Abstract Objective This study aims to determine the social determinants and behavioural factors influencing frequency of toothbrushing among primary school children residing in the rural community of Lithgow in New South Wales, Australia. All six primary schools of Lithgow were approached to participate in a cross-sectional survey prior to implementation of water fluoridation. A validated oral health survey questionnaire was completed by 703 parents of the children. Multivariable logistic regression analysis was employed to determine significant predictors associated with frequency of toothbrushing. Results Parents with a positive attitude towards water fluoridation had 74% higher odds (OR = 1.74, 95% CI 1.17–2.60) of their children brushing twice or more daily. Children living in a single parent household had 34% reduced odds (OR = 0.66, 95% CI 0.43–0.99) of brushing twice daily. Poor maternal oral health was significantly associated with suboptimal dental hygiene practices in children, where mothers who had any tooth extracted had 7% reduced odds of their children brushing their teeth twice or more daily (OR = 0.93, 95% CI 0.90–0.97). Subsequently, children with increased consumption of chocolates per day were less likely to brush twice or more daily. Finally, children with dental insurance had two times higher odds (OR = 2.04, 95% CI 1.40–2.96) of brushing twice daily.