The greatest problem of the service life of vocal prostheses is bacterial and in particular mycotic colonization of their surface which causes impaired tightness of the closing valve of the prosthesis with subsequent leakage of fluids and food into the airways. The objective of the present work was to prevent colonization of the silicone surface and to prolong thus the service life of the prosthesis. Two types of silicone were tested (Silastic Q7-4550-50 ShA and Q7-4765-65) during 4, 8 and 12-week exposure. Neither of these materials was attacked by mycotic agents in vitro. The infested prostheses were examined under the microscope after varying intervals in vivo. The silicone of the implanted prosthesis was colonized by numerous microorganisms, in particular moulds. The results confirm the depth degradation of silicone rubber located in islets.

        Key words: silicone, biodegradation, vocal prosthesis.