The advancement of biological strategies, specifically tissue engineering, has emerged as a prominent approach in dental research in the current era. This approach focuses on the regeneration and biomineralization of dental tissues that have been lost. In the context of dentin pulp regeneration, the intricate process is driven by the interactions between various elements such as stem cells, signaling molecules, biomaterials, and the microenvironment in the periapical region.^[1] Notably, this innovative treatment method gained recognition from the American Dental Association in 2011. However, despite its acceptance, the establishment of evidence-based guidelines that offer the most suitable outcomes is still a work in progress. These guidelines are gradually being developed through numerous clinical and fundamental research studies.^[2]

In the last 15 years, there have been numerous endeavors in the medical and dental fields to regenerate and replace diseased tissue or organs. One significant advantage of reconstruction techniques is the ability to recreate the original texture and architecture of the affected area. In the field of endodontics, similar efforts have been made through root restorative (RE) procedures. These procedures aim to replace damaged tooth structures, including dentin and root structures, as well as cells of the dentin–pulp complex using biologically based methods. Since its reintroduction, RE has garnered immense interest globally, not only among practitioners but also researchers, academics, and financial institutions. Over the past 15 years, it has emerged as one of the rapidly expanding fields in dentistry.^[3] The results of Sheikhshoaei et al., who dealt with co-citation and word co-occurrence networks of Iranian articles in the field of dentistry, confirm these findings.^[4]

On the other hand, the assessment of research activities is widely recognized as a crucial tool in attaining research performance standards within scientific institutions. The advancement of scientific knowledge has greatly contributed to the expansion of research endeavors in various scientific domains. The quantification of scientific output plays a pivotal role in determining productivity levels. Moreover, the evaluation of scientific output extends to the realm of health-related sciences, where studies have been conducted to gauge the scientific contributions made in these fields.^[5,6] For example, Shirani et al. reviewed high-quality articles on COVID-19 and effectively summarized them for healthcare providers and the general population.^[7] Furthermore, in other studies, artificial neural network methods have been used to analyze the content of scientific resources.^[8,9]

One of the scientometric methods employed to gain insights into published research across diverse scientific disciplines is the creation of a scientific map. This approach not only provides a comprehensive overview of the research landscape but also highlights the most influential subject areas. The primary objective of scientific maps is to present a holistic view of research progress, interconnections between different fields, and the evolution of these fields over time^[10,11] Drawing a scientific map serves as a potent bibliographic method for analyzing research output. It offers a visual representation of the relationships between scientific disciplines, subject areas, experts, and scholarly texts. The process of creating a scientific map involves observing a specific scientific subject area and delineating the boundaries of research to ascertain its structure and interactions. The ultimate aim of drawing a scientific map is to elucidate the structural and dynamic aspects of research.^[12,13] In this regard, three key components are taken into consideration when constructing the scientific structure: individual elements, interconnected elements that form a network, and the interpretation of relationships between these elements. Scientists and researchers have employed various tools to illustrate and depict the structure of science in different fields.^[14,15]

Even though several studies have explored and evaluated the outcomes of various aspects of dental restoration from different angles,^[3,4,16-18] a comprehensive analysis utilizing the concept mapping method, which is considered a crucial scientific approach for gaining insights into research perspectives, has not yet been conducted specifically in the field of dental pulp reconstruction. Consequently, the objective of this research is to examine the scientific progression of dental restoration through the implementation of the scientific mapping approach. In addition, this study aims to investigate and analyze the scientific metrics of global scientific publications related to dental pulp restoration within the Web of Science database. Thus, the aim of conducting a bibliometric analysis of global research related to dental pulp regeneration is to offer a comprehensive view of the advancements in this significant area of dental research. This analysis also aims to identify key themes that can serve as reference points for shaping research policies in the field.

The purpose of this study was to create a comprehensive scientific overview of knowledge production in the area of dental pulp regeneration. The findings regarding the overlapping map and the conceptual completion of the subject area of dental pulp regeneration show that over time, the number of keywords has increased. Likewise, there has been an increase in the number of shared keywords between consecutive subperiods. For instance, there were 306 shared keywords between the first and second subperiods, and this number grew to 428 between the fourth and fifth subperiods. Moreover, the similarity index also increased across the subperiods, from 0.57 between the first and second subperiods to 0.69 between the fourth and fifth subperiods. These findings indicate that researchers in the field of dental pulp regeneration are establishing a more consolidated terminology. However, it is worth noting that there is a significant presence of new and transient keywords. This means that there are a considerable number of keywords that are only used in one subperiod and not in subsequent periods. For example, in the fourth subperiod (2019–2021), out of a total of 118 new keywords, 39 were identified as transient keywords.

