Participants

This study was designed as a pre–post pilot intervention without a control group and was conducted between April 2023 and December 2024. A total of 84 participants (52 children and 32 parents/guardians) were recruited from two community children’s cafeterias in Tokyo. These cafeterias were selected based on their established collaboration with the research team and their stable user populations, which made them suitable settings for a feasibility-oriented pilot intervention. A convenience sampling approach was used, as the primary aim of this study was to assess the feasibility and preliminary changes associated with the integrated oral health and nutrition education program. Participants were eligible if they were regular attendees of the cafeterias and did not have any food allergies that would interfere with the program activities. Written and verbal informed consent was obtained from parents or legal guardians, and assent was obtained from all participating children. Participation was voluntary, and all data were anonymized prior to analysis.

This study was conducted in accordance with the principles of the Declaration of Helsinki (World Medical Association, 2015) and the Ethical Guidelines for Life Science and Medical Research Involving Human Subjects (March 23, 2021). Ethical approval was obtained from the Ethics Committee of the Faculty of Dentistry, Institute of Science Tokyo (approval number: D2022-026). The study was also registered with the University Hospital Medical Information Network (UMIN) (trial ID: UMIN000048328).

Intervention

The Comprehensive Awareness Modification of Mouth, Chewing, and Meal (CAMCAM) program for Children (CAMCAM-P for kids) was implemented over a 6-month period. Once a month, participants attended an educational session on oral health, chewing, and nutrition, and received a specially designed bento meal (CAMCAM Bento) intended to promote chewing.

Each educational session lasted approximately 10 min. Overall, six sessions were conducted during the intervention period. Lectures were delivered by dentists, dental hygienists, and registered dietitians using presentation slides covering topics related to oral health, chewing, and nutrition.

The CAMCAM Bento consisted of rice as the staple food, a main dish, and side dishes. The bento was designed to increase chewing frequency by (1) using foods with higher chewiness, (2) cutting ingredients into larger pieces, (3) shortening cooking times, and (4) reducing moisture content.

In addition, a mobile application was used to disseminate short informational messages (approximately 200 characters) once a week on topics related to oral health, nutrition, and chewing, and to allow participants to view recorded lectures.

Questionnaire

A child-specific CAMCAM Checklist was developed to evaluate changes in participants’ awareness and behaviors associated with participation in the program. The questionnaire was developed by the research team based on a review of previous studies and existing oral health and nutrition education materials [19–21], and through discussion with dentists and dental hygienists. The checklist was designed as an original instrument tailored to the objectives and context of this study. The full questionnaire is provided in Supplementary Appendix 1 to ensure transparency and reproducibility.

The questionnaire consisted of items related to oral health, dietary behaviors, and chewing.

Oral health items included questions on toothbrushing behaviors (frequency of toothbrushing, frequency of autonomous toothbrushing [children only], and frequency of parental-assisted brushing [parents/guardians only]), frequency of observing the oral cavity, regular dental visits, and frequency of fluoride use.

Diet-related items included dietary habits (number of meals, frequency of breakfast consumption, frequency of eating breakfast together, and consideration of nutritional balance) [20]. Food intake diversity was assessed using the Dietary Variety Score [21], a previously established measure.

Chewing-related items assessed the frequency of behaviors such as “paying attention to the number of chewing cycles,” “leaving hard foods uneaten,” and “consuming foods that require chewing.”

Changes in awareness and behaviors related to oral health, nutritional balance, and chewing were evaluated using the Transtheoretical Model (TTM) [22]. The TTM categorizes behavior change into five stages: precontemplation (not currently performing the behavior and not interested), contemplation (not currently performing the behavior but intending to do so within 6 months), preparation (not currently performing the behavior but intending to do so within 1 month), action (performing the behavior for < 1 month), and maintenance (performing the behavior for ≥ 1 month).

