Merin

The samples were sputter-coated with platinum to facilitate the observation of the sample surface. Scanning electron microscopy (SEM, Merin, Carl Zeiss, Oberkochen, Germany) images were obtained at an accelerating voltage of 15 kV and a magnification of 50×.

For microscopic examination, S. mutans attached to specimens were fixed with 2% paraformaldehyde–glutaraldehyde in 0.1 M PBS at 37 °C for at least 30 min^{19 (link)}. Subsequently, specimens were post-fixed with 1% OsO₄, dissolved in 0.1 M PBS for 2 h, dehydrated in ethanol, treated with isoamyl acetate, and dried to a critical point (LEICA EM CPD300; Leica, Wien, Austria). Thereafter, the discs were coated with Pt–ion (5 nm) using an ion coater (ACE600; Leica) and observed under scanning electron microscopy (FE-SEM; Merin, Carl Zeiss, Oberkochen, Germany) at 2 kV^{26 (link)}.

MG-63 cells and HGFs were used for SLA and MA discs, respectively and seeded at 1 × 10⁴ cells/disc on the surface of each specimen in a 24-well plate. After incubation for 24 h, a specimen from each of the eight groups was prefixed with Karnovsky’s fixative (2% glutaraldehyde-paraformaldehyde; Invitrogen) in 0.1 M phosphate buffer (PB, pH 7.4) for 6 h and washed twice for 30 min in 0.1 M PB. The specimens were postfixed with 1% osmium tetraoxide dissolved in 0.1 M PB for 1.5 h, and washed with 0.1 M PB for 10 min. Specimens were then dehydrated in increasing concentrations of ethanol (50%, 60%, 70%, 80%, 90%, 95%, and 100%), infiltrated with isoamyl acetate, and subjected to critical point drying (Leica EM CPD300; Leica Mikrosysteme GmbH, Vienna, Austria). The specimens were coated with platinum (5 nm thickness) using an ion coater (Leica EM ACE600; Leica Mikrosysteme GmbH) and evaluated by field-emission SEM (Merin; Carl Zeiss, Jena, Germany). Representative images were captured at specific magnifications (500x, 2000x).