Purpose: The purpose of this study was to investigate changes in 25-hydroxyvitamin D (25(OH)D) levels in children with severe early childhood caries (S-ECC) following rehabilitative surgery using general anesthesia (GA). Methods: Children with S-ECC were recruited on the day of surgery for a prospective study investigating changes in nutritional status and well-being before and after surgery. Venipunctures for 25(OH)D were performed while children were in the operating room, and parents completed a questionnaire regarding nutritional intake, oral health, quality of life, and family demographics. Participants returned at a minimum of three months for a follow-up venipuncture, questionnaire, and dental examination. Analyses included descriptive, bivariate, and multivariable regression analyses. A P-value of ≤ 0.05 was significant. Results: Overall, 150 children participated, with a mean age of 47.7±14.1 months. The mean baseline 25(OH)D concentration was 49.8±16.9 nmol/L, with 17 percent having deficient levels. Overall, 106 returned for follow-up. Paired t-tests revealed significant improvements in the mean 25(OH)D levels following rehabilitation (50.1±17.1 nmol/L versus 61.2±18.7, P<0.001). The proportion with optimal and adequate 25(OH)D levels increased from 9.2 percent to 24.1 percent and from 48.3 percent to 67.8 percent, respectively, while those classified as deficient decreased from 17.2 percent to 8.1 percent from baseline to follow-up. Conclusions: Significant improvements in vitamin D concentrations were observed following dental rehabilitation. This provides additional evidence of the association between oral health and nutritional status.