Table 1 Cleaning and disinfection methods used in this study
Group | Cleaning method | Cleaning solutions and Devices, respectively, Manufacturer |
|---|---|---|
NC | The samples were dried with oil-free air without further cleaning. Uncleaned abutments served as the control group | – |
CP | Three-stage cleaning process in an ultrasonic bath at 37 kHz, all grouped samples were immersed successively for 10 min at 60 °C: pure acetone, pure ethanol, and an antibacterial solution. The samples were stored in distilled water at 60 °C for 5 min between the ultrasonic immersions. In total, the cleaning process took 45 min [2] | SONICA CL4% Easyclean, Renfert, Hilzingen, Germany |
FP | Three-stage cleaning process in an ultrasonic bath at 40 kHz. The two-piece abutments were immersed for 5 min each at 30 °C in three different solutions. The first solution contained an industrially prefabricated cleaning liquid with a disinfecting effect, followed by 80% ethanol and purified water [5] | Finevo cleaning system Finevo Ultrasonic, bredent GmbH & Co. KG, Senden, Germany |
SC | Steam cleaning for 30 s with 4 bars at 158 °C and 10 cm distance to the cleaning object | Distilled water Wasistream Classic II, Wassermann, Hamburg, Germany |
PL | A low-pressure plasma unit conducted the cleaning with a high-frequency generator of 100 kHz/200 W. The samples were individually screwed into an individualised sample holding device and positioned centrally in the vacuum chamber. The automatic program was set according to the manufacturer’s recommendations: process gases argon and oxygen in the same mixing ratio via mass flow controller (MFC), 0.20 mbar set pressure, a set temperature of 70 °C, and reduced power of 80%. The treatment lasted 22 min, with an effective plasma treatment of 20 min | Argon and oxygen gas Femto PCCE Zahntechnik, Diener Electronic, Ebhausen, Germany |
UD | Ultrasonic cleaning at 37 kHz with disinfecting solution for 5 min at 30 °C and subsequent rinsing with sterile water | MD 520 Impression Disinfection Ampuwa Easyclean, Renfert, Hilzingen, Germany |
LA | All dental labs have been instructed to supply the two-piece abutment ready for patient care. The method used to clean and disinfect the two-piece abutments was deliberately left in the dark | Unknown |