A scoping review is an effective method for exploring the use of quantum dots in dentistry and identifying under-researched areas. The current study aimed to gather and evaluate the latest evidence on applying quantum dots in dental practices. In line with the guidelines provided by Levac, Colquhoun, O'Brien and the framework of Arskey and O'Malley, we employed a five-stage process for this review. These stages included defining the research questions, identifying relevant studies, selecting the appropriate ones, charting the data, and compiling the findings for reporting.

This section outlines the research methodology and the specific research questions: “What is the current scope and extent of research on the applications of quantum dots in dentistry, including their usage, benefits, challenges, and future prospects?”

Under the supervision of a research librarian (M.A.W), a comprehensive search was conducted in databases including OVID Medline, EMBASE, and SCOPUS. This search focused exclusively on English-language articles, imposing no restrictions on the year of publication. The latest actualization was in June 2024, where we identified all relevant studies on the subject. The search strategy involved querying terms in the titles, abstracts, and keywords sections. These terms were customized for each database using the Boolean operators “AND” and “OR.” As described ((“quantum dots” OR “quantum dot” OR “QDs” OR “QD”) AND (“dentistry” OR “dental” OR “tooth” OR “teeth” OR “oral health” OR “oral” OR “dental materials” OR “dental material” OR “caries” OR “streptococcus mutans” OR “S. mutans”) were the search terms used to find the articles. Additionally, a manual search supplemented this approach. Following the removal of duplicate entries, three review authors (TA, MA, and IG) independently screened each study, focusing on titles, abstracts, and keywords for potential inclusion. Those studies fulfilling the inclusion criteria were then fully analyzed. The authors resolved any disagreements through a joint decision-making process.

The inclusion criteria for the studies during stages II and III are (1) The study must specifically investigate the use of quantum dots in dentistry. This includes but is not limited to, applications in dental diagnostics, treatment procedures, imaging techniques, and material science; (2) Studies designed as experimental studies, observational studies, and clinical trials; and (3) Only peer-reviewed studies will be included to ensure the quality and reliability of the data. The following exclusion criteria were applied: (1) Articles mentioning quantum dots but not providing specific data or detailed analysis of their application in dentistry.; (2) Articles published in languages other than English, as these could present challenges in accurate interpretation and analysis; (3) Reviews, Case reports, and grey literature, including non-peer-reviewed articles, conference abstracts, editorials, and commentaries, which may lack the necessary scientific rigor and validation.

Data extraction was developed in Microsoft Excel and underwent a review by all the authors involved in the study to establish and document the necessary variables for effective data extraction. Subsequently, two authors, TA and IG, were tasked to extract data from the selected studies.

The data was extracted using a Microsoft® Excel form version 2016. The primary information extracted was (1) Authors and Year of Publication: To identify the study and track its temporal relevance; (2) Study Location: To understand the geographical distribution and context of the research; (3) Quantum Dot Characteristics: Details about the quantum dots used, including their composition, size, synthesis method, and functional properties; (4) Type of Dental Application: Specific dental application where quantum dots are applied (e.g., imaging, diagnostics, treatment); (5) Type of Dental Specialty: Specific dental area of interest where quantum dots are applied (e.g., general dentistry, operative dentistry, prosthodontics, etc); (6) Safety and Biocompatibility: Information on the safety profile and biocompatibility of quantum dots used in dental applications, including any reported adverse effects; (7) Findings and Outcomes: Key results of the study, focusing on the effectiveness, benefits, and limitations of quantum dots in dental applications.

Searches ended on June, 2024, with 1,430 studies imported for screening. Figure 2 shows a PRISMA flowchart with the search and selection process details. After deleting duplicates, 606 studies were selected for title and abstract screening. Full-text screening was permitted for 71 records. After a full-text review, only 22 studies were relevant, leaving 22 for content analysis.

Figure 3 displays the global trends and areas of investigations of QDs in Dentistry. In Figure 3A, the distribution of dental studies by year shows a steady increase in the number of studies conducted from 2009 to 2024. Notably, there was a constant rate of studies at 5% from 2009 until 2018. A notable increase began in 2019, stabilizing at 9% until 2022, before surging to 14% in both 2023 and 2024. This indicates a growing interest and focus in dental research investigating QDs. Figure 3B shows the geographical distribution and highlights that most research is concentrated in three countries. China leads with 14 studies, followed by Brazil, India, and Iran. This geographical distribution underscores the significant research output from the United States in dentistry.

The majority of the studies (82%) focused on treatment applications in dentistry, while a smaller portion (18%) addressed imaging technologies (Figure 3C). This suggests a predominant research interest in developing and enhancing dental treatment methodologies. Regarding the areas of application, QD studies spanned various dental fields with a predominant focus on Restorative Dentistry, which accounted for 45% of the research. This was followed by Periodontics and Orthodontics, which represented 32% and 18% of the studies, respectively. Dental Tissue Engineering was the least studied area, making up only 5% of the total. This distribution strongly emphasizes restorative practices, reflecting ongoing efforts to improve and innovate in restorative dental materials (Figure 3D).

