Objective: Professional organizations recommend a preventive dental visit by 1 year of age. This study compared dental treatment and expenditures for Medicaid children who have a preventive visit before the age of 18 months with those who have a visit at age 18–42 months. Methods: This retrospective cohort study used reimbursement claims for 19,888 children enrolled in North Carolina Medicaid (1999–2006). We compared the number of dental treatment procedures at age 43–72 months for children who had a visit by age 18 months with children who had a visit at ages 18–24, 25–30, 31–36, and 37–42 months using a zero-inflated negative binomial model. The likelihood and amount of expenditures at age 43–72 months were compared by group using a logit and ordinary least squares regression. Results: Children who had a primary or secondary preventive visit by age 18 months had no difference in subsequent dental outcomes compared with children in older age categories. Among children with existing disease, those who had a tertiary preventive visit by age 18 months had lower rates of subsequent treatment [18–24 mo incidence density ratio (IDR): 1.19, 95% confidence interval (CI), 1.03–1.38; 25–30 mo IDR: 1.21, 95% CI, 1.06–1.39; 37–42 mo IDR: 1.39, 95% CI, 1.22–1.59] and lower treatment expenditures compared with children in older age categories. Conclusions: In this sample of preventive dental users in Medicaid, we found that children at highest risk of dental disease benefited from a visit before the age of 18 months, but most children could delay their first visit until the age of 3 years without an effect on subsequent dental outcomes.