Findings regarding thematic evolution, based on the number of articles, show that stem cells are not only very important in dental pulp regeneration, but their importance is increasing day by day. Stem cells are undifferentiated cells and can differentiate into various types of vascular cells, nerves, fibroblasts, etc., As a result, the subject of stem cells is related to almost all other subjects related to the restoration of the dental pulp and even the restoration of the periodontium and is the focus of research.

Compared to the number of published documents, the findings show that from the citation point of view, the topic of stem cells has a lesser role and even decreases from period to period. The reason can be the obvious role of stem cells in pulp and periodontium regeneration and its generality in most research. But here other issues become more prominent. Epigenetics is directly related to stem cells and includes gene changes that cause the proliferation and differentiation of stem cells into different types of cells. Clinical outcome is related to furcation and bioactive glass, and bioactive glass itself is related to clinical outcome. The importance of bioactive glass is in vital pulp therapy. End filling material is very important, but it is not related to another issue. Its importance is also in pulp regeneration in teeth with immature apex.

By analyzing data from five different periods over the past decade (2013–2023), it was observed that the topic cluster of the animal model was well-established during the years 2015–2013. This is because preclinical tests are necessary for dental pulp regeneration, and rat and dog teeth were commonly used in these studies.^[23] Another crucial area of research focused on the nervous system, as regenerating nervous tissue is a complex and challenging biological process. Since the regeneration of dental pulp also requires the regeneration of nerve terminal clusters, research in this field is of utmost importance. It was found that Dental pulp stem cells (DPSCs) have the potential to transform into neural cells through proliferation and differentiation.^[24] The clusters related to epigenetics and clinical trials were situated within the motor theme. Epigenetics, in particular, played a significant role in the development of knowledge regarding pulp regeneration. This cluster also had the highest emission rate, indicating its importance. Epigenetic modulations lead to changes in the gene content of DPSCs, which in turn promote their proliferation and differentiation into various types of cells such as vascular and nerve cells.^[25,26] Epigenetics has proven to be effective in the regeneration of dental pulp in cases of reversible pulpitis.^[27] While clinical outcomes are of utmost importance, it is crucial to examine theoretical findings at the patient’s bedside and test the success rate of the pulp regeneration process. Stem cell and hydroxyapatite clusters are key components in this field. Stem cells, in particular, play a fundamental role in pulp regeneration and have shown the highest centrality and overall significance in the progress of this field. In addition, a significant number of research studies have focused on stem cells. Dental pulp stem cells (DPSCs) are essential in the regeneration of lost dental pulp as they possess the ability to grow and differentiate into various cell types within the dental pulp tissue.^[28-30] Hydroxyapatite, on the other hand, is an important but relatively underdeveloped topic that ranks second in terms of centrality. Regenerating dental pulp requires three essential factors: stem cells, growth factors, and a network or scaffold.^[31] Hydroxyapatite, in its various forms, can aid in the absorption of materials and cells by forming a network within the pulp space.^[32] Furthermore, it can also be utilized for direct pulp cap procedures.^[33]

Between 2015 and 2017, the motor theme section focused on the topic of end filling material, which was considered to be of utmost importance and highly developed. This issue held significant relevance in the treatment of immature teeth requiring root canal treatment. When the pulp tissue is removed from the canals for root canal treatment in these teeth, it is common practice to fill them with either calcium hydroxide or MTA. However, this approach halts the growth and development of the root, leaving the tooth apex exposed. Alternatively, pulp regeneration can be pursued. This involves inducing apical bleeding and forming a blood clot to create a seal in the apical canals, allowing the roots to continue developing. Within the realm of end filling material, the focus lies on determining the best material for achieving an apical seal.^[34] In the highly developed and isolated theme quadrant, the regenerative endodontic therapy cluster was situated, representing an independent and specialized area of study. Stem cell and bioactive glass clusters were located in the basic and transversal quadrants, with stem cells being the most prominent in terms of centrality and number of articles during this period. Detailed explanations were provided regarding stem cells, while bioactive glass, which had the highest citation rate, was suggested as a potential scaffold material, although further research and investigation were required.^[35] It is worth noting that bioactive glass also had other applications, such as direct pulp caps. Following the bioactive glass cluster, the rat cluster received significant citations, primarily focusing on animal trial subjects.

