Objective: Monolithic zirconia and glass ceramics are increasingly used in implant crowns. Limited data is available on bacterial adhesion and early biofilm formation on these materials.

Methods: Four different materials were investigated: (1) Lithium disilicate glass-ceramics (LDS), (2) Fully stabilized zirconia (FSZ), (3) Partially stabilized zirconia (PSZ), and (4) Dual curing cement (DCC). The materials’ surfaces were characterized with spinning disc confocal microscopy and by water contact angle and surface free energy (SFE) measurements. For the adhesion tests the materials were rolled in suspensions of Streptococcus mutans. Early biofilm formation was studied on the materials and allowing the biofilms to form for 24 h. S. mutans cell counts were determined by plate culturing. ANOVA and post-hoc Tukey’s tests (p<0.05) were used for statistical evaluation.

Results: The LDS surfaces were clearly hydrophilic with the highest SFE value (p<0.001). For S. mutans adhesion, the ranking of the materials from lowest to highest was: LDS = FSZ < DCC < PSZ (p<0.05). No significant differences among the materials were noticed in biofilm formation. C

onclusions: LDS has lower S.mutans adhesion than other materials examined in this study, but the difference was not reflected in early biofilm formation.