Participants
carious lesions, allergy, carious lesion, radiolucency
CARIES, ALLERGY
Children in six public schools in Nonthaburi Province located at the central region of Thailand were invited to participate in the study. The fluoride concentration in the drinking water in the study area was less than 0.03 ppm. The inclusion criteria were healthy children aged 4–6 years who could cooperate with the clinical examination and had at least one quadrant showing sound contact surfaces of posterior teeth. Children were excluded if they had a history of fluoride, silver, or colophony agent allergy, or had undergone topical fluoride administration within the previous six months or were resistant to bitewing radiography.The inclusion criteria at the tooth surface level were the distal surfaces of the canine or first molar, or the mesial surfaces of the first or second molars showing clinically sound and radiographically sound or initial carious lesion. Initial approximal carious lesions were defined as radiolucency confined to the enamel or outer third of dentine (RA1–RA3 according to the International Caries Detection and Assessment System/International Caries Classification and Management System (ICDAS/ICCMS™) radiographic scoring system) [