Ethics approval and consent to participate
This clinical trial was approved by the Committee for Ethics in Research Involving Human Beings (CAAE: 50783521.9.0000.5419) and is outlined according to CONSORT recommendations. The trial has been registered with the Brazilian Registry of Clinical Trials (# RBR-7s8bw6m).
This study is a randomized, double-blind, parallel clinical trial with voluntary participation and 6 months of follow-up. The protocol follows the recommendations of the 2013 interventional trials (SPIRIT) guidelines.
Sample size and power calculation
To calculate the sample size, we used the study by Zolfaghari et al. , which measured the efficacy of a game for delivering oral health knowledge to children and mothers. Considering an alpha value of 5% and a test power of 80%, the sample calculation requirement was 44 mother-child pairs per group (control and experimental).
Participants and study setting
After anamnesis and initial clinical examination, the dental examination will be performed at the Clinical Research Center of the Faculty of Dentistry of Ribeirão Preto of the University of São Paulo, Brazil (FORP/USP). Once the study details are explained and queries are addressed, volunteers (mothers) are expected to sign the informed consent form (TCLE), and the children are expected to sign the assent form.
All mothers have to be at least 18 years old
Children (6–12 years old) of both sexes
Participants (mother-child pairs) with good general health (reported by the mother)
Mothers using WhatsApp on their smartphones
Participants (mothers and children) exhibiting learning difficulties
Mothers with total upper and lower dental prostheses
The following study groups will be created in parallel to evaluate the proposed intervention. (1) Control group: Both mothers and children will undergo clinical examination, prophylaxis, topical fluoride application, and oral hygiene guidance on a single dental office visit.
(2) Experimental group: Both mothers and children will receive clinical examinations, prophylaxis, topical fluoride application, and oral hygiene guidance on a dental office visit. Additionally, the digital platform WhatsApp will be used to provide educational videos to the mother-child pairs, twice per week (Tuesday and Thursday) at 7 PM over a period of 4 weeks. A WhatsApp video presenting a story on oral health, along with a reminder to perform their oral hygiene routine (toothbrushing and flossing) will be sent to the mother-child pairs in the experimental group. Topics including oral hygiene, dental biofilms, white spot lesions, dental caries, and the importance of dental appointments will be covered.
At the end of four weeks (T1), three months (T2), and six months (T3), the mother-child pairs will undergo follow-up clinical evaluations at FORP/USP. If needed, dental treatment will be performed by a research team at the same institution.
Oral examination of the mother-child pairs will be performed by a trained and calibrated examiner. The Visible Plaque Index (VPI) will be used to evaluate the mesial, distal, vestibular, and lingual surfaces of the incisors and first upper and lower molars according to the criteria set by Ainamo and Bay . Evaluations will be performed by direct visualization of the vestibular and palatine/lingual surfaces. A flat oral mirror # 5 (Golgran, São Caetano do Sul, São Paulo, Brazil) will be used for the visual examination. The established scores for the VPI are: (1) presence and (0) absence. For the Gingival Bleeding Index (GBI), a periodontal probe (Golgran, São Caetano do Sul, São Paulo, Brazil) will be used to evaluate the subgingival surfaces 1 mm into the sulcular epithelium. The bleeding on probing index will also be recorded as: (1) presence of bleeding and (0) absence of bleeding. Oral hygiene will be considered unsatisfactory if the percentage of visible biofilm is greater than 15% and/or gingivitis is present, as indicated by bleeding at more than 15% of the evaluated sites [27,28].
After brushing, a clinical oral examination will be performed to verify the participants’ oral health condition, and the data will be recorded using the dmft and DMFT index for deciduous and permanent teeth, respectively . Dental caries will be evaluated using the Nyvad Criteria to assess severity and activity of carious lesions , including lesions of rough and opaque white spots . The initial evaluation aims to verify the inclusion criteria for the study participants. Subsequent evaluations will aim to assess the effectiveness of the interventions for improving the oral hygiene of the mother-child pairs.
Randomization and allocation concealment
Patients will be randomized using a simple draw. A number will be assigned to each mother-child pair. A virtual randomization program  will be used to generate the allocation sequence in the groups, and the names of the mother-child pairs of the randomized groups (control and experimental) will be recorded by L.G.F. so that the clinical examiner (Y.J.S.R.) and the statistical evaluator (F.W.G.P.S.) will not have access to this information. L.G.F. will also be responsible for sending the video individually to each participant of the experimental group using the WhatsApp application. The participants will be blinded to the data collection. Both the examiner involved in the intervention and the statistician who will analyze the data through appropriate statistical tests will be blinded.
