Based on the results of the SEM qualitative analysis, gauze soaked in saline and the rotary stainless steel instrument consistently showed good cleansability on rough and machined surface implants compared with the other methods. Conversely, the Er:YAG laser showed inferior cleansability to all other methods especially on rough surface implants. The ultrasonic scaler and air abrasive exhibited fair to good cleansability on both surface implants. Generally, the cleansability of each method appeared to be better on machined surface implants than rough surface implants.

The cleansability of gauze soaked in saline has previously been evaluated with and without antiseptics in vitro and in vivo [6, 9, 23, 26]. Charalampakis et al. [23] examined the efficacy of mechanical and chemical decontamination methods using titanium disks contaminated intraorally for 4 days. They employed four decontamination methods: gauze in saline, chlorhexidine, delmopinol, and an essential oil mixture. The SEM analysis demonstrated that three different rough surface disks harbored complex and firmly attached biofilms after gauze scrubbing irrespective of which antiseptic or saline was used. However, the disks with a turned surface hosted fewer biofilm clusters after scrubbing. This finding is in line with our result showing the better cleansability of gauze soaked in saline on the machined surface implants compared with the rough surface implants. The ultrasonic scaler, air abrasives, and Er:YAG laser have also been well investigated and used for the treatment of peri-implantitis [7, 27]. Schmage et al. [28] revealed the high cleansability of air abrasives and considerable cleansability of ultrasonic scalers and Er:YAG laser on titanium disks contaminated by a biofilm layer of Streptococcus mutans. The cleaning score of the air abrasives was the highest, and two types of ultrasonic scaler with a non-metal tip and the Er:YAG laser showed medium cleaning scores but better cleansability than non-metal curettes or a prophylaxis brush/cup. In the present study, the ultrasonic scaler displayed modest results. The tip used in this study was specially designed for cleansing contaminated implants with complicated macro- and microstructures. As the tip dimension was small in order to cleanse very narrow spaces, such as the valley of micro- or macrothreads, good cleansability was expected to be seen in such areas. This method could remove biofilms from small areas, but not in their entirety and not from the valley of microthreads. Moreover, the overall effect of biofilm removal did not appear impressive. One possible explanation for this result is that a treatment time of 1 min was not sufficient to use this small tip effectively. If more time was given to the ultrasonic scaler group, it might be possible to eliminate more biofilms, especially from microstructured areas of the implant.