GLOBAL RESEARCH TRENDS IN AGE ESTIMATION FROM CRANIOFACIAL AND DENTAL STRUCTURES: A BIBLIOMETRIC ANALYSIS (1976–2024)

SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 9 SEPTEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 227 GLOBAL RESEARCH TRENDS IN AGE ESTIMATION FROM CRANIOFACIAL AND DENTAL STRUCTURES: A BIBLIOMETRIC ANALYSIS (1976–2024) B. Karip1, F. Ok2, F. Temizsoy Korkmaz3 Department of Anatomy, Hamidiye Faculty of Medicine, University of Health Sciences, Istanbul, Türkiye1,2,3 Council of Forensic Medicine, Ministry of Justice, Istanbul, Türkiye1 https://doi.org/10.5281/zenodo.17313226 Abstract. Age estimation from craniofacial and dental structures is a critical component in forensic science, anthropology, and legal medicine, providing essential information for human identification and medico-legal investigations. This study aimed to map global research trends, identify key contributors, and explore thematic developments in age estimation from craniofacial and dental structures using bibliometric analysis. A comprehensive search of the PubMed database was conducted in August 2025 using a Boolean query combining terms related to age estimation, craniofacial and dental structures, and forensic sciences. Retrieved records were exported in CSV format and cleaned to remove duplicates and standardize metadata. Bibliometric analyses were performed using Python to examine publication trends, prolific authors, leading journals, collaboration patterns, and keyword co-occurrence networks. A total of 71 publications were identified, with the earliest record from 1976 and a notable increase after 2015, peaking in 2024. The most productive authors included Galić I, Friedrich RE, and Scheuer HA. Collaboration network analysis revealed well-connected clusters, particularly among European researchers. Keyword co-occurrence mapping identified two main thematic clusters: (1) methodological approaches to age estimation and validation, and (2) anatomical studies focused on craniofacial and dental features, notably the mandible and third molars. The field of age estimation from craniofacial and dental structures has experienced growing scientific attention, with increasing international collaboration and methodological diversification. This study provides valuable insights for researchers and practitioners, identifying thematic gaps and collaboration opportunities to support the development of more standardized and validated age estimation techniques Keywords: age Estimation, Craniofacial Structures, Dental Structures, Forensic Odontology, Bibliometric Analysis. Introduction Age estimation is a cornerstone of forensic science, playing a vital role in human identification, medico-legal investigations, and anthropological research. This process contributes to the creation of a biological profile that includes sex, age, population affinity, and stature— information that can greatly assist law enforcement and medicolegal authorities in narrowing investigative scope and identifying unknown individuals (Bailey & Vidoli, 2023). In both clinical and legal contexts, the evaluation of teeth and bone development serves as a key indicator of age, supporting growth assessment, treatment planning, and the provision of evidence in judicial proceedings. This is especially important in cases involving unidentified deceased individuals or biological traces, where precise age determination can yield crucial leads for ongoing SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 9 SEPTEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 228 investigations (Wang et al., 2022). Historically, forensic anthropology has relied heavily on skeletal and dental analyses for age estimation (Ubelaker & Khosrowshahi, 2019). Over recent decades, numerous methods have been introduced, with the expanding body of literature reflecting advancements in forensic odontology, anthropology, and imaging technologies. While this methodological diversity underscores the field’s dynamism, it also introduces challenges due to variations in sampling strategies, analytical techniques, and statistical approaches, highlighting the need for standardized parameters to ensure method validation (Corron et al., 2018). Despite notable progress, a universally accepted, highly accurate method for age estimation has yet to be established, mainly due to inherent biological variability and the influence of environmental factors (Marcante et al., 2025). Moreover, while chronological age represents the actual time elapsed since birth, biological age—often assessed through skeletal and dental development— offers a more refined perspective on an individual’s physiological maturity (Kaledzera et al., 2023). Bibliometric analysis offers a systematic approach to mapping the research landscape, identifying influential publications, emerging trends, and gaps in the field of age estimation. Such analyses provide valuable insights for researchers and practitioners, guiding future studies and enhancing the application of age estimation methods in both clinical and forensic settings. This methodology, rooted in quantitative and qualitative evaluation of research trends over time, leverages literature databases and metrological characteristics to provide a comprehensive overview of scholarly output within a specific domain (Xie et al., 2020; Herrera-Franco et al., 2021). This approach is crucial for understanding the historical development of a field, discerning its current intellectual structure, and forecasting potential future directions for research (Xu et al., 2024). Moreover, bibliometric studies facilitate the identification of key authors, institutions, and collaborations, thereby illuminating the foundational intellectual contributions and collaborative networks that drive advancements in the discipline (Ellegaard & Wallin, 2015). Bibliometric analysis, a method coined by Pritchard in 1969, systematically quantifies and structures bibliometric information to delineate the factors constituting scientific research within a specific field, encompassing co-authorship, co-occurrence, citation, co-citation, and bibliographic coupling analyses (Ho & Luong, 2022). Although many techniques have been developed for estimating age from craniofacial and dental structures, no single method has gained universal acceptance for accuracy and reliability. Variations in skeletal and dental development, influenced