2.1 Research Design

This research study was Mixed methods employed an Explanatory Sequential Design.

2.2 Research Methodology

2.3 Ethics Considerations

This research study was designed with a strong emphasis on ethical principles and the protection of participants. The study protocol was reviewed and approved by the Human Research Ethics Committee of the Sirindhorn University of Public Health, Chonburi, with Certificate of Approval (COA) number 2023/T07, obtained August 21, 2023.

3.1 Quantitative Analysis

Part 2: Knowledge of health literacy principles

Table 1 summarizes the distribution of scores and incorrect responses across various health literacy skill domains. The majority (57.74%) scored 2 out of 7 points, with comprehension being the most challenging domain (97.61% incorrect responses). Decision-making and application showed the lowest levels of misunderstanding (5.39% and 3.67% incorrect, respectively).

The scores were classified into five levels (Excellent, Good, Moderate, Fair, and Needs Improvement), with a range of 1.4 for each level. The overall knowledge of health literacy principles was found to be at a fair level (mean = 2.54, SD = 0.81), as shown in Table 1.

Part 3: Testing of knowledge of nutrition for oral health

The finding indicated that the top mode of the knowledge scores was 4 points, achieved by 2639 individuals, accounting for 25.1%. This was followed by 2 points, achieved by 2635 individuals (25.1%), and 5 points, achieved by 2129 participants (20.2%), respectively.

The scores were classified into five levels (Excellent, Good, Moderate, Fair, and Needs Improvement), with a range of 1.4 for each level. Overall knowledge of nutrition for oral health was found to be at a moderate level, with a mean of 3.60 and a standard deviation of 1.34, as shown in Table 2.

Part 4: Evaluation of nutritional literacy for individual oral health

The scores were tabulated, and the results were interpreted using a five-level rating scale based on a five-point Likert scale [11], with a range of 0.8 for each level. The overall evaluation of nutritional literacy for individual oral health according to the perceptions of VHVs was at a high level, with a mean of 4.06 (SD = 0.39), as shown in Table 3.

Part 5: Relationship testing

3.2 Qualitative Analysis

Public Health Region 1 comprises eight provinces: Chiang Mai, Chiang Rai, Lamphun, Lampang, Phrae, Nan, Phayao, and Mae Hong Son. The study included 20 VHVs from Public Health Region 1. VHVs play a crucial role in supporting and promoting community health by providing health promotion and ongoing advice on disease treatment and disease prevention to the local population. They also serve as key change agents in terms of health behaviors by communicating public health information; providing recommendations and disseminating knowledge; planning and coordinating public health development activities; and offering various health services such as health promotion, disease surveillance and prevention, basic medical and pharmaceutical assistance according to the regulations of the Ministry of Public Health, patient referrals, rehabilitation, and community health activities. VHVs receive compensation and welfare benefits according to the regulations of the Ministry of Public Health. In this study, VHVs can be categorized into two main groups: (1) VHVs who exclusively perform their duties as village health volunteers, and (2) VHVs who serve both as village health volunteers and as committee members or participants in other community organizations. Examples include caregivers for the bedridden elderly, members of women's development groups, savings groups, volunteer teachers, or members of local administrative organizations. Although most VHVs have attained an educational level under a bachelor's degree, they demonstrate significant potential and capability in community development through collaboration and support from both public and private sectors. The analysis revealed two main themes: understanding of oral health nutrition literacy and experiences related to oral health nutrition literacy.

The participants demonstrated diverse interpretations regarding the distinction between knowledge and health literacy. One portion of the participants interpreted both concepts as identical, articulating for example, “There are the same, right?” (P1). Conversely, some participants expressed uncertainty regarding the distinction between them, saying, “They're not the same, but I don't understand. Nothing has changed, even after the training and meetings, it's still the same as before” (P13).

Regarding skill in accessing information, participants expressed different perspectives. Some reported receiving information from various media “I got from various media channels” (P7, P11, P13, and P20), “I got it from dentists, they were providing knowledge and from hospital public relations” (P1 and P11), while several participants had the ability to search for information on their own “I can search for it on Google” (P1, P3, P4, P6, P9 and P13).

