This study used quantitative content analysis to systematically review YouTube videos on fluoride use.

A total of 86 videos were deemed eligible for analysis. These videos were categorized as follows: 50 (58%) videos advocating fluoride use, 19 (22%) opposing fluoride use, and 17 (20%) presenting mixed or neutral viewpoints.

We conducted internet searches on October 15, 2023, using keyword combinations input in Japanese text (Multimedia Appendix 1) with methodologies used in previous research analyzing YouTube videos on health-related information [39]. A comprehensive search was conducted on YouTube using a range of relevant keywords, including “fluoride,” as well as additional terms identified via Google Trends, such as the following:

“fluoride AND coating,” “fluoride AND processing,” “dentist AND fluoride,” “fluoride AND coat,” “fluoride AND toothpaste,” “fluoride AND pan coating,” “fluoride AND resin,” “fluoride AND danger,” “fluoride AND rinse,” and “fluoride.”

The search results were sorted based on “view count,” and the top 50 videos for each keyword were selected for analysis.

To minimize bias, all searches were performed using Google Chrome in incognito mode to prevent the influence of personal browsing history or tailored search results. After each search, we closed the browser and reopened it in incognito mode, and no personal Google accounts were used. For each search formula, the top 50 results were reviewed, and duplicate results were excluded. Results concerning no association with fluoride use for caries prevention (eg, content about Teflon-coated cookware), videos shorter than 1 minute in length, or videos presented in non-Japanese languages were excluded. TV news clips were also excluded to ensure a homogeneous sample by focusing on content originally created for the YouTube platform, rather than repurposed broadcast media.

Descriptive statistics, including means, ranges, and percentages, were computed for each variable in the basic video information dataset. This analysis provided a comprehensive overview of metrics, such as the average number of views per day, total view count, and distribution of video sources and content codes. To assess the reliability of the coding, the Cohen κ coefficient was used to evaluate the interrater agreement. The analysis was conducted using R for Mac (version 4.4.2; R Foundation for Statistical Computing).

This study did not involve human or animal participants, and all data were collected from publicly available web-based sources. To maintain anonymity, all identifying information, such as YouTube user IDs, was deidentified during data reporting. This study was granted an exemption from ethical approval by the ethics review committee of the Graduate School of Medicine, University of Tokyo.

This study analyzed fluoride-related content on YouTube and categorized videos into proponent and opponent stances to evaluate the nature of the information being disseminated. Results revealed that the number of videos produced by proponents surpassed those produced by opponents, aligning with the trends identified in previous studies on fluoride-related content on Instagram [35]. However, previous studies analyzed the content of fluoride-related posts on YouTube and Instagram, which exhibited strong antifluoride tendencies [33,34,36]. Beyond differences in language and search timing, Japan’s sociocultural and policy context is also likely to have influenced these findings. Unlike many countries where community water fluoridation is implemented, Japan does not add fluoride to public water supplies [7]. As a result, caries prevention relies largely on individual and parental decisions (eg, whether to accept topical fluoride or purchase fluoride-containing products) rather than on passive, population-wide exposure. In this setting, messages portraying fluoride as unsafe may have a more direct impact on behavior. Moreover, because medical professionals in Japan traditionally hold strong authority in treatment decisions [16], statements made by dentists, including those expressing skepticism toward fluoride or endorsing holistic positions, may exert substantial influence even when not strongly evidence-based.

Proponent videos displayed a relatively high proportion (9/50, 18%) of content with fewer than 1 average daily view, compared to only 5% (1/19) for opponent videos, suggesting that opponent videos achieved more consistent viewership. Furthermore, 95% (18/19) of the opponent videos garnered more than 19 daily views, compared to only 44% (22/50) of proponent videos. This indicates that the opponent content may have reached a broader audience. Videos with over 1000 likes constituted 37% (7/19) of the opponent videos compared to 14% (7/50) of the proponent videos. Notably, 10% (5/50) of the proponent videos did not permit likes to be counted, potentially limiting their ability to visibly demonstrate audience support.

The content themes of proponent and opponent videos generally mirrored those identified in previous studies [30,32]. Most proponent videos, created predominantly by dental professionals (30/50, 60%), focused on themes such as the “mechanism of fluoride in preventing caries” (32/50, 64%), the “role of fluoride in caries prevention” (24/50, 48%), and “evidence-based guidelines” (24/50, 48%). These videos emphasize scientific and objective information. Among the extracted videos, almost all uploaded by dentists and dental hygienists mentioned the “mechanism of action of fluoride” (29/30, 97%). The caries prevention mechanism of fluoride is associated with various processes, including enamel remineralization and its effects on oral microorganisms, which are consistent with established facts regarding caries prevention [1]. This suggests that dental professionals produce persuasive content based on evidence and expertise. Studies indicate that expert-driven health communication is more effective in influencing individuals to adopt healthy behaviors [22-24]. However, the objective and fact-based nature of such content may limit its engagement potential for general audiences [20,21], thereby reducing its dissemination.

By contrast, videos by nonmedical individuals or organizations frequently highlighted themes such as dietary habits for caries prevention (3/15, 20%), the importance of regular dental checkups (3/15, 20%), and general claims regarding the safety of fluoride (1/15, 7%). These themes are often presented without supporting evidence, thereby reducing their credibility.

