IN-VITRO AND IN-VIVO MICROBIAL ADHESION AND GROWTH ON ARGON PLASMA-TREATED SILICONE-RUBBER VOICE PROSTHESES

Patients who undergo a total laryngectomy usually receive a silicone r ubber voice prosthesis for voice rehabilitation. Unfortunately, biofil m formation on the esophageal side of voice prostheses limits their li fetime to 3-4 mon on average. The effects of repeated argon plasma tre atment of medical grade, hydrophobic silicone rubber on in vitro adhes ion and growth of bacteria and yeasts isolated from voice prostheses, as well as in vivo biofilm formation are presented here. In vitro expe riments demonstrated that initial microbial adhesion over a 4 h time s pan to plasma-treated, hydrophilized, silicone rubber was generally le ss than on original, hydrophobic silicone rubber, both in the absence and presence of a salivary conditioning film on the biomaterial. Growt h studies over a time period of 14 d at 37 degrees C in a modified Rob bins device, showed that fewer Candida cells adhered on plasma-treated , hydrophilized silicone rubber as compared to on original, hydrophobi c silicone rubber. For the in vivo evaluation of biofilm formation on plasma-treated silicone rubber voice prostheses, seven laryngectomized patients received a partly hydrophilized ''Groningen Button'' voice p rosthesis for a planned evaluation period of 4 wk. After removal of th e voice prostheses, the border between the hydrophilized and the origi nal, hydrophobic side of the prostheses was clearly visible. However, biofilm formation was, unexpectedly, less on the original, hydrophobic sides, although the microbial compositions of the biofilms on both si des were not significantly different. Summarizing, this study demonstr ates that in vitro microbial adhesion and growth on silicone rubber ca n be reduced by plasma treatment, but in vivo biofilm formation on sil icone rubber voice prostheses is oppositely enhanced by hydrophilizing the silicone rubber surface. Nevertheless, from the results of this s tudy the important conclusion can be drawn that in vivo biofilm format ion on voice prostheses is controlled by the hydrophobicity of the bio materials surface used. (C) 1998 Chapman & Hall.