Background and problem statement. Traditionally, caries treatment has been based on restorative procedures performed by dentist using dental biomaterials. Besides its high cost, this canonical approach for caries therapy has very limited coverage and only a small proportion of the population can satisfy the high demand. The latter is especially critical in developing countries. Available evidence has shown that some caries lesions, either cavitated or non-cavitated, may be treated by the placement of sealants. This minimally invasive treatment is more cost-effective than the restorative approach and it allows better coverage. Sealants placed on the active lesions hamper lesion progression, most likely by inhibiting nutrient uptake of the invading associated microbiota. The most commonly used material in clinical practice is resin sealant. Despite its advantages and simplicity of use, this material is highly sensitive to contamination by saliva or other ubiquitous oral fluids. Furthermore, adhesion to enamel is compromised when this tissue is immature. This pitfall of the technique is particularly crucial when it comes to treating lesions in erupting molars in children. Hence, glass ionomer cement (GI) sealants emerge as a potential alternative to resin sealants. GI sealants are more suitable to be used under non-ideal clinical conditions, such as in the presence of humidity or on lesions of immature erupting molars. Although there exists vast evidence on the use of sealants as preventive agents, studies dealing with this biomaterial as a therapeutic agent for caries lesions are more limited and scarce. In regard to the material, only few clinical studies with unclear conclusions are available. This proposal, therefore, will seek to compare progression of caries lesions treated with either resin or GI sealants, in occlusal cavitated lesions (Code 3, ICDAS) of permanent molars of 6 to 12 year-old children.

Methodology. A randomized controlled clinical trial (RCT) is proposed. Once approved by the Bioethics Committee and after obtaining a signed informed consent from their parents, volunteer children will be invited to participate. Two hundred caries lesions (Code 3, ICDAS) will be randomized to one of the two arms of the study, resin or GI sealants. The materials chosen to conduct the study would be Concise and Ketac Molar, respectively, both from 3M, St. Paul, MN. Sample size was estimated using a 95% significance level. Based on the caries prevalence of the population and studies performed by the investigators, the number of volunteers was estimated to be about one hundred volunteers to gather the required two hundred lesions. Three evaluations will be conducted every six months until completion of eighteen month of follow-up. All the exams and controls will be performed at the Dental Clinics of the University of Talca by one trained and calibrated examiner. Sealants will be placed following manufacturer's instructions. Participants will be randomly allocated to either study arm, regardless of the clinical indication, so selection bias will be avoided. Material retention and lesion progression will be the primary end-point at each control. Likewise, caries incidence in untreated teeth will be a secondary outcome of the study.