# Correlation of Parental and Child Dental Plaque Levels: A Clinical Study
## 2 Materials and Methods  
This clinical study was conducted at the Borgo Cavalli Clinical Polyclinic in Treviso and involved a total of 196 participants, comprising 49 mother-child pairs and 49 father-child pairs, which resulted in a total of 98 children. The children, aged between 6 and 15 years, included 37 females and 61 males. Children younger than 6 years were excluded from the study due to the insufficient number of permanent teeth required for an accurate assessment of the plaque index. All patients enrolled in the study come from families with an Equivalent Financial Situation Indicator (EFSI) of less than EUR 15,000 per year, classifying them as lower-income families. Patients and parents and the second investigator (RGP) were unaware about the study's specifics, helping to reduce the risk of bias, such as coming to the Dental Department having brushed better than usual. Informed consent was taken prior to the oral hygiene session, where the first investigator ([PERSON]) applied Mira-2-Ton (Duisburg, Germany) to the patients' dental surfaces and a second blinded investigator ([PERSON]) assessed the stained surfaces of the teeth. During the initial visit to the clinic, the plaque index for each child was evaluated using the O'Leary Plaque Control Record (Figure 1), a standardized method designed to quantify the amount of dental plaque present. This assessment began with the application of a liquid plaque disclosing an agent known as \"Mira-2-Ton\". This agent serves to stain the plaque, making it more visible against the tooth surface. Following this, a dental explorer was employed by the clinician to meticulously examine each tooth and visually identify any areas where plaque was present. A principal investigator ([PERSON]) administered the Mira-2-Ton solution to the patients' dental surfaces, while a second investigator ([PERSON]), who was unaware of the study's hypothesis, evaluated the stained areas on the teeth. The process of identifying plaque involves carefully running the explorer along the surfaces of the teeth, allowing the dental professional to accurately record the presence of plaque in specific locations. For each child participant, the plaque index was subsequently calculated as a percentage, representing the number of dental surfaces that exhibited visible plaque in relation to the total number of surfaces examined. This method not only provides a clear quantification of plaque accumulation but also helps to highlight areas that may require more attention in the child's oral hygiene routine. Figure 1: Example of O’Leary Plaque Control Record. To analyze the collected data, we employed a beta regression model using a software program (SPSS v.18, IBM, Chicago, IL, USA), which is particularly suitable for handling proportional outcomes, such as the plaque index (PI_CHILD) that ranges from 0 to 1. The beta regression model allows us to evaluate not only the mean or expected value of the dependent variable but also its precision, or variability. The first step in our data analysis involved clearly defining the research problem: determining how various factors influence a child's plaque index (PI_CHILD). We hypothesized that several key predictors might impact this outcome, including the parents' plaque index (PI_PARENTS), the child's age (AGE_CHILD), and which parent accompanied the child to the dentist (ID_PARENTS)--either the mother or the father. Data preparation consisted of gathering the relevant variables: PI_CHILD, PI_PARENTS, AGE_CHILD, and ID_PARENTS. We then specified the statistical model using the following formula:  
PI_CHILD-ID_PARENTS + PI_PARENTS + ID_PARENTS \(\times\) PI_PARENTS. In this notation, the symbol \"-\" denotes the relationship between the response variable (PI_CHILD) and the predictor variables. The model included an interaction term (ID_PARENTS \(\times\) PI_PARENTS) to evaluate not only the individual effects of the parent's identity (ID_PARENTS) and the parents' plaque index (PI_PARENTS) but also the combined influence of these factors on the child's plaque index.