Opponent videos predominantly focused on concerns regarding “additives other than fluoride” (14/19, 74%), fluoride being “unsafe” (7/19, 37%), and fluoride being “dangerous” (6/19, 32%). These messages often align with broader preferences for natural or organic products and lifestyles that avoid synthetic additives [33]. Many of these videos also promoted specific fluoride-free products, subtly influencing consumer choice. Although excessive use of fluoride can lead to fluorosis [12], harmful effects are dose-dependent, and adverse outcomes are rare in typical use conditions [13]. Opponent videos that portray fluoride as “unsafe” or “dangerous” unnecessarily provoke fear, spread misinformation, and reinforce misconceptions.

In addition, 32% (6/19) of the opponent videos discussed alternatives to fluoride-containing products, providing practical guidance that may appeal to viewers. However, such content often serves as a marketing strategy to promote specific products [33,35]. Many topics mentioned in the videos were consistent with those in previous studies. However, new findings were observed in this study. Notably, 1 (15%) antifluoride video created by a dentist included content that not only opposed fluoride use but also criticized treatments involving metal prostheses, such as full metal crowns. This finding suggests a potential link between antifluoride sentiments and a broader skepticism toward established, evidence-based dental practices. Previous studies have stated insufficient evidence to support or refute the superiority of metal-free materials over metal-ceramics or other standard restorations for fixed prosthetic treatments [40]. Metal prostheses are a treatment option covered by public health insurance in Japan. Given the high level of trust placed on health care professionals, particularly in Japan, where medical decisions are often heavily influenced by doctors’ opinions [16], such videos may significantly influence the decision-making processes of patients.

Unlike previous studies, this study did not find any videos from either the pro- or antifluoride groups that mentioned water fluoridation or fluoride supplementation. This is likely because these fluoride application methods are not used in Japan [7]. Although easy access to health information brings many benefits, it also makes it easier for false, biased, or harmful content to spread [18]. Opponent videos often leverage sensational narratives to emphasize fluoride’s alleged risks, trigger strong emotions, and motivate viewers to share content or join discussions [20].

Social media platforms also enable the formation of echo chambers in which individuals with similar beliefs reinforce each other’s views, thereby further perpetuating misinformation [26]. The dissemination of such misconceptions can hinder the active use of fluoride by the general public, particularly in Japan, where there are no opportunities to receive passive fluoride application methods, such as water fluoridation. In addition, negative attitudes toward fluoride have led some parents to refuse fluoride treatment for their children [36], and these individuals often reject vaccinations [37]. This rejection of preventive health measures, fueled by misinformation on platforms such as YouTube, poses significant risks, potentially increases the prevalence of preventable diseases, escalates health care costs, and causes unnecessary suffering for individuals and families [38].

This study is the first attempt at conducting a content analysis of Japanese YouTube videos addressing fluoride use for caries prevention, categorizing information into proponent and opponent perspectives. However, this study has several limitations.

First, it focused exclusively on Japanese YouTube videos, limiting the findings to information disseminated in Japanese and excluding perspectives from other cultural and linguistic contexts. Nevertheless, the results aligned with those of previous studies that analyzed fluoride-related social media content in other languages [35]. Second, our analysis was restricted to publicly available video sequences. YouTube also hosts “unlisted” videos, which are accessible only via direct links, and “private” videos, which are visible solely to individuals authorized by the uploader. As these visibility settings can change at any time, we excluded videos shared in closed or restricted communities. However, focusing on publicly accessible videos remains a significant endeavor, as they are most likely to appear in search results and reach a broad audience. Third, qualitative evaluation of video content may involve a degree of subjectivity. Although this study implemented a categorization process that required evaluative judgment, triangulation by multiple researchers was conducted to minimize bias and validate the findings. Finally, the findings are specific to the data collection period (October 15, 2023). Social media content is dynamic, and trends may shift over time or in response to current events, potentially leading to different patterns in other periods.

Despite these limitations, this study is noteworthy for its originality, as it offers a comprehensive content analysis of fluoride-related information on Japanese YouTube videos categorized by proponent and opponent perspectives.

This study provides a comparative analysis of proponent and opponent content associated with fluoride use for caries prevention on YouTube. Proponent videos outnumbered opponent videos; the latter demonstrated a more consistent reach among viewers, achieving higher average daily views and a greater proportion of likes. Opponent videos relied on emotionally charged, sensational, and straightforward messages, such as “fluoride is harmful to the human body,” which provoked anxiety, encouraged empathy, and facilitated content sharing.

By contrast, proponent videos, predominantly produced by experts, such as dentists and dental hygienists, disseminate accurate, evidence-based information. However, these videos lack the emotional engagement necessary to capture the viewers’ attention and effectively foster resonance.

The potential consequences of such misinformation are significant. Parents opposing fluoride use have been shown to reject not only fluoride treatments for caries prevention but also vaccinations, reflecting a broader resistance to preventive health care measures. This could lead to an increased disease burden, higher healthcare costs, and unnecessary suffering from preventable illnesses among children and communities.

To counter these challenges, it is imperative to develop communication strategies that amplify the impact of proponent messages. These strategies should balance scientific rigor with accessible, practical, and engaging content that resonates with the viewers’ daily lives. Moreover, since antifluoride content often functions as a marketing strategy to promote specific fluoride-free products, it is imperative that communication strategies also counter these commercial motivations behind misinformation. Efforts must prioritize expanding the reach of accurate information to effectively combat the spread of misinformation and support public health initiatives.