OBJECTIVES: to determine the efficacy of a dental nurse-delivered intervention, the Dental Recur Brief Negotiated Interview for Oral Health (DR-BNI), in reducing the re-occurrence of dental caries in children who had a primary tooth extracted two years previously. METHOD: Two-arm, multi-centre randomised controlled trial (RCT), with blinded outcome assessment. 12 Centres in the UK; n=241, 5-7 year-old children scheduled to have primary teeth extracted. Test intervention (n=119): DR-BNI informed by motivational interviewing (MI). 30-minute structured conversation with parents led by trained dental nurses. Forward focus to prevent caries in future. Preventive goals agreed, review appointment made with general dental practice (GDP). GDP advised to treat child as high caries-risk. Control intervention (n=122): conversation about future eruption of permanent teeth, advised attend GDP as usual. Baseline: mean dmft 6.8 in DR-BNI group, 6.3 in control, median 5 teeth extracted, mainly under general anaesthesia. RESULTS: Final dental assessments by a single examiner visiting 189 schools two years after intervention; 193 (80%) of 241 children examined. 62% in control group developed new caries in teeth that were caries free or unerupted at baseline. In the test group, this was 44%, a significant reduction (p=0.021). The odds of new caries experience occurring were reduced by 51% in the DR-BNI group compared to control. Relative risk: 29% decrease in the risk of new caries experience in the DR-BNI group compared to control. In a wide range of high caries risk children, this single, low cost, low intensity intervention was successful in significantly reducing the risk of new caries experience. CONCLUSION: this trial has implications for changing paediatric dental practice internationally. Training in, and implementation of, an MI-informed brief intervention provides opportunities for dental nurses to go beyond clinical prevention to facilitate behaviour change, and to support oral health improvements for high caries risk children.