This study was performed following an ex vivo design to overcome the drawbacks of previous studies. One particular difference in this study was the use of a commercially available screw-shaped implant. As the implant shape and design have rather complicated macro- and microstructures compared with titanium disks or different forms of titanium commonly used in experimental studies, previous results could not be easily interpreted and extrapolated to the clinical setting [14, 19]. However, the use of genuine implants allowed us to evaluate the cleansability of each method on contaminated implant surfaces. Without any limitations of accessibility and visibility, the efficacy of each decontamination method could be evaluated in a limited time frame.

Another critical difference in this study was the evaluation of dental plaque on implant surfaces collected in the mouth of participants rather than a single bacterial species [14, 20] or artificial biofilms [21, 22]. Dental plaque comprises 700–1000 bacterial species and is significantly different to a single bacterial colony or artificial biofilms. By assessing CFU counts via culture technique, the ability of each method to physically disrupt oral biofilms on contaminated implant surfaces could be evaluated. Conversely, a limitation of this study is that biofilms that cause peri-implantitis differ from those evaluated in this study. The biofilms in peri-implantitis form in anaerobic deep submucosal areas [23]. However, in this study, only supragingival oral biofilms could accumulate on the mounted implant surfaces. It seems difficult to reproduce the same quality of submucosal biofilms around implants, which are thought to be an etiological factor of peri-implant disease in the laboratory [24]. To date, there are a few studies that have tried to reproduce submucosal biofilms [22, 25], but such systems have not yet been completely established. This limitation of the present study should be kept in mind.

To the best of our knowledge, there is only one study that has used a similar experimental design to that of this study. Augthun et al. [10] examined the cultivability of mouse fibroblasts after cleansing machined or plasma-splayed surface implants carried on acrylic plates that had been contaminated with supragingival plaque from individuals. A plastic hand scaler and an air-abrasive system with sodium bicarbonate powder were employed in their study. A similar number of viable fibroblasts were observed after cleansing the implant with the air abrasive as the non-contaminated control implant. However, the number of viable cells was significantly reduced on the implant cleansed with the plastic scaler. This study had two drawbacks. First, they did not employ a quantitative analysis to evaluate the cleansing effect. Second, the SEM analysis used to evaluate the cleansing effect was too low (10- to 100-fold). In the present study, the presence of residual biofilms after instrumentation was determined using higher magnification SEM analysis (up to 5000-fold) and CFU counts. In this context, our findings may provide more accurate evidence than that demonstrated by the aforementioned study.