OBJECTIVES: The aim of this in-vitro study was to investigate the masking efficacy of adhesively sealed enamel cracks with resin infiltration compared with the use of a universal adhesive. METHODS: Enamel cracks were induced on the labial surfaces of bovine teeth using a pendulum impact tester. Specimens were treated adhesively by resin infiltration with ICON (DMG) or Scotchbond Universal Plus (3M). Standardized digital images were taken pre- and postoperatively by three methods: flashlight from the front, transmitted light from behind, and DiagnoCam (KaVo). Four calibrated raters performed the qualitative visual evaluation of all images of each type: severely visible enamel cracks (1), clearly visible enamel cracks (2), slightly visible/aesthetically acceptable enamel cracks (3) and no visible enamel cracks (4). Specimens were selected to measure infiltration depth by confocal microscopy. RESULTS: Postoperatively, the masking efficacy in teeth with enamel cracks was significantly higher using ICON compared with Scotchbond Universal Plus in all groups (p <
0.001). Infiltration depths of ICON were significantly higher compared to those of Scotchbond Universal Plus (p <
0.002). CONCLUSIONS: Resin infiltration offers a straightforward and effective treatment option for masking trauma-induced enamel cracks, demonstrating superior efficacy over adhesive sealing. Further studies are necessary to evaluate the long-term stability of the optical improvements achieved through resin infiltration. CLINICAL SIGNIFICANCE: Resin infiltration might pose a therapeutic option for clinicians to enhance the aesthetic appearance of trauma-induced enamel cracks.