Abstract

This double-blind, placebo-controlled, cluster-randomized clinical trial evaluated the effectiveness of daily Lactobacillus rhamnosus SP1 supplementation in reducing caries progression in preschool children. A total of 205 children aged 2-3 years from 10 public nursery schools in Santiago, Chile, were randomized by nursery school clusters (1:1) to receive either probiotic-supplemented milk (1 x 107 CFU/mL) or standard milk once daily for 10 months. Examinations were conducted at baseline and 12 months using ICDAS criteria. The primary outcome was the proportion of children whose caries status progressed to cavitated lesions (ICDAS 5-6). Progression occurred in 26.8% of children in the probiotic group (33/123) and 46.3% in the control group (38/82). Surface-level transitions were minimal in both groups and are reported descriptively. No intervention-related adverse events were observed, and adherence exceeded 80%. Daily consumption of milk supplemented with L. rhamnosus SP1 for 10 months reduced the number of preschool children who developed cavitated carious lesions over a 12-month period and may represent a safe and feasible adjunct for community-based prevention of early childhood caries. The trial was prospectively registered at ClinicalTrials.gov (NCT01648075).