Evaluating the efficiency of three methods to clean and disinfect screw- and cement-retained prostheses

Screw- and cement-retained prostheses (SCRPs) may be contaminated during fabrication in a dental laboratory, leading to mechanical and biological complications related to the implant treatment. Studies that explored methods to efficiently and conveniently clean and disinfect SCRPs are sparse.

The purpose of this clinical study was to compare the efficiency of 3 methods to remove contaminants and microorganisms present on the surface of an SCRP.

Forty-eight 1-unit SCRPs fabricated in a dental laboratory were randomly divided into 3 groups: wiping, soaking, or ultrasonic cleaning. The presence of contaminants was determined by scanning electron microscopy, and microbial cells were cultured before and after treatment. Bacterial colony-forming units (CFUs) on the surface of the SCRPs and contamination density at the implant-abutment interface and emergence profile area were assessed. Statistical tests including ANCOVA were used to compare the efficiency of different methods before and after treatment (α=.05).

Significant differences in contamination density were noted during the treatment at the implant-abutment interface and at the emergence profile area in the 3 groups (P<.05), but no significant differences were observed in the number of CFUs (P>.05). There were significant differences among the 3 methods for cleaning efficiency both at the implant-abutment interface (P=.023) and the emergence profile area (P=.038). At the implant-abutment interface, the contamination density after treatment was lower in the ultrasonic cleaning group than that in the soaking group (P=.007), whereas at the emergence profile area, the contamination density after treatment was lower in the ultrasonic cleaning group than that in the wiping group (P=.019) and the soaking group (P=.048).

All 3 treatment methods reduced contaminants on the SCRP surface, but ultrasonic cleaning yielded the most favorable results. However, none of the methods provided additional disinfection for SCRPs previously disinfected by ozone and UV in a dental laboratory.