In order to improve their mechanical properties, tetragonal zirconium polycrystals (TZP) are strengthened by the use of certain elements such as yttrium (zirconium stabilized by yttrium, i.e., Y-TZP). This form of material can be applied to high-strength single crown frames, bridges and implants using CAD/CAM techniques [6]. Zirconia partially stabilized by yttrium (Y-TZP) contains a highly crystalline phase and low translucency, which causes opacity [7]. To exclude the white opaque color of zirconia, transparent porcelain can be used to veneer restorations. However, there raises another problem, the chipping of veneering porcelain [8]. To overcome this clinical limitation, monolithic zirconia, in an anatomical form without veneers, is used. Monolithic zirconia has the required translucency and excellent mechanical properties without the risk of chipping of the veneering ceramic [9]. Restorations made with this type of zirconia require shorter clinical working time and reduced costs. Dental plaque causes an inflammatory reaction, which is the main cause of periodontal and peri-implant diseases that can lead to progressive bone loss around the tooth but also around the implant. Early bacterial colonization is a condition and the first step in biofilm formation that leads to infection [10]. Studies have reported a high prevalence of _C. albicans_ and _S. aureus_ rates in saliva samples from elderly adults and hospitalized patients than healthy persons [11]. Clinical investigations have showed that the presence of _C. albicans_ in the peri-implantitis gingival zone was revealed [12]. _C. albicans_ is associated with diseases such as peri-implantitis and periodontitis. This opportunistic pathogen is usually the cause of denture-associated stomatitis. Streptococci, mainly in the supragingival area, are microorganisms of an indigenous oral microbiota. _S. sanguinis_ is usually found in healthy individuals, but under certain conditions, it can lead to the settlement of some pathogenic microorganisms, such as _Porphyromonas gingivalis_[13]. Biofilm formation, which is created by the process of bacterial adhesion to the substrate, is related to surface properties, such as surface roughness, hydrophobicity and interaction, between existing microorganisms [14]. Streptococcus is one of the first colonizers of the initial supragingival biofilm. Also, this microorganism is present in greater quantity in the first hours of oral biofilm formation. Microorganisms from the oral cavity tend to adhere to the surface of dental materials. Certain parts of restorations are particularly susceptible to plaque accumulation, because there is poor mechanical cleaning. These are the following surfaces: interface between tooth and restoration [15], the cervical part of the proximal surface and along the gingival margin. This is a particularly sensitive topic, bearing in mind that zirconia is also used to make implant-supported prosthetic restorations, where the implant, gingiva and zirconia are in contact [16]. In order to maintain patients' oral hygiene, dentists use various manual (curettes) and machine instruments (ultrasonic scaling, brushes and pastes). The question arises whether these routines and recommended oral hygiene maintenance procedures damage the surfaces of zirconia restorations and increase surface roughness, thereby creating better conditions for the creation of a biofilm through the adhesion process of various microorganisms [17; 18; 19]. The restoration surface roughness is extremely important because of the increased accumulation of plaque, which affects the optical properties of the restoration and the wear of the opposing dentition [20]. On solid surfaces, the ability of microorganisms to aggregate and the environmental conditions are important factors in the formation of an oral biofilm. Certainly, the finishing technique on ceramics significantly affects the surface properties of these materials and the formation of the oral biofilm.