Statement of problem: Microbial adhesion on occlusal devices may lead to oral diseases such as candidiasis. Whether chitosan and eugenol provide antibiofilm effects is unclear. Purpose: The purpose of this in vitro study was to evaluate the biofilm formation of C. albicans strains on occlusal device materials and the antibiofilm effects of chitosan and eugenol against C. albicans on these surfaces. Material and methods: A total of 88 specimens (5×10×2 mm) were produced from occlusal device materials with 4 production techniques: vacuum-formed thermoplastic (Group V), head-press (Group H), computer-aided design and computer-aided manufacture (CAD-CAM) (Group C), and 3-dimensionally (3D) printed (Group D) (n=22). After various finishing procedures, the surface properties of the specimens were evaluated by using surface free energy (SFE), surface roughness (SR) measurements, and elemental and topographic analysis. Biofilm formation of C. albicans strain and the antibiofilm effects of chitosan and eugenol against biofilm formation on these surfaces were also examined with a crystal violet assay. The distribution's normality was statistically analyzed with the Kolmogorov-Smirnov test. One-way and two-way analysis of variance with post hoc Tukey tests were used for statistical evaluations (α=.05). Results: Surface roughness values in Groups D and H were significantly higher than in other groups (P<.05). While the highest surface free energy values (except γp) were in Group V, Group C had the highest γp. The lowest biofilm value appeared in Group H. Chitosan exhibited an antibiofilm effect in all groups except Group H, while eugenol was effective in all groups. Conclusions: The production method affected the susceptibility of occlusal device materials to the adhesion of C. albicans. Eugenol was an effective antibiofilm agent for device materials.