ANALYSIS OF VARIABLES ASSOCIATED WITH TOOTH BRUSHING USING THE CHAID METHOD

Objective: To analyze variables associated with the tooth brushing technique that influence effective removal of dental biofilm in schoolchildren with no oral hygiene training, using the CHAID method (Chi Squared Automatic Interaction Detector). Methods: The study comprised 945 schoolchildren (age: 6-7 years) from the City of Buenos Aires; the children’s parents/caregivers gave their informed consent and the children gave their assent to participate. Systematic observation of their tooth brushing procedure was performed (Rossi, 2016). The following independent variables were analyzed: toothbrush-gripping technique (palm/other), orientation of the bristles with respect to the teeth (perpendicular/at an angle), type of movement (horizontal: back and forth/vertical: up and down), number of brushed tooth surfaces (1 or 2/3), brushing upper and lower teeth simultaneously (open/closed mouth), brushing all 6 sextants (complete/incomplete). The presence of biofilm was recorded using the O’Leary index (OI); cut-off was set at 20% (dependent variable). Following, an oral hygiene educational intervention was conducted. Observation and clinical examination were performed by 4 calibrated dentists (Kappa ?0.75). Univariate analysis by chi square test, binary logistic regression (LR), and CHAID were carried out. Results: The following characteristics were found to be associated (x2) with a decrease in the presence of dental biofilm: bristles at an angle with respect to the teeth, brushing upper and lower teeth simultaneously with mouth open, and 3 brushed tooth surfaces (p<0.001). The variables identified by LR were orientation of the bristles with respect to the teeth OR 3.86 (95%CI: 2.85-5.22), number of brushed tooth surfaces OR 2.07 (95%CI: 1.19-3.59), and brushing all 6 sextants OR 2.28 (95%CI: 1.68-3.10), with a predictive power of 70.2%. CHAID analysis showed a predictive power of 70.8%. Results showed that 83.7% of schoolchildren who applied the significantly associated variables had an OI<20% (p<0.001). Conclusion: Orientation of the bristles at an angle with respect to the teeth, brushing upper and lower teeth simultaneously with mouth open, and brushing all 3 tooth surfaces are variables associated with greater effectiveness in removing the dental biofilm.