Participants reported possessing an understanding of the communication process, including the elements of a communication model (sender, message, channel and receiver), but their understanding was not comprehensive. As one participant stated, “The content is sometimes similar, but I don't know if it's old or new. The content is from what year, it's hard to find” (P10 and P16).

Many participants understood that the ability to comprehend information or messages would be improved if the content or text was short and clear, easy to remember and accompanied by visuals; for example, “There needs to be videos or pictures, otherwise, I won't understand” (P1, P7, P8, P9, P10, P12, P13, P15, P17, P18, and P20).

Although the participants demonstrated an understanding of the concept of inquiry, most struggled to formulate clear and goal-oriented questions to obtain the desired information. Even those who claimed to be capable of asking questions did not evaluate their inquiries afterward. For instance, one participant stated, “I can't ask questions, but I'll just repeat what the doctor said before; otherwise, they'll think I don't know” (P3 and P10). Another participant mentioned, “I didn't prepare any questions. If I think of something when I meet the doctor, I'll just ask” (P2 and P8).

In relation to the awareness that consumption of fizzy drinks can lead to tooth decay, participants exhibited diverse decision-making approaches. Some opted to cease drinking such beverages altogether and transitioned to plain water “Decided to stop drinking fizzy drink and then switch to drinking plain water” (P9). Conversely, others persisted in their soft drink consumption, rationalizing their behavior with sentiments like: “Decided to still drink, I already love to drink. If I have decayed teeth, I'll see the dentist” (P18). Others decided to reduce their consumption without considering it harmful “Decided to drink less. Anyway, I don't drink much in the first place” (P20).

Participants understood the crucial need to practice what they learned. Factors contributing to effective application included the ability to remember it themselves “Remember in my mind to eat fruit and then drink water” (P13), and the ability to remind themselves, as well as seeking support from others or using reminder tools “Set a timer on my phone to drink water after eating fruit” (P8), “Ask relatives or close people to help remind me” (P10 and P11), and “Write it on the water bottle” (P9).

In the context of health literacy, VHVs were unable to explain the different between knowledge and literacy even after attending the training sessions, meetings, and seminars, which adhered to conventional teaching methods without significant modifications or advancements. Notably, VHVs did not receive explicit training focused on health literacy skills. As articulated by one participant, “Teaching and training techniques for health literacy among public health personnel still rely on traditional lecture-based methods rather than fostering learning processes that develop health literacy skills.” (P1). Similarly, another participant recounted, “During VHV meetings, the doctor's presentation included slides that referenced the term ‘literacy’ ” (P2, P4, P5, and P8). Ultimately, despite training and ongoing meetings, the status quo persisted, as expressed by P13, “Nothing has changed; it remains as it was before.”

Regarding access to information, most VHVs had experiences of self-searching “Searched from Google” (P1, P3, P4, P6, P9, and P13), “In the past, it was newspapers, now I read books about teeth and oral cavity or ask the doctor. If I don't understand, I will consult dental expertise” (P6 and P16), and “These days, I use Facebook, Line, there's information to read, YouTube/TikTok too” (P4 and P13). Some also received information directly from experts through training “Received training from expert staff who came to teach in the village” (P15 and P17).

In the context of communication, VHVs possessed experience in disseminating health information to the local population; however, they frequently encountered challenges. The VHVs occasionally lacked credibility and preparedness, leading recipients to harbor skepticism toward the information provided as they mention “The people we teach don't believe in the importance of teeth; they say we're not dentists” (P1 and P5). VHVs also sometimes lacked understanding and the ability to identify the main points in the information to be communicated and failed to verify the timeliness of the information “Just forwarded the message to the target group, sometimes I don't really understand but I just send it, through Line or give out brochures, sometimes I even gave out outdated brochures” (P3 and P9), and “It was like that before, where I couldn't explain further, like the 222 toothbrushes, when people in the area asked, I couldn't answer” (P14, and P19). Additionally, confusion existed between the message and the communication channel, and recipients' adherence to existing beliefs hindered effective communication “They don't really believe the VHVs; they believe that if their teeth hurt, they should just go see the doctor” (P17 and P19).

