The aim was to determine the effect of feeding and oral habits, toothbrushing, socioeconomic status and allergic rhinitis on the development of dental caries in primary dentition. In a cross-sectional study, data were obtained by means of a structured questionnaire on 1,160 children, 4–5 years old (mean = 4.5 ± 0.5) and born in 1999, 2000 or 2001. The children also had a physical examination by an allergist and dentists. Dental caries was diagnosed according to WHO criteria. Caries experience was measured as number of deft and defs. Logistic regression analysis assessed the association between dental caries and independent variables. The dental caries prevalence was 17.9%, 28.8% of the children had allergic rhinitis symptoms, digit sucking was reported by 9.8% and pacifier use by 13.6% of the children. The mean number of deft of the sample was 1.02 (SD = 2.37) and that of defs was 1.33 (SD = 3.54). Analysis showed that breast-feeding for >12 months (p < 0.01), toothbrushing frequency (p < 0.01), sugar consumption (p < 0.01) and pacifier use (p < 0.01) each had a significant association with dental caries occurrence in primary dentition. Children with pacifier use and allergic rhinitis had more than double the risk of dental caries development. Allergic rhinitis alone has no effect on dental caries. Healthcare professionals attempting to limit dental caries should consider the effect of prolonged breast-feeding, sugary product consumption between meals and nonnutritive habits on dental caries.