Dental Caries and Related Factors in 6-Year-Old Schoolchildren in Chile: National Evidence for Assessment and Decision-Making (6yOH-Chile)

Dental caries is the most prevalent chronic non-communicable disease in childhood worldwide. In Chile, the last nationally representative oral health survey was conducted in 2007 and reported a caries experience prevalence of 70.4% (mean dmft = 3.7) among 6-year-old schoolchildren. More than 15 years have elapsed without updated population-based data, limiting the evaluation of the national oral health targets established for 2020. The First National Child Health Survey (ENSI) did not include oral examinations due to operational complexity, perpetuating this critical information gap. This cross-sectional, population-based study aims to estimate the prevalence, severity, extent, and activity of dental caries lesions in both primary and permanent dentitions in a nationally representative sample of 6-year-old schoolchildren in Chile in 2024/25, using ICDAS-ICCMS. A probabilistic, stratified, two-stage cluster sampling design will be implemented, stratified by school administrative dependency (public, publicly funded private, and fee-paying private schools) and rurality, across all 16 regions of Chile. The estimated sample size is 2,421 schoolchildren (total selected sample: n = 2,882, including replacements), drawn from a sampling frame of 226,959 eligible first-grade students based on the 2023 Ministry of Education enrollment registry. In addition to the clinical oral examination, a structured questionnaire will be administered to parents and caregivers to assess sociodemographic characteristics, oral hygiene habits, fluoride exposure, dental care utilization, and school-based preventive interventions. The findings will provide updated nationally representative epidemiological indicators to support the evaluation of the National Oral Health Plan 2021-2030 targets and to inform oral health policies and resource allocation in Chile.

Inclusion Criteria: * Age 6 years at the time of invitation to participate. * Regular attendance at a school selected through the sampling procedure. * Written informed consent provided by a parent Exclusion Criteria: * • Schools in geographically remote municipalities: Easter Island (Isla de Pascua), Juan Fernandez, Cabo de Hornos, Antartica, Laguna Blanca, Rio Verde, San Gregorio, Tierra del Fuego, Porvenir, Primavera, Timaukel, Ultima Esperanza, Torres del Paine * Hospital-based educational establishments * Classrooms with 5 or fewer enrolled students * Children who decline to participate (no verbal assent)