Regarding comprehension, VHVs were unable to remember and grasp the key points of complex oral health information, which could impact their ability to provide proper care and practice oral health. This was often due to the complexity of the oral health information, which is full of medical terminology and difficult for the general public to understand. The presentation of the information also did not facilitate learning and lacked appropriate formatting, visuals, or media to aid in remembering and understanding. As one participant stated, “Some dental issues are hard to understand, a lot of English words need to be put in Thai” (P1, P2, P11, P14, P15, P16, P19, and P20). Lack of interest and awareness of the recipients also affected their ability to understand and remember the information “The patients don't really care about what we tell them, when we visit again, they can't remember what we said” (P6 and P12). The abundance of information in the digital age also made it difficult to filter and remember the useful information “There's too much information about good foods for teeth online; I get confused about which one is correct” (P14 and P19). Many participants also lacked regular reviews or opportunities to practice teaching the information received, which could further impede their ability to remember oral health information “If you only teach once, I can't remember some items; if I don't try to practice, I still won't understand. It needs to be taught many times before I can remember and understand” (P1, P2, P3, P5, P7, P8, P10, P11, P12, P14, P15, P17, P18, P19, and P20). Personal beliefs and cultural values can also lead to different understandings or perceptions of oral health information “Some people believe that sucking on salt can relieve toothache; they won't go see the doctor, no matter what you tell them, they won't believe you” (P10 and P15).

In terms of inquiry skills, VHVs gained practical experience in eliciting medical histories from patients within the community. However, their use of questioning techniques often lacked strategic planning and subsequent evaluation “I didn't prepare any questions. If I think of something when I meet the doctor, I'll just ask” (P2 and P8) and “I asked, but I didn't think about the question further, as long as I got the answer I wanted” (P6 and P17).

In terms of decision-making, VHVs demonstrated two types of decision-making skills: (1) evaluating alternatives and (2) weighing pros and cons “Decided not to drink, because drinking causes stomach acidity” (P2), “Decided not to drink; it's very inappropriate to drink because it's an acid that destroys health. And from what I've heard and experienced before, they use it to clean engines, remove rust, clean bathroom stains, and other items, so for personal health, it's best not to drink it at all” (P7), and “Decided to stop drinking sugary drinks because they cause tooth decay” (P8, P14 and P17). Some VHVs made decisions without benefit evaluating by comparing other alternatives choices “Decided based on the situation and context of each case” (P19) and “Decided to change behavior by reducing the frequency of drinking” (P12).

Regarding application, VHVs had plans to remind themselves, ask others to help them, or use reminder tools “Use the method of remembering and practicing until it becomes a habit” (P1), “Set a reminder note on my mobile phone” (P12), “Asked relatives or close people to help remind me” (P10, P11), and “Shared information in the Line group” (P17).

3.3 Data Integration

Case 1: Quantitative study data revealed that the correlation analysis showed when the score of nutrition for individual oral health literacy increases, it results in a decrease in the score of knowledge of health literacy principles and also leads to a decrease in the score of knowledge of nutrition for oral health.

Although 58% of the VHVs have received training in nutrition for individual oral health literacy and self-assessed their knowledge of health literacy and nutrition for individual oral health literacy, but the qualitative study results indicated that VHVs still lack the skills and knowledge to apply the health literacy principles in their work.

This finding was consistent with the VHVs' understanding that no difference existed between knowledge and literacy. Their training followed the same traditional teaching methods without any changes or development, and they did not receive clear training on health literacy skills.

Regarding communication, while VHVs communicated with the community, they often encountered problems, indicating a lack of communication skills. They also struggled to remember and comprehend complex oral health information because the information often contains medical terminology and is presented in a way that does not facilitate learning, lacking appropriate formatting, visuals, or media.

Case 2: The quantitative analysis showed that the VHVs' knowledge of nutrition for oral health increased, and their knowledge of health literacy principles also improved. This finding was consistent with the qualitative findings that VHVs often sought help from dentists to understand oral health-related issues. Training and information for VHVs were provided by dentists and hospital public relations staff. Additionally, 58% of VHVs had received training in nutritional literacy for individual oral health, which explains the increase in knowledge of health literacy principles.