In general, significantly more S. sanguinis adhered to ceramic surfaces than to titanium surfaces (p < 0.05 for all comparisons, except for smooth ceramic compared with rough titanium: p = 0.244) (Fig. 3b). Titanium specimens (smooth titanium 3263 ± 475 rfu; medium titanium 3331 ± 641 rfu; rough titanium 3656 ± 855 rfu) tended to show higher streptococcal adhesion on rough surfaces in comparison to medium and smooth surfaces, but the differences between the tested material groups were not statistically significant (p > 0.05 for all comparisons). On ceramic surfaces (smooth ceramic 4668 ± 1562 rfu; medium ceramic 5590 ± 1493 rfu, rough ceramic 6875 ± 428 rfu), higher surface roughness led to increased S. sanguinis adhesion (p < 0.05 for all comparisons, except for smooth ceramic compared with medium ceramic: p = 0.244).

S. epidermidis (Fig. 4a) tended to show higher bacterial adhesion on hydrophobic surfaces (titanium smooth 5337 ± 1511 rfu, titanium rough 5916 ± 2472 rfu, ceramic smooth 3395 ± 1738 rfu, and ceramic rough 2676 ± 1476 rfu) than on hydrophilic surfaces (titanium smooth 3897 ± 985 rfu, titanium rough 5662 ± 1884 rfu, ceramic smooth 2522 ± 775 rfu, and ceramic rough 1644 ± 1225 rfu), but these differences were not statistically significant (p > 0.05 for all comparisons). A comparison of rough and smooth specimens did not show any differences in staphylococcal adhesion (p > 0.05 for all comparisons).

In general, the potential to adhere S. sanguinis was significantly higher for all ceramic surfaces—hydrophobic and hydrophilic—than for titanium specimens (p < 0.05 for all 16 comparisons) (Fig. 4b). A comparison of hydrophobic and hydrophilic surfaces did not show any statistically significant differences (for smooth titanium: p = 0.997; for rough titanium: p = 0.999; for smooth ceramic: p = 0.723; and for rough ceramic: p > 0.999). Hydrophilic titanium and hydrophilic ceramic surfaces did not show any statistically significant differences between rough and smooth surfaces (p > 0.05 for both comparisons).