Figure 1 summarizes the study design, randomization process, group allocation, and evaluation periods.
A literacy assessment instrument (BOHLAT-P) will be used to evaluate the mothers’ oral health knowledge, textual understanding, and numerical skills [32,33]. The first part evaluates basic knowledge in oral health, from images illustrating normal deciduous dentition and dental caries. The second part measures the numerical abilities of the individual, being represented by four groups of questions. The first refers to an appointment appointment card already completed, questioning the date and time of the next appointment, which contact number of the clinic. The second group of questions is related to a drug prescription, in which the respondent is asked about the date of validity of the medication presented, adequate dose interval and duration of treatment. The third group of questions revolves around post-surgical instructions, which cover aspects such as warm diet introduction period, oral hygiene and conduct facing complications. The fourth group of questions has as its central axis a dentifrice label, addressing points such as brushing frequency and ideal dentifrice amount. The last part of the instrument evaluates textual comprehension and vocabulary. It consists of a dialogue between the dentist and the child’s mother addressing the exchange of dentitions with blank passages to be completed from the answer options presented. Lastly, there is a brushing guide whose instructions need to be sorted correctly.
A self-report questionnaire containing a series of questions ordered in the form of questions, addressing issues such as identification, socioeconomic status, maternal and paternal education, occupation of the mother and person with higher family income, health conditions, access to health services and oral health care measures will be applied before interventions [34-35].
Measurements will be taken at baseline, post-intervention (i.e., 30 days after completion of the intervention), and at the 3-month and 6-month follow-up points. All follow-up assessments will be conducted by a researcher blinded to the group allocation of the participants.
Sociodemographic and socioeconomic data will be collected at baseline, including the participant’s age, gender, skin color, household income, and educational literacy level.
Measurement of primary outcomes
The primary outcome is defined as the effectiveness of educational videos via WhatsApp for controlling dental biofilm and dental caries in mother-child pairs. This outcome will be achieved by evaluating the VPI, GBI, and dmft indexes for deciduous teeth, and the DMFT for permanent dentition. Dental caries will be evaluated using the Nyvad Criteria to assess severity and activity of carious lesions. These results will be compared with those of the control group throughout the follow-up.
Measurement of secondary outcomes
The secondary outcome is defined as the participant responses to the questionnaire on socioeconomic data, oral hygiene, and visits to the dentist. Quality of life will be evaluated using the BOHLAT-P questionnaire . This questionnaire contains 49 questions and is divided into three domains: oral health knowledge, textual understanding, and numerical skills . The mother will answer the BOHLAT-P questionnaire alone, and the researchers will provide help if requested.
The data will be collected in standardized dental records identified by numbers (obtained after randomization) for each participant (mother-child). All data will be scanned and stored in a Microsoft Excel spreadsheet for further statistical analysis at the end of the study. Upon completion of the study, data will be made publicly available at the University of Sao Paulo institutional repository.
Strategies for study retention
During the study period, participants from both groups (control and experimental) will receive a text message informing them of the day and time for the next dental evaluation. In the case of no attendance, calls will be made to the participant (mother) to reschedule the missed dental evaluation.
Data will be analyzed using the GraphPad Prism 8.0 software (GraphPad Software Inc., San Diego, CA, USA). Descriptive analyses, including percentages, means, and standard deviations, will be reported. Answers to the BOHLAP-T questionnaire will be dichotomized into correct and wrong answers. Each correct answer will receive a score of 1, and each wrong answer will receive a score of 0. The maximum and minimum scores are 49 and 0, respectively.. The Chi-square test will be used to analyze categorical variables, the Mann Whitney test will be used to compare the inter-group differences and Friedman test will be used to calculate intra-group differences in relation to VP and GBI. The following tests will be used to analyze the experience of caries: t of "Student" and of Chi-Square. The significance level will be set at 5%.
We intend to disseminate the methods and results of our study to the general public through social media, presentations at international congresses on corresponding areas of interest (for example, dentistry), and by submission of manuscripts describing our findings to appropriate scientific journals.