by both biological and environmental factors, pose inherent challenges to standardization. Each method offers specific advantages and limitations, and many experts recommend using multiple complementary approaches, along with repeated measurements, to improve accuracy and consistency. Despite significant progress in recent decades, the literature highlights the need for further refinement of these techniques to apply them in clinical and forensic settings better. Therefore, evaluating the scope, trends, and themes in the scientific literature is crucial for understanding progress in the field. Accordingly, this study conducts a bibliometric analysis of global research on age estimation from craniofacial and dental structures, aiming to identify publication trends, key contributors, and thematic developments over time. than 40 words, then it should be written without using “” as a separate paragraph, indented and in 8,5 fonts. Method Search Strategy and Data Collection SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 9 SEPTEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 229 A thorough bibliographic search was conducted in the PubMed database to find publications related to age estimation from craniofacial and dental structures in forensic contexts. The search strategy used Boolean operators to combine keywords concerning age estimation, craniofacial anatomical structures, dental features, and forensic sciences. The first domain encompassed terms referring to the process of age assessment, including age estimation, age determination, chronological age, dental age, skeletal age, biological age, and maturity estimation. The second domain addressed craniofacial anatomical structures, incorporating keywords such as craniofacial, cranial, facial, skull, mandible, maxilla, sphenoid, zygomatic, orbital, temporal bone, cranial suture, and foramen. The third domain focused on dental anatomy and developmental markers, represented by terms including dental, tooth, teeth, dentition, molar, canine, incisor, third molar, pulp/tooth ratio, cementum annulation, eruption stage, and mineralization stage. Finally, the forensic context was addressed through terms such as forensic, forensic medicine, forensic anthropology, forensic odontology, and legal medicine. This structured combination of concepts was applied to ensure a comprehensive retrieval of relevant literature for the bibliometric analysis. The search was conducted in August 2025 without restrictions on the year of publication. All retrieved records were exported in CSV format, containing metadata fields such as title, authors, journal, publication year, and DOI. Inclusion and Exclusion Criteria Only articles directly addressing age estimation from craniofacial and/or dental structures in forensic contexts were included. Eligible publications encompassed original research articles, reviews, and case studies. Non-English language publications, conference abstracts without full text, editorial materials, and studies outside the scope of forensic applications (e.g., purely archaeological or clinical without forensic relevance) were excluded. Duplicates were identified and removed before analysis. Data Processing and Analysis The retrieved dataset was cleaned to remove duplicate entries and standardize author and journal names to ensure consistency. Bibliometric analyses were performed using Python, employing the pandas, matplotlib, and networkx libraries. The analyses included: 1. Annual publication trends – determination of the total number of publications per year. 2. Productivity analysis – identification of the most prolific authors, journals, and countries. 3. Collaboration networks – co-authorship analysis based on shared author names. 4. Keyword co-occurrence analysis – extraction of keywords from article titles to identify prevailing research themes. Visualization Network maps representing co-authorship relationships and keyword co-occurrence patterns were generated using a force-directed layout algorithm. These visualizations allowed for the identification of collaborative clusters among authors and thematic connections between research topics. Results Publication Trends SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 9 SEPTEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 230 A total of 71 publications were retrieved from PubMed (Table 1). The earliest record dates back to 1976, with a gradual increase in publications over the years. A notable surge in research output was observed after 2015, reaching its peak in 2024 with 10 publications (Figure 1). Figure 1: Annual distribution of publications on age estimation from craniofacial and dental structures in forensic contexts (1976–2025), based on PubMed search results. Most Productive Authors and Journals The most prolific contributors were Galić I (3 publications), Friedrich RE (3 publications), and Scheuer HA. (3 publications) (Figure 2). Figure 2: Top contributing authors in the field of forensic craniofacial and dental age estimation The distribution of publications among journals indicated that the International Journal of Legal Medicine (n = 9) and Forensic Science International (n = 8) were the most prolific outlets for studies in this domain. These were followed by the Journal of Forensic and Legal Medicine (n = 4) and Cureus (n = 4). Several other journals, including Journal of Forensic Sciences and Archives of Kriminology, contributed between three and four publications each (Figure 3). Collaboration Network The co-authorship network revealed several well-connected clusters, indicating strong collaboration patterns, particularly among European research groups. Co-authorship network SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 9 SEPTEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 231 analysis of the 50 most active authors revealed distinct collaborative clusters with strong intragroup connections. Asian research teams—particularly from China—formed a tightly connected network, while European and South Asian clusters also displayed high collaboration density. Key connecting authors, such as Willems G, Thevissen P, and Galic I, linked multiple clusters, indicating their influential role in bridging research communities (Figure 4). Figure 3: Top 15 journals publishing on age estimation from craniofacial and dental structures. The International Journal of Legal Medicine