Objective: To study the influence of perfluoroalkylsiloxane (PA) surface modification of silicone rubber voice prostheses on biofouling.
Design: Placebo-controlled clinical trial.
Setting: Tertiary referral center, with specialization in head and neck cancer treatment.
Patients: Eighteen consecutive patients with laryngectomies and experienced in the use of a voice prosthesis who visited the outpatient clinic for prosthesis replacement.
Material: Eighteen partially surface-modified voice prostheses (3 with short-chain PAs [1 fluorocarbon unit] and 15 with long-chain PAs [8 fluorocarbon units]) were inserted via the patients' tracheoesophageal shunts and remained in place for 2 to 8 weeks.
Intervention: Replacement of the prostheses.
Main outcome measures: Evaluation of biofilm formation on short- and long-chain PA-modified and original silicone rubber surfaces on the esophageal side of the voice prosthesis.
Results: The planimetrical biofilm scores of the surfaces of all 3 short-chain PA-treated voice prostheses indicated more biofouling on the treated surfaces than on the untreated surfaces of the same prostheses. For the long-chain PA-treated prostheses, the planimetrical biofilm scores, as well as the numbers of colony-forming units per cm(-2) for bacteria and yeasts, indicated less biofouling on the treated side than on the control side for 9 of the 13 prostheses that could be analyzed (2 were lost to analysis). Identical fungal strains, mainly Candida sp, were isolated from biofilms on each side of the esophageal flange.
Conclusions: Chemisorption of long-chain PAs by the silicone rubber used for voice prostheses reduces biofilm formation in vivo and therefore can be expected to prolong the life of these prostheses. Chemisorption of short-chain PAs by silicone rubber seems to have an adverse effect.