Control group (no treatment): 30 specimens were stored in distilled water.
Icon (resin infiltration): 30 specimens were treated with resin material for infiltration (Icon, DMG, Hamburg, Germany). The infiltration treatment was performed following the manufacturer’s instructions:
Icon-Etching for 2 min.
Water rinse and air dry for 30 s.
Icon-Dry for 30 s.
Previous steps repeated 2 more times.
Icon-Infiltrant for 3 min then light cure 40 s.
Icon-Infiltrant for 1 min then light cure 40 s.
Finishing and polishing with Sof–Lex XT discs (3M ESPE, St Paul, Minnesota) gradually from the mid-coarse to the extra-fine disc. A slow-speed handpiece was used with water spray (15,000 rpm, 15 seconds/disc) using intermittent brushing movement and gentle pressure.
3. MI Paste Plus: 30 specimens were treated with MI Paste Plus (MI Paste Plus, GC America Inc, Alsip, IL, USA) application to the site by a cotton swab then washed with normal saline after 5 min.