citations. While almost all clusters were similar in themes, the clusters represented in red seemed more prominent (Figure 8). However, this analysis could not draw any conclusion due to the close thematic resemblance across publications in all clusters. Co-citation network.
Bibliographic Coupling
The network visualization with a time overlay (year) was selected for this analysis. The results yielded 364 total nosed with 354 inter-connected nodes. A visual representation of these interconnected nodes is presented in Figure 9. As observed with co-citation analysis, the various clusters were somewhat similar in themes. The analysis yielded no characteristically different clusters based on the article theme. However, they did seem to represent a weak thematic correlation based on the year of publication. Bibliographic coupling.
Keyword Analysis
The analysis of the various keywords in the retrieved data identified 23 keywords used at least 50 times. The unit of analysis was a combination of author keywords and index keywords. The data were visualized as a network (Figure 10). The analysis revealed striking thematic resemblance within different clusters (represented as different colors) ranging from evaluation of physical properties of 3DP implants to CMF surgical application of outputs generated from 3DP. Keyword analysis.
Co-Authorship Analysis
For co-authorship analysis, the minimum number of publications was arbitrarily set at 5. Heatmaps visualizations were generated for author-level and country-level analyses (Figure 11 and Figure 12). Under author-level analysis, the results virtually mimicked the results received under high-yield authors, with these authors representing the highest collaboration. The same observations were also noted for country-level analysis. Co-authorship analysis per author. Co-authorship analysis per country.
Discussion
In this study, we present the first bibliometric analysis for 3D printing in Cranio-Maxillofacial surgery utilizing published data since 1994. While being a new modality for healthcare management in CMF surgery, 3DP has seen an exponential increase in its acceptance.25-28 This was evident in this study, where we observed a noticeable increase in research since the first study in the database.
While the research in this field has seen an exponential increase, analyses have shown a striking regionalization of research activities, with most African continent countries conspicuously absent from research activities. Additionally, a vast majority of research was noticed to be limited to the USA and China. This is not unexpected, given the high technological and economic resources available in these countries, thereby supporting the availability of necessary infrastructure to the research scholars. 29 Nevertheless, there appears to be an inter-country collaboration that may further research in this field by involving scholars from countries who may not have access to infrastructure but can support clinical applications from a broader patient population perspective.
Although the country-level analysis indicated a certain level of cross-border collaboration, the author’s analysis seemingly represented most of the research being regionalized. This observation may be explained by research conducted in institutes with access to the necessary infrastructure to conduct such research. With the advent of point-of-care manufacturing of 3DP-generated implants,4,30-34 this perceived regionalization may increase in the immediate future. Nevertheless, as the technology becomes more widely available, such regionalization may get reduced. Additionally, the funding analysis showed that the public sector funds most of the research. We believe that this field of research can benefit from a collaboration with private sector industries that may help with more accessibility to the necessary infrastructure to a broader audience, thus diversifying the research in the field.
Highly Cited Articles.
Furthermore, hybrid systems that combine different 3DP technologies and allow complex structures to take shape are another 3DP trend that has the potential to mitigate the drawbacks of any single 3DP technique. We believe that with continued technological advancement, it will become a new hotspot in the future. Given the potential of this modality, we believe that more research is needed in this field from which the CMF fraternity can gain vastly. Overall, our study has quantitatively provided evidence of advancing research in the field of 3DP in CMF surgery, albeit in a regionalized manner. We believe there is a need for broader availability of necessary infrastructure to ascertain a robust and diversified evaluation. Furthermore, it is of note that bioprinting is rapidly gaining traction in the biomedical fraternity, and while new to the field of surgery, more research in bioprinting for its application in CMF surgery is needed.
Together, our multi-technique evaluation addressed the current gaps in the literature to show the intellectual structure of the topic in an all-encompassing way. In-depth analysis of the 3DP evolution, identification and interpretation of its current state (in terms of significant works and conceptual space), and the ability to predict its future trajectory were all made possible. This has resulted in an integrative and comprehensive framework for the history, present, and future of the study of distributed work, guiding researchers about its conceptual space and nomological network and, most crucially, directing future research on this and related disciplines.
Additionally, the analysis offered a summary of the present status of research, which might assist researchers in identifying knowledge gaps, areas in which additional research is required, and new research collaborations. The most significant authors and organizations in the field can be found using these findings. Understanding who is leading the medical 3DP field can assist researchers in considering collaborating with these authorities. In addition, it is possible to follow the development of research methodology, the rise of new themes, and the decrease of dated ones over time. Keywords represent the research field’s focus and results and demonstrate its trends. Investigating the research’s popularity provided a solid foundation for analyzing the evolution of key phrases in 3DP in CMF surgery. We identified the major hot spots in the field over the last 30 years using keyword co-word analysis. This strategy can assist researchers in keeping abreast of the most recent findings in the area. The results can then assist in determining the impact of the research by looking at citation trends and other bibliographic information. These pieces of information can aid researchers in comprehending the effects of their research and the larger area of research.
Furthermore, the data from the analysis can help researchers, policymakers, and industry stakeholders identify research areas that can generate significant impact and contribute to the development of new technologies, applications, and therapies. This approach can assist the funding organizations in identifying the areas with the best chance of advancing the topic. This bibliometric approach can help researchers stay current on the most recent research, inform funding decisions for further field study, and give insightful information about the research landscape. Therefore, our study increases our understanding of this crucial area and provides a starting point for further research.
It is important to note that all bibliometric studies have limitations, and our study is no exception. For instance, being quantitative assessment, such studies may completely omit the qualitative evaluation. Further to that, the citation counts may be driven more by the number of peers conducting research in the same domain, rather than on the intrinsic quality or originality of the published results. It is noteworthy that the results of such studies may influence researchers to gravitate towards trendy research in fields where many other researchers are active and where scientific funds can more easily be obtained. Therefore, it is of utmost importance that caution should be exercised while drawing conclusions from bibliometric methods. They are at their best as statistical methods, and the results from such studies should always be contextualized using results from other altimetric analyses such as such as scientometric studies ie, bibliometric measurements are only indicators and not a replacement for qualitative evaluation methods, such as research content evaluation.38,39
Conclusions
To our knowledge, this is the first bibliometric analysis to quantify the research in the niche field of 3DP in CMF surgery. This study not only looked at the current status of research but also identified key areas of further advancement. Therefore, the results from this study may be used to indicate the overall state and general trend on the research subject.
Footnotes
Author Contributions
Conceptualization, V.M., N.S., F.M.T; methodology, V.M., N.S.; software, V.M.; validation, V.M., N.S.; formal analysis, V.M.; investigation, V.M., B.B., data curation, V.M.; visualization, V.M., M.C., N.S., writing— original draft preparation, V.M.; writing—review and editing, V.M., B.B., P.H., M.C., F.M.T., N.S; supervision, F.M.T., N.S.; project administration, N.S. All authors have read and agreed to the published version of the manuscript.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Ethical Approval
Ethical review and approval were waived for this study due to not involving humans or animals.
Data Availability
The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author.
