The purpose of this study was to compare with a clinical randomized controlled split-mouth design study the changes in the therapeutic effect of infiltrating versus sealing proximal caries lesions and placebo treatment after 1, 2 and 3 years. The outcome was lesion progression, evaluated by radiographic techniques.

Fissure sealing has been shown to inhibit not only the formation of occlusal caries but also to impede the progression of existing caries lesions. Lately, the concept of sealing caries to arrest lesion progression has been transferred to approximal surfaces. In a clinical study sealed approximal lesions showed significantly reduced progression after 18 month compared with those that were treated only with preventive measures.

The pores of enamel caries lesions provide diffusion pathways for acids and dissolved minerals. The aim of caries infiltration is to occlude these pores by infiltration with light curing resins in order to block the diffusion of acids into the lesion body. In contrast to caries sealing, caries infiltration aims to occlude the pores within the lesion rather then placing a diffusion barrier on the lesion surface. Several studies showed significantly reduced progression of infiltrated enamel lesions in demineralizing environments.

This split-mouth placebo-controlled randomized clinical trial was conducted on 16-35 year-old subjects in Bogotá, Colombia (IRB UB.162-2008).

The sample size calculated was of minimum 29 patients with 3 approximal lesions around the EDJ or in the dentin outer third.

The study population was students and patients from Unversidad El Bosque. Two visits were planned for the patients within same week. In the first visit baseline standardized bitewing radiographs were obtained and 3 proximal selected lesions were randomly selected. A clinical examination was conducted to assess DMF-T/S, and individual caries risk. Elastic orthodontic bands were placed between teeth of selected surfaces for elective temporary separation.

In the second visit selected lesions were visually classified with ICDAS criteria and activity status of lesions was assessed. The 3 lesions were randomly allocated to: A. Infiltration, B. Sealing, C. Placebo, and lesions were treated.

Subjects were clinically examined after one, two, and three years by two examiners (AC, JSL) blinded to the selected treatment groups and referral for operative treatment were done if needed. Standardized bitewing radiographs were made each year.

Lesions progression was assessed on radiographs by pair-wise reading by an external examiner blinded to groups. Additionally, after one year reading of images was conducted by digital-subtraction radiography of scanned images. For reproducibility assessment the examiner repeated 20% of radiograph readings by both methods one week after the first reading.

Statistical analysis Intra-examiner reliability for radiographs readings was assessed by unweighted kappa scores; caries experience (DMF-T/S), individual caries risk levels, ICDAS criteria, radiographic scores, and progression' status of selected lesions were reported descriptively.

The outcome variable of changes in lesion progression after 1, 2 and 3 years was assessed by pair-wise radiographic reading and after one year also by digital-subtraction radiography.

Differences in lesion progression between treatments at each follow-up were tested by the Cochran Q test and in case of significant difference between groups, by the McNemar Change test, including the therapeutic effect and the 95% confidence intervals [Siegel & Castellan, 1988].

In all tests p-values less than 0.05 were considered significant.

Inclusion Criteria:

• Subjects were to have at least three caries proximal lesions on their posterior permanent teeth with a radiographic severity classification of the lesion score of 3 -Around the enamel dentin junction (EDJ) or 4 -Dentin-outer 1/3.

Exclusion Criteria:

• Under orthodontic treatment at enrollment
• Moving from the city (Bogota) in the following three years after commencing the study.