In the original TTM, maintenance is defined as sustaining the behavior for ≥ 6 months; however, Walton, et al. [23] recommended a shorter evaluation period of 2 months for studies involving fifth- and sixth-grade elementary school students, as 6 months exceeds the recall capacity of children in this age group. Given that the participants in the present study included children from the first grade of elementary school and above, who were of an even younger age range, the maintenance stage for children was defined as “sustaining the behavior for ≥ 1 month.”

Measures

Oral function assessments were conducted only in children. Oral function was evaluated using the Simplified Debris Index and Simplified Calculus Index of the Oral Hygiene Index–Simplified [24], the PMA index [25], tongue–lip motor function (oral diadochokinesis [ODK]), masticatory performance, lip pressure, and tongue motor function. Additionally, lip closure, lingual frenulum abnormalities, mouth breathing, palatine tonsil hypertrophy, and the presence of unfavorable oral habits were evaluated. Interviews were also conducted with the children and their parents or guardians.

Masticatory performance was evaluated using a chewing ability test gum (XYLITOL® chewing ability test gum, Lotte Co., Ltd.). Participants were instructed to chew the gum for 1 min, and the degree of color change was assessed using a five-grade color chart [26–28].

ODK was assessed using an automatic speech analyzer (Kenkou-kun Handy, Takei Scientific Instruments Co., Ltd., Japan). The number of repetitions of monosyllabic sounds (/pa/, /ta/, /ka/) was recorded. Oral motor ability related to articulation was evaluated by measuring the number of syllables produced per second [29].

Lip pressure was measured using a dental lip strength measurement device (Lipple-kun, Shofu Inc., Japan) [30]. Participants were instructed to insert a button into the oral vestibule and close their lips. After pulling the button horizontally, the force required to dislodge the button from the oral vestibule was measured. Following one practice trial, measurements were taken three times, and the mean value was calculated as the lip pressure.

Tongue motor function was assessed using a tongue pressure measurement device (TPM-01, JMS Co., Ltd.). Participants were instructed to press a small balloon-type disposable oral probe against the palate as forcefully as possible [31,32]. After one practice trial, measurements were performed three times, and the mean value was used for analysis.

Based on a comprehensive evaluation of questionnaire responses, measurement results, and interview findings, the prevalence of oral hypofunction was determined [7,33].

Statistical analysis

Comparisons before and after the intervention of the CAMCAM-P for kids were analyzed using the Wilcoxon signed-rank test. A p value of <0.05 was considered statistically significant. All statistical analyses were performed using SPSS version 29.0 software (SPSS Inc., Chicago, IL, USA).

1. Effects on Oral Health, Nutrition, and Mastication

Regarding oral health, increases in the frequency of fluoride use, the proportion of children who brushed their teeth independently, and the proportion of children who observed their oral cavity were observed. These changes may be attributed to the educational sessions, which included instruction on the proper use of fluoride. These likely enhanced participants’ interest in their oral health, leading to immediate changes in feasible oral health behaviors. More than half of the participants already exhibited desirable habits regarding the frequency of tooth brushing and regular dental visits before the intervention. The proportion of participants who were receiving regular dental checkups was higher than the national average [34], suggesting that a ceiling effect may have limited the detection of further changes in these behaviors.

The results of the oral examinations revealed grade-specific characteristics. Among lower-grade children, improvements in lip function, tongue function, and masticatory-related functions were observed. Previous studies targeting Japanese children in the third grade and above have reported sex differences in ODK values depending on grade, possibly influenced by physical growth and development [35]; however, such sex differences were not observed in the present study. In contrast, an improvement in gingival inflammation was noted among higher-grade children. This finding may be explained by the increase in the proportion of higher-grade children who reported brushing their teeth independently, suggesting that heightened awareness of their own oral health contributed to the improvement in gingival status.

At the same time, the number of children classified as having oral hypofunction increased after the intervention. In this study, oral hypofunction was assessed using multiple domains that included both objective functional measures and observational/self-reported indicators, such as lip incompetence. The post-intervention increase in classification was primarily attributable to increased reporting of lip incompetence rather than decline in objective oral functional performance.