ranked first with nine publications, followed closely by Forensic Science International (eight publications) and the Journal of Forensic and Legal Medicine (six publications). Figure 4: The top 30 most frequently occurring keywords extracted from article titles in the field of age estimation from craniofacial and dental structures. The horizontal bars represent keyword frequencies, highlighting "estimation," "dental," and "forensic" as the most prevalent terms, indicating the dominant research focus areas within the literature. Keyword Co-occurrence Title-based keyword extraction identified “estimation” (n = 22), “dental” (n = 20), and “forensic” (n = 16) as the most frequently used terms, reflecting the methodological and disciplinary focus of the literature. Other high-frequency terms included “children” (n = 14), “third” (n = 12), and “population” (n = 10), highlighting the frequent emphasis on pediatric and third molar-based age estimation approaches. Keywords related to methodology (“assessment,” SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 9 SEPTEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 232 “method,” “radiographic”) and anatomical focus (“molar,” “mandibular,” “skeletal”) were also prevalent (Figure 5). The keyword co-occurrence network displayed two major thematic clusters: Methodological focus – techniques for age estimation and validation studies. Anatomical focus – studies on craniofacial and dental structures, especially the mandible and third molars. Discussion This bibliometric analysis provides a comprehensive overview of global research trends, influential contributors, and thematic developments in the field of age estimation from craniofacial and dental structures, offering valuable insights into the evolution, collaborative patterns, and emerging focuses of this multidisciplinary domain. The assessment of age, particularly in subadults, is a critical component within forensic anthropology, necessitating robust and standardized methodologies to ensure accuracy and comparability across diverse studies (Corron et al., 2018). While numerous methods exist for age estimation, the assessment of dental and skeletal maturity stands out as an exceptionally reliable biological indicator for chronological age in children and adolescents [12]. The utility of dental and skeletal maturity in age estimation is predicated on their predictable developmental sequences, offering a more precise measure than chronological age alone, especially given the variability introduced by genetic and environmental factors [13]. This comprehensive approach is essential for narrowing investigative scopes and providing crucial demographic information for identification purposes in forensic contexts (Wang et al., 2022). In this study, different studies using different methods were evaluated. Our analysis revealed that the International Journal of Legal Medicine and Forensic Science International were the leading publication venues in age estimation research from craniofacial and dental structures, each producing a substantial number of articles over the study period. These journals have long-standing reputations in forensic science and are indexed in major databases, which may explain their high publication counts. The strong representation of Journal of Forensic and Legal Medicine and Cureus highlights the relevance of both traditional forensic platforms and emerging open-access journals in disseminating recent findings. This distribution suggests that research dissemination occurs through both highly specialized forensic journals and broader interdisciplinary outlets, potentially increasing the reach and impact of studies in this field. The inclusion of journals like Cureus also underscores a growing trend towards open-access publishing within forensic sciences, facilitating wider accessibility to research findings beyond traditional subscription models. This accessibility is critical for practitioners and researchers globally, particularly in areas where conventional journal subscriptions are cost-prohibitive, fostering a more equitable and rapid exchange of scientific advancements in forensic odontology and anthropology (Hansoti et al., 2016). This evolving landscape of scholarly communication, marked by a blend of established and open-access platforms, critically influences the speed and breadth with which novel methodologies and findings in age estimation are integrated into forensic practice, ultimately enhancing the reliability and scientific foundation of expert testimonies in legal proceedings (Palmela Pereira, 2014).. This shift towards open access, while beneficial for dissemination, necessitates rigorous peer review processes to maintain the scientific integrity and methodological standardization crucial for forensic validation (Corron et al., 2018). The author collaboration network showed distinct clusters, indicating strong intra-group collaboration but limited inter-group connectivity. Chinese research teams, as represented by authors such as Ma JW and Yu HX, formed dense collaboration clusters, likely reflecting centralized institutional projects or national funding initiatives. Similarly, European clusters, SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 9 SEPTEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 233 including contributors like Galic I and Cameriere R, demonstrated high connectivity within their networks, consistent with the tradition of multi-center studies in forensic odontology. The relatively sparse connections between clusters suggest potential opportunities for fostering crossregional collaborations, which could enhance methodological diversity and broaden population coverage in age estimation studies. This further underscores the critical role of inter-institutional and international partnerships in advancing the rigor and generalizability of forensic research, particularly in fields such as age estimation, where demographic variability is a significant factor. Such collaborations, despite their time-consuming nature, are pivotal for diffusing ideas and producing impactful science by integrating diverse perspectives and enhancing the potential for discovery (Fu et al., 2022). These robust collaborative networks are not merely conduits for information exchange but also serve as foundational structures for the emergence of "super social ties," characterized by profound trust and shared commitment, which significantly amplify research productivity and impact (Petersen, 2015). This phenomenon is particularly evident in the increasing probability of producing highly cited publications when teams exhibit greater diversity, such as a wider representation of institutions (Yuxiao et al., 2018). This institutional diversity not only enriches the scientific discourse through varied approaches but also mitigates inherent biases that might arise from localized research perspectives. This underscores the principle that broader geographic and institutional collaboration can significantly enhance the impact and citation potential of scientific endeavors, as diverse inputs from multiple locations are associated with higher-impact publications (Freeman & Huang, 2015). The most frequent keywords extracted from article titles—estimation, dental, forensic, children, and third—clearly indicate the dominance of dental maturity and third molar development as focal points in the literature. High-frequency terms such as population and assessment reflect the emphasis on validating age estimation methods across diverse demographic groups. Interestingly, the appearance of terms like Demirjian and Cameriere highlights the continued relevance of established methods while also pointing to the importance of methodological comparison in current research. The relatively high occurrence of radiographic and panoramic further confirms that imaging-based approaches remain the primary tool for data acquisition in this field. This underscores a critical need for rigorous methodological standardization, particularly given the acknowledged disparities in sampling and statistical approaches across numerous publications that can lead to difficulties in method definition, application, and comparison (Corron et al., 2018). Such discrepancies necessitate a more refined understanding of population-specific variations in dental development, as evidenced by studies examining diverse populations to improve the accuracy and applicability of these estimation techniques (Moze & Roberts, 2012). This focus on population-specific variations is crucial, given that the accuracy of methods like Demirjian's can differ significantly between sexes and age groups, sometimes overestimating or underestimating actual age (Tomás et al., 2014). The keyword co-occurrence network revealed interconnected thematic clusters, with estimation and dental acting as central nodes linking other high-frequency terms. This suggests that most studies frame their research explicitly within the forensic context (forensic, identification, human) while simultaneously grounding their methodology in specific anatomical and developmental parameters (third molar, skeletal, mineralization). The prominence of terms related to population groups (adolescents, children) indicates that age estimation is predominantly studied in younger cohorts, where chronological age determination has critical implications for both clinical treatment planning and legal judgments. Moreover, the interconnections between SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 9 SEPTEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 234 method, comparison, and development suggest an ongoing emphasis on evaluating the accuracy, applicability, and limitations of different age estimation approaches. Further analysis of the network topology could elucidate specific research gaps or oversaturated areas within forensic age estimation, thereby guiding future investigative efforts. Limitations This bibliometric analysis is subject to several limitations that should be considered when interpreting the findings. First, the search was restricted to the PubMed database, which, while comprehensive for biomedical and forensic literature, may have excluded relevant studies indexed in other databases such as Scopus or Web of Science. As a result, the dataset may not fully capture research published in non-indexed or regional journals. Second, only articles containing specific search terms in the title or abstract were included, potentially omitting studies that addressed age estimation from craniofacial and dental structures but used different terminology. Third, bibliometric indicators such as publication counts, co-authorship networks, and keyword frequencies reflect research activity and collaboration patterns but do not directly assess the methodological quality or scientific impact of individual studies. Conclusion and Implications This bibliometric analysis provides a detailed overview of global research trends, collaborative networks, and thematic developments in age estimation from craniofacial and dental structures within forensic contexts. The findings highlight a growing research interest over recent decades, with a marked increase in publications after 2015 and strong contributions from both established forensic journals and open-access platforms. Co-authorship and keyword analyses revealed distinct methodological and anatomical research clusters, underscoring the multidisciplinary nature of this field. Despite methodological diversity, the consistent focus on craniofacial and dental indicators reinforces their central role in accurate age estimation, particularly in medico-legal and anthropological applications. These insights can guide future research by identifying collaboration opportunities, thematic gaps, and emerging trends, ultimately supporting the development of more standardized, validated, and globally applicable age estimation methodologies. Declarations Acknowledgments: The authors used language support tools (ChatGPT 4.0® by OpenAI, San Francisco, USA, and Grammarly®) to assist in language checks, grammar refinement, and style consistency during manuscript preparation. Authors’ contributions: All authors were responsible for all aspects of the work, including: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, and Writing – review & editing. Competing interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Ethics approval and consent to participate: Not Applicable Publisher’s note: Advanced Research Journal remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. REFERENCES SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 9 SEPTEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 235 1. Bailey, C., & Vidoli, G. (2023). 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