Abstract: Objective: to evaluate the effect of resin infiltration to prevent demineralization and caries formation after interproximal reduction. Methods: Patients after interproximal reduction procedures were treated by resin infiltration and fluoride varnish according to the manufacturer’s instructions. They were randomly divided into two groups following a split-mouth study. In group A, resin infiltration was applied in quadrants 1 and 3, and fluoride varnish was applied in quadrants 2 and 4. In group B, resin infiltration was applied in quadrants 2 and 4, while the fluoride varnish was applied in patients' oral quadrants 1 and 3. The patients were followed for twelve months, during which time their teeth were checked every three months. To investigate the differences in frequencies and ranks of demineralization and caries formation in different time between the two groups, two methods of visual inspection and radiological examination were carried out. Results: The results showed that there was no statistically significant difference between the two groups at the first 9 months. While, In the 12th month, the score of ICON group in visual inspection and radiological examination were significantly less than the control group. Conclusion: ICON resin infiltration can well prevent enamel demineralization and caries formation after interproximal reduction.

Key words: resin infiltration, interproximal reduction, caries prevention, split-mouth study, fluoride varnish