Clinical care pathways have placed renewed emphasis on caries risk assessment and the ability to predict and prevent further disease. With diet considered a key factor in the development of caries, the level of caries risk posed by dietary habits, such as the frequency of intake and timing of free sugars is questioned. Objective: To identify reliable and simple dietary risk factors for caries experience. Research Design: A cross-sectional observational study of a convenience sample with data gained from clinical examinations, questionnaire and a 24 hour dietary-recall interview. Participants: 128 subjects aged 11-12 from comprehensive schools in Greater Manchester and Newcastleupon-Tyne, UK. Outcome measures: free sugars consumed between meals, before bed and total % of total free sugars consumed were assessed from dietary assessments led by a dietitian. D4-6MFT was generated with a caries threshold of ICDAS stage 4 from clinical examinations. Results: Analysis revealed no significant differences in caries experience when looking specifically at caries into dentine, referred to as the cavity group (split at D4-6MFT), between high and low deprivation, consumption of free sugars between meals and free sugars (%). The consumption of free sugars within the hour before bed revealed a statistically significant difference between the cavity/ no cavity groups (p=0.002). Logistic regression analysis on the cavity/no cavity groups revealed an odds ratio of 2.4 (95%CI 1.3,4.4) for free sugars consumption before bedtime. Conclusions: The study suggests that the consumption of free sugars before bedtime may be an important risk factor for adolescent caries into dentine experience. Key words: dental caries, diet, dental cavity, sugars, snacks, UK