By contrast, several objective indicators demonstrated favorable changes after the intervention, including ODK, tongue pressure, and mastication-related measures. Therefore, the apparent inconsistency between improved functional measures and increased oral hypofunction classification may reflect differences in measurement characteristics between subjective indicators and objective performance-based assessments. Participation in the program may have increased awareness of oral habits and symptoms among children and parents/guardians, resulting in more accurate recognition and reporting after the intervention.

Given the exploratory nature of this pilot study and the absence of a control group, these findings should be interpreted cautiously. Further studies with larger sample sizes, validated pediatric assessment criteria, and longitudinal or controlled designs are warranted to clarify the reproducibility and clinical relevance of oral hypofunction findings in children.

There were no significant changes in masticatory performance before and after the intervention. This may be partly due to a temporary decline associated with the transition from deciduous molars to permanent teeth [36]. Nevertheless, masticatory performance is associated with ODK and tongue pressure [37], and the observed improvements in these functions suggest that increased awareness of chewing and behavioral changes related to mastication may have positively influenced oral motor function.

In terms of nutritional balance, both children and parents/guardians demonstrated changes in awareness and behavior. Previous research has shown that parental knowledge of nutritional balance is strongly correlated with children’s fruit and vegetable intake [14]. Accordingly, it is likely that improvements in nutritional knowledge through the program contributed to increased intake frequencies of various food groups. These findings further support the need for implementing interventions in both children and their parents/guardians to improve dietary diversity in children. Additionally, most participants in this study reported eating breakfast regularly. Children who consume breakfast tend to have diets of higher nutritional quality [38] and are more likely to have earlier sleep habits [39], suggesting the establishment of generally favorable lifestyle behaviors. Thus, the study population may have already maintained relatively well-regulated daily habits.

With respect to mastication, the behavioral change indicators demonstrated enhanced awareness and behavioral modification in children and their parents/guardians. Similar improvements in awareness of chewing have been reported in the original version of this program [15]. These findings indicate that the present program is effective in promoting awareness of mastication even when the target population includes children and their parents/guardians, highlighting the robustness and adaptability of the intervention.

2. Behavioral change indicators

The TTM comprises four elements: stages of change, processes of change, decisional balance, and self-efficacy. In this study, the stages of change were positioned as a core component of the TTM [40]. Participants’ current status was assessed based on the five stages of change, and interventions were designed to correspond to their respective stages. In this study, the CAMCAM checklist served as the primary outcome measure, while the TTM stages of change were used as secondary outcome indicators to evaluate the effectiveness of the intervention program. Although an upward trend in stage progression was observed in children and their parents/guardians, significant behavioral changes were not observed in most items of the primary outcome. This may be explained by the fact that, at early stages of change, participants’ intention to modify behavior is present but requires additional effort to translate intention into action. Understanding participants’ stages before the intervention suggests that more individualized approaches may have been necessary for those in the early stages. Furthermore, differences in intervention effects between lower- and higher-grade children were suggested, highlighting the potential need for grade-specific program implementation.

3. Limitations and future directions

This program combined three elements—oral health, nutrition, and mastication—into a single intervention. Although numerous health programs targeting children exist, including those focused on oral health or food education, most are conducted independently, and few programs integrate these elements into a comprehensive approach. Moreover, interventions are often delivered separately to children and parents/guardians, with limited programs providing the same intervention to both groups. Therefore, if the CAMCAM-P for kids can be disseminated at the community level, it may be effective in supporting the early development of oral functions and the establishment of desirable dietary habits.

This study has some limitations. First, this was a pilot study using a single-group pre–post design without a contemporaneous control group; therefore, causal inferences cannot be made, and the observed changes may have been influenced partly by normal growth and development. Second, the sample size was relatively small, which limited subgroup analyses. Third, participants ranged widely in age and developmental stage, from early elementary school children to adolescents, and responses to the intervention may have varied according to school grade and behavioral readiness stage. Future studies with larger samples and controlled designs are warranted to confirm these preliminary findings and further refine the CAMCAM-P for kids by optimizing intervention frequency according to behavioral stage and tailoring program content to developmental level.