Figure 3E illustrates the percentage distribution of QDs based on their composition. The largest proportion of QDs belongs to the Graphene-Based Quantum Dots category, accounting for 41% of the total compositions. Metal Oxide Quantum Dots make up 23%, reflecting their widespread use in various applications. The Carbon Quantum Dots category represents 18% of the total, while Other Quantum Dots and Hybrid and Multi-Component Quantum Dots each represent 9% of the distribution. These findings indicate a strong focus on graphene-based QDs, likely due to their favorable electrical and optical properties. Figure 3F highlights the size distribution of the QDs. The majority, 52%, fall under the Very Small category (less than 5 nm in size), indicating a trend toward developing extremely small QDs for applications that require nanoscale materials, such as bioimaging and drug delivery. The Small (5–10 nm) and Medium (10–20 nm) size categories each represent 19% of the distribution, while the Large QDs (greater than 20 nm) make up 10% of the total. This size distribution suggests a preference for very small QDs in dental research, where surface area and quantum effects are critical for performance.

Hydrothermal synthesis is the most common method, accounting for 50% of the total, reflecting its effectiveness in producing high-quality QDs. Sol-gel synthesis follows, representing 23% of the total, a method known for its simplicity and versatility in forming QD structures (Figure 3G). The purchased and used category directly accounts for 14%, indicating that some of the QDs used in research are commercially available. Solvothermal and Pyrolysis methods contribute 9% and 5%, respectively, representing less frequently used but still significant approaches to QD synthesis. This panel underscores the prominence of hydrothermal and sol-gel methods in QD fabrication.

The primary goals of the studies involving QDs are summarized in Figure 4A. Most of the research aimed at conveying antibacterial activity by incorporating QDs, representing 50% of the total, showcasing the emphasis on preventing bacterial infections and promoting oral health. Fluorescence activity is the second most explored property, representing 21%, highlighting the potential for QDs to be used in diagnostic applications. Osteogenesis activity is the third common property, representing 17%, indicating the possibility of QDs to promote bone regeneration. Lastly, remineralization accounts for 5%, suggesting using QDs to reinforce tooth enamel and dentin structures.

Types of materials that incorporate QDs are illustrated in Figure 4B. The largest category is Stock Solution, comprising 50%, showing that QDs are often studied dispersed in solution form. Resin Composite accounts for 14%, demonstrating its intense investigations in conjunction with QDs for develop antibacterial resin composites. Dental Adhesive System follows at 14%. Other categories include Orthodontic Coating/Bonding (9%), Photosensitizer (5%), Dental Cement (5%), and Glass Ionomer Cement (5%), which indicates diverse applications of QDs across different dental materials.

In further consideration of the prevailing target involving QDs to convey antibacterial activity, 73% of main outcome for QDs' studies has shown statistical bacterial reduction compared to a control group (Figure 4C). The outcomes of the remaining studies have demonstrated no significant difference (27%).

In relation to the distribution of microorganisms tested. Streptococcus mutans, a major cariogenic pathogen, constituted 53% of the bacteria examined. Porphyromonas gingivalis and Escherichia coli both represented 12%, while other microorganisms accounted for the remaining 23% (Figure 4D). The methodologies used to assess the antibacterial activity are detailed in Figure 4E. Colony Forming Unit (CFU) and other assays (31% each) were the most frequently used methods. Broth microdilution and disk diffusion methods (DDM) contributed 23% and 15% of the assays, respectively, highlighting the diversity of techniques used to evaluate antibacterial efficacy. Figure 5 illustrates the antibacterial mechanisms of quantum dots (QDs).

Table 1 shows the results from the cytotoxicity and biocompatibility assessments of various quantum dots (QDs), demonstrating consistent findings across multiple studies. Most QDs showed no significant cytotoxic effects compared to control groups under the tested conditions. For example, studies using human gingival fibroblasts (HGFs), including those by Garcia et al. (18), Pourhajibagher et al. (19), Cao et al. (25), and Hosseinpour-Nader et al. (27), reported no statistically significant cytotoxic effects. These studies utilized Sulforhodamine B colorimetric and MTT assays, supporting that QDs can be safely applied in dental-related contexts with minimal adverse cellular effects. Similarly, in Liang et al. (20), evaluations using the MTT assay and hemolysis assay on human immortalized liver cells (L0–2) and rat red blood cells (RBCs) revealed no toxic effects up to concentrations of 100 μg/ml, indicating a low systemic toxicity risk for these quantum dots. Furthermore, the stem cells from human exfoliated deciduous teeth (SHEDs) tested in Yang et al. (21) showed no cytotoxic effects up to 50 μg/ml, further highlighting the potential of QDs for dental and regenerative applications. In periodontal ligament fibroblasts (PDLFs) and periodontal ligament stem cells (PDLSCs), the findings of Hu et al. (22) and Liang et al. (26) indicated no cytotoxicity at concentrations up to 800 ppm and 50 μg/ml, respectively, reinforcing the safety of QDs in periodontal treatment settings.