A novel implant cleaning method - In vitro non-contact biofilm removal from SLA and polished titanium surfaces using cavitation from an ultrasonic scaler

Objectives: Removal of biofilm from dental implants is difficult and many methods damage the surface coating. The aim of this study was to investigate the ability of cavitation from ultrasonic scalers to remove biofilm grown on polished and sandblasted, large-grit acid-etched (SLA) titanium surfaces via high speed imaging and scanning electron microscopy (SEM).

Methods: 24 CpTi Grade II discs were either polished to mimic a dental implant collar or sandblasted and acid etched to produce a surface mimicking the Straumann SLA surface. Streptococcus mutans biofilm was grown on the discs in a bioreactor. A Satelec P5 Newtron ultrasonic generator with tip 10P was operated at medium power at either 0.5 mm or 1 mm away from each disc for 30s. High speed video was recorded during the removal process at 128,000 frames per second to visualise cavitation. SEM images of the discs before and after removal were used to evaluate the effectiveness of cleaning, using SEM finder grids and image registration to show the exact areas the biofilm had been removed from. The results were compared to a control experiment performed at low power where cavitation did not occur around the scaler.

Results: SEM showed biofilm was removed from the discs at distances of both 0.5 mm and 1 mm away when the ultrasonic scaler was operated at medium power, but not at low power. High speed videos showed cavitation clouds from the scaler tip impacting on the disc at 0.5 mm separation. This did not occur at 1 mm separation, but cavitation bubbles were still observed to be growing and collapsing on the surface of the disc.

Conclusions: Cavitation does remove biofilm from roughened dental implant surface without causing damage. Ultrasonic scalers may be used in a non-contact mode as a new method of cleaning dental implants.