Method: Bovine enamel discs (n=30) with a diameter of 3 mm were randomly assigned to 3 groups (n=10). They were etched with 37% phosphoric acid for 30 s and treated with resins of different monomer contents forming three test groups: 1) Untreated specimens serving as control; 2) Icon (DMG) + Transbond XT Primer (3M ESPE); 3) Icon + Heliobond (Ivoclar Vivadent). All specimens were immersed in hydrochloric acid (pH 2.6) for up to 9 days, during which they were exposed to 1800 toothbrush-strokes per day. Calcium dissolution into the acid solution was assessed by colorimetric analysis using Arsenazo III method at 24-hour intervals. Data were analysed by Kruskal-Wallis tests.
Result: Untreated specimens presented a constant rate of calcium dissolution throughout the whole experimental period. Mean daily Ca loss over 9 days amounted to 4.4±0.2 μmol/ml. Compared to the control, Icon + Transbond XT Primer presented significantly lower Ca loss at all time points. Icon + Heliobond resulted in a significantly lower Ca release than the control except for the last day. Mean daily Ca loss of the sealing groups increased from the first to the last day but this effect was significant only for the group Icon + Heliobond.
Conclusion: Under these in vitro conditions, applying the low-viscosity caries infiltrant prior to conventional orthodontic adhesive provides a stable protective effect against enamel demineralization.