During the period from 2017 to 2019, the field of polymers was situated within the motor theme quadrant and emerged as a significantly crucial and advanced subject. Among all the clusters, the polymer cluster exhibited the highest density and citation count, indicating its utmost significance. This particular cluster holds great importance because polymers are recommended materials for scaffold construction. The utilization of polymeric scaffolds, in conjunction with stem cells known as DPSCs, facilitates cell attachment, cell proliferation, and angiogenesis.^[36,37] In the quadrant characterized by highly developed and isolated themes, clusters related to adhesive systems and promotion were identified. The adhesive system cluster’s significance can be attributed to its association with direct pulp cap treatment, which likely contributed to its emergence within this cluster.

From 2019 to 2021, the motor theme focused on neurotrophins and their associated complications. Neurotrophins, which are proteins present in both the brain and peripheral tissues, play a crucial role in stimulating the growth of nerve cells and damaged cells.^[38] Consequently, they are essential for the reconstruction of tooth pulp. The complications arising from this process include the response of the pulp tissue, the materials utilized, the clinical response, and the patient’s overall response. It is of utmost importance to identify and address these complications effectively. In the highly developed and isolated theme quadrant, clusters of lesions, blocks, and systems are situated. Within this range, lesions exhibit the highest density. Apical lesions can significantly impact the treatment of pulp regeneration and influence the prognosis of the tooth. However, Schmalz et al. were able to successfully perform pulp regeneration in a tooth with a preexisting lesion.^[39]

Between the years 2021 and 2023, the motor theme section housed stem cells and agents. Notably, during this period, stem cells made their way into the motor quarter, signifying significant advancements in research within this cluster. The cluster transitioned from an undeveloped state to a developed one. Within the highly developed and isolated theme quadrant, clusters such as ligament stem cells, neurons, dental follicle stem cells, and regulators were present. The presence of dental follicle stem cells and ligament stem cells as separate clusters within this section indicates that these subsets of stem cells have been extensively studied and given importance in different periods. The significance of the neuron cluster was previously mentioned. The regulator’s cluster holds great specialization and importance in the field of dental pulp regeneration. Various processes involved in this treatment, such as stem cell differentiation, rely on regulatory factors.^[40] In the basic and transversal theme quadrants, the calcium silicate cement cluster can be found. This cluster was proposed as a novel material for vital pulp therapy and had connections to various other topics. The importance of this cement lies in its potential use for direct pulp cap treatment, pulp regeneration, and filling dental pulp in pulpotomy treatment, thereby preserving the vitality of the remaining dental pulp.^[41,42]

In general, it has been observed that the stem cell cluster consistently had the highest number of articles across all periods. As we progressed through time, the significance of this cluster continued to grow, eventually becoming a crucial component in the motor theme during the last period. In addition, a significant portion of the studies conducted during different periods focused on identifying suitable materials for scaffold formation. Various materials, including polymers and bioactive glasses, were proposed as viable options for scaffold formation in different periods. Another area of emphasis in the research was the study of different types of cells and their formation processes. Understanding how these cells are formed and their characteristics was a key aspect of the research conducted during various periods. Finally, growth factors and regulators, such as the cluster of regulators that play a vital role in dental pulp regeneration, were also given considerable attention in different periods. It is anticipated that these factors will continue to gain importance in future studies related to pulp regeneration.

Further investigations are required to advance dental pulp regeneration despite the extensive research conducted on this topic. Dental pulp stem cells (DPSCs), scaffold networks, growth factors, and regulatory factors are the three main factors that influence dental pulp regeneration. These factors play a crucial role in absorbing different materials and cells, providing a scaffold for regeneration, and promoting the growth and regulation of dental pulp. By analyzing maps and thematic clusters in dental pulp regeneration research, as well as considering indicators such as repetition frequency, centrality, and citation of these clusters, researchers can identify the strengths, weaknesses, and gaps in current research. This analysis can inform future research policies and enhance the effectiveness of dental